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FEATURES Six Direct Voltage Measurement Inputs (Including Two Processor Core Voltages) with On-Chip Attenuators On-Chip Temperature Sensor Five Digital Inputs for VID Bits Fully Supports Intel's LANDesk Client Manager (LDCM) Register-Compatible with LM7x Products Two Fan Speed Monitoring Inputs I2 C (R) Compatible System Management Bus (SMBus) Chassis Intrusion Detect Interrupt Output Programmable RESET I/O Pin Shutdown Mode to Minimize Power Consumption Limit Comparison of all Monitored Values APPLICATIONS Network Servers and Personal Computers Microprocessor-Based Office Equipment Test Equipment and Measuring Instruments
Low Cost Microprocessor System Hardware Monitor ADM9240
PRODUCT DESCRIPTION
The ADM9240 is a complete system hardware monitor for microprocessor-based systems, providing measurement and limit comparison of up to four power supplies and two processor core voltages, plus temperature, two fan speeds and chassis intrusion. Measured values can be read out via an I2C-compatible serial System Management Bus, and values for limit comparisons can be programmed in over the same serial bus. The high speed successive approximation ADC allows frequent sampling of all analog channels to ensure a fast interrupt response to any out-of-limit measurement. The ADM9240's 2.85 V to 5.75 V supply voltage range, low supply current and I2C compatible interface, make it ideal for a wide range of applications. These include hardware monitoring and protection applications in personal computers, electronic test equipment and office electronics.
FUNCTIONAL BLOCK DIAGRAM
VCC
VID0 VID1 VID2 VID3 VID4 AND DEVICE ID REGISTER VID0 - 3 AND FAN DIVISOR REGISTERS
SERIAL BUS ADDRESS REGISTER SERIAL BUS INTERFACE
NTEST_OUT/A0 A1 SDA SCL VALUE AND LIMIT REGISTERS LIMIT COMPARATORS CI INTERRUPT STATUS REGISTERS INT MASK REGISTERS INT CONFIGURATION REGISTER
VID4
FAN1 FAN2
FAN SPEED COUNTER ADDRESS POINTER REGISTER TEMPERATURE CONFIGURATION REGISTER
+VCCP1 +2.5VIN +3.3VIN +5VIN +12VIN +VCCP2 BANDGAP TEMPERATURE SENSOR INPUT ATTENUATORS AND ANALOG MULTIPLEXER
9-BIT ADC ANALOG OUTPUT REGISTER AND 8-BIT DAC NTEST_IN/AOUT RESET
ADM9240
CHASSIS INTRUSION CLEAR REGISTER
GNDA
GNDD
I2 C is a registered trademark of Philips Corporation.
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Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 (c) Analog Devices, Inc., 1998
ADM9240-SPECIFICATIONS1, 2 (T = T
A
MIN
to TMAX , VCC = VMIN to VMAX, unless otherwise noted)
Max 5.75 2.0 100 3 2 Units V mA mA A C C C Test Conditions/Comments
Parameter POWER SUPPLY Supply Voltage, VCC Supply Current, ICC
Min 2.85
Typ 5 1.4 1.0 25
Interface Inactive, ADC Active ADC Inactive, DAC Active Shutdown Mode -40C TA +125C TA = +25C
TEMPERATURE-TO-DIGITAL CONVERTER Accuracy Resolution ANALOG-TO-DIGITAL CONVERTER (INCLUDING MUX AND ATTENUATORS) Total Unadjusted Error, TUE Differential Nonlinearity, DNL Power Supply Sensitivity Total Monitoring Cycle Time Input Resistance ANALOG OUTPUT Output Voltage Range Total Unadjusted Error, TUE Full-Scale Error Zero Error Differential Nonlinearity, DNL Integral Nonlinearity Output Source Current Output Sink Current FAN RPM-TO-DIGITAL CONVERTER Accuracy Full-Scale Count FAN1 and FAN2 Nominal Input RPM 100 0 1 2 1 2 1 0.5
1 311 311 140
2 1 331 353 200 1.25 3 3 1
% LSB %/V s s k V % % LSB LSB LSB mA mA % % rpm rpm rpm rpm
Note 3 +25C TA +125C (Note 4) -40C TA +125C (Note 4)
IL = 2 mA No Load Monotonic by Design
6 12 255 8800 4400 2200 1100
+25C TA +125C -40oC TA +125C Divisor = 1, Fan Count = 153 (Note 5) Divisor = 2, Fan Count = 153 (Note 5) Divisor = 3, Fan Count = 153 (Note 5) Divisor = 4, Fan Count = 153 (Note 5) +25C TA +125C -40oC TA +125C IOUT = 5.0 mA, VCC = 4.25 V-5.75 V IOUT = 3.0 mA, VCC = 2.85 V-3.45 V IOUT = -5.0 mA, VCC = 4.25 V-5.75 V IOUT = -3.0 mA, VCC = 2.85 V-3.45 V
Internal Clock Frequency DIGITAL OUTPUT NTEST_OUT Output High Voltage, VOH
21.1 19.8 2.4 2.4
22.5 22.5
23.9 25.2
kHz kHz V V
Output Low Voltage, VOL
0.4 0.4
V V
OPEN-DRAIN DIGITAL OUTPUTS (INT, RESET, CI) Output Low Voltage, VOL High Level Output Current, IOH RESET and CI Pulsewidth 20 0.1 45
0.4 0.4 100
V V A ms
IOUT = -5.0 mA, VCC = 5.75 V IOUT = -3.0 mA, VCC = 3.45 V VOUT = VCC
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Parameter OPEN-DRAIN SERIAL DATA BUS OUTPUT (SDA) Output Low Voltage, VOL Min Typ Max Units Test Conditions/Comments
0.4 0.4
V V A
High Level Output Current, IOH SERIAL BUS DIGITAL INPUTS (SCL, SDA) Input High Voltage, VIH Input Low Voltage, VIL Hysteresis DIGITAL INPUT LOGIC LEVELS (A0, A1, CI, RESET, VID0 - VID4, FAN1, FAN2) Input High Voltage, VIH Input Low Voltage, VIL Input High Voltage, VIH Input Low Voltage, VIL NTEST_IN Input High Voltage, VIH Input High Voltage, VIH DIGITAL INPUT CURRENT Input High Current, IIH Input High Current, A0, A1, IIH Input Low Current, IIL Input Capacitance, CIN SERIAL BUS TIMING7 Clock Frequency, fSCLK Glitch Immunity, tSW Bus Free Time, tBUF Start Setup Time, tSU;STA Start Hold Time, tHD;STA SCL Low Time, tLOW SCL High Time, tHIGH SCL, SDA Rise Time, tR SCL, SDA Fall Time, tF Data Setup Time, tSU;DAT Data Hold Time, tHD;DAT
0.1
100
IOUT = -3.0 mA, VCC = 4.25 V-5.75 V IOUT = -3.0 mA VCC = 2.85 V-3.45 V VOUT = VCC
0.7 x VCC 500
0.3 x VCC
V V mV
2.4 0.8 2.0 0.4 2.4 2.0 -1 -200
V V V V V V A A A pF kHz ns s ns ns s s ns s ns ns
VCC = 4.25 V-5.75 V VCC = 4.25 V-5.75 V VCC = 2.85 V-3.45 V VCC = 2.85 V-3.45 V VCC = 4.25 V-5.75 V VCC = 2.85 V-3.45 V VIN = VCC VIN = VCC (Note 6) VIN = 0
75 1 20 400 50
1.3 600 600 1.3 0.6 300 300 100 900
See Figure 1 See Figure 1 See Figure 1 See Figure 1 See Figure 1 See Figure 1 See Figure 1 See Figure 1 See Figure 1 See Figure 1 See Figure 1
NOTES 1 All voltages are measured with respect to GND, unless otherwise noted. 2 Typicals are at TA = +25C and represent most likely parametric norm. Shutdown current typ is measured with V CC = 3.3 V. 3 TUE (Total Unadjusted Error) includes Offset, Gain and Linearity errors of the ADC, multiplexer and on-chip input attenuators, including an external series input protection resistor value between zero and 1 k. 4 Total monitoring cycle time is the time taken to measure all six analog inputs plus the temperature sensor. 5 The total fan count is based on 2 pulses per revolution of the fan tachometer output. 6 A0 and A1 have internal 75 k pull-down. 7 Timing specifications are tested at logic levels of V IL = 0.3 x VCC for a falling edge and V IH = 0.7 x VCC for a rising edge. Specifications subject to change without notice.
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ADM9240
ABSOLUTE MAXIMUM RATINGS*
Positive Supply Voltage (VCC) . . . . . . . . . . . . . . . . . . . . . 6.5 V Voltage on Any Input or Output Pin . . -0.3 V to (VCC + 0.3 V) (Except Analog Inputs) 16 V VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +16 V All Other Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . +7.5 V Ground Difference (GNDD-GNDA) . . . . . . . . . . . . 300 mV Input Current At Any Pin . . . . . . . . . . . . . . . . . . . . . . . 5 mA Package Input Current . . . . . . . . . . . . . . . . . . . . . . . . 20 mA Maximum Junction Temperature (TJ max) . . . . . . . . . . 150C Storage Temperature Range . . . . . . . . . . . . . -65C to +150C Lead Temperature, Soldering Vapor Phase 60 (sec) . . . . . . . . . . . . . . . . . . . . . . . . +215C Infrared 15 (sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . +200C ESD Rating All Pins Except Pin 15 . . . . . . . . . . . . . . . . 2000 V ESD Rating Pin 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 V
Start Condition (S) Bit 7 MSB (A7)
*Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
THERMAL CHARACTERISTICS
24-Lead Small Outline Package: JA = 50C/Watt, JC = 10C/Watt
ORDERING GUIDE Temperature Range -40C to +125C Package Description Package Option
Model ADM9240ARU
24-Lead TSSOP RU-24
PIN CONFIGURATION
Bit 6 (A6) NTEST_OUT/A0 A1 SDA
PROTOCOL
tSU;STA
SCL
tLOW
tHIGH
1/fSCL
1 2 3 4 5 6
24 23 22 21
VID0 VID1 VID2 VID3 VID4
tBUF
SDA
tr
tf
SCL FAN1 FAN2
ADM9240
20
tHD;STA
Bit 0 LSB (R/W)
tSU;DAT
Stop Condition (P)
tHD;DAT
CI GNDD
+VCCP1 TOP VIEW 19 7 (Not to Scale) 18 +2.5VIN
8 9 10 11 17 16 15 14 13
+3.3VIN +5VIN +12VIN +VCCP2 GNDA
PROTOCOL
Acknowledge (A)
VCC INT NTEST_IN/AOUT
SCL
RESET 12
SDA
tVD;DAT
tSU;STO
Figure 1. Diagram for Serial Bus Timing
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PIN FUNCTION DESCRIPTIONS
Pin Number 1 2 3 4 5 6 7
Mnemonic NTEST_OUT/A0 A1 SDA SCL FAN1 FAN2 CI
Description Digital I/O. Dual Function Pin. The lowest order programmable bit of the Serial Bus Address. This pin functions as an output when doing a NAND Tree test. Digital Input. The highest order programmable bit of the Serial Bus Address. Digital I/O. Serial Bus Bidirectional Data. Open-drain output. Digital Input. Serial Bus Clock. Digital Input. 0 to VCC amplitude fan tachometer input. Digital Input. 0 to VCC amplitude fan tachometer input. Digital I/O. An active high input from an external circuit that latches a Chassis Intrusion event. This line can go high without any clamping action regardless of the powered state of the ADM9240. The ADM9240 provides an internal open drain on this line, controlled by Bit 6 of Register 40h or Bit 7 of Register 46h, to provide a minimum 20 ms pulse on this line, to reset the external Chassis Intrusion Latch. Digital Ground. Internally connected to all of the digital circuitry. Power (+2.85 V to +5.75 V). Typically powered from +3.3 V or +5 V power rail. Bypass with the parallel combination of 10 F (electrolytic or tantalum) and 0.1 F (ceramic) bypass capacitors. Digital Output. Interrupt Request (open drain). The output is enabled when Bit 1 of the Configuration Register is set to 1. The default state is disabled. Digital Input/Analog Output. An active-high input that enables NAND Tree mode boardlevel connectivity testing. Refer to section on NAND Tree testing. Also functions as a programmable analog output when NAND Tree is not selected Digital I/O. Master Reset, 5 mA driver (open drain), active low output with a 20 ms minimum pulsewidth. Available when enabled via Bit 7 in Register 44h, and set using Bit 4 in Register 40h. Also acts as reset input when pulled low (e.g., power-on reset). Analog Ground. Internally connected to all analog circuitry. The ground reference for all analog inputs. Analog Input. Monitors processor core voltage +VCCP2 (0 V-3.6 V). Can also be used to monitor the -12 V supply by adding two external resistors. Analog Input. Monitors +12 V supply. Analog Input. Monitors +5 V supply. Analog Input. Monitors +3.3 V supply. Analog Input. Monitors +2.5 V supply. Analog Input. Monitors processor core voltage +VCCP1 (0 V-3.6 V). Digital Input. Core Voltage ID readouts from the processor. This value is read into the VID4 Status Register. Digital Input. Core Voltage ID readouts from the processor. This value is read into the VID0-VID3 Status Register. Digital Input. Core Voltage ID readouts from the processor. This value is read into the VID0-VID3 Status Register. Digital Input. Core Voltage ID readouts from the processor. This value is read into the VID0-VID3 Status Register. Digital Input. Core Voltage ID readouts from the processor. This value is read into the VID0-VID3 Status Register.
8 9
GNDD VCC INT NTEST_IN/AOUT
10 11
12
RESET
13 14 15 16 17 18 19 20 21 22 23 24
GNDA +VCCP2 +12 VIN +5 VIN +3.3 VIN +2.5 VIN +VCCP1 VID4 VID3 VID2 VID1 VID0
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ADM9240
GENERAL DESCRIPTION INTERNAL REGISTERS OF THE ADM9240
The ADM9240 is a complete system hardware monitor for microprocessor-based systems. The device communicates with the system via a serial System Management Bus. The serial bus controller has two hardwired address lines for device selection (Pin 1 and Pin 2), a serial data line for reading and writing addresses and data (Pin 3), and an input line for the serial clock (Pin 4). All control and programming functions of the ADM9240 are performed over the serial bus. An on-chip analog-to-digital converter with six multiplexed analog inputs measures power supply voltages (+12 V, +5 V, +3.3 V, +2.5 V--Pins 15 to 18) and processor core voltages (+VCCP1 and +VCCP2--Pins 19 and 14). The ADC also accepts input from an on-chip bandgap temperature sensor that monitors system ambient temperature. Two count inputs (Pins 5 and 6) are provided for monitoring the speed of fans with tachometer outputs. To accommodate fans with different speeds and different tacho outputs, a divisor of 1, 2, 4 or 8 can be programmed into the counter. Five digital inputs (VID4 to VID0--Pins 20 to 24) read the processor Voltage ID code, while a chassis intrusion input (Pin 7) is provided to detect unauthorized tampering with the equipment. When the ADM9240 monitoring sequence is started, it cycles sequentially through the measurement of analog inputs and the temperature sensor, while at the same time the fan speed inputs are independently monitored. Measured values from these inputs are stored in value registers. These can be read out over the serial bus, or can be compared with programmed limits stored in the limit registers. The results of out-of-limit comparisons are stored in the interrupt status registers and will generate an interrupt on the INT line (Pin 10). Any or all of the Interrupt Status Bits can be masked by appropriate programming of the Interrupt Mask Register. A RESET input/output (Pin 12) is provided. Pulling this pin low will reset all ADM9240 internal registers to default values. The ADM9240 can also be programmed to give a low-going 20 ms reset pulse at this pin. The ADM9240 contains an on-chip, 8-bit digital-to-analog converter with an output range of zero to 1.25 V (Pin 11). This is typically used to implement a temperature-controlled fan by controlling the speed of a fan dependent upon the temperature measured by the on-chip temperature sensor. Testing of board level connectivity is simplified by providing a NAND tree test function. The AOUT (Pin 11) also doubles as a NAND test input, while Pin 1 doubles as a NAND tree output.
A brief description of the ADM9240's principal internal registers is given below. More detailed information on the function of each register is given in Tables V to XVII. Configuration Register: Provides control and configuration. Serial Address Register: Stores the serial bus address of the ADM9240. Address Pointer Register: Contains the address that selects one of the other internal registers. When writing to the ADM9240, the first byte of data is always a register address, which is written to the Address Pointer Register. Interrupt (INT) Status Registers: Two registers to provide status of each Interrupt event. Interrupt (INT) Mask Registers: Allow masking of individual Interrupt sources. Temperature Configuration Register: The configuration of the temperature interrupt is controlled by the lower three bits of this register. VID/Fan Divisor Registers: The status of the VID0 to VID4 pins of the processor can be written to and read from these registers. Divisor values for fan-speed measurement are also stored in one of these registers. Value and Limit Registers: The results of analog voltage inputs, temperature and fan speed measurements are stored in these registers, along with their limit values. Analog Output Register: The code controlling the analog output DAC is stored in this register. Chassis Intrusion Clear Register: A signal latched on the chassis intrusion pin can be cleared by writing to this register.
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SERIAL BUS INTERFACE
Control of the ADM9240 is carried out via the serial bus. The ADM9240 is connected to this bus as a slave device, under the control of a master device, e.g., the PIIX4. The ADM9240 has a 7-bit serial bus address. When the device is powered up, it will do so with a default serial bus address. The five MSBs of the address are set to 01011, the two LSBs are determined by the logical states of Pin 1(NTEST_OUT/A0) and Pin 2 (A1) at power-up. These pins have internal 75 k pull-down resistors, so if they are left open-circuit the default address will be 0101100. The facility to make hardwired changes to A1 and A0 allows the user to avoid conflicts with other devices sharing the same serial bus, for example if more than one ADM9240 is used in a system. Once the ADM9240 has been powered up, the five MSBs of the serial bus address may be changed by writing a 7-bit word to the serial Address Pointer Register (the hardwired values of A0 and A1 cannot be overwritten). Thereafter, the new serial bus address must be used to select the ADM9240, until it is changed again, or the device is powered off. The serial bus protocol operates as follows: 1. The master initiates data transfer by establishing a START condition, defined as a high-to-low transition on the serial data line SDA while the serial clock line SCL remains high. This indicates that an address/data stream will follow. All slave peripherals connected to the serial bus respond to the START condition, and shift in the next eight bits, consisting of a 7-bit address (MSB first) plus an R/W bit, which determines the direction of the data transfer, i.e., whether data will be written to or read from the slave device. The peripheral whose address corresponds to the transmitted address responds by pulling the data line low during the low period before the ninth clock pulse, known as the acknowledge bit. All other devices on the bus now remain idle while the selected device waits for data to be read from or written to it. If the R/W bit is a 0, the master will write to the slave device. If the R/W bit is a 1, the master will read from the slave device. 2. Data is sent over the serial bus in sequences of nine clock pulses, eight bits of data followed by an acknowledge bit
1 SCL 9
from the slave device. Transitions on the data line must occur during the low period of the clock signal and remain stable during the high period, as a low-to-high transition when the clock is high may be interpreted as a STOP signal. The number of data bytes that can be transmitted over the serial bus in a single READ or WRITE operation is limited only by what the master and slave devices can handle. 3. When all data bytes have been read or written, stop conditions are established. In WRITE mode, the master will pull the data line high during the tenth clock pulse to assert a STOP condition. In READ mode, the master device will override the acknowledge bit by pulling the data line high during the low period before the ninth clock pulse. This is known as No Acknowledge. The master will then take the data line low during the low period before the tenth clock pulse, then high during the tenth clock pulse to assert a STOP condition. Any number of bytes of data may be transferred over the serial bus in one operation, but it is not possible to mix read and write in one operation, because the type of operation is determined at the beginning and cannot subsequently be changed without starting a new operation. In the case of the ADM9240, write operations contain either one or two bytes, and read operations contain one byte and perform the following functions: To write data to one of the device data registers or read data from it, the Address Pointer Register must be set so that the correct data register is addressed, then data can be written into that register or read from it. The first byte of a write operation always contains an address that is stored in the Address Pointer Register. If data is to be written to the device, then the write operation contains a second data byte that is written to the register selected by the Address Pointer Register. This is illustrated in Figure 2a. The device address is sent over the bus followed by R/W set to 0. This is followed by two data bytes. The first data byte is the address of the internal data register to be written to, which is stored in the Address Pointer Register. The second data byte is the data to be written to the internal data register.
1
9
SDA START BY MASTER
0
1
0
1
1
A1
A0
R/W ACK. BY ADM9240
D7
D6
D5
D4
D3
D2
D1
D0 ACK. BY ADM9240
FRAME 1 SERIAL BUS ADDRESS BYTE 1 SCL (CONTINUED)
FRAME 2 ADDRESS POINTER REGISTER BYTE 9
SDA (CONTINUED)
D7
D6
D5
D4
D3
D2
D1
D0 ACK. BY STOP BY ADM9240 MASTER
FRAME 3 DATA BYTE
Figure 2a. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register
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ADM9240
When reading data from a register there are two possibilities: 1. If the ADM9240's Address Pointer Register value is unknown or not the desired value, it is first necessary to set it to the correct value before data can be read from the desired data register. This is done by performing a write to the ADM9240 as before, but only the data byte containing the register address is sent, as data is not to be written to the register. This is shown in Figure 2b. A read operation is then performed consisting of the serial bus address, R/W bit set to 1, followed by the data byte read from the data register. This is shown in Figure 2c. 2. If the Address Pointer Register is known to be already at the desired address, data can be read from the corresponding data register without first writing to the Address Pointer Register, so Figure 2b can be omitted. Notes: 1. Although it is possible to read a data byte from a data register without first writing to the Address Pointer Register, if the Address Pointer Register is already at the correct value, it is not possible to write data to a register without writing to the Address Pointer Register, because the first data byte of a write is always written to the Address Pointer Register. 2. In Figures 2a to 2c, the serial bus address is shown as the default value 01011(A1)(A0), where A1 and A0 are hardwired to either Logic 0 or Logic 1.
ANALOG INPUTS
The ADM9240 has six analog inputs. Four of these are dedicated to monitoring the following power supply voltages: +12 V, +5 V, +3.3 V, +2.5 V. These inputs are multiplexed into the on-chip, successive approximation, analog-to-digital converter. This has a resolution of ten bits, but only eight bits are used for the voltage measurement and limit comparison. The basic input range of the ADC is 0 V to 2.5 V, and the power supply inputs are scaled by onchip attenuators such that the ADC produces an output of 3/4 x full scale or 192 decimal, when the input voltage is at its nominal value. The use of on-chip scaling guarantees accuracy and removes the need for precision external resistors.
1 SCL
9
1
9
SDA START BY MASTER
0
1
0
1
1
A1
A0
R/ W ACK. BY ADM9240
D7
D6
D5
D4
D3
D2
D1
D0 ACK. BY ADM9240 STOP BY MASTER
FRAME 1 SERIAL BUS ADDRESS BYTE
FRAME 2 ADDRESS POINTER REGISTER BYTE
Figure 2b. Writing to the Address Pointer Register only
1 SCL
9
1
9
SDA START BY MASTER
0
1
0
1
1
A1
A0
R/ W ACK. BY ADM9240
D7
D6
D5
D4
D3
D2
D1
D0 NO ACK. STOP BY BY MASTER MASTER
FRAME 1 SERIAL BUS ADDRESS BYTE
FRAME 2 DATA BYTE FROM ADM9240
Figure 2c. Reading Data from a Previously Selected Register
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The input ranges of the analog inputs are shown in more detail in Table I. The +VCCP1 and +VCCP2 inputs are used to measure processor core voltages, and have an input range from 0 V to 3.6 V. If only a single processor core voltage is being monitored, the VCCP2 input may be used to monitor the -12 V supply. This is achieved by using a resistive divider network referenced to a known positive dc voltage. This is illustrated in Figure 4.
INPUT CIRCUITS
42.7k +VCCP2 97.3k 122.2k +12V 22.7k 91.6k +5V 55.2k 61.1k +3.3V 80.9k 36.7k +2.5V 111.2k 42.7k 97.3k 50pF 25pF 25pF 25pF MUX 35pF 50pF
The internal structure for the analog inputs is shown in Figure 3. Each input circuit consists of an input protection diode, an attenuator, plus a capacitor to form a first order low-pass filter which gives the input immunity to high frequency noise.
+VCCP1
Figure 3. Internal Structure of Analog Inputs
Table I. A/D Output Code vs. VIN
+12 VIN <0.062 0.062-0.125 0.125-0.187 0.188-0.250 0.250-0.313 0.313-0.375 0.375-0.438 0.438-0.500 0.500-0.563
+5 VIN <0.026 0.026-0.052 0.052-0.078 0.078-0.104 0.104-0.130 0.130-0.156 0.156-0.182 0.182-0.208 0.208-0.234
Input Voltage +3.3 VIN +2.5 VIN <0.0172 0.017-0.034 0.034-0.052 0.052-0.069 0.069-0.086 0.086-0.103 0.103-0.120 0.120-0.138 0.138-0.155 <0.013 0.013-0.026 0.026-0.039 0.039-0.052 0.052-0.065 0.065-0.078 0.078-0.091 0.091-0.104 0.104-0.117 l l l 0.833-0.846 l l l 1.667-1.680 l l l 2.500-2.513 l l l 3.190-3.203 3.203-3.216 3.216-3.229 3.229-3.242 3.242-3.255 3.255-3.268 3.268-3.281 3.281-3.294 3.294-3.307 3.307-3.320 >3.320 -9-
+VCCP1 <0.014 0.014-0.028 0.028-0.042 0.042-0.056 0.056-0.070 0.070-0.084 0.084-0.098 0.098-0.112 0.112-0.126
+VCCP2 <0.014 0.014-0.028 0.028-0.042 0.042-0.056 0.056-0.070 0.070-0.084 0.084-0.098 0.098-0.112 0.112-0.126
A/D Output Decimal Binary 0 1 2 3 4 5 6 7 8 00000000 00000001 00000010 00000011 00000100 00000101 00000110 00000111 00001000
4.000-4.063
1.666-1.692
1.100-1.117
0.900-0.914
0.900-0.914
64 (1/4 Scale)
01000000
8.000-8.063
3.330-3.560
2.200-2.217
1.800-1.814
1.800-1.814
128 (1/2 Scale) 10000000
12.000-12.063
5.000-5.026
3.300-3.317
2.700-2.714
2.700-2.714
192 (3/4 Scale) 11000000
15.313-15.375 15.375-15.438 15.438-15.500 15.500-15.563 15.563-15.625 15.625-15.688 15.688-15.750 15.750-15.813 15.813-15.875 15.875-15.938 >15.938 REV. 0
6.380-6.406 6.406-6.432 6.432-6.458 6.458-6.484 6.484-6.510 6.510-6.536 6.536-6.562 6.562-6.588 6.588-6.615 6.615-6.640 >6.640
4.210-4.230 4.230-4.245 4.245-4.263 4.263-4.280 4.280-4.300 4.300-4.314 4.314-4.331 4.331-4.348 4.348-4.366 4.366-4.383 >4.383
3.445-3.459 3.459-3.473 3.473-3.487 3.487-3.501 3.501-3.515 3.515-3.529 3.529-3.543 3.543-3.558 3.558-3.572 3.572-3.586 >3.586
3.445-3.459 3.459-3.473 3.473-3.487 3.487-3.501 3.501-3.515 3.515-3.529 3.529-3.543 3.543-3.558 3.558-3.572 3.572-3.586 >3.586
245 246 247 248 249 250 251 252 253 254 255
11110101 11110110 11110111 11111000 11111001 11111010 11111011 11111100 11111101 11111110 11111111
ADM9240
SETTING OTHER INPUT RANGES
If any of the inputs is unused, and there is a requirement for monitoring another power supply such as -12 V, the input range of the unused input can easily be scaled and offset to accommodate this. For example, if only one processor core voltage is to be monitored, the unused VCCP input can be used to monitor another supply voltage. If the voltage to be monitored is positive, it is simply a matter of using an input with a lower full scale than the voltage to be measured and adding an external input attenuator, but bear in mind that the input resistance (140 k) of the on-chip attenuator will load the external attenuator. This can be accounted for in the calculation, but the values of the on-chip attenuator resistors are not precise and vary with temperature. Therefore, the external attenuator should have a much lower output resistance to minimize the loading. If this is not acceptable, a buffer amplifier can be used. If the input voltage range is negative, it must first be converted to a positive voltage. The simplest way to do this is simply to attenuate and offset the voltage, as shown in Figure 4, which shows the +VCCP2 input scaled to measure a -12 V input. Using the values shown, the input range is zero to -13.5 V, which will accommodate a +12.5% tolerance on the nominal value.
+5V
the 5 V supply increases the ADC input by the DV x RP/ (R2+RP), while a decrease in the 5 V supply correspondingly decreases the input to the ADC. 3. The on-chip input attenuators will load the external attenuator, as mentioned earlier. This technique can be applied to any other unused input. By suitable choice of V+ and the input resistors, a variety of negative and/or bipolar input ranges can be obtained.
TEMPERATURE MEASUREMENT SYSTEM
The ADM9240 contains an on-chip bandgap temperature sensor. The on-chip ADC performs 9-bit conversions on the output of this sensor and outputs the temperature data in 9-bit twos complement format, but only the eight most significant bits are used for temperature limit comparison. The full 9-bit temperature data can be obtained by reading the 8 MSBs from the Temperature Value Register (Address 27h) and the LSB from Bit 7 of the Temperature Configuration Register (Address 4Bh). The format of the temperature data is shown in Table II. Theoretically, the temperature sensor and ADC can measure temperatures from -128C to +127C with a resolution of 0.5C, although temperatures below -40C and above +125C are outside the operating temperature range of the device.
Table II. Temperature Data Format
R1 2.7k -13.2V TO 0V IN 0V TO 3.6V
R2 1k +VCCP2 R3 39k 140k
Temperature -128C -125C -100C -75C -50C -25C -0.5C 0C +0.5C +10C +25C +50C +75C +100C +125C +127C
LIMIT VALUES
Digital Output 1 0000 0000 1 0000 0110 1 0011 1000 1 0110 1010 1 1001 1100 1 1100 1110 1 1111 1111 0 0000 0000 0 0000 0001 0 0001 0100 0 0011 0010 0 0110 0100 0 1001 0110 0 1100 1000 0 1111 1010 0 1111 1111
Figure 4. Scaling VCCP2 to -12 V (+10%)
The resistor ratios are calculated as follows: R1/R2 = |V-|(max)/V+ (to give zero volts at the input for the most negative value of V-. R2 has no effect under this condition as the voltage across it is zero) and: (V+ - VFS)/VFS = R2/RP = (R1 and R2 in Parallel) (to give a voltage VFS at the input when V- is zero, where VFS is the normal full-scale voltage of the input used). This is a simple and cheap solution, but the following points should be noted. 1. Since the input signal is not inverted, an increase in the magnitude of the -12 V supply (going more negative), will cause the input voltage to fall and give a lower output code from the ADC. Conversely, a decrease in the magnitude of the -12 V supply will cause the ADC code to increase. This means that the upper and lower limits will be transposed. 2. Since the offset voltage is derived from the +5 V supply, variations in this supply will affect the ADC code. It is therefore a good idea to read the value of the +5 V supply and adjust the limits for the -12 V supply accordingly. The 5 V supply is attenuated by a factor RP/(R2+R P), where RP is the parallel combination of R1 and R3. An increase in -10-
Limit values for analog measurements are stored in the appropriate limit registers. In the case of voltage measurements, high and low limits can be stored so that an interrupt request will be generated if the measured value goes above or below acceptable values. In the case of temperature, a Hot Temperature Limit can be programmed, and a Hot Temperature Hysteresis Limit, which will usually be some degrees lower. This can be useful as it allows the system to be shut down when the hot limit is exceeded, and automatically restarted when it has cooled down to a safe temperature.
REV. 0
ADM9240
MONITORING CYCLE TIME
The monitoring cycle begins when a one is written to the Start Bit (Bit 0), and a zero to the INT_Clear Bit (Bit 3) of the Configuration Register. INT_Enable (Bit 1) should be set to one to enable the INT output. The ADC measures each analog input in turn, starting with VCCP2 and finishing with the on-chip temperature sensor. As each measurement is completed the result is automatically stored in the appropriate value register. This "round-robin" monitoring cycle continues until it is disabled by writing a 0 to Bit 0 of the Configuration Register. The counter controlling the multiplexer is driven by an on-chip clock of nominally 22.5 kHz, so the entire measurement sequence takes (nominally): 44.4 s x 7 = 310.8 s This rapid sampling of the analog inputs ensures a quick response in the event of any input going out of limits, unlike other monitoring chips that employ slower ADCs. When a monitoring cycle is started, monitoring of the fan speed inputs begins at the same time as monitoring of the analog inputs. However, the two monitoring cycles are not synchronized in any way, and the monitoring cycle time for the fan inputs is dependent on fan speed and much slower than for the analog inputs. For more details see the Fan Speed Measurement section.
INPUT SAFETY
If the op amp is powered from -12 V, precautions such as a clamp diode to ground may be needed to prevent the baseemitter junction of the transistor being reverse-biased in the unlikely event that the output of the op amp should swing negative for any reason. The positive output swing of the op amp should be as close to +12 V as possible so that the maximum voltage can be obtained from the transistor. Even if the op amp swings to the rail, the maximum voltage from the emitter of the transistor will be about 11.4 V. typical values for this condition would be: Gain = 11.4/1.25 = 9.12 = 1 + R1/R2 R1 = 82 k, R2 = 10 k (nearest preferred value) giving an actual gain of 9.2. The transistor should have a reasonably high hFE to avoid its base current pulling down the output of the op amp, it must have an ICMAX greater than the maximum fan current and be capable of dissipating power due to the voltage dropped across it when the fan is not operating at full speed. Depending on the fan parameters, some suitable devices would be 2N2219A, 2N3019 or ZTX450.
+12V NTEST_IN/AOUT
Scaling of the analog inputs is performed on-chip, so external attenuators are normally not required. However, since the power supply voltages will appear directly at the pins, it is advisable to add small external resistors in series with the supply traces to the chip to prevent damaging the traces or power supplies should an accidental short such as a probe connect two power supplies together. As the resistors will form part of the input attenuators, they will affect the accuracy of the analog measurement if their value is too high. The analog input channels are calibrated assuming an external series resistor of 500 , and the accuracy will remain within specification for any value from zero to 1 k, so a standard 510 resistor is suitable. The worst such accident would be connecting -12 V to +12 V-- a total of 24 V difference, with the series resistors this would draw a maximum current of approximately 24 mA.
ANALOG OUTPUT
R1 R2
Figure 5. Analog Output Driving Fan
LAYOUT AND GROUNDING
Analog inputs will provide best accuracy when referred to the GNDA pin. A separate, low impedance ground plane for analog ground, which provides a ground point for the voltage dividers and analog components, will provide best performance but is not mandatory. The power supply bypass, the parallel combination of 10 F (electrolytic or tantalum) and 0.1 F (ceramic) bypass capacitors connected between Pin 9 and ground, should also be located as close as possible to the ADM9240.
The ADM9240 has a single analog output from an unsigned 8-bit DAC which produces 0 V-1.25 V. The analog output register defaults to FF during power-on reset, which produces maximum fan speed. The analog output may be amplified and buffered with external circuitry such as an op amp and transistor to provide fan speed control. A suitable drive circuit is given in Figure 5. Care must be taken when choosing the op amp to ensure that its input common-mode range and output voltage swing are suitable. The op amp may be powered from the +12 V rail alone or from 12 V. If it is powered from +12 V then the input commonmode range should include ground to accommodate the minimum output voltage of the DAC, and the output voltage should swing below 0.6 V to ensure that the transistor can be turned fully off. REV. 0 -11-
ADM9240
FAN INPUTS
+12V VCC
Two inputs are provide for monitoring the condition of cooling fans. Signal conditioning in the ADM9240 accommodates the slow rise and fall times typical of fan tachometer outputs. The maximum input signal range is 0 to VCC. In the event that these inputs are supplied from fan outputs that exceed 0 to VCC, either resistive attenuation of the fan signal or diode clamping must be included to keep inputs within an acceptable range. Figures 6a to 6c show circuits for most common fan tacho outputs. If the fan tacho output has a resistive pull-up to VCC it can be connected directly to the fan input, as shown in Figure 6a.
+12V VCC
< 1k R1* TACHO OUTPUT
FAN1 OR FAN2
FAN SPEED COUNTER
R2*
*SEE TEXT
Figure 6d. Fan with Strong Tachometer Pull-Up to >VCC or Totem-Pole Output, Attenuated with R1/R2
INPUT CURRENT LIMITING
PULL-UP 4.7k TYP. TACHO OUTPUT
FAN1 OR FAN2
FAN SPEED COUNTER
Figure 6a. Fan with Tachometer Pull-Up to +VCC
If the fans are powered while the ADM9240 is unpowered, the inputs of the ADM9240 will try to clamp the fan output voltage. In this case the input current must be limited to less than the maximum value in the Absolute Maximum Ratings table. The pull-up resistor of the fan tacho output may provide this current limiting but, if its value is too low, it may be necessary to add additional resistance in series with the fan input pins.
FAN SPEED MEASUREMENT
If the fan output has a resistive pull-up to +12 V (or other voltage greater than VCC), the fan output can be clamped with a Zener diode, as shown in Figure 6b. The Zener voltage should be chosen so that it is greater than VIH but less than VCC, allowing for the voltage tolerance of the Zener. A value of about 0.8 x VCC is suitable.
+12V *CHOOSE ZD1 VOLTAGE APPROX. 0.8 VCC VCC
PULL-UP 4.7k TYP.
TACHO OUTPUT ZD1* ZENER
FAN1 OR FAN2
FAN SPEED COUNTER
The fan counter does not count the fan tacho output pulses directly, because the fan speed may be less than 1000 rpm and it would take several seconds to accumulate a reasonably large and accurate count. Instead, the period of the fan revolution is measured by gating an on-chip 22.5 kHz oscillator into the input of an 8-bit counter for two periods of the fan tacho output, as shown in Figure 7, so the accumulated count is actually proportional to the fan tacho period and inversely proportional to the fan speed. The monitoring cycle begins when a one is written to the start bit (Bit 0), and a zero to the INT_Clear bit (Bit 3) of the Configuration Register INT_Enable (Bit 1) should be set to one to enable the INT output. The measurement begins on the rising edge of a fan tacho pulse, and ends on the next-but-one rising edge. Once the fan speeds have been measured, they will be stored in the Fan Speed Value Registers and can be read at any time. The measurements will be updated as long as the monitoring cycle continues.
22.5kHz CLOCK
Figure 6b. Fan with Tachometer Pull-Up to Voltage >V CC (e.g., 12 V) Clamped with Zener Diode
If the fan has a strong pull-up (less than 1 k) to +12 V, or a totem-pole output, a series resistor can be added to limit the zener current, as shown in Figure 6c. Alternatively, a resistive attenuator may be used, as shown in Figure 6d. R1 and R2 should be chosen such that: 2 V < VPULL-UP x R2/(RPULL-UP + R1 + R2) < VCC If the value of the pull-up resistor is not known, the value of R1 and R2 should be made fairly large, but not so large that the input leakage current will cause a large voltage drop across them. With a pull-up voltage of 12 V and pull-up resistor less than 1 k, suitable values for R1 and R2 would be 100 k and 47 k. This will give a high input voltage of 3.83 V.
+12V *CHOOSE ZD1 VOLTAGE APPROX. 0.8 VCC VCC
CONFIG REG. BIT 0
FAN1 INPUT
FAN2 INPUT FAN1 MEASUREMENT PERIOD START OF MONITORING CYCLE FAN2 MEASUREMENT PERIOD
TACHO OUTPUT PULL-UP TYP. < 1k OR TOTEM-POLE R1 10k
FAN1 OR FAN2 ZD1* ZENER
FAN SPEED COUNTER
Figure 7. Fan Speed Measurement
Figure 6c. Fan with Strong Tachometer Pull-Up to >VCC or Totem-Pole Output, Clamped with Zener and Resistor
-12-
REV. 0
ADM9240
To accommodate fans of different speed and/or different numbers of output pulses per revolution, a prescaler (divisor) of 1, 2, 4 or 8 may be added before the counter. The default value is 2, which gives a count of 153 for a fan running at 4400 rpm producing two output pulses per revolution. The count is calculated by the equation: Count = (22.5 x 103 x 60) /(rpm x Divisor) For constant speed fans, fan failure is normally considered to have occurred when the speed drops below 70% of nominal, which would correspond to a count of 219. Full scale (255) would be reached if the fan speed fell to 60% of its nominal value. For temperature controlled variable speed fans the situation will be different. Table III shows the relationship between fan speed and time per revolution at 60%, 70% and 100% of nominal rpm for fan speeds of 1100 rpm, 2200 rpm, 4400 rpm and 8800 rpm, and the divisor that would be used for each of these fans, based on two tacho pulses per revolution.
Table III. Fan Speeds and Divisors
Time per 70% Rev (ms) rpm 6.82 13.64 27.27 54.54 6160 3080 1540 770 Time per 60% Rev (ms) rpm 9.74 19.48 38.96 77.92 5280 2640 1320 660 Time per 60% Rev (ms) 11.36 22.73 45.45 90.9
FAN MANUFACTURERS
Manufacturers of cooling fans with tachometer outputs are listed below: NMB Tech 9730 Independence Ave. Chatsworth, California 91311 818-341-3355 818-341-8207 Model 2408NL 2410ML 3108NL 3110KL Frame Size 2.36 in sq. x 0.79 in (60 mm sq. x 20 mm) 2.36 in sq. x 0.98 in (60 mm sq. x 25 mm) 3.15 in sq. x 0.79 in (80 mm sq. x 20 mm) 3.15 in sq. x 0.98 in (80 mm sq. x 25 mm) Airflow CFM 9-16 14-25 25-42 25-40
Mechatronis Inc. P.O. Box 613 Preston, WA 98050 800-453-4569 Models--Various sizes available with tach output option. Sanyo Denki/Keymarc Electronics 468 Amapola Ave. Torrance, CA 90501 310-783-5400 Models--109P Series
CHASSIS INTRUSION INPUT
Divisor 1 2 4 8
Nominal rpm 8800 4400 2200 1100
Note that Fan 1 and Fan 2 Divisors are programmed into Bits 4 to 7 of the VID0-VID3/Fan Divisor Register.
LIMIT VALUES
Fans in general will not overspeed if run from the correct voltage, so the failure condition of interest is underspeed due to electrical or mechanical failure. For this reason only low speed limits are programmed into the limit registers for the fans. It should be noted that, since fan period rather than speed is being measured, a fan failure interrupt will occur when the measurement exceeds the limit value.
MONITORING CYCLE TIME
The Chassis Intrusion (CI) input is an active high input/opendrain output intended for detection and signalling of unauthorized tampering with the system. An external circuit powered from the system's CMOS backup battery is used to detect and latch a chassis intrusion event, whether the system is powered up or not. Once a chassis intrusion has been detected and latched, the CI input will generate an interrupt when the system is powered up. The actual detection of chassis intrusion is performed by an external circuit that will, for example, detect when the cover has been removed. A wide variety of techniques may be used for the detection: - - - - Microswitch that opens or closes when the cover is removed. Reed switch operated by magnet fixed to the cover. Hall-effect switch operated by magnet fixed to the cover. Phototransistor that detects light when cover is removed.
The monitoring cycle time depends on the fan speed and number of tacho output pulses per revolution. Two complete periods of the fan tacho output (three rising edges) are required for each fan measurement. Therefore, if the start of a fan measurement just misses a rising edge, the measurement can take almost three tacho periods. In order to read a valid result from the fan value registers, the total monitoring time allowed after starting the monitoring cycle should therefore be three tacho periods of FAN1 plus three tacho periods of FAN2 at the lowest normal fan speed. Although the fan monitoring cycle and the analog input monitoring cycle are started together, they are not synchronized in any other way.
The chassis intrusion interrupt will remain asserted until the external detection circuit is reset. This can be achieved by setting Bit 6 of the Configuration Register, or Bit 7 of the Chassis Intrusion Clear Register to one, which will cause the CI pin to be pulled low for at least 20 ms. These register bits are self-clearing.
REV. 0
-13-
ADM9240
The chassis intrusion circuit should be designed so that it can be reset by pulling its output low. A suitable chassis intrusion circuit using a phototransistor is shown in Figure 8. Light falling on the phototransistor when the PC cover is removed will cause it to turn on and pull up the input of N1, thus setting the latch N3/N4. After the cover is replaced, a low reset on the CI output will pull down the input of N4, resetting the latch.
1N914 CMOS BACKUP BATTERY MRD901 1N914 +5V VC R1 10k CI
AD22105
RSET TEMP. SENSOR Q1
Figure 8b. Using the CI Input with a Temperature Sensor
74HC132
100k CI 470k
Note: The chassis intrusion input does not have a protective clamp diode to VCC, as this could pull down the chassis intrusion latch and reset it when the ADM9240 was powered down.
THE ADM9240 INTERRUPT STRUCTURE
10k
Figure 8a. Chassis Intrusion Detector and Latch
The Interrupt Structure of the ADM9240 is shown in Figure 9. As each measurement value is obtained and stored in the appropriate value register, the value and the limits from the corresponding limit registers are fed to the high and low limit comparators. The result of each comparison (1 = out of limit, 0 = in limit) is routed to the corresponding bit input of the Interrupt Status Registers via a data demultiplexer and used to set that bit high or low as appropriate. The Interrupt Mask Registers have bits corresponding to each of the Interrupt Status Register Bits. Setting an Interrupt Mask Bit high forces the corresponding Status Bit output low, while setting an Interrupt Mask Bit low allows the corresponding Status Bit to be asserted. After masking, the status bits are all ORed together to produce the INT output, which will pull low if any unmasked status bit goes high, i.e., when any measured value goes out of limit. The INT output is enabled when Bit 1 of the Configuration Register (INT_Enable) is high, and Bit 3 (INT_Clear) is low.
The Chassis Intrusion input can also be used for other types of alarm input. Figure 8b shows a temperature alarm circuit using an AD22105 temperature switch sensor. This produces a lowgoing output when the preset temperature is exceeded, so the output is inverted by Q1 to make it compatible with the CI input. Q1 can be almost any small-signal NPN transistor, or a TTL or CMOS inverter gate may be used if one is available. See the AD22105 data sheet for information on selecting RSET.
+VCCP2 HIGH LIMIT FROM VALUE AND LIMIT REGISTERS 1 = OUT OF LIMIT VALUE HIGH AND LOW LIMIT COMPARATORS DATA DEMULTIPLEXER +12V +3.3V +2.5V +5V +VCCP1 TEMP FAN1 FAN2 MASK GATING STATUS BIT MASK BIT 10 INT INTERRUPT STATUS REGISTERS
LOW LIMIT
CI (CHASSIS INTRUSION)
MASKING DATA FROM BUS
INTERRUPT MASK REGISTERS
INT_ENABLE
INT_CLEAR
CONFIGURATION REGISTER
Figure 9. Interrupt Register Structure
-14-
REV. 0
ADM9240
INTERRUPT CLEARING
Reading an Interrupt Status Register will output the contents of the Register, then clear it. It will remain cleared until the monitoring cycle updates it, so the next read operation should not be performed on the register until this has happened, or the result will be invalid. The time taken for a complete monitoring cycle is mainly dependent on the time taken to measure the fan speeds, as described earlier. The INT output is cleared with the INT_Clear bit, which is Bit 3 of the Configuration Register, without affecting the contents of the Interrupt (INT) Status Registers. When this bit is high, the ADM9240 monitoring loop will stop. It will resume when the bit is low.
TEMPERATURE INTERRUPT MODES
goes below THOTHYST. Operation in the one-time interrupt mode is illustrated in Figure 11. Again, the interval between read operations is shown as being longer than the monitoring cycle time.
THOT
TEMP THOTHYST
INT
READ
READ
READ
READ
READ
READ
READ
As mentioned earlier, two limit values can be programmed for the temperature measurement, a Hot Temperature Limit (THOT), and a Hot Temperature Hysteresis Limit (THOTHYST ), which is normally some degrees lower. The interrupt function of the temperature sensor differs from the interrupt operation of the other inputs in that there are three interrupt modes, called "One-Time Interrupt" mode, "Default Interrupt" mode and "Comparator" mode.
DEFAULT INTERRUPT MODE
Figure 11. INT Output in One-Time Interrupt Mode
COMPARATOR MODE
Exceeding THOT causes the INT output to go Low. INT will remain Low until the temperature goes below THOT. Once the temperature goes below THOT, INT will go High. THOTHYST is ignored. In other words, Comparator Mode operates like a thermostat with no hysteresis. Operation in the comparator mode is illustrated in Figure 12.
THOT
Exceeding THOT causes an Interrupt that will remain active indefinitely until reset by reading Interrupt Status Register 1 or cleared by the INT_Clear bit in the Configuration register. Once an Interrupt event has occurred by crossing THOT , then reset, an Interrupt will occur again once the next temperature conversion has completed. The interrupts will continue to occur in this manner until the temperature goes below THOTHYST. Operation in the default interrupt mode is illustrated in Figure 10. For clarity, in this illustration the interval between read operations is shown as considerably longer than the monitoring cycle time, so that the interrupt is always reasserted after being reset, before the next read operation occurs.
THOT
TEMP INT
Figure 12. INT Output in Comparator Mode
RESET INPUT/OUTPUT
TEMP THOTHYST INT
RESET (Pin 12) is an I/O pin that can function as an opendrain output, providing a low going 20 ms output pulse when Bit 4 of the Configuration Register is set to 1, provided the reset function has first been enabled by setting Bit 7 of Interrupt Mask Register #2 to 1. The bit is automatically cleared when the reset pulse is output. Pin 11 can also function as a RESET input by pulling this pin low to reset the internal registers of the ADM9240 to default values. Only those registers that have power on default values as listed in Table VI are affected by this function. The DAC register, Value and Limit Registers are not affected.
NAND TREE TESTS
READ
READ
READ
READ
READ
READ
READ
Figure 10. Temperature INT Output in Default Interrupt Mode
ONE-TIME INTERRUPT MODE
Exceeding THOT causes an Interrupt that will remain active indefinitely until reset by reading Interrupt Status Register 1 or cleared by the INT_Clear bit in the Configuration Register. Once an Interrupt event has occurred by crossing THOT , then reset, an Interrupt will not occur again until the temperature
A NAND tree is provided in the ADM9240 for Automated Test Equipment (ATE) board level connectivity testing. The device is placed into NAND Test Mode by powering up with Pin 11 held high. This pin is sampled automatically after power-up and if it connected high, then the NAND test mode is invoked. In NAND test mode, all digital inputs may be tested as illustrated below. A0/NTEST_OUT will become the NAND tree output pin. To perform a NAND tree test, all pins included in the NAND tree should be driven high.
REV. 0
-15-
ADM9240
The structure of the NAND tree is shown in Figure 13. Beginning with A1 and working clockwise around the chip, each pin can be toggled and a resulting toggle can be observed on NTEST_OUT/A0. Allow for a typical propagation delay of 500 ns.
A1 SDA SCL FAN1 FAN2 VID0 VID1 VID2 VID3 VID4
Bit 0 of the Configuration Register controls the monitoring loop of the ADM9240. Setting Bit 0 low stops the monitoring loop and puts the ADM9240 into a low power mode thereby reducing power consumption. Serial bus communication is still possible with any register in the ADM9240 while in low power mode. Setting Bit 0 high starts the monitoring loop. Bit 1 of the Configuration Register enables or disables the INT Interrupt output. Setting Bit 1 high enables the INT output, setting Bit 1 low disables the output. Bit 3 of the Configuration Register is used to clear the INT interrupt output when set high. The ADM9240 monitoring function will stop until Bit 3 is set low. Interrupt Status Register contents will not be affected. Bit 4 of the Configuration Register is used to initiate a minimum 20 ms RESET signal on the RESET output if the function is enabled by Bit 7 in Register 44. Bit 6 of the Configuration Register is used to reset the Chassis Intrusion (CI) output pin when set high. Bit 7 of the Configuration Register is used to start a Configuration Register Initialization when taken high.
STARTING CONVERSION
NTEST_OUT
Figure 13. NAND Tree
Note: If any of the inputs shown in Figure 9 are unused, they should not be connected directly to ground, but via a resistor such as 10 k. This will allow the ATE (Automatic Test Equipment) to drive every input high so that the NAND tree test can be properly carried out.
USING THE ADM9240
POWER-ON RESET
When power is first applied, the ADM9240 performs a "poweron reset" on several of its registers. Registers whose power-on values are not shown have power-on conditions that are indeterminate (this includes the Value and Limit Registers). The ADC is inactive. In most applications, usually the first action after power-on would be to write limits into the Limit Registers. Power-on reset clears or initializes the following registers (the initialized values are shown in Table VI: - - - - - - - - - - - Configuration Register Serial Address Register Interrupt (INT) Status Registers #1 and #2 Interrupt (INT) Mask Registers #1 and #2 VID /Fan Divisor Register VID4 Register Chassis Intrusion Clear Register Temperature Configuration Register Test Register Compatibility Register Analog Output Register
The monitoring function (analog inputs, temperature and fan speeds) in the ADM9240 is started by writing to the Configuration Register and setting Start (Bit 0), high, INT_Enable (Bit 1) high and INT_Clear (Bit 3) low. Apart from initially starting together, the analog measurements and fan speed measurements proceed independently and are not synchronized in any way. The analog measurements will be completed in no more than 353 s. The time taken to complete the fan speed measurements depends on the fan speed and the number of tacho output pulses per revolution. Once the measurements have been completed, the results can be read from the Value Registers at any time. Table IV shows the measurement sequence for the analog inputs.
Table IV. Measurement Sequence
Measurement # 1 2 3 4 5 6 7
Parameter Analog +VCCP2 Analog +12 VIN Analog +5 VIN Analog +3.3 VIN Analog +2.5 VIN Analog +VCCP1 Temperature Reading
INITIALIZATION
Configuration Register INITIALIZATION performs a similar, but not identical, function to power-on reset. The Test Register and Analog Output Register are not initialized. Configuration Register INITIALIZATION is accomplished by setting Bit 7 of the Configuration Register high. This bit automatically clears after being set.
Using the Configuration Register
LOW POWER AND SHUTDOWN MODE
Control of the ADM9240 is provided through the Configuration Register. The ADC is stopped upon power-up, and the INT_Clear signal is asserted, clearing the INT output. The Configuration Register is used to start and stop the ADM9240; enable or disable interrupt outputs and modes, and provide the initialization function described above.
The ADM9240 can be placed in a low power mode by setting Bit 0 of the Configuration register to 0. This disables the internal ADC. Full shutdown mode may then be achieved by setting Bit 0 of the Test Register to 1. This turns off the analog output and stops the monitoring cycle, if running, but it does not affect the condition of any of the registers. The device will return to its previous state when this bit is reset to zero.
-16-
REV. 0
ADM9240
APPLICATION CIRCUIT
Figure 14 shows a generic application circuit using the AD9240. The analog monitoring inputs are connected to the power supplies including two processor core voltage inputs. The VID inputs are connected to the processor voltage ID pins. There are two tacho inputs from fans, and the analog output is used to control the speed of a third fan. A chassis intrusion latch with an opto-sensor is connected to the CI input. Of course, in an actual application, every input and output may not be used, in which case unused analog and digital inputs should be tied to analog or digital ground as appropriate.
+12V +3.3V NTEST_OUT/A0 VID0
A1 +3.3V SDA SERIAL BUS SCL 1N914 CMOS BACKUP BATTERY MRD901 1N914 +3.3V
VID1
VID2
FROM VID PINS OF PROCESSOR
VID3
FAN1
VID4 510
74HC132
100k 470k
FAN2
+VCCP1
CI
ADM9240
510
+2.5VIN
GNDD 10k 10 F 0.1 F +3.3V +
510
+3.3VIN
510 VCC INT 510
+5VIN
+12VIN
+12V NTEST_IN/AOUT 2N2219A 82k OP295 GNDA RESET 10k 510 +VCCP2
Figure 14. Application Circuit
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ADM9240
Table V. Address Pointer Register
Bit 7-0
Name Address Pointer
R/W Write
Description Address of ADM9240 Registers. See the tables below for detail.
Table VI. List of Registers
Address 15h
Description Test Register
Power on Value 0000 0000
Notes A7-A0 (Binary Bit 7-0) Setting Bit 0 of this register to 1 selects shutdown mode. Caution: Do Not write to any other bits in this register. Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only
19h 20h 21h 22h 23h 24h 25h 26h 27h 28h 29h 2Ah 2Bh 2Ch 2Dh 2Eh 2Fh 30h 31h 32h 33h 34h 35h 36h 37h 38h 39h 3Ah 3Bh 3Ch 3Dh 3Eh 3Fh 40h 41h 42h 43h 44h 45h 46h 47h 48h 49h 4Bh
Programmed Value of Analog Output +2.5 V Measured Value +VCCP1 Measured Value +3.3 V Measured Value +5 V Measured Value +12 V Measured Value VCCP2 Measured Value Reserved Temperature Reading FAN1 Reading FAN2 Reading Reserved +2.5 V High Limit +2.5 V Low Limit +VCCP1 High Limit +VCCP1 Low Limit +3.3 V High Limit +3.3 V Low Limit +5 V High Limit +5 V Low Limit +12 V High Limit +12V Low Limit VCCP2 High Limit VCCP2 Low Limit Reserved Reserved Hot Temperature Limit (High) Hot Temperature Hysteresis Limit (Low) FAN1 Fan Count Limit FAN2 Fan Count Limit Reserved Company ID Number Revision Number Configuration Register Interrupt INT Status Register 1 Interrupt INT Status Register 2 INT Mask Register 1 INT Mask Register 2 Compatibility Register Chassis Intrusion Clear Register VID0-3/Fan Divisor Register Serial Address Register VID4 Register Temperature Configuration Register
1111 1111 Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate Indeterminate 0010 0011 Die Revision 0000 1000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0101 (VID3-VID0) 0010 11(A1)(A0) 1000 000(VID4) 0000 0001
This location will contain the company identification number (Read Only). This location will contain the revision number of the part. (Read Only). See Table VII See Table VIII See Table IX See Table X See Table XI See Table XII See Table XIII See Table XIV See Table XV See Table XVI See Table XVII
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ADM9240
Table VII. Register 40h, Configuration Register (Power-On Default = 08h)
Bit 0
Name START
R/W R/W
Description Logic 1 enables startup of ADM9240, Logic 0 places it in standby mode. Caution: the outputs of the Interrupt pins will not be cleared if the user writes a zero to this location after an interrupt has occurred (see "INT_Clear" bit). At startup, limit checking functions and scanning begins. Note, all high and low limits should be set into the ADM9240 prior to turning on this bit. (Power-Up Default = 0.) Logic 1 enables the INT output. 1 = Enabled 0 = Disabled (Power-Up Default = 0). Default = 0. During Interrupt Service Routine (ISR) this bit is asserted Logic 1 to clear INT output without affecting the contents of the Interrupt Status Register. The device will stop monitoring. It will resume upon clearing of this bit. (Power-Up Default = 1.) Creates a RESET (Active Low) signal for 20 ms minimum (Power-Up Default = 0). This bit is cleared once the pulse goes active. Default = 0. A "1" outputs a minimum 20 ms active low pulse on the Chassis Intrusion pin. (Power-Up Default = 0.) (Note: This bit performs the same function as Bit 7 in Register 46h). Logic 1 restores power-up default values to the Configuration register, Interrupt status registers, Interrupt Mask Registers, Fan Divisor Register and the Temperature Configuration Register. This bit automatically clears itself since the power-on default is zero.
1 2 3
INT_Enable Reserved INT_Clear
R/W R/W
4 5 6 7
RESET Reserved CI_Reset Initialization
R/W R/W R/W R/W
Table VIII. Register 41h, Interrupt Status Register 1 (Power-On Default = 00h)
Bit 0 1 2 3 4 5 6 7
Name +2.5 V_Error VCCP_Error +3.3 V_Error +5 V_Error Temp_Error Reserved FAN1_Error FAN2_Error
R/W Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only
Description A "1" indicates a high or low limit has been exceeded. A "1" indicates a high or low limit has been exceeded. A "1" indicates a high or low limit has been exceeded. A "1" indicates a high or low limit has been exceeded. A "1" indicates that a temperature interrupt has been set. Undefined. A "1" indicates that a fan count limit has been exceeded. A "1" indicates that a fan count limit has been exceeded.
Table IX. Register 42h, Interupt Status Register 2 (Power-On Default = 00h)
Bit 0 1 2 3 4 5 6 7
Name +12 V_Error VCCP2_Error Reserved Reserved Chassis_Error Reserved Reserved Reserved
R/W Read Only Read Only Read Only Read Only Read Only Read Only Read Only Read Only
Description A "1" indicates a high or low limit has been exceeded. A "1" indicates a high or low limit has been exceeded. Undefined. Undefined. A "1" indicates chassis intrusion has gone high. Undefined. Undefined. Undefined.
Note: Any time the STATUS Register is read out, the conditions (i.e., Register) that are read are automatically reset. In the case of the channel priority indication, if two or more channels were out of limits, another indication would automatically be generated if it were not handled during the ISR. In the Mask Register, the errant voltage interrupt may be disabled until the operator has time to clear the errant condition or set the limit higher/lower.
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ADM9240
Table X. Register 43h, INT Interrupt Mask Register 1 (Power-On Default = 00h)
Bit 0 1 2 3 4 5 6 7
Name +2.5 V +VCCP1 +3.3 V +5 V Temp Reserved FAN1 FAN2
R/W Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write
Description A "1" disables the corresponding interrupt status bit for INT A "1" disables the corresponding interrupt status bit for INT A "1" disables the corresponding interrupt status bit for INT A "1" disables the corresponding interrupt status bit for INT A "1" disables the corresponding interrupt status bit for INT Power-On Default = 0. A "1" disables the corresponding interrupt status bit for INT A "1" disables the corresponding interrupt status bit for INT interrupt. interrupt. interrupt. interrupt. interrupt. interrupt. interrupt.
Table XI. Register 44h, INT Mask Register 2 (Power-On Default = 00h)
Bit 0 1 2 3 4 5 6 7
Name +12 V VCCP2 Reserved Reserved CI Reserved Reserved RESET Enable
R/W Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write Read/Write
Description A "1" disables the corresponding interrupt status bit for INT interrupt. A "1" disables the corresponding interrupt status bit for INT interrupt. Power-up default set to Low. Power-up default set to Low. A "1" disables the corresponding interrupt status bit for INT interrupt. Undefined. Undefined. A "1" enables the RESET function in the configuration register.
Table XII. Register 45h, Reserved Compatibility (Power-On Default = 00h)
Bit 0-7
Name Reserved
R/W Read/Write
Description Reserved for Compatibility.
Table XIII. Register 46h, Chassis Intrusion Clear (Power-On Default = 00h)
Bit 0-6 7
Name Reserved Chassis Int. Clear
R/W Read/Write Read/Write
Description Undefined (Power On Default = 00h) A "1" outputs a minimum 20 ms active low pulse on the chassis intrusion pin. The register bit clears itself after the pulse has been output.
Table XIV. Register 47h, VID0-3/Fan Divisor Register (Power-On Default 0101(VID3-VID0))
Bit 0-3 4-5
Name VID FAN1 Divisor
R/W Read Read/Write
Description The VID[3:0] inputs from processor core power supplies to indicate the operating voltage (e.g., 1.3 V to 3.5 V). Sets Counter Prescaler for FAN1 Speed Measurement <5:4> = 00 - Divide by 1 <5:4> = 01 - Divide by 2 <5:4> = 10 - Divide by 4 <5:4> = 11 - Divide by 8 Sets Counter Prescaler for FAN2 Speed Measurement <7:6> = 00 - Divide by 1 <7:6> = 01 - Divide by 2 <7:6> = 10 - Divide by 4 <7:6> = 11 - Divide by 8
6-7
FAN2 Divisor
Read/Write
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ADM9240
Table XV. Register 48h, Serial Address Register (Power-On Default = 0010 11(A1)(A0))
Bit 0-6
Name Serial Bus Address
R/W Read/Write
Description Serial Bus Address (Bits 0 and 1 are Set by A0, A1 and Bit 7 is Read Only)
Table XVI. Register 49h, VID 4/Device ID Register (Power-On Default 1000000(VID4))
Bit 0 1-7
Name VID4 Reserved
R/W Read Read/Write
Description VID4 Input from Pentium(R)
Table XVII. Register 4Bh, Temperature Configuration Register (Power-On Default = 01h)
Bit 0-1
Name Hot Temperature Interrupt Mode Select Bits
R/W Read/Write
Description If Bit 0 and Bit 1 of this register are both zero or one, this selects the default interrupt mode, which gives the user an interrupt if the temperature goes above the hot limit. The interrupt will be cleared once the status register is read, but it will again be generated when the next conversion has completed. It will continue to do so until the temperature goes below the hysteresis limit. A 0 on Bit 1 and a 1 on Bit 0 selects the one-time interrupt mode, which gives the user an interrupt when the temperature goes above the hot limit. The interrupt will be cleared once the status register is read. Another interrupt will not be generated until the temperature first goes below the hysteresis limit. No more interrupts will be generated until the temperature again goes above the hot limit. The corresponding bit will be cleared in the status register every time it is read, but may not set again when the next conversion is done. Note that this is the power-up default mode. A 1 on Bit 1 and a 0 on Bit 0 selects the comparator mode. This gives an INT when the temperature exceeds the hot limit. This INT remains active until the temperature goes below the hot limit (no hysteresis), when the INT will become inactive. Default = 00000 LSB of Temperature Reading = 0.5C
2-6 7
Reserved Temp
Read/Write Read only
Pentium is a registered trademark of Intel Corp.
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ADM9240
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
24-Lead TSSOP (RU-24)
0.311 (7.90) 0.303 (7.70)
24
13
0.177 (4.50) 0.169 (4.30)
1
12
0.006 (0.15) 0.002 (0.05)
PIN 1 0.0433 (1.10) MAX 0.0256 (0.65) BSC 0.0118 (0.30) 0.0075 (0.19) 0.0079 (0.20) 0.0035 (0.090)
0.256 (6.50) 0.246 (6.25)
SEATING PLANE
8 0
0.028 (0.70) 0.020 (0.50)
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REV. 0
PRINTED IN U.S.A.
C3295-8-3/98

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