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19-3713; Rev 1; 7/05
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs
General Description Features
Two Thermistor Inputs Two Open-Drain PWM Outputs for Fan-Speed Control Local Temperature Sensor Six GPIOs (MAX6616) Programmable Fan-Control Characteristics Controlled PWM Rate-of-Change Ensures Unobtrusive Fan-Speed Adjustments Fail-Safe System Protection OT Output for Throttling or Shutdown Nine Different Pin-Programmable SMBus Addresses 16-Pin and 24-Pin QSOP Packages
MAX6615/MAX6616
The MAX6615/MAX6616 monitor two temperature channels, either the internal die temperature and the temperature of an external thermistor, or the temperatures of two external thermistors. The temperature data controls a PWM output signal to adjust the speed of a cooling fan, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. The fans' tachometer output signals are monitored by the MAX6615/MAX6616 to detect fan failure. If a fan failure is detected, the FAN_FAIL output is asserted. The 2-wire serial interface accepts standard system management bus (SMBus TM) write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. The programmable alarm output can be used to generate interrupts, throttle signals, or overtemperature shutdown signals. The MAX6616 features six GPIOs to provide additional flexibility. All of the GPIOs power-up as inputs, with the exception of GPIO0, which powers up as either an input or an output as determined by connecting the PRESET pin to ground or VCC. The MAX6616 is available in a 24-pin QSOP package, while the MAX6615 is available in a 16-pin QSOP package. Both devices operate from a single-supply voltage range of 3.0V to 5.5V, have operating temperature ranges of -40C to +125C, and consume just 500A of supply current.
Ordering Information
PART MAX6615AEE MAX6616AEG TEMP RANGE -40C to +125C -40C to +125C PIN-PACKAGE 16 QSOP 24 QSOP
Functional Diagram
FAN_FAIL VCC
Applications
Desktop Computers Servers Power Supplies Networking Equipment Workstations
SCL TH1 REF TH2
THERMISTORS AND LOCAL TEMP SENSOR
PWM GENERATOR AND TACH COUNTER
TACH1 PWM1 TACH2 PWM2 OT
SMBus is a trademark of Intel Corp.
SDA
SMBus INTERFACE AND REGISTERS
LOGIC
GPIO0* GPIO5*
Typical Application Circuits and Pin Configurations appear at end of data sheet.
MAX6615 MAX6616
GND ADD0 *MAX6616 ONLY ADD1
PRESET*
________________________________________________________________ Maxim Integrated Products
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
ABSOLUTE MAXIMUM RATINGS
All Voltages Are Referenced to GND Supply Voltage (VCC) ...............................................-0.3V to +6V PWM_, TACH_, OT, FAN_FAIL ............................-0.3V to +13.5V ADD0, ADD1, SDA, SCL ..........................................-0.3V to +6V All Other Pins..............................................-0.3V to (VCC + 0.3V) SDA, OT, FAN_FAIL, PWM_, GPIO_ Current....................50mA TH_ Current ........................................................................1mA REF Current ......................................................................20mA Continuous Power Dissipation (TA = +70C) 16-Pin QSOP (derated at 8.3mW/C above +70C)............................................................666.7mW 24-Pin QSOP (derated at 9.5mW/C above +70C)...........................................................761.9 mW ESD Protection (all pins, Human Body Model) ....................2kV Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +5.5V, TA= 0C to +125C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25C.)
PARAMETER Operating Supply Voltage Standby Current Operating Current External Temperature Error Internal Temperature Error Temperature Resolution Conversion Time Conversion Rate Timing Error PWM Frequency Error INPUT/OUTPUT Output Low Voltage Output High Leakage Current Logic Low Input Voltage Logic High Input Voltage Input Leakage Current Input Capacitance Serial Clock Frequency Clock Low Period Clock High Period Bus Free Time Between STOP and START Conditions SMBus START Condition Setup Time CIN fSCLK tLOW tHIGH tBUF tSU:STA 90% of SCL to 90% of SDA 10% to 10% 90% to 90% 10 4 4.7 4.7 4.7 5 400 SMBus TIMING (Figures 2, 3) (Note 2) kHz s s s s VOL IOH VIL VIH 2.1 1 VCC = +3V, IOUT = 6mA 0.4 1 0.8 V A V V A pF -20 -20 IS SYMBOL VCC Interface inactive, ADC in idle state Interface inactive, ADC active VCC = +3.3V, 0.15V VTH_ +0.71V (excludes thermistor errors, thermistor nonlinearity) (Note1) VCC = +3.3V, 0C TA +85C, VCC = +3.3V, 0C TA +125C 0.125 250 +20 +20 0.5 CONDITIONS MIN 3.0 TYP MAX 5.5 10 1 1 2.5 4 UNITS V A mA C C C ms % %
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +5.5V, TA= 0C to +125C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25C.)
PARAMETER START Condition Hold Time STOP Condition Setup Time Data Setup Time Data Hold Time SMBus Fall Time SMBus Rise Time SMBus Timeout SYMBOL tHD:STO tSU:STO tSU:DAT tHD:DAT tF tR (Note 3) 29 37 CONDITIONS 10% of SDA to 10% of SCL 90% of SCL to 10% of SDA 10% of SDA to 10% of SCL 10% of SCL to 10% of SDA MIN 4 4 250 300 300 1000 55 TYP MAX UNITS s s ns ns ns ns ms
MAX6615/MAX6616
Note 1: 1C of error corresponds to an ADC error of 7.76mV when VREF = 1V. Note 2: Guaranteed by design and characterization. Note 3: Production tested.
Typical Operating Characteristics
(VCC = +3.3V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX6615/6 toc01
THERMISTOR TEMPERATURE DATA vs. THERMISTOR TEMPERATURE
MAX6615/6 toc02
LOCAL TEMPERATURE ERROR vs. DIE TEMPERATURE
MAX6615/6 toc03
1000 LOCAL SUPPLY CURRENT (A) REMOTE 100
120 THERMISTOR TEMPERATURE DATA (C) 100 80 60 40 20 0
2
TEMPERATURE ERROR (C)
1
0
10 SHUTDOWN
-1
1 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
-2 0 20 40 60 80 100 120 0 25 50 75 100 THERMISTOR TEMPERATURE (C) DIE TEMPERATURE (C)
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25C, unless otherwise noted.)
GPIO SINK CURRENT vs. SUPPLY VOLTAGE
MAX6615/6 toc04
GPIO OUTPUT VOLTAGE vs. GPIO SINK CURRENT
MAX6615/6 toc05
PWM FREQUENCY vs. DIE TEMPERATURE
4 3 FREQUENCY SHIFT (Hz) 2 1 0 -1 -2 -3 -4 -5 NORMALIZED AT TA = +25C 0 25 50 75 100 125
MAX6615/6 toc06
50 45 40 IGPIO_ (mA) 35 30 25 20 15 3.0 3.5 4.0 4.5 5.0 VGPIO_ = 0.4V
0.9 0.8 0.7 0.6 VGPIO_ (V) 0.5 0.4 0.3 0.2 0.1 0 VCC = 5V VCC = 3V
5
5.5
0
10
20
30
40
50
60
70
80
VCC (V)
IGPIO_ (mA)
DIE TEMPERATURE (C)
PWM FREQUENCY vs. SUPPLY VOLTAGE
0.08 FREQUENCY SHIFT (Hz) 0.06 0.04 0.02 0 -0.02 NORMALIZED AT VCC = 5.0V -0.04 3.0 3.5 4.0 4.5 5.0 5.5 VCC (V)
MAX6615/6 toc07
0.10
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs
Pin Description
PIN MAX6616 1, 2, 5, 20, 23, 24 3 4 6 7 8 9 10, 15 11 12 13 14 16 17 18 19 21 22 MAX6615 -- 1 2 3 4 5, 10 6 -- 7 8 9 -- 11 12 13 14 15 16 NAME GPIO0- GPIO5 PWM1 TACH1 ADD0 ADD1 GND TH1 N.C. REF TH2 FAN_FAIL PRESET OT VCC SDA SCL TACH2 PWM2 FUNCTION Active-Low, Open-Drain GPIOs. Can be pulled up to 5.5V regardless of VCC. Fan Driver Output 1. The pullup resistor can be connected to a supply voltage as high as 12V, regardless of the supply voltage. See the PWM Output section for configuration. Fan Tachometer Input. Accepts logic-level signal from fan's tachometer output. Can be connected to a supply voltage as high as 12V, regardless of the supply voltage. SMBus Slave Address Selection SMBus Slave Address Selection Ground. Must be connected together for MAX6615. External Thermistor Input 1. Connect a thermistor in series with a fixed resistor between REF and ground. No Connection Reference Voltage Output. Provides 1V during measurements. High impedance when not measuring. External Thermistor Input 2. Connect a thermistor in series with a fixed resistor between REF and ground. Fan-Failure Output. Asserts low when either fan fails. Can be pulled up as high as 5.5V regardless of VCC. High impedance when VCC = 0V. Connect to GND or VCC to set POR state of the GPIO0. Overtemperature Output. Active low, open drain. Typically used for system shutdown or clock throttling. Can be pulled up as high as 5.5V regardless of VCC. High impedance when VCC = 0V. Power Supply. 3.3V nominal. Bypass with a 0.1F capacitor to GND. SMBus Serial-Data Input/Output. Pull up with a 10k resistor. Can be pulled up as high as 5.5V regardless of VCC. High impedance when VCC = 0V. SMBus Serial-Clock Input. Pull up with a 10k resistor. Can be pulled up as high as 5.5V regardless of VCC. High impedance when VCC = 0V. Fan Tachometer Input. Accepts logic-level signal from fan's tachometer output. Can be connected to a supply voltage as high as 12V, regardless of the supply voltage. Fan Driver Output 2. The pullup resistor can be connected to a supply voltage as high as 12V, regardless of the supply voltage. See the PWM Output section for configuration.
MAX6615/MAX6616
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
WRITE BYTE FORMAT S -- ADDRESS 7 BITS WR -- ACK -- COMMAND 8 BITS ACK -- DATA 8 BITS ACK -- P 1
SLAVE ADDRESS: EQUIVALENT TO CHIP-SELECT LINE OF A 3-WIRE INTERFACE READ BYTE FORMAT S -- ADDRESS 7 BITS WR -- ACK -- COMMAND 8 BITS
COMMAND BYTE: SELECTS WHICH REGISTER YOU ARE WRITING TO
DATA BYTE: DATA GOES INTO THE REGISTER SET BY THE COMMAND BYTE (TO SET THRESHOLDS, CONFIGURATION MASKS, AND SAMPLING RATE) RD -- ACK -- DATA 8 BITS /// -- P --
ACK --
S --
ADDRESS 7 BITS
SLAVE ADDRESS: EQUIVALENT TO CHIPSELECT LINE SEND BYTE FORMAT S -- ADDRESS 7 BITS WR -- ACK --
COMMAND BYTE: SELECTS WHICH REGISTER YOU ARE READING FROM COMMAND 8 BITS ACK -- P --
SLAVE ADDRESS: REPEATED DUE TO CHANGE IN DATA- FLOW DIRECTION RECEIVE BYTE FORMAT S -- ADDRESS 7 BITS RD -- ACK --
DATA BYTE: READS FROM THE REGISTER SET BY THE COMMAND BYTE DATA 8 BITS /// -- P --
COMMAND BYTE: SENDS COMMAND WITH NO DATA, USUALLY USED FOR ONE-SHOT COMMAND S = START CONDITION P = STOP CONDITION Figure 1. SMBus Protocols SHADED = SLAVE TRANSMISSION /// = NOT ACKNOWLEDGED
DATA BYTE: READS DATA FROM THE REGISTER COMMANDED BY THE LAST READ BYTE OR WRITE BYTE TRANSMISSION; ALSO USED FOR SMBUS ALERT RESPONSE RETURN ADDRESS
Detailed Description
The MAX6615/MAX6616 accurately monitor two temperature channels, either the internal die temperature and the temperature of an external thermistor, or the temperatures of two external thermistors. They report temperature values in digital form using a 2-wire SMBus/I2C*-compatible serial interface. The MAX6615/ MAX6616 operate from a supply voltage range of 3.0V to 5.5V and consume 500A (typ) of supply current. The temperature data controls the duty cycles of two PWM output signals that are used to adjust the speed of a cooling fan. They also feature an overtemperature alarm output to generate interrupts, throttle signals, or shutdown signals. The MAX6616 also includes six GPIO input/outputs to provide additional flexibility. The GPIO0 power-up state is set by connecting the GPIO PRESET input to ground or VCC.
have nine different slave addresses available; therefore, a maximum of nine MAX6615/MAX6616 devices can share the same bus. The MAX6615/MAX6616 employ four standard SMBus protocols: write byte, read byte, send byte, and receive byte (Figures 1, 2, and 3). The shorter receive byte protocol allows quicker transfers, provided that the correct data register was previously selected by a read byte instruction. Use caution with the shorter protocols in multimaster systems, since a second master could overwrite the command byte without informing the first master. Temperature data can be read from registers 00h and 01h. The temperature data format for these registers is 8 bits, with the LSB representing 1C (Table 1) and the MSB representing 128C. The MSB is transmitted first. All values below 0C clip to 00h. Table 3 details the register address and function, whether they can be read or written to, and the power-on reset
*Purchase of I2C components from Maxim Integrated Products, Inc., or one of its sublicensed Associated Companies, conveys a license under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips.
SMBus Digital Interface
From a software perspective, the MAX6615/MAX6616 appear as a set of byte-wide registers. Their devices use a standard SMBus 2-wire/I2C-compatible serial interface to access the internal registers. The MAX6615/MAX6616
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
A tLOW B tHIGH C D E F G H I J K L M
SMBCLK
SMBDATA
tSU:STA tHD:STA A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE
tSU:DAT E = SLAVE PULLS SMBDATA LINE LOW F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE H = LSB OF DATA CLOCKED INTO SLAVE I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION
tSU:STO
tBUF
Figure 2. SMBus Write Timing Diagram
A
tLOW
B
tHIGH
C
D
E
F
G
H
I
J
K
L
M
SMBCLK
SMBDATA tSU:STA tHD:STA tSU:DAT tHD:DAT F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO MASTER H = LSB OF DATA CLOCKED INTO MASTER I = MASTER PULLS DATA LINE LOW
tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION
A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW
Figure 3. SMBus Read Timing Diagram
(POR) state. See Tables 3-7 for all other register functions and the Register Descriptions section.
Temperature Measurements
The averaging ADC integrates over a 120ms period (each channel, typically), with excellent noise rejection. For internal temperature measurements, the ADC and associated circuitry measure the forward voltage of the internal sensing diode at low- and high-current levels and compute the temperature based on this voltage. For thermistor measurements, the reference voltage and the thermistor voltage are measured and offset is applied to yield a value that correlates well to thermistor temperature within a wide temperature range. Both channels are automatically converted once the conversion process has started. If one of the two channels is not used, the circuit still performs both measurements, and the data from the unused channel may be ignored. If either of the measured temperature values is below
0, the value in the corresponding temperature register is clipped to zero when a negative offset is programmed into the thermistor offset register (17h). Local (internal) temperature data is expressed directly in degrees Celsius. Two registers contain the temperature data for the local channel. The high-byte register has an MSB of 128C and an LSB of 1C. The low- byte register contains 3 bits, with an MSB of 0.5C and an LSB of 0.125C. The data format is shown in Table 1. Thermistors allow measurements of external temperatures. Connect a thermistor in series with a resistor, REXT. The thermistor should be connected between the TH_ input and ground, and REXT should be connected between the reference output, REF, and the TH_ input, as shown in the Typical Application Circuit. The voltage across R EXT is measured by the ADC, resulting in a value that is directly related to tempera7
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Table 1. Temperature Data Format (High Byte and Low Byte)
TEMPERATURE (C) 140.0 127.0 25.375 25.0 0.5 0.0 <0 HIGH BYTE BINARY VALUE 1000 1100 0111 1111 0001 1001 0001 1001 0000 0000 0000 0000 0000 0000 HEX VALUE 8Ch 7Fh 19h 19h 00h 00h 00h 0000 0000 0000 0000 0110 0000 0000 0000 1000 0000 0000 0000 0000 0000 LOW BYTE BINARY VALUE HEX VALUE 00h 00h 60h 00h 80h 00h 00h
ture. The thermistor data in the temperature register(s) gives the voltage across REXT as a fraction of the reference voltage. The LSB of the high byte has a nominal weight of 7.68mV.
produces a full-scale output voltage when PWM = 0V, bit D4 in register 02h should be set to zero. 3) PWM_ directly drives the logic-level PWM speedcontrol input on a fan that has this type of input. This approach requires fewer external components and combines the efficiency of (1) with the low noise of (2). An example of PWM_ driving a fan with a speedcontrol input is shown in Figure 6. Bit D4 in register 02h should be set to 1 when this configuration is used. Whenever the fan has to start turning from a motionless state, PWM_ is forced high for 2s. After this spin-up period, the PWM_ duty cycle settles to the predetermined value. Whenever spin-up is disabled (bit 2 in the configuration byte = 1) and the fan is off, the duty cycle changes immediately from zero to the nominal value, ignoring the duty-cycle rate-of-change setting. The frequency-select register controls the frequency of the PWM signal. When the PWM signal modulates the power supply of the fan, a low PWM frequency (usually 33Hz) should be used to ensure the circuitry of the
VCC 5V
OT Output
The OT output asserts when a thermal fault occurs, and can therefore be used as a warning flag to initiate system shutdown, or to throttle clock frequency. When temperature exceeds the OT temperature threshold and OT is not masked, the OT status register indicates a fault and OT output becomes asserted. If OT for the respective channel is masked off, the OT status register continues to be set, but the OT output does not become asserted. The fault flag and the output can be cleared by reading the OT status register. The OT output can also be cleared by masking the affected channel. If the OT status bit is cleared, OT reasserts on the next conversion if the temperature still exceeds the OT temperature threshold.
PWM Output
The PWM_ signals are normally used in one of three ways to control the fan's speed: 1) PWM_ drives the gate of a MOSFET or the base of a bipolar transistor in series with the fan's power supply. The Typical Application Circuit shows the PWM_ driving an n-channel MOSFET. In this case, the PWM invert bit (D4 in register 02h) is set to 1. Figure 4 shows PWM_ driving a p-channel MOSFET and the PWM invert bit must be set to zero. 2) PWM_ is converted (using an external circuit) into a DC voltage that is proportional to duty cycle. This duty-cycle-controlled voltage becomes the power supply for the fan. This approach is less efficient than (1), but can result in quieter fan operation. Figure 5 shows an example of a circuit that converts the PWM signal to a DC voltage. Because this circuit
8
10k PWM P
Figure 4. Driving a p-Channel MOSFET for Top-Side PWM Fan Drive
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs
+12V
500k
+3.3V 18k PWM 1F 10k
0.01F 120k VOUT TO FAN
1F
0.1F
27k +3.3V
Figure 5. Driving a Fan with a PWM-to-DC Circuit
VCC 5V
corresponding fan. The value is clipped to a maximum of 240. Any value entered above that is changed to 240 automatically. In this control mode, the value in the maximum duty-cycle register is ignored and does not affect the duty cycle used to control the fan. Automatic PWM Duty-Cycle Control In the automatic control mode, the duty cycle is controlled by the local or remote temperature according to the settings in the control registers. Below the fan-start temperature, the duty cycle is either 0% or is equal to the fan-start duty cycle, depending on the value of bit D3 in the configuration byte register. Above the fanstart temperature, the duty cycle increases by one duty-cycle step each time the temperature increases by one temperature step. The target duty cycle is calculated based on the following formula; for temperature > FanStartTemperature: DC = FSDC + (T - FST) x where: DC = DutyCycle FSDC = FanStartDutyCycle T = Temperature FST = FanStartTemperature DCSS = DutyCycleStepSize TS = TempStep Duty cycle is recalculated after each temperature conversion if temperature is increasing. If the temperature begins to decrease, the duty cycle is not recalculated until the temperature drops by 5C from the last peak temperature. The duty cycle remains the same until the temperature drops 5C from the last peak temperature or the temperature rises above the last peak temperature. For example, if the temperature goes up to +85C and starts decreasing, duty cycle is not recalculated until the temperature reaches +80C or the temperature rises above +85C. If the temperature decreases further, the duty cycle is not updated until it reaches +75C. For temperature < FanStartTemperature and D2 of configuration register = 0: DutyCycle = 0 For temperature < FanStartTemperature and D2 of configuration register = 1: DutyCycle = FanStartDutyCycle Once the temperature crosses the fan-start temperature threshold, the temperature has to drop below the fanstart temperature threshold minus the hysteresis before
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MAX6615/MAX6616
DCSS TS
4.7k PWM
Figure 6. Controlling a PWM Input Fan with the MAX6615/ MAX6616s' PWM Output (Typically, the 35kHz PWM Frequency Is Used)
brushless DC motor has enough time to operate. When driving a fan with a PWM-to-DC circuit as shown in Figure 5, the highest available frequency (35kHz) should be used to minimize the size of the filter capacitors. When using a fan with a PWM control input, the frequency normally should be high as well, although some fans have PWM inputs that accept low-frequency drive. The duty cycle of the PWM can be controlled in two ways: 1) Manual PWM control: setting the duty cycle of the fan directly through the fan target duty-cycle registers (0Bh and 0Ch). 2) Automatic PWM control: setting the duty cycle based on temperature. Manual PWM Duty-Cycle Control Clearing the bits that select the temperature channels for fan control (D5 and D4 for PWM1 and D3 and D2 for PWM2) in the fan-configuration register (11h) enables manual fan control. In this mode, the duty cycle written to the fan target duty-cycle register directly controls the
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Fan-Fail
When the fan tachometer count is larger than the fan tachometer limit, the fan is considered failing. The MAX6615/MAX6616 PWM_ drives the fan with 100% duty cycle for about 2s immediately after detecting a fan-fail. At the end of that period, another measurement is initiated. If the fan fails both measurements, the FAN_FAIL bit, as well as the FAN_FAIL output, assert if the pin is not masked. If the fan fails only the first measurement, the fan goes back to normal settings. If one fan fails, it can be useful to drive the other fan with 100% duty cycle. This can be enabled with bit D0 of the fan-status register (1Ch).
DUTY CYCLE REGISTER 02h, BIT D3 = 1 FAN-START DUTY CYCLE TEMP STEP REGISTER 02h, BIT D3 = 0 TEMPERATURE FAN-START TEMPERATURE DUTY-CYCLE STEP SIZE
Slave Addresses
Figure 7. Automatic PWM Duty Control
the duty cycle returns to either 0% or the fan-start duty cycle. The value of the hysteresis is set by D7 of the fan-configuration register. The duty cycle is limited to the value in the fan maximum duty-cycle register. If the duty-cycle value is larger than the maximum fan duty cycle, it is set to the maximum fan-duty cycle as in the fan maximum duty-cycle register. The temperature step is bit D6 of the fan-configuration register (0Dh). Notice if temperature crosses FanStartTemperature going up with an initial DutyCycle of zero, a spin-up of 2s applies before the duty-cycle calculation controls the value of the fan's duty cycle. FanStartTemperature for a particular channel follows the channel, not the fan. If DutyCycle is an odd number, it is automatically rounded down to the closest even number. Duty-Cycle Rate-of-Change Control To reduce the audibility of changes in fan speed, the rate of change of the duty cycle is limited by the values set in the duty-cycle rate-of-change register. Whenever the target duty cycle is different from the instantaneous duty cycle, the duty cycle increases or decreases at the rate determined by the duty-cycle rate-of-change byte until it reaches the target duty cycle. By setting the rate of change to the appropriate value, the thermal requirements of the system can be balanced against good acoustic performance. Slower rates of change are less noticeable to the user, while faster rates of change can help minimize temperature variations. Remember that the fan controller is part of a complex control system. Because several of the parameters are generally not known, some experimentation may be necessary to arrive at the best settings.
The MAX6615/MAX6616 appear to the SMBus as one device having a common address for both ADC channels. The devices' address can be set to one of nine different values by pinstrapping ADD0 and ADD1 so that more than one MAX6615/MAX6616 can reside on the same bus without address conflicts (see Table 2). The address input states are checked regularly, and the address data stays latched to reduce quiescent supply current due to the bias current needed for highimpedance state detection.
Power-On Defaults
At power-on, or when the POR bit in the configuration byte register is set, the MAX6615/MAX6616 have the default settings indicated in Table 3. Some of these settings are summarized below: * * * * * * * Temperature conversions are active. Channel 1 and channel 2 are set to report the remote temperature channel measurements. Channel 1 OT limit = +110C. Channel 2 OT limit = +80C. Manual fan mode. Fan duty cycle = 0. PWM invert bit = 0.
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs
Table 2. Slave Address Decoding (ADD0 and ADD1)
ADDO GND GND GND High-Impedance High-Impedance High-Impedance VCC VCC VCC ADD1 GND High-Impedance VCC GND High-Impedance VCC GND High-Impedance VCC ADDRESS 0011 000 0011 001 0011 010 0101 001 0101 010 0101 011 1001 100 1001 101 1001 110
Register Descriptions
The MAX6615/MAX6616 contain 32/34 internal registers. These registers store temperature data, allow control of the PWM outputs, determine if the devices are measuring from the internal die or the thermistor inputs, and set the GPIO as inputs or outputs. Temperature Registers (00h and 01h) The temperature registers contain the results of temperature measurements. The value of the MSB is 128C and the value of the LSB is 1C. Temperature data for thermistor channel 1 is in the temperature channel 1 register (00h). Temperature data for thermistor channel 2 (01h) or the local sensor (selectable by bit D2 in the configuration byte) is in the temperature channel 2 register. Configuration Byte (02h) The configuration byte register controls timeout conditions and various PWM signals. The POR state of the configuration byte register is 18h. See Table 4 for configuration byte definitions. Channel 1 and Channel 2 OT Limits (03h and 04h) Set channel 1 (03h) and channel 2 (04h) temperature thresholds with these two registers. Once the temperature is above the threshold, the OT output is asserted low (for the temperature channels that are not masked). The POR state of the channel 1 OT limit register is 6Eh, and the POR state of the channel 2 OT limit register is 50h.
MAX6615/MAX6616
Note: High-Impedance means that the pin is left unconnected and floating.
GPIO Inputs/Outputs and Preset (MAX6616)
The MAX6616 has six GPIO ports. GPIO0 has a POR control pin (PRESET). When PRESET is connected to GND at POR, GPIO0 is configured as an output and is low. When PRESET is connected to VCC at POR, GPIO0 is configured as an input. Since GPIO0 is a highimpedance node in this state, it can be connected to a pullup resistor and also serve as an output (high). The rest of the GPIO ports, GPIO5-GPIO1, are configured as high-impedance outputs after power-on, so they will be in the high state if connected to pullup resistors. All GPIOs are at their preset values within 1ms of powerup. During power-up, GPIO1 and GPIO2 are low while the remaining GPIOs go into high-impedance state. Figure 8 shows the states of the GPIO lines during power-up. After power has been applied to the MAX6616, the GPIO functions can be changed through the SMBus interface.
OT Status (05h)
A 1 in D7 or D6 indicates that an OT fault has occurred in the corresponding temperature channel. Only reading its contents clears this register. Reading the contents of the register also clears the OT output. If the fault is still present on the next temperature measurement cycle, the bits and the OT output are set again. The POR state of the OT status register is 00h.
OT Mask (06h)
Set bit D7 to 1 in the OT mask register to prevent the OT output from asserting on faults in channel 1. Set bit D6 to 1 to prevent the OT output from asserting on faults in channel 2. The POR state of the OT mask register is 00h. PWM Start Duty Cycle (07h and 08h) The PWM start duty-cycle register determines the PWM duty cycle where the fan starts spinning. Bit D2 in the configuration byte register (MIN DUTY CYCLE) determines the starting duty cycle. If the MIN DUTY CYCLE bit is 1, the duty cycle is the value written to the fanstart duty-cycle register at all temperatures below the fan-start temperature. If the MIN DUTY CYCLE bit is
VCC POR (INTERNAL) STATE DETERMINED BY PRESET HIGH-IMPEDANCE STATE HIGH-IMPEDANCE STATE
GPIO0 GPIO1, GPIO2 GPIO3, GPIO4, GPIO5 1ms
Figure 8. Power-On GPIO States
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11
Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Table 3. Register Map
R/W ADD R R 00h 01h POR STATE 0000 0000 0000 0000 FUNCTION Temperature channel 1 Temperature channel 2 D7 MSB (128C) MSB (128C) Standby: 0 = run; 1= standby D6 -- -- D5 -- -- Timeout: 0= enabled; 1= disabled D4 -- -- D3 -- -- D2 -- -- Min duty cycle: 0 = 0%; 1 = fan-start duty cycle -- D1 -- -- Temp Ch2 sources: 1 = local; 0= remote2 -- D0 LSB (1C) LSB (1C) Spin-up disable: 0 = enable; 1= disable
R/W
02h
0001 1000
Configuration byte
POR: 1 = reset
Fan 1 PWM invert
Fan 2 PWM invert
R/W
03h
0110 1110 0101 0000 00xx xxxx 00xx xxxx 0110 000x 96 = 40% 0110 000x 96 = 40% 1111 000x 240 = 100% 1111 000x 240 = 100% 0000 000x 0000 000x
Temperature channel 1 OT limit Temperature channel 2 OT limit OT status
MSB
--
--
--
--
LSB (1C)
R/W
04h
MSB
-- Channel 2: 1 = fault Channel 2: 1 = masked
--
--
--
--
--
LSB (1C)
R
05h
Channel 1: 1 = fault Channel 1: 1= masked MSB (128/240)
--
--
--
--
--
--
R/W
06h
OT mask
--
--
--
--
--
--
R/W
07h
PWM1 start duty cycle
--
--
--
--
--
LSB (2/240)
--
R/W
08h
PWM2 start duty cycle
MSB (128/240)
--
--
--
--
--
LSB (2/240)
--
R/W
09h
PWM1 max duty cycle
MSB (128/240)
--
--
--
--
--
LSB (2/240)
--
R/W
0Ah
PWM2 max duty cycle
MSB (128/240)
--
--
--
--
--
LSB (2/240)
--
R/W
0Bh
PWM1 target duty cycle PWM2 target duty cycle
MSB (128/240) MSB (128/240)
--
--
--
--
--
LSB (2/240) LSB (2/240)
--
R/W
0Ch
--
--
--
--
--
--
12
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Table 3. Register Map (continued)
R/W ADD POR STATE 0000 000x FUNCTION PWM1 instantaneous duty cycle PWM2 instantaneous duty cycle Channel 1 fan-start temperature Channel 2 fan-start temperature Fan configuration Duty-cycle rate of change Duty-cycle step size PWM frequency select GPIO function D7 D6 D5 D4 D3 D2 D1 D0
R
0Dh
MSB (128/240)
--
--
--
--
--
LSB (2/240)
--
R
0Eh
0000 000x
MSB (128/240)
--
--
--
--
--
LSB (2/240)
--
R/W
0Fh
0000 0000 0000 0000 0000 000x 1011 01xx 0101 0101 010x xxxx
MSB
--
--
--
--
--
--
LSB
R/W
10h
MSB Hysteresis: 0 = 5C, 1 = 10C Fan 1 MSB
-- Temp step: 0 = 1C, 1 2C --
-- Fan 1: control 1 = Ch 1 Fan 1 LSB --
-- Fan 1: control 1 = Ch 2 Fan 2 MSB Fan 1 LSB -- GPIO4: 0= output; 1 = input GPIO4
-- Fan 2: control 1 = Ch 1 -- Fan 2 MSB -- GPIO3: 0= output; 1 = input GPIO3
-- Fan 2: control 1 = Ch 2 Fan 2 LSB --
--
LSB
R/W
11h
--
--
R/W
12h
--
-- Fan 2 LSB -- GPIO0: 0= output; 1 = input GPIO0
R/W
13h
Fan 1 MSB
--
--
R/W
14h
Select A
Select B
Select C GPIO5: 0= output; 1 = input GPIO5
-- GPIO2: 0= output; 1 = input GPIO2
-- GPIO1: 0= output; 1 = input GPIO1
R/W
15h
xx00 000* xx11 111* (Note 1) 0000 0000 1111 1111 1111 1111 1111 1111 1111 1111
--
--
R/W
16h
GPIO value Thermistor offset register Tach1 value register Tach2 value register Tach1 limit register Tach2 limit register
--
--
R/W
17h
Th1 MSB (sign) -- -- -- --
--
--
Th1 LSB (2C) -- -- -- --
Th2 MSB (sign) -- -- -- --
--
--
Th2 LSB (2C) -- -- -- --
R R R/W R/W
18h 19h 1Ah 1Bh
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
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13
Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Table 3. Register Map (continued)
R/W ADD POR STATE FUNCTION D7 D6 D5 1= disabled fan 1 tach LSB (1/8C) LSB (1/8C) 0 1 D4 D3 D2 D1 D0 1 = fan 1 fail sets fan 2 100% -- -- 1 0
R/W
1Ch
0000 0000
Fan status byte
1 = fan 1 failure
1 = fan 2 failure
1= disabled fan 2 tach
1= 1= measure measure fan 1 fan 2 when it is when it is full speed full speed -- -- 0 1 -- -- 0 0
1 = mask FAN_FAIL pin
R R R R
1Eh 1Fh FDh FEh
0000 0000 0000 0000 0000 0001 0110 1000 0100 1101
Channel 1 temp LSBs Channel 2 temp LSBs Read device revision Read device ID Read manufacturer ID
MSB (1/2C) MSB (1/2C) 0 0
-- -- 0 1
-- -- 0 0
-- -- 0 0
R
FFh
0
1
0
0
1
1
0
1
*GPIO0 POR values are set by PRESET.
Table 4. Configuration Byte Definition (02h)
BIT 7 6 5 4 3 NAME RUN/STANDBY POR TIMEOUT FAN1 PWM INVERT FAN2 PWM INVERT POR STATE 0 0 0 1 1 FUNCTION Set to zero for normal operation. Set to 1 to suspend conversions and PWM outputs. Set to 1 to perform reset of all device registers. Set TIMEOUT to zero to enable SMBus timeout for prevention of bus lockup. Set to 1 to disable this function. Set fan PWM invert to zero to force PWM1 low when the duty cycle is 100%. Set to 1 to force PWM1 high when the duty cycle is 100%. Set fan PWM invert to zero to force PWM2 low when the duty cycle is 100%. Set to 1 to force PWM2 high when the duty cycle is 100%. Set min duty cycle to zero for a 0% duty cycle when the measured temperature is below the fan-temperature threshold in automatic mode. When the temperature equals the fantemperature threshold, the duty cycle is the value in the fan-start duty-cycle register, and it increases with increasing temperature. Set min duty cycle to 1 to force the PWM duty cycle to the value in the fan-start duty-cycle register when the measured temperature is below the fan-temperature threshold. As the temperature increases above the temperature threshold, the duty cycle increases as programmed. Selects either local or remote 2 as the source for temperature channel 2 register data. When D1 = 0, the MAX6615/MAX6616 measure remote 2 and when D1 = 1, the MAX6615/MAX6616 measure the internal die temperature. Set spin-up disable to 1 to disable spin-up. Set to zero for normal fan spin-up.
2
MIN DUTY CYCLE
0
1 0
TEMPERATURE SOURCE SELECT SPIN-UP DISABLE
0 0
14
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Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs
zero, the duty cycle is zero below the fan-start temperature and has this value when the fan-start temperature is reached. A value of 240 represents 100% duty cycle. Writing any value greater than 240 causes the fan speed to be set to 100%. The POR state of the fan-start duty-cycle register is 96h, 40%. PWMOUT Max Duty Cycle (09h and 0Ah) The PWM maximum duty-cycle register sets the maximum allowable PWM duty cycle between 2/240 (0.83% duty cycle) and 240/240 (100% duty cycle). Any values greater than 240 are recognized as 100% maximum duty cycle. The POR state of the PWM maximum dutycycle register is F0h, 100%. In manual-control mode, this register is ignored. PWM Target Duty Cycle (0Bh and 0Ch) In automatic fan-control mode, this register contains the present value of the target PWM duty cycle, as determined by the measured temperature and the dutycycle step size. The actual duty cycle requires time before it equals the target duty cycle if the duty-cycle rate-of-change register is set to a value other than zero. In manual fan-control mode, write the desired value of the PWM duty cycle directly into this register. The POR state of the fan-target duty-cycle register is 00h. PWM1 Instantaneous Duty Cycle, PWM2 Instantaneous Duty Cycle (0Dh, 0Eh) These registers always contain the duty cycle of the PWM signals presented at the PWM output. The POR state of the PWM instantaneous duty-cycle register is 00h. Channel 1 and Channel 2 Fan-Start Temperature (0Fh and 10h) These registers contain the temperatures at which fan control begins (in automatic mode). See the Automatic PWM Duty-Cycle Control section for details on setting the fan-start thresholds. The POR state of the channel 1 and channel 2 fan-start temperature registers is 00h. Fan Configuration (11h) The fan-configuration register controls the hysteresis level, temperature step size, and whether the remote or local diode controls the PWM2 signal (see Table 3). Set bit D7 of the fan-configuration register to zero to set the hysteresis value to 5C. Set bit D7 to 1 to set the hysteresis value to 10C. Set bit D6 to zero to set the fancontrol temperature step size to 1C. Set bit D6 to 1 to set the fan-control temperature step size to +2C. Bits D5 to D2 select which PWM_ channel 1 or channel 2 controls (see Table 3). If both are selected for a given PWM_, the highest PWM value is used. If neither is selected, the fan is controlled by the value written to the fan-target duty-cycle register. Also in this mode, the value written to the target duty-cycle register is not limited by the value in the maximum duty-cycle register. It is, however, clipped to 240 if a value above 240 is written. The POR state of the fan-configuration register is 00h. Duty-Cycle Rate of Change (12h) Bits D7, D6, and D5 (channel 1) and D4, D3, and D2 (channel 2) of the duty-cycle rate-of-change register set the time between increments of the duty cycle. Each increment is 2/240 of the duty cycle (see Table 5). This allows the time from 33% to 100% duty cycle to be adjusted from 5s to 320s. The rate-of-change control is always active in manual mode. To make instant changes, set bits D7, D6, and D5 (channel 1) or D4, D3, and D2 (channel 2) = 000. The POR state of the duty-cycle rateof-change register is B4h (1s between increments).
MAX6615/MAX6616
Table 5. Setting the Time Between DutyCycle Increments
D7:D5, D4:D2 000 001 010 011 100 101 110 111 TIME BETWEEN INCREMENTS (s) 0 0.0625 0.125 0.25 0.5 1 2 4 TIME FROM 33% TO 100% (s) 0 5 10 20 40 80 160 320
Table 6. Setting the Duty-Cycle Step Size
CHANGE IN DUTY CYCLE PER TEMPERATURE STEP 0 2/240 4/240 6/240 8/240 10/240 ... 16/240 ... 31/240 TEMPERATURE RANGE FOR FAN CONTROL (1C STEP, 33% TO 100%) 0 80 40 27 20 16 ... 10 ... 5
D7:D4, D3:D0
0000 0001 0010 0011 0100 0101 ... 1000 ... 1111
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15
Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Table 7. PWM Frequency Select
PWM FREQUENCY (Hz) 20 33 50 100 35k SELECT A 0 0 1 1 X SELECT B 0 1 0 1 X SELECT C 0 0 0 0 1
The MSB is the sign bit and the LSB is 2C. The POR state for this register is 00h.
Tachometer Value Registers (18h and 19h)
The tachometer value registers contain the tachometer count values for each fan. The MAX6615/MAX6616 measure the tachometer signal every 67s. It counts the number of clock cycles between two tachometer pulses and stores the value in the corresponding channel register. The POR state of this register is 00h.
Note: At 35kHz, duty-cycle resolution is decreased from a resolution of 2/240 to 4/240.
Tachometer Limit Registers (1Ah and 1Bh)
The tachometer limit registers contain the tachometer limits for each fan. If the value in the tach1 value register (18h) ever exceeds the value stored in 1Ah, a channel 1 fan failure is detected. If the value in the Tach2 value register (19h) ever exceeds the value stored in 1Bh, a channel 2 fan failure is detected. The POR state of these registers is 00h.
Duty-Cycle Step Size (13h) Bits D7-D4 (channel 1) and bits D3-D0 (channel 2) of the duty-cycle step-size register change the size of the dutycycle change for each temperature step. The POR state of the duty-cycle step-size register is 55h (see Table 6). PWM Frequency Select (14h) Set bits D7, D6, and D5 (select A, B, and C) in the PWM frequency-select register to control the PWM frequency (see Table 7). The POR state of the PWM frequencyselect register is 40h, 33Hz. The lower frequencies are usually used when driving the fan's power-supply pin as in the Typical Application Circuit, with 33Hz being the most common choice. The 35kHz frequency setting is used for controlling fans that have logic-level PWM input pins for speed control. The minimum duty-cycle resolution is decreased from 2/240 to 4/240 at the 35kHz frequency setting. For example, a result that would return a value of 6/240 is truncated to 4/240.
Fan Configuration/Status Register (1Ch)
The fan configuration/status register contains the status and tachometer control bits for both fans. Bits D7 and D6 indicate whether a fan has failed the maximum tachometer limits in registers 1Ah and 1Bh. Setting bits D5 and D4 disables the tachometer for each fan. The speed is not measured when these bits are set. Setting bits D3 and D2 measure the fan speed only during spin-up or when it reaches 100% duty cycle. Bit D1 is the FAN_FAIL output mask. Bit D0 is the FAN_FAIL cross drive enable. Setting this bit enables fan 2 to go to full speed when fan 1 fails or vice versa.
GPIO Function Register (15h) (MAX6616)
The GPIO function register (15h) sets the GPIO states. Write a zero to set a GPIO as an output. Write a 1 to set a GPIO as an input.
Extended Temperature Registers (1Eh and 1Fh)
The extended temperature registers contain the low-byte results of temperature measurements. The value of the MSB is 0.5C and the value of D5 is 0.125C. The POR states of these registers are 00h.
GPIO Value Register (16h) (MAX6616)
The GPIO value register (16h) contains the state of each GPIO input when a GPIO is configured as an input. When configured as an output, write a 1 or zero to set the value of the GPIO output.
Thermistor Offset Register (17h)
The thermistor offset register contains the offset for both of the thermistors in two's complement. Bits D7, D6, D5, and D4 set the offset for temperature channel 1. Bits D3, D2, D1, and D0 set the offset for temperature channel 2. The values in this register allow the thermistor temperature readings to be shifted to help compensate for different thermistor characteristics or different values of REXT and apply to thermistor measurements only.
16 ______________________________________________________________________________________
Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
MAX6615/MAX6616 ERROR
4 OPTIMIZED FOR +30C TO +100C 2 MEASUREMENT (C) 0 ERROR (C) -2 -4 -6 -8 -10 -12 0 20 40 100 80 TEMPERATURE (C) 60 120 140 20 0 -50 0 50 TEMPERATURE (C) 100 150 100 80 60 40 120
MEASUREMENT vs. TEMPERATURE
Figure 9. Data Error vs. Temperature Using a Betatherm 10K3A1 Thermistor
Figure 10. Measured Temperature vs. Actual Temperature
Applications Information
Thermistor Considerations
NTC thermistors are resistive temperature sensors whose resistance decreases with increasing temperature. They are available in a wide variety of packages that are useful in difficult applications such as measurement of air or liquid temperature. Some can operate over temperature ranges beyond that of most ICs. The relationship between temperature and resistance in an NTC thermistor is very nonlinear and can be described by the following approximation: 1 = A + B In(R) + C[In(R)]3 T where T is absolute temperature in Kelvin, R is the thermistor's resistance, and A, B, and C are coefficients that vary with manufacturer and material characteristics. The highly nonlinear relationship between temperature and resistance in an NTC thermistor makes it somewhat more difficult to use than a digital-output temperaturesensor IC. However, by connecting the thermistor in series with a properly chosen resistor and using the MAX6615/MAX6616 to measure the voltage across the resistor, a reasonably linear transfer function can be obtained over a limited temperature range. Accuracy increases over smaller temperature ranges. Figures 9 and 10 show a good relationship between temperature and data. This data was taken using a popular thermistor model, the Betatherm 10K3A1, with REXT = 1.6k. Using these values produces data with
good conformance to real temperature over a range of about +30C to +100C. Different combinations of thermistors and REXT result in different curves.
ADC Noise Filtering
The integrating ADC has inherently good noise rejection, especially at low-frequency signals such as 60Hz/120Hz power-supply hum. Lay out the PC board carefully with proper external noise filtering for highaccuracy thermistor measurements in electrically noisy environments. Filter high-frequency electromagnetic interference (EMI) at TH_ and REF with an external 100pF capacitor connected between the two inputs. This capacitor can be increased to about 2000pF (max), including cable capacitance. A capacitance higher than 2000pF introduces errors due to the rise time of the switched current source.
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
17
Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Pin Configurations
TOP VIEW
PWM1 1 TACH1 2 ADD0 3 ADD1 4 GND 5 TH1 6 REF 7 TH2 8 16 PWM2 15 TACH2 14 SCL GPIO2 1 GPIO1 2 PWM1 3 TACH1 4 GPIO0 5 ADD0 6 ADD1 7 GND 8 TH1 9 24 GPIO3 23 GPIO4 22 PWM2 21 TACH2
MAX6615
13 SDA 12 VCC 11 OT 10 GND 9 FAN_FAIL
MAX6616
20 GPIO5 19 SCL 18 SDA 17 VCC 16 OT 15 N.C. 14 PRESET 13 FAN_FAIL
QSOP
N.C. 10 REF 11 TH2 12
QSOP
Typical Application Circuits
VCC VFAN (5V OR 12V) 10k 3.0V TO 5.5V 4.7k BETATHERM 10K3A1 TH1 THERMISTOR 1.6k 100pF REF BETATHERM 10K3A1 1.6k 100pF TH2 THERMISTOR TO SMBus MASTER SCL OT GND(5) GND(10) ADD0 ADD1 TACH2 SDA VCC 10k TO CLOCK THROTTLE OR SYSTEM SHUTDOWN VCC FAN_FAIL PWM1 VFAN VFAN (5V OR 12V)
VFAN
MAX6615
TACH1 PWM2 4.7k
18
______________________________________________________________________________________
Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs
Typical Application Circuits (continued)
VCC VFAN (5V OR 12V) 10k 3.0V TO 5.5V 4.7k BETATHERM 10K3A1 TH1 THERMISTOR 1.6k 100pF REF BETATHERM 10K3A1 1.6k 100pF TH2 THERMISTOR TO SMBus MASTER SCL OT VCC 10k GPIO0 VCC 10k GPIO1 VCC 10k GPIO2 PRESET GND GPIO5 GPIO4 VCC 10k GPIO3 VCC 10k VCC TACH2 SDA VCC 10k TO CLOCK THROTTLE OR SYSTEM SHUTDOWN VCC FAN_FAIL PWM1 VFAN VFAN (5V OR 12V)
MAX6615/MAX6616
VFAN
MAX6616
TACH1 PWM2 4.7k
10k
ADD0 ADD1
______________________________________________________________________________________
19
Dual-Channel Temperature Monitors and Fan-Speed Controllers with Thermistor Inputs MAX6615/MAX6616
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
QSOP.EPS
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
21-0055
E
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

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