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FEATURES Superior Upgrade for MAX1232 and Dallas DS1232 Low Power Consumption (500 A max) Adjustable Precision Voltage Monitor with +4.5 V and +4.75 V Options Adjustable STROBE Monitor with 150 ms, 600 ms or 1.2 sec Options No External Components Fast (20 ns) Strobe Pulsewidth APPLICATIONS Microprocessor Systems Portable Equipment Computers Controllers Intelligent Instruments Automotive Systems Protection Against Damage Caused by
VCC TOLERANCE 5%/10% TOLERANCE SELECT
Microprocessor Supervisory Circuit ADM1232A
FUNCTIONAL BLOCK DIAGRAM
RESET RESET GENERATOR RESET PB RESET DEBOUNCE WATCHDOG TIMEBASE SELECT WATCHDOG TIMER STROBE
VREF
TD
GND
ADM1232A
P Failure
GENERAL DESCRIPTION
+5V
The ADM1232A is a superior, pin-compatible upgrade for the MAX1232 and the DS1232LP and DS1232. The ADM1232A can detect strobe pulsewidths as narrow as 20 ns, making it compatible with high speed microprocessors. The Analog Devices ADM1232A is a microprocessor monitoring circuit that can monitor: 1. Microprocessor Supply Voltage. 2. Whether a Microprocessor has locked up. 3. An External Interrupt. The ADM1232A is available in four different packages: 1. 2. 3. 4. The ADM1232AARM in an 8-lead SOIC (RM-8). The ADM1232AAN in an 8-lead PDIP (N-8). The ADM1232AARW in a 16-lead wide SOIC (R-16). The ADM1232AARN is an 8-lead narrow SOIC (R-8).
+5V
10k
ADM1232A
ADM1232 RESET STROBE STROBE RESET GND TD TOLERANCE TOLERANCE
MICROPROCESSOR
I/O RESET
Figure 1. Typical Supply Monitoring Application
REV. 0
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., 1999
ADM1232A-SPECIFICATIONS (V
Parameter
TEMPERATURE POWER SUPPLY Voltage Current STROBE AND PB RESET INPUTS Input High Level Input Low Level INPUT LEAKAGE CURRENT (STROBE, TOLERANCE) TD OUTPUT CURRENT RESET RESET, RESET OUTPUT VOLTAGE RESET/RESET Min -40 4.5
CC
= Full Operating Range, TA = TMIN to TMAX unless otherwise noted)
Max +85 Units C V A A V V A A mA mA V When V CC Is at 4.5 V-5.5 V When V CC Is at 4.5 V-5.5 V While sourcing less than 500 A, RESET remains within 0.5 V of V CC on power-down until VCC drops below 2.0 V. While sinking less than 500 A, RESET remains within 0.5 V of GND on power-down until V CC drops below 2.0 V. Test Conditions/Comments TA = TMIN to TMAX
Typ
5.0 20 200
5.5 50 500 VCC + 0.3 +0.8 +1.0
VIL , VIH = CMOS Levels VIL , VIH = TTL Levels
2.0 -0.3 -1.0 1.6 8 -8 10 -12
VCC - 0.5 VCC - 0.1
RESET/RESET High Level RESET/RESET Low Level 1 V OPERATION RESET Output Voltage RESET Output Voltage VCC TRIP POINT 5% 10% CAPACITANCE Input (STROBE, TOLERANCE) Output (RESET, RESET) PB RESET Time Delay RESET ACTIVE TIME STROBE Pulsewidth Timeout Period
0.4 2.4 VCC - 0.1 0.1 4.5 4.25 4.62 4.37 4.74 4.49 5 7 20 1 250 20 62.5 250 500 10 0 50 250 610 1000
V V V V V V pF pF ms ms ms ns ms ms ms S S s ms While Sourcing Less than 50 A While Sinking Less than 50 A TOLERANCE = GND TOLERANCE = VCC TA = +25C TA = +25C PB RESET Must Be Held Low for a Minimum of 20 ms to Guarantee a Reset
4 610
20 1000
150 600 1200
250 1000 2000
TD = 0 V TD = Floating TD = VCC Guaranteed by Design Guaranteed by Design After VCC Falls Below the Set Tolerance Voltage (Figure 5) After VCC Rises Above the Set Tolerance Voltage
VCC Fall Time Rise Time VCC FAIL DETECT TO RESET OUTPUT DELAY RESET AND RESET Are Logically Correct
Specifications subject to change without notice.
-2-
REV. 0
ADM1232A
ABSOLUTE MAXIMUM RATINGS*
(TA = +25C unless otherwise noted)
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +5.5 V Logic Inputs . . . . . . . . . . . . . . . . . . . . . -0.3 V to VCC + 0.3 V Storage Temperature Range . . . . . . . . . . . . -65C to +150C Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300C Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215C Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220C N-8 Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 mW Derate by 13.5 mW/C above 25C JA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 100C/W R-16 Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 mW Derate by 12 mW/C above 25C JA Thermal Impedance (Still Air) . . . . . . . . . . . . . . 73C/W
RM-8 Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 mW Derate by 12 mW/C above 25C JA Thermal Impedance (Still Air) . . . . . . . . . . . . . 206C/W R-8 Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 W Derate by 12 mW/C above 25C JA Thermal Impedance (Still Air) . . . . . . . . . . . . . 153C/W
*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 listed in the operational sections of this specification is not implied. Exposure to absolute maximum ratings for extended periods of time may affect device reliability.
ORDERING GUIDE
Model ADM1232AARM ADM1232AAN ADM1232AARW ADM1232AARN
Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C
Package Options* RM-8 N-8 R-16 R-8
*N = Plastic DIP; R = Small Outline; RM = SOIC.
CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADM1232A features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
REV. 0
-3-
ADM1232A
PIN FUNCTION DESCRIPTIONS
Mnemonic PB RESET TD
Function Push Button Reset Input. This debounced input will ignore pulses of less than 1 ms and is guaranteed to respond to pulses greater than 20 ms. Time Delay Set allows the user to select the maximum amount of time the ADM1232A will allow the STROBE input to remain inactive (i.e., STROBE is not receiving any high-to-low transitions), without forcing the ADM1232A to generate a RESET pulse. (See STROBE specifications, Figure 4 and the note on STROBE timeout selection.) Tolerance Input. This input will determine how much the supply voltage will be allowed to decrease (as a percentage tolerance) before a RESET is asserted. Connect to VCC for 10% and GND for 5%. 0 V ground reference for all signals. Active high logic output. Will be asserted when: 1. VCC decreases below the amount specified by the TOLERANCE input or, 2. PB RESET is forced low or, 3. If there are no high-to-low transitions within the limits set by TD at STROBE or, 4. During power-up. Inverse of RESET, with an open drain output. The STROBE input is used to monitor the activity of a microprocessor. If there are no high-to-low transitions within the time specified by TD, a reset will be asserted. Power supply input +5 V.
TOLERANCE GND RESET
RESET STROBE VCC
PIN CONFIGURATIONS R-16 RM-8 N-8 and R-8
NC 1 PB RESET 2 NC 3
16 NC 15 VCC 14 NC
PB RESET 1 TD 2
8 VCC
PB RESET 1 TD 2
8 VCC
TOP VIEW TOLERANCE 3 (Not to Scale) 6 RESET GND 4
ADM1232A 7 STROBE
TOP VIEW TOLERANCE 3 (Not to Scale) 6 RESET GND 4
ADM1232A 7 STROBE
TD 4 STROBE TOP VIEW NC 5 (Not to Scale) 12 NC TOLERANCE 6 NC 7 GND 8 11 RESET 10 NC 9 RESET
ADM1232A 13
5 RESET
5 RESET
NC = NO CONNECT
-4-
REV. 0
ADM1232A
The PB RESET input makes it possible to manually reset a system using either a standard push-button switch or a logic low input. An internal debounce circuit provides glitch immunity when used with a switch, reducing the effects of glitches on the line. The debounce circuit is guaranteed to cause the ADM1232A to assert a reset if PB RESET is brought low for more than 20 ms and is guaranteed to ignore low inputs of less than 1 ms.
VCC
CIRCUIT INFORMATION PB RESET
STROBE Timeout Selection
TD or time delay set is used to set the Strobe Timeout Period. The Strobe Timeout Period is defined as being the maximum time between high-to-low transitions (Figure 4) that STROBE will accept before a reset will be asserted. The Strobe timeout settings are listed in Table I.
Table I.
Condition TD = 0 V TD = Floating TD = VCC
TD
Min 62.5 250 500
Typ 150 600 1200
Max 250 1000 2000
Units ms ms ms
VCC
ADM1232A
ADM1232 PB RESET RESET STROBE STROBE RESET GND TOLERANCE TOLERANCE
MICROPROCESSOR
I/O RESET
STROBE PULSEWIDTH STROBE
STROBE TIMEOUT PERIOD
Figure 4. STROBE Parameters Figure 2. Typical Push Button Reset Application
VCC PB RESET TIME PB RESET VIL RESET ACTIVE TIME RESET RESET PB RESET DELAY RESET OUTPUT DELAY WHEN IS VCCFALLING RESET +5V +4.5V (5% TRIP POINT) +4.25V (10% TRIP POINT) VIH RESET OUTPUT DELAY WHEN IS VCC RISING +5V
Figure 5. Reset Output Delay
RESET
TOLERANCE
Figure 3. PB RESET
The TOLERANCE input is used to determine the level VCC can vary below 5 V without the ADM1232A asserting a reset. Connecting TOLERANCE to ground will select a -5% tolerance level and will cause the ADM1232A to generate a reset if VCC falls below 4.75 V (typical). If TOLERANCE is connected to VCC a -10% tolerance level is selected and will cause the ADM1232A to generate a reset if VCC falls below 4.5 V (typical). Check the parameters for the VCC trip point in the ADM1232A Specifications for more information.
RESET AND RESET OUTPUTS
While RESET is capable of sourcing and sinking current, RESET is an open drain MOSFET which sinks current only. Therefore, it is necessary to pull this output high.
REV. 0
-5-
ADM1232A
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
0.4133 (10.50) 0.3977 (10.00)
16 9
0.430 (10.92) 0.348 (8.84)
8 5
0.4193 (10.65) 0.3937 (10.00)
0.2992 (7.60) 0.2914 (7.40)
0.280 (7.11) 0.240 (6.10)
1 4
PIN 1 0.210 (5.33) MAX 0.0291 (0.74) 0.0098 (0.25)
0.060 (1.52) 0.015 (0.38) 0.130 (3.30) MIN SEATING PLANE
0.325 (8.25) 0.300 (7.62) 0.195 (4.95) 0.115 (2.93)
1
8
PIN 1 0.0118 (0.30) 0.0040 (0.10)
0.1043 (2.65) 0.0926 (2.35)
45
0.160 (4.06) 0.115 (2.93) 0.022 (0.558) 0.100 0.070 (1.77) 0.014 (0.356) (2.54) 0.045 (1.15) BSC
0.015 (0.381) 0.008 (0.204)
0.0500 (1.27) BSC
8 0.0192 (0.49) 0 SEATING 0.0125 (0.32) 0.0138 (0.35) PLANE 0.0091 (0.23)
0.0500 (1.27) 0.0157 (0.40)
8-Lead SOIC (RM-8)
0.122 (3.10) 0.114 (2.90)
8-Lead Narrow SOIC (R-8)
0.1968 (5.00) 0.1890 (4.80)
8 5
8
5
0.122 (3.10) 0.114 (2.90)
0.199 (5.05) 0.187 (4.75)
1 4
0.2440 (6.20) 0.2284 (5.80)
1
4
0.1574 (4.00) 0.1497 (3.80)
PIN 1 PIN 1 0.0256 (0.65) BSC 0.120 (3.05) 0.112 (2.84) 0.006 (0.15) 0.002 (0.05) 0.018 (0.46) SEATING 0.008 (0.20) PLANE 0.043 (1.09) 0.037 (0.94) 0.011 (0.28) 0.003 (0.08) 0.120 (3.05) 0.112 (2.84)
0.102 (2.59) 0.094 (2.39)
0.0196 (0.50) 0.0099 (0.25)
45
0.0098 (0.25) 0.0040 (0.10) 0.0500 0.0192 (0.49) SEATING (1.27) 0.0138 (0.35) 0.0098 (0.25) PLANE BSC 0.0075 (0.19)
8 0
33 27
0.0500 (1.27) 0.0160 (0.41)
0.028 (0.71) 0.016 (0.41)
-6-
REV. 0
PRINTED IN U.S.A.
C3421-8-7/99
16-Lead Wide SOIC (R-16)
8-Lead PDIP (N-8)

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