CAT1232LP, CAT1832 5 V and 3.3 V Supply Monitor, Watchdog Timer, Manual Reset, with Active High & Low Resets FEATURES DESCRIPTION Selectable reset voltage tolerance The CAT1232LP and CAT1832 microprocessor supervisors can halt and restart a hung-up or CAT1232LP for 5 V supply stalled microprocessor, restart a microprocessor CAT1832 for 3.3 V supply after a power failure, and debounce a manual/push- Selectable watchdog period: button microprocessor reset switch. The devices are 150 ms, 600 ms or 1.2 s drop in replacements for the Maxim/Dallas Semiconductor DS1232LP and DS1832 supervisors Two reset outputs Active high, push-pull reset output Precision reference and comparator circuits monitor the 5 V or 3.3 V system power supply voltage, V . CC Active low, open-drain reset output During power-up or when the power supply falls (CAT1232LP) outside selectable tolerance limits, both the RESET Active low, push-pull reset output (CAT1832) and RESET become active. After the power supply Debounced manual push-button reset voltage rises above the RESET threshold voltage, the Compact SOIC and MSOP packages reset signals remain active for a minimum of 250ms, allowing the power supply and system processor to stabilize. The trip-point tolerance input, TOL, selects For Ordering Information details, see page 11. the trip level tolerance to be either 5% or 10% for the CAT1232LP 5 V supply and 10% or 20% for the APPLICATIONS CAT1832 3.3 V supply. Microprocessor Systems Each device has a push-pull, active HIGH reset output. The CAT1232LP also has an open drain, Portable Equipment active LOW reset output while the CAT1832 also has Controllers a push-pull, active LOW reset output. Single Board Computers A debounced manual reset input activates the reset Instrumentations outputs and holds them active for a minimum period of 250 ms after being released. Telecommunications Also included is a watchdog timer to reset a microprocessor that has stopped due to a software or hardware failure. Three watchdog time-out periods are selectable: 150 ms, 600 ms and 1.2 s. If the ST input is not strobed low before the watchdog time out period expires, the reset signals become active for a FUNCTIONAL DIAGRAM minimum of 250 ms. V CC RESET TOL Tolerance Selection + (CAT1232LP) V CC Reference 40k RESET PBRST Push Button Debounce RESET Reset & (CAT1832) TD Watchdog Timebase Selection Watchdog Timer ST Watchdog Transition Detector 2009 SCILLC. All rights reserved. 1 Doc. No. MD-3018 Rev. F Characteristics subject to change without notice CAT1232LP, CAT1832 PIN CONFIGURATION SOIC 8 Lead SOIC 16 Lead MSOP 8 Lead NC 1 16 NC PDIP 8 Lead PBRST 2 15 V CC 1 8 V PBRST CC NC 3 14 NC TD 2 7 ST CAT TD 4 13 ST CAT TOL 3 6 RESET NC 5 12 NC GND 4 5 RESET TOL 6 11 RESET NC 7 10 NC GND 8 9 RESET PIN DESCRIPTION Pin Number Pin Number 8-Lead 16-Lead Package Package Name Function 1 2 PBRST Debounced manual pushbutton reset input Watchdog typical time delay selection: a) t = 150 ms for TD = GND TD 2 4 TD b) t = 600 ms for TD = Open TD c) t = 1200 ms for TD = V TD CC CAT1232LP TOL selects 5% (TOL = GND) or 10% (TOL = V ) trip CC 3 6 TOL point tolerance. CAT1832 TOL selects 10% (TOL = GND) or 20% TOL = V ) trip point tolerance. CC 4 8 GND Ground Active HIGH reset output. RESET is active 1. If V falls below the reset voltage trip point CC 5 9 RESET 2. If PBRST is low 3. If ST is not strobed low before the timeout period set by TD expires. 4. During power-up. 6 11 RESET Active LOW reset output. (See RESET) 7 13 Strobe Input ST 8 15 V Power Supply CC 1, 3. 5, 7, 10, NC No internal connection 12, 14, 16 (*) ABSOLUTE MAXIMUM RATINGS Parameters Ratings UnitsParameters Ratings Units Voltage on V -0.5 to 7.0 V Maximum Junction Temperature 125 C CC -0.5 to V + 0.5 V Storage Temperature Range -65 to +150 C Voltage on ST and TD CC Voltage on PBRST, Lead Soldering Temperature (10s) 300 C -0.5 to V + 0.5 V CC RESETand RESET Operating Temperature Range -40 to +85 C Note: * Stresses above 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 outside of those listed in the operational sections of this specification is not implied. Exposure to any absolute maximum rating for extended periods may affect device performance and reliability. Doc. No. MD-3018 Rev. F 2 2009 SCILLC. All rights reserved. Characteristics subject to change without notice