Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset PDIP 8

1 of 7 111899

FEATURES

 Halts and restarts an out-of-control

microprocessor

 Holds microprocessor in check during power

transients

 Automatically restarts microprocessor after

power failure

 Monitors pushbutton for external override

 Accurate 5% or 10% microprocessor power

supply monitoring

 Eliminates the need for discrete components

 Space-saving, 8-pin mini-DIP

 Optional 16-pin SOIC surface mount package

 Industrial temperature -40°C to +85°C

available, designated N

PIN ASSIGNMENT

PIN DESCRIPTION

PBRST - Pushbutton Reset Input

TD - Time Delay Set

TOL - Selects 5% or 10% V

Detect

GND - Ground

RST - Reset Output (Active High)

RST - Reset Output (Active Low, open

drain)

ST - Strobe Input

- +5 Volt Power

NC - No Connections

DESCRIPTION

The DS1232 MicroMonitor™ Chip monitors three vital conditions for a microprocessor: power supply,

software execution, and external override. First, a precision temperature-compensated reference and

comparator circuit monitors the status of V

. When an out-of-tolerance condition occurs, an internal

power fail signal is generated which forces reset to the active state. When V

returns to an in-tolerance

condition, the reset signals are kept in the active state for a minimum of 250 ms to allow the power supply

and processor to stabilize.

DS1232

MicroMonitor Chip

www.maxim-ic.com

DS1232S 16-Pin SOIC (300-mil)

See Mech. Drawings Section

PBRST

TOL

GND

VCC

RST

PBRST

DS1232 8-Pin DIP (300-mil)

See Mech. Drawings Section

TOL

GND

VCC

RST

MicroMonitor is a trademark of Dallas Semiconductor.

Summary of content (7 pages)

PAGE 1
DS1232 MicroMonitor Chip www.maxim-ic.
PAGE 2
DS1232/DS1232S The second function the DS1232 performs is pushbutton reset control. The DS1232 debounces the pushbutton input and guarantees an active reset pulse width of 250 ms minimum. The third function is a watchdog timer. The DS1232 has an internal timer that forces the reset signals to the active state if the strobe input is not driven low prior to timeout. The watchdog timer function can be set to operate on timeout settings of approximately 150 ms, 600 ms, and 1.2 seconds.
PAGE 3
DS1232/DS1232S MICROMONITOR BLOCK DIAGRAM Figure 1 PUSHBUTTON RESET Figure 2 WATCHDOG TIMER Figure 3 3 of 7
PAGE 4
DS1232/DS1232S TIMING DIAGRAM: PUSHBUTTON RESET Figure 4 TIMING DIAGRAM: STROBE INPUT Figure 5 WATCHDOG TIMEOUTS Table 1 TD PIN TIME-OUT MIN TYP MAX GND 62.
PAGE 5
DS1232/DS1232S TIMING DIAGRAM: POWER-DOWN Figure 6 TIMING DIAGRAM: POWER-UP Figure 7 5 of 7
PAGE 6
DS1232/DS1232S ABSOLUTE MAXIMUM RATINGS* Voltage on V CC Pin Relative to Ground Voltage on I/O Relative to Ground Operating Temperature Operating Temperature (Industrial Version) Storage Temperature Soldering Temperature * -0.5V to +7.0V -0.5V to VCC + 0.5V 0°C to 70°C -40°C to +85°C -55°C to +125°C 260°C for 10 seconds This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied.
PAGE 7
DS1232/DS1232S (0°C to 70°C; VCC=5V ± 10%) AC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL MIN = VIL tPB 20 RESET Active Time tRST 250 Pulse Width tST 20 PBRST ST TYP 610 VCC Slew Rate 4.75V to 4.25V tF 300 tRPU 250 610 tR 0 5 PBRST Stable Low to RST and RST 1000 NOTES ms ns tRPD VCC Slew Rate 4.25V to 4.75V UNITS ms VCC Fail Detect to RST and RST VCC Detect to RST and RST Transition MAX 100 175 6, 8 μs μs tPDLY 1000 ms 4 μs 20 ms NOTES: 1.