FEATURES
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Halts and restarts an out-of-controlmicroprocessor
Holds microprocessor in check during powertransients
Automatically restarts microprocessor afterpower failure
Monitors pushbutton for external overrideAccurate 5% or 10% microprocessor powersupply monitoring
Eliminates the need for discrete componentsSpace-saving, 8-pin mini-DIP
Optional 16-pin SOIC surface mount packageIndustrial temperature -40°C to +85°Cavailable, designated N
PIN ASSIGNMENT PBRSTTDTOLGND12348 7 6 5 VCC ST RST RST DS1232 8-Pin DIP (300-mil) See Mech. Drawings Section NCPBRSTNCTDNCTOLNCGND1234567816 15 14 13 12 11 10 9 NC VCC NC ST NC RST NC RST DS1232S 16-Pin SOIC (300-mil) See Mech. Drawings Section
PIN DESCRIPTION
PBRST
TD TOL GND RST
RST
ST
VCC NC
-Pushbutton Reset Input-Time Delay Set
-Selects 5% or 10% VCC Detect-Ground
-Reset Output (Active High)-Reset Output (Active Low, opendrain)
-Strobe Input-+5 Volt Power-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 VCC. When an out-of-tolerance condition occurs, an internal power fail signal is generated which forces reset to the active state. When VCC 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.
111899
DS1232/DS1232S
MICROMONITOR BLOCK DIAGRAM Figure 1
PUSHBUTTON RESET Figure 2
WATCHDOG TIMER Figure 3
DS1232/DS1232S
TIMING DIAGRAM: PUSHBUTTON RESET Figure 4
TIMING DIAGRAM: STROBE INPUT Figure 5
WATCHDOG TIMEOUTS Table 1
TD PIN GND Float VCC
TIME-OUT
MIN62.5 ms 250 ms 500 ms
TYP150 ms 600 ms 1200 ms
MAX250 ms 1000 ms 2000 ms
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 + 0.5V0°C to 70°C-40°C to +85°C-55°C to +125°C260°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. Exposure toabsolute maximum rating conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONSPARAMETERSupply Voltage ST and PBRST Input High Level (0°C to 70°C) SYMBOLMIN TYP MAX UNITS NOTES1 VCC 4.5 5.0 5.5 V 1 VIH 2.0 VCC+0.3 V VIL -0.3+0.8 V 1 ST and PBRST Input Low Level DC ELECTRICAL CHARACTERISTICS
PARAMETERInput Leakage Output Current @ 2.4V Output Current @ 0.4V Low Level @ RST Output Voltage @ -500 μA Operating Current
VCC Trip Point (TOL=GND) VCC Trip Point (TOL=VCC)
SYMBOL
IIL -1.0IOH -8VOLVOH ICC
VCC -0.5V
(0°C to 70°C; VCC=4.5 to 5.5V)
+1.0 μA
-10
3
MIN TYP MAX UNITS NOTES
mA 5 1
IOL 8 10 mA 0.4 VVCC
-0.1V
V 1, 7
0.5 2.0 mA 2
1 1 VCCTP 4.50 4.62 4.74 V VCCTP 4.25 4.37 4.49 V CAPACITANCE
PARAMETERInput Capacitance Output Capacitance
SYMBOLCINCOUT
5 pF
(tA=25°C)
MIN TYP MAX UNITS NOTES
7 pF DS1232/DS1232S
AC ELECTRICAL CHARACTERISTICS (0°C to 70°C; VCC=5V ± 10%)
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