DS1232 ,MicroMonitor ChipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 5% or 10% V DetectCCG ..
DS1232LP+ ,Low-Power MicroMonitor ChipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 5% or 10% V DetectCCG ..
DS1232LPN ,Low-Power MicroMonitor ChipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 5% or 10% V DetectCCG ..
DS1232LPS ,Low power micromonitor chipPIN DESCRIPTIONPBRST – Pushbutton Reset InputTD – Time Delay SetTOL – Selects 5% or 10% V DetectCCG ..
DS1232LPS-2 ,Low power micromonitor chipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 5% or 10% V DetectCCG ..
DS1232LPS-2+ ,Low-Power MicroMonitor ChipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 5% or 10% V DetectCCG ..
DTA125TUA , -100mA / -50V Digital transistor (with built-in resistors)
DTA143EE ,Pre-biased TransistorsMaximum ratings applied to the device are individual stress limit values (notnormal operating condi ..
DTA143EE TL , PNP -100mA -50V Digital Transistors (Bias Resistor Built-in Transistors)
DTA143EE TL , PNP -100mA -50V Digital Transistors (Bias Resistor Built-in Transistors)
DTA143EE TL , PNP -100mA -50V Digital Transistors (Bias Resistor Built-in Transistors)
DTA143EETL , PNP -100mA -50V Digital Transistors (Bias Resistor Built-in Transistors)
DS1232
MicroMonitor Chip
FEATURESHalts and restarts an out-of-control
microprocessorHolds microprocessor in check during powertransientsAutomatically restarts microprocessor after
power failureMonitors pushbutton for external overrideAccurate 5% or 10% microprocessor powersupply monitoringEliminates the need for discrete componentsSpace-saving, 8-pin mini-DIPOptional 16-pin SOIC surface mount packageIndustrial temperature -40°C to +85°Cavailable, designated N
PIN ASSIGNMENT
PIN DESCRIPTIONPBRST - Pushbutton Reset Input
TD - Time Delay Set
TOL - Selects 5% or 10% VCC Detect
GND - Ground
RST - Reset Output (Active High)
RST - Reset Output (Active Low, open drain) - Strobe Input
VCC - +5 Volt Power
NC - No Connections
DESCRIPTIONThe 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 internalpower fail signal is generated which forces reset to the active state. When VCC returns to an in-tolerance
DS1232
MicroMonitor ChipPBRST
TOL
GND
VCC
RST
RST
PBRST
TOL
GND
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 ontimeout settings of approximately 150 ms, 600 ms, and 1.2 seconds.
OPERATION - POWER MONITORThe DS1232 detects out-of-tolerance power supply conditions and warns a processor-based system ofimpending power failure. When VCC falls below a preset level as defined by TOL (Pin 3), the VCC
comparator outputs the signals RST (Pin 5) and RST (Pin 6). When TOL is connected to ground, the RST
and RST signals become active as VCC falls below 4.75 volts. When TOL is connected to VCC, the RST
and RST signals become active as VCC falls below 4.5 volts. The RST and RST are excellent control
signals for a microprocessor, as processing is stopped at the last possible moments of valid VCC. On
power-up, RST and RST are kept active for a minimum of 250 ms to allow the power supply and
processor to stabilize.
OPERATION - PUSHBUTTON RESETThe DS1232 provides an input pin for direct connection to a pushbutton (Figure 2). The pushbutton reset
input requires an active low signal. Internally, this input is debounced and timed such that RST and RSTsignals of at least 250 ms minimum are generated. The 250 ms delay starts as the pushbutton reset input is
released from low level.
OPERATION - WATCHDOG TIMERA watchdog timer function forces RST and RST signals to the active state when the ST input is not
stimulated for a predetermined time period. The time period is set by the TD input to be typically 150 ms
with TD connected to ground, 600 ms with TD left unconnected, and 1.2 seconds with TD connected to
VCC. The watchdog timer starts timing out from the set time period as soon as RST and RST are inactive.
If a high-to-low transition occurs on the ST input pin prior to timeout, the watchdog timer is reset and
begins to timeout again. If the watchdog timer is allowed to timeout, then the RST and RST signals are
driven to the active state for 250 ms minimum. The ST input can be derived from microprocessoraddress signals, data signals, and/or control signals. When the microprocessor is functioning normally,
these signals would, as a matter of routine, cause the watchdog to be reset prior to timeout. To guarantee
that the watchdog timer does not timeout, a high-to-low transition must occur at or less than the minimum
shown in Table 1. A typical circuit example is shown in Figure 3.
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
TIME-OUT
DS1232/DS1232S
TIMING DIAGRAM: POWER-DOWN Figure 6
TIMING DIAGRAM: POWER-UP Figure 7
DS1232/DS1232S
ABSOLUTE MAXIMUM RATINGS*Voltage on V CC Pin Relative to Ground -0.5V to +7.0V
Voltage on I/O Relative to Ground -0.5V to VCC + 0.5V
Operating Temperature 0°C to 70°C
Operating Temperature (Industrial Version) -40°C to +85°C
Storage Temperature -55°C to +125°CSoldering Temperature 260°C for 10 secondsThis 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 to
absolute maximum rating conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS (0°C to 70°C)
DC ELECTRICAL CHARACTERISTICS (0°C to 70°C; VCC=4.5 to 5.5V)
CAPACITANCE (tA=25°C)
