level of 1.2V also.

Manual Reset Operation

Push-button switch input, PBRST, allows the user to override the

internal trip point detection circuits and issue reset signals. The

pushbutton input is debounced and is pulled HIGH through an

internal 40k

Ω resistor.

become active and remain active for a minimum time period of

250ms after PBRST returns HIGH.

The debounced input is guaranteed to recognize pulses greater

than 20ms. No external pull-up resistor is required, since PBRST

is pulled HIGH by an internal 40k

Ω resistor.

The PBRST can be driven from a TTL or CMOS logic line or short-

ed to ground with a mechanical switch.

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©

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IMP1

832

Application Information

Supply Voltage Monitor

The IMP1832 monitors the microprocessor or microcontroller

power supply and issues reset signals, both active HIGH and

active LOW, that halt processor operation whenever the power

supply voltage levels are outside a predetermined tolerance.

Tolerance levels are set with the TOL pin.

RESET and RESET signals are generated at the last moment of a

minimum of 250ms after the supply has returned to intolerance

level. This allows the power supply and monitored processor to

stabilize before instruction execution is allowed to begin.

Trip Point Tolerance Selection

RESET remain active for a minimum time period of 250ms.

Figure 1. Timing Diagram: Power Up

Figure 2. Timing Diagram: Power Down

1832_04.eps

RESET

RESET

Figure 3. Timing Diagram: Pushbutton Reset

RESET

RESET

PBRST

1832_07.eps

Figure 4. Application Circuit: Pushbutton Reset

1832_05.eps

PBRST

Supply

Voltage

1

TD

2

ST

TOL

IMP1832

µP

3

4

RESET

GND

8

7

6

5

RESET

RESET

RESET

RESET

1832_03.eps