IMP IMP1832S, IMP1832, IMP1832SEMA Datasheet

Also included is a watchdog timer to stop and restart a
microprocessor that is “hung-up”. Three watchdog time­out periods are selectable: 150ms, 610ms and 1,200ms. If the
ST input is not strobed LOW before the time-out period
expires, a reset is issued.

Devices are available in 8-pin DIP, 8-pin SO and compact
8-pin MicroSO packages.

©

1999 IMP, Inc. 408-432-9100/www.impweb.com 1

Key Features

◆

Pin compatible with the Dallas Semiconductor
DS1832
— Over 40% lower supply current

◆

3.3V supply monitor

◆

Push-pull output

◆

Selectable watchdog period

◆

Debounce manual push-button reset input

◆

Precision temperature-compensated voltage
reference and comparator

◆

Power-up, power-down and brownout detection

◆

250ms minimum reset time

◆

Active LOW and HIGH reset signal

◆

Selectable trip point tolerance: 10% or 20%

◆

Low-cost 8-pin DIP/SO and 8-pin MicroSO
packages

◆

Wide operating temperature –40°C to +85°C

Block Diagram

IMP1

IMP1

832

832

POWER MANAGEMENT

3.3V

3.3V µµ

P P

P Pooww

er Suppl

er Supplyy

Monit

Monit

or and R

or and R

eset Cir

eset Cir

cuit

cuit

– Select

– Select

able T

able Trriipp-P-P

oint T

oint T

oler

oler

ance and

ance and

WWatc

atc

hdog P

hdog Perer

iod

iod

– Push-Butt

– Push-Butt

on R

on R

eset

eset

– Push-Pull R

– Push-Pull R

eset Outputs

eset Outputs

The IMP1832 microprocessor supervisor can halt and restart a “hung­up” or “stalled” microprocessor, restart a microprocessor after a power
failure, and debounce a manual push-button microprocessor reset
switch. The IMP1832 features over 40% lower supply current than the
pin compatible Dallas Semiconductor DS1832.

Precision temperature compensated reference and comparator circuits
monitor the 3.3V, V

CC

input voltage. During power-up or when the V

CC

power supply falls outside selectable tolerance limits, both RESET and
RESET become active. When V

CC

rises above the threshold voltage, the
reset signals remain active for an additional 250ms minimum, allowing
the power supply and system microprocessor to stabilize. The trip point
tolerance signal, TOL, selects the trip level tolerance to be either 10- or
20-percent.

RESET and RESET outputs are push-pull.
A debounced manual reset input, PBRST, activates the reset outputs for

a minimum period of 250ms.

V

CC

TOL

PBRST

TD

ST

8

3

1

2

7

10%/20% Tolerance

V

CC

40k

W

Timebase Selection

Transition Detector

Selection

Reference

Push Button

Debounce

Watchdog

Watchdog

+

–

IMP1832

Reset &

Watchdog Timer

V

CC

6

V

CC

5

4

GND

RESET

RESET

1832_02.eps

2

408-432-9100/www.impweb.com

©

1999 IMP, Inc.

Pin Configuration

IMP1

IMP1

832

832

Pin Descriptions

Ordering Information

DIP/SO/MicroSO

rebmuNtraPegakcaP

erutarepmeTgnitarepO

egnaR

ylppuSmumixaM

(tnerruC µ )A

gnirotinoMegatloV

noitacilppA

2381PMIPID-8 – 04C° 58otC° 02V3.3

S2381PMIOS-8 – 04C° 58otC° 02V3.3

AMES2381PMIOSorciM-8 – 04C° 58otC° 02V3.3

spe.10t_2381

Pin Number

8-Pin Package Name Function

1 PBRST Debounced manual pushbutton reset input
2 TD Watchdog time delay selection. (t

TD

= 150ms for TD = GND, tTD= 610ms for TD = Open,

and tTD=1200ms for TD = VCC)
3 TOL Selects 10% (TOL connected to GND) or 20% (TOL connected to VCC) trip point tolerance
4 GND Ground
5 RESET Active HIGH reset output. RESET is active:

1. If VCCfalls below the reset voltage trip point.

2. IfPBRST is LOW.

3. If ST is not strobed LOW before the timeout period set by TD expires.

4. During power-up.
6 RESET Active LOW reset output. (See RESET)
7 ST Strobe Input
8V

CC

5V power

PBRST

TD

TOL

GND

1V
2

IMP1832

3
4

8

CC

7ST
6 RESET
5

RESET

1832_01.eps

©

1999 IMP, Inc. 408-432-9100/www.impweb.com 3

IMP1

IMP1

832

832

Absolute Maximum Ratings

Electrical Characteristics

Voltage on VCC . . . . . . . . . . . . . . . . . . . . . . . . –0.5V to 7V

Voltage on ST, TD . . . . . . . . . . . . . . . . . . . . . – 0.5V to V

CC

+ 0.5V

Voltage on PBRST, RESET, RESET . . . . . . . . – 0.5V to V

CC

+ 0.5V

Operating Temperature Range . . . . . . . . . . . –40°C to 85°C

Soldering Temperature . . . . . . . . . . . . . . . . . . 260°C for 10 seconds

Storage Temperature . . . . . . . . . . . . . . . . . . . –55°C to 125°C

Voltages measured with respect to ground.
These are stress ratings only and functional operation is not implied.

Parameter Symbol Conditions Min Typ Max Units

Supply Voltage (VCC)V

CC

1.0 5.5 V

ST and PBRST Input High Level V

IH

VCC≥ 2.7V 2 VCC+ 0.3V V

ST and PBRST Input High Level V

IH

VCC< 2.7V VCC- 0.4V V

ST and PBRST Input Low Level V

IL

–0.3 0.5 V

VCCTrip Point (TOL = GND) V

CCTP

2.80 2.88 2.97 V

VCCTrip Point (TOL = VCC)V

CCTP

2.47 2.55 2.64 V

Watchdog Time-Out Period t

TD

TD = GND 62.5 150 250 ms

Watchdog Time-Out Period t

TD

TD = V

CC

500 1200 2000 ms

Watchdog Time-Out Period t

TD

TD floating 250 610 1000 ms

Output Voltage V

OH

I = –500µA, VCC< 2.7V VCC- 0.3V VCC- 0.1V V

Output Current I

OH

Output = 2.4V, VCC≥ 2.7V 350 µA

Output Current I

OL

Output = 0.4V, VCC≥ 2.7V 10 mA

Input Leakage I

IL

–1.0 1.0 µA

RESET Low Level V

OL

0.4 V
Internal Pull-Up Resistor PBRST pin 40 kΩ
Operating Current I

CC1

Outputs open. VCC≤ 3.6V 20 µA
and all inputs at VCCor GND

Input Capacitance C

IN

5pF

Output Capacitance C

OUT

7pF

PBRST Manual Reset t

PB

PBRST = V

IL

20 ms

Minimum Low Time
Reset Active Time t

RST

250 610 1000 ms

ST Pulse Width t

ST

Must not exceed tRDminimum. 20 ns
Watchdog cannot be disabled.

VCCFail Detect to t

RPD

Pulses < 2µs at V

CCTP

58µs

RESET or RESET minimum will not cause reset.
VCCSlew Rate t

F

20 µs

PBRST Stable LOW to t

PDLY

20 ms

RESET and RESET Active
VCCDetect to RESET or t

RPU

t

rise

= 5µs 250 610 1000 ms

RESET Inactive
VCCSlew Rate t

R

0ns

Unless otherwise stated, 1.2V ≤ VCC≤ 5.5V and over the operating temperature range of –40°C to +85°C . All voltages are referenced
to ground.