©

1999 IMP, Inc.

408-432-9100/www.impweb.com

1

Key Features

x

Lower power, pin-compatible replacements for

the Dallas DS1834

— 40% lower maximum supply current:

30µA vs 50µA

x

Monitor 5V and 3.3V supplies simultaneously

x

5V and 3.3V power-on reset

x

350ms reset time

x

Debounced pushbutton reset input

x

Push-Pull CMOS output

— IMP1834, IMP1834D

— Eliminates external pull-up resistors

— Active LOW (IMP1834), HIGH (IMP1834D)

x

Open drain output

— IMP1834A

— Active LOW

x

Selectable 5V and 3.3V trip point tolerance

x

Internal power drawn from highest input

voltage, 5V or 3.3V

x

Precision temperature-compensated voltage

reference and comparator

x

Low-cost surface mount SO, compact

MicroSO and DIP packages

x

Wide operating temperature, –40

°C to +85°C

Block Diagram

8

1834_01.eps

40k

Ω

5VTOL

5V Tolerance

Bias

IMP1834

PBRST

1

3

–

+

Low TC

Reference

3.3VTOL

5

6

GND

4

5VRESET

5VRESET (IMP1834D)

For IMP1834D

350 ms

Delay

For IMP1834D

3.3V Tolerance

Bias

2

–

+

3.3VRESET

3.3VRESET (IMP1834D)

350 ms

Delay

7

Pushbutton Level

Sense and Debounce

IMP1

4/A/D

Dual 5V and 3.3V

er

Suppl

eset

– Push-Pull and Open-Dr

ain Outputs

– Select

ance

The IMP1834 supervisors simultaneously monitor both 3.3V and 5V

power sources and issue reset signals when either supply is out of toler-

ance. When an out-of-tolerance condition is detected, the output-reset

signal of the affected supply becomes active and resets the system micro-

processor/microcontroller. On power-up and after the supply voltage

returns to an in-tolerance condition, the reset signal remains active for

approximately 350ms. This allows the power supply and system micro-

processor to stabilize.

The IMP1834 supervisors are pin-compatible with devices from Dallas

Semiconductor and require up to 40% less current.

Tolerance levels are independently selectable for both supplies.

Tolerance options are 5- and 10-percent for the 5V supply and for the

3.3V supply, 10- and 20-percent.

The IMP1834 and IMP1834D have push-pull reset output stages. The

IMP1834A active LOW reset outputs are open drain devices that can

both be connected to either 5 volt or 3.3 volt supply. The IMP1834 and

IMP1834A have active LOW reset outputs. The IMP1834D has active

HIGH reset outputs.

All devices can issue reset signals through an internally debounced

pushbutton reset input that affects both reset outputs.

All devices operate over the extended industrial temperature range.

Devices are available in 8-pin DIP, surface mount 8-pin SO and 8-pin

MicroSO packages. Die are also available.

1834_02.eps

5VRESET

2

3.3VRESET

7

IMP1834A