EM6323/24

Copyright

© 2006, EM Microelectronic-Marin SA

03/06 - rev.H

1

www.emmicroelectronic.com

Reset Circuit with Manual Reset and Watchdog

Description

The EM6323/24 are low power, high precision reset ICs

featuring a manual reset and a watchdog inputs. They have

different threshold voltages and several timeout reset periods

with internal pull-up) and a watchdog input pins. EM6324 has

only a watchdog input pin (WDI). The watchdog function can

be disabled by driving WDI with a three-state driver or by

leaving WDI unconnected. This is useful when the MCU is in

sleep mode.

Small SOT23-5L package as well as ultra-low supply current

of 3.8µA make the EM6323 and the EM6324 an ideal choice

for portable and battery-operated devices.

Typical Application

V

DD

WDI

GND

RESET

MR

EM632x

V

DD

I/O

GND

RESET

MPU, DSP

V

DD

GND

*

RESET

RESET

Fig. 1

Block Diagram

Fig. 2

Features

!

!

Operating temperature range: -40°C to +125°C

!

±1.5% reset threshold accuracy

!

2.93V, 2.63V, 2.2V, 1.8V, 1.66V, 1.57V, 1.38V, 1.31V

!

200ms reset timeout period (1.6ms, 25ms, 1600ms on

request)

!

1.6s watchdog timeout period (6.2ms, 102ms, 25.6s on

request)

!

3 reset output options:

!

Detection of microcontroller in sleep mode

Applications

!

Workstations

!

Point of sales (POS)

!

Personal computers

!

Routers, hubs and switches

!

Handheld GPS

!

Vending machines and ATM

!

Automotive systems

Pin Configuration

Fig. 3

Pin Description

SOT23-5L

EM6323 EM6324

Name

Function

1

1

RESET

Active-low RESET output (push-pull or open-drain)

2

2

GND

Ground

3

-

MR

Manual Reset input with an internal pull-up 30k

Ω resistor. Reset remains active as long as MR is low

-

3

RESET

Active-high RESET output (push-pull)

4

4

WDI

Watchdog input. WDI must be driven with a CMOS output. If the microcontroller I/O is put in a high

impedance condition, the circuit will detect this condition as a microcontroller in sleep mode and prevent

its watchdog from timing out

5

5

Supply Voltage (5.5V max.)

1

3

2

5

4

watchdog)

RESET

push-pull

RESET

MR

V

DD

WDI

GND

1

3

2

5

4

V

DD

WDI

GND

RESET

push-pull/open-drain

V

DD

GND

+

-

Voltage

Reference

MR

Reset

Logic

+ Timer

WDI

Transition

Detector

Watchdog Logic

+ Timer

Oscillator

Filter

RESET

RESET