SS8039 datasheet(5/7 Pages) SSC

5 / 7 page

SS8039

www.SiliconStandard.com

5 of 7

Rev.2.02 1/06/2004

Pin Description

NAME

FUNCTION

GND

Ground

RESET

(SS8039L)

RESET

Output remains low while VCC is below the reset threshold, and for at least 140ms after VCC

rises above the reset threshold.

RESET

(SS8039H)

RESET Output remains high while V CC is below the reset threshold, and for at least 140ms after VCC

rises above the reset threshold.

Manual Reset Input. A logic low on MR asserts reset. Reset remains asserted as long as MR is

low and for

at least 140ms after MR returns high, This active-low input has an internal 20kΩ pull- up

resistor. It can be driven from a TTL or CMOS-logic line, or shorted to ground with a switch. Leave

open if unused.

VCC

Supply Voltage (+5V, +3.3V, +3.0V)

Detailed Description

A microprocessor’s (µP’s) reset input starts the µP in a

known state. The SS8039L and SS8039H assert reset

to prevent

code-execution errors during power-up,

power-down, or brownout conditions. They assert a reset

signal whenever the VCC supply voltage declines below a

preset threshold, keeping it asserted for at least 140ms

after VCC has risen above the reset threshold.

The SS8039L/SS8039H have a push-pull output stage.

The manual reset input (MR) can also initiate a reset.

See the Manual Reset Input Section.

Manual Reset Input

Fig.1 Maximum Transient Duration Without

Many µP-based products require manual reset capability

Causing a Reset Pulse vs. Reset Comparator Overdrive

allowing the operator, a test technician, or external logic

circuitry to initiate a reset. A logic low on MR asserts

reset. Reset remains asserted while MR is low, and for

the Reset Active Timeout Period (t RP) after

returns

high. This input has an internal 20k

Ω pull-up resistor, so

it can be left open if it is not used. MR can be driven with

TTL or CMOS-logic levels, or with open-drain / collector

outputs. Connect a normally open momentary switch

from MR to GND to create a manual-reset function;

external debounce circuitry is not required. If MR is

driven from long cables or if the device is used in a

noisy environment, connecting a 0.1µF capacitor from

to ground provides additional noise immunity.

Figure2. RESET Valid to VCC = Ground Circuit

RESET

GND

100k

RESET

GND

SS8039

100k

100

200

300

400

500

600

100

1000

Reset Comparator Overdrive, V TH-VCC (mV)

SS8039 Datasheet(PDF) 5 Page - Silicon Standard Corp.

SS8039 Datasheet(HTML) 5 Page - Silicon Standard Corp.

Html Pages

1 2 3 4 5 6 7

Datasheet Download

Link URL