STM6779 datasheet(8/29 Pages) STMICROELECTRONICS

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Description

STM6717/6718/6719/6720/STM6777/6778/6779/6780

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VCC1. It can be driven from a TTL or CMOS logic line, or with open drain/collector outputs,

or connected to VSS through a switch. If unused, leave this pin open or connect it to VCC1.

Connect a normally open momentary switch from MR to VSS; external debounce circuitry is

not required. (If MR is driven from long cables or if the device is used in noisy environments,

connecting a 0.1µF capacitor from MR to VSS provides additional noise immunity.

1.1.4

Manual reset delay input (MRC) - STM6777/78/79/80)

This pin is either left open or connected to VSS via a capacitor. By selecting the appropriate

capacitor, the manual reset process, initiated by pressing the push-button Manual Reset

Input, can be delayed by any value from 6µs or more (see Table 7 on page 21).

1.1.5

Primary supply voltage monitoring input (VCC1)

It also is the input for the primary reset threshold monitor. Available fixed (customer-

selectable, factory-programmed) reset thresholds include 4.63V to 1.58V.

1.1.6

Secondary supply voltage monitoring input (VCC2)

This function is available on the STM6717/18/19/20/77/78. Fixed (customer-selectable,

factory-programmed) reset thresholds include 3.08V to 0.79V.

1.1.7

Adjustable reset comparator input (RSTIN; STM6719/20/79/80)

This is a high impedance input. RST is driven low when the voltage at the RSTIN pin falls

below 0.626V (internal reference voltage at this comparator). The monitored voltage reset

threshold is set with an external resistor-divider network.

Table 3.

Pin functions

Name

Function

STM6717

STM6718

STM6719

STM6720

STM6777

STM6778

STM6779

STM6780

1111

RST

Active-low reset output

3333

Push-button reset input

––54

MRC

Manual reset delay input

5666

VCC1 Primary supply voltage input

444–

VCC2 Secondary supply voltage input

–5–5

RSTIN Adjustable reset comparator input

2222

VSS

Ground

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