PT7M6314US Datasheet, PDF(4/8 Page) Pericom Semiconductor Corporation

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PT7M6314US Datasheet, PDF (4/8 Pages) Pericom Semiconductor Corporation – Supervisory Circuit

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Block Diagram

63kâ¦

Vcc

VCC

Resistor

Divider

T.C.

Reference

PT7M6314US

Supervisory Circuit

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4us one-shot

Logic Control

&Timing

Delay

5kâ¦

RST

GND

Function Description

Power Monitor

A microprocessorâs (ÂµPâs) reset input starts the ÂµP in a known state. Whenever the ÂµP is in an unknown state, it should be held in

reset. The supervisory circuits assert reset during power-up and prevent code execution errors during power-down or brownout

conditions.

On power-up, once Vcc reaches about 1.0V, RST is a guaranteed logic low of 0.4V or less. As Vcc rises, RST stays low. When

Vcc rises above the reset threshold VRST, an internal timer releases RST after about 1570ms (PT7M6314USxxD4). RST asserts

whenever Vcc drops below the reset threshold, i.e. brownout condition. If brownout occurs in the middle of a previously initiated

reset pulse, the pulse continues for at least another 1.6ms or 26ms or 200ms or 1570ms (PT7M6314USxxD4). On power-down,

once Vcc falls below the reset threshold, RST stays low and is guaranteed to be 0.4V or less until Vcc drops below 1V.

Manual Reset

The manual-reset input (MR) allows reset to be triggered by a pushbutton switch. The switch is effectively debounced by the

1.6ms (PT7M6314USxxD1) or 26ms (PT7M6314USxxD2) or 200ms (PT7M6314USxxD3) or 1570ms (PT7M6314USxxD4)

reset pulse width.

Reset Output: Bi-direction

The PT7M6314USxxâs RESET output is designed to interface with ÂµPs that have bidirectional reset pins, such as the Motorola

68HC11. Like an open-drain output, the PT7M6314USxx allows the ÂµP or other devices to pull RST low and assert a reset

condition. However, unlike a standard open-drain output, it includes the commonly specified 5kï pull-up resistor with a P-

channel active pull-up in parallel. This structure can speed the rising edge when the reset condition releases. The reset condition

will occur when Vcc drops below the reset threshold, or Manual Reset is set to ground, or RST is pulled down.

2016-01-0003

PT0196-6

01/15/16

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