MIC2778(1999) 查看數據表（PDF） - Micrel

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MIC2778
(Rev.:1999)

Voltage Monitor with Adjustable Hysteresis

Micrel 

MIC2778

Functional Diagram

VBATT

LTH

VLO

HTH

VHI

Low-Voltage

Detect

High-Voltage

Detect

Delay

Line

1.24V

Bandgap

Reference

GND

RQ

SQ

RST

MIC2778

Micrel

Functional Description

The MIC2778 monitors the voltage of a battery and detects

when it is discharged below a programmed level. Upon being

replaced, or being recharged above a second higher pro-

grammed trip point, the output remains low for a minimum of

140ms and then sends a reset signal to a microprocessor or

other downstream component.

Voltage Low Output

The voltage-low output (RST) is an active-low, open-drain

output which sinks current when the MIC2778 detects a low

input voltage.

Trip Points

Battery voltage is monitored by a comparator via a voltage

divider network. The divided voltage is compared to an

internal reference voltage. When the voltage at the LTH input

pin drops below the internal reference voltage, the output

pulls low. At this point, the voltage at HTH is assumed to be

below the reference voltage.

Delay

At power-on or when the battery is replaced or recharged,

and the voltage at HTH exceeds the reference voltage, the

output goes high after a minimum delay of 140ms.

MIC2778

4

October 1999

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