POWER MANAGEMENT

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Low quiescent current, less than 10µA typical

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Input voltage range 1.8V to 6.8V

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Adjustable or preset voltage trip point

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Selectable timer delays of 0, 40 and 80ms without use of

external resistor

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SOT-23 5 lead package

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Accuracy is 2% over specified temperature range

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30V maximum rating

SC1437

Precision Voltage Detector With

Programmable Trigger Voltage & Timer Delay

Description

Features

Typical Application Circuit

Applications

Revision 01/10/2001

The SC1437 is a battery over voltage detection circuit with driver

for external MOSFET. The trip point is adjustable with an external

resistor divider connected to the SENSE pin. The trip point is

preset to a nominal trip voltage of 4.2V if no external divider is

used. Other internal trip voltages of 4.5V and 4.7V are available,

specified by different part numbers. An internal delay, with two

selectable times or bypass, is on-board to suppress accidental

over voltage conditions due to glitches on the battery supply volt-

age, V+. The delay is externally adjustable by pulling the SEL pin

high, low, or left floating. During an actual over voltage condition,

the internal driver will pull the over voltage pin (OV) down to the

voltage present at the V- pin. This insures the external N-Channel

MOSFET will be completely off during an over voltage condition.

Supply current during the monitoring mode of operation is ap-

proximately 10µA. If an over voltage condition is detected, supply

currents increase when the timer is started. A voltage comparator

will engage at voltages greater than 6.8V, which bypasses the

timer and open circuits the battery by turning off the external

MOSFET. This important function protects the battery during the

timer delay in the event of a charger failure. There are three

functional options available. With the B option the OV pin is active

low. With the L option the OV pin is active high. With the H option

the OV pin is open drain, active high. All options are available in a

5 lead SOT-23 package.

BATTERY

2

SEL

V-

OV

V+

SENSE

0.1uF

100

0.1uF

100

SC1437

1

4

3

5

+

-

R2

R1

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Battery packs

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Programmable Fuse

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Power Monitoring

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