SC1437 Datasheet, PDF (1/8 Pages) Semtech Corporation – Precision Voltage Detector With Programmable Trigger Voltage & Timer Delay

SC1437
Precision Voltage Detector With
Programmable Trigger Voltage & Timer Delay
POWER MANAGEMENT
Description
Features
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.
! Low quiescent current, less than 10µA typical
! Input voltage range 1.8V to 6.8V
! Adjustable or preset voltage trip point
! Selectable timer delays of 0, 40 and 80ms without use of
external resistor
! SOT-23 5 lead package
! Accuracy is 2% over specified temperature range
! 30V maximum rating
Applications
! Battery packs
! Portable electronics
! Lithium Ion protection circuits
! Programmable Fuse
! Power Monitoring
! CPU Reset Circuits
Typical Application Circuit
R1
BATTERY
R2
Revision 01/10/2001
+
100
100
1 _SEL
4
SENSE
3 _OV
V+ ⁵
V- ²
0.1uF
SC1437
0.1uF
-
VTRIP = 2.1(1+^R2/_R1)
0.476 < (^R2/_R1) < 2
1
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