SC1437

Precision Voltage Detector With Programmable Trigger Voltage & Timer Delay POWER MANAGEMENT Description 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 voltage, 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 approximately 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 opti...