UC3909 Datasheet | Unitrode

UC2909 - Obsolete Device UC2909 UC3909 Switchmode Lead-Acid Battery Charger Features - Accurate and Efficient Control of Battery Charging - Average Current Mode Control from Trickle to Overcharge - Resistor Programmable Charge Currents - Thermistor Interface Tracks Battery Requirements Over Temperature - Output Status Bits Report on Four Internal Charge States - Undervoltage Lockout Monitors VCC and VREF DESCRIPTION The UC3909 family of Switchmode Lead-Acid Battery Chargers accurately controls lead acid battery charging with a highly efficient average current mode control loop. This chip bines charge state logic with average current PWM control circuitry. Charge state logic mands current or voltage control depending on the charge state. The chip includes undervoltage lockout circuitry to insure sufficient supply voltage is present before output switching starts. Additional circuit blocks include a differential current sense amplifier, a 1.5% voltage reference, a - 3.9m V/°C thermistor linearization circuit, voltage and current error amplifiers, a PWM oscillator, a PWM parator, a PWM latch, charge state decode bits, and a 100m A open collector output driver. BLOCK DIAGRAM Pin numbers refer to J, N, DW packages. 1/99 UDG-95007-1 UC2909 - Obsolete...