Overview: IMP560
POWER MANAGEMENT Power Efficient EL Lamp Driver
The IMP560 is an Electroluminescent (EL) lamp driver designed for systems with low EL lamp drive voltage requirements. It is ideal for low ambient light applications or where small lamps are used. With just onehalf the inductor current of the IMP803, the IMP560 reduces system power consumption and extends battery life. Input supply voltage range is 2.0V to 6.5V and quiescent current is a low 420µA. Typical EL lamp drive voltage is ±56V. All four EL lamp-driving functions are on-chip. These are the switchmode power supply, its high-frequency oscillator, the high-voltage H-bridge lamp driver and its low-frequency oscillator. EL lamps of up to 6nF capacitance can be driven to high brightness. The circuit requires few external ponents; a single inductor, a single diode, two capacitors and three resistors. Two of these resistors set the frequencies for two internal oscillators. An internal circuit shuts down the switching regulator when the lamp drive voltage exceeds 120V peak-to-peak. This conserves power and extends battery life. A disable mode puts the chip into a low current drain mode. With a 3.0V supply, quiescent current drops to 200nA maximum, 50nA typical. The chip is disabled by connecting the oscillator frequency setting resistor RSW to ground. The IMP560 is available in MicroSO and SO-8 packages and in die or wafer form.
