The IMP528 is an Electroluminescent (EL) lamp driver with the four EL lamp driving functions on-chip. These are the switch-mode power supply, its high-frequency oscillator, the high-voltage H-bridge lamp driver and its low-frequency oscillator. The IMP528 drives EL lamps of up to 50nF capacitance to high brightness; EL lamps with capacitances greater than 50nF can be driven, but will be lower in light output. The typical regulated output voltage that is applied to the EL lamp is 220V peak-to peak. The circuit requires few external components; a single inductor, single diode, two capacitors and two resistors. Two of these resistors set the frequency for two internal oscillators.

Unlike other EL lamp drivers, the IMP528 does not require an external protection resistor in series with the EL lamp.

The IMP528 operates over a 2.0V to 6.5V supply voltage range. A regulated, low-power source can supply the low quiescent current of the IMP528. The inductor may be driven from an independent, unregulated supply voltage in dual supply applications.

An internal circuit shuts down the switching regulator when the lamp drive voltage reaches 220V peak-to-peak. This conserves power and extends battery life.

The IMP528 is available in MicroSO and SO-8 packages and in die or wafer form.

Key Features

◆ 220V peak-to-peak typical AC output voltage

◆ Low Power: 420μA typical VDD current

◆ Wide operating voltage range-from 2.0V to 6.5V

◆ Large output load capability - drives lamps with more than 50nF capacitance

◆ Eliminates external protection resistor in series with EL lamp

◆ Adjustable output lamp frequency for control of lamp color, lamp life, and power consumption

◆ Adjustable converter frequency to minimize power consumption

◆ High-Voltage CMOS Process

◆ MicroSO package option

Applications

◆ GPS units/Pagers/Cellular phones

◆ PDAs/Handheld computers

◆ Safety illumination

◆ Portable instrumentation

◆ Battery-operated displays

◆ LCD modules

◆ Toys