Overview: IMP525
POWER MANAGEMENT Single Cell Battery Powered Electroluminescent Lamp Driver/Inverter
The IMP525 is an Electroluminescent (EL) lamp driver designed for systems that must operate below 1 volt. The input supply voltage range is 0.9V to 2.5V. Typical output lamp drive voltage is 112V. All four EL lampdriving functions are 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. EL lamps of up to 6nF capacitance can be driven to high brightness. The circuit requires few external ponents; one inductor, one diode, one capacitor and two resistors. The resistors set the frequency for the two oscillators. A disable mode puts the chip into a low current-drain state. When disabled, quiescent current drops to 2µA maximum with a VDD of 1.5V. The chip can be disabled by connecting RSW, the oscillator frequency setting resistors, to ground. A disable pad, accessible only on the die, can also be used to disable the driver. An internal circuit shuts down the switching regulator when the lamp drive voltage exceeds 112V peak-to-peak. This conserves power and extends battery life. The IMP525 is available in MicroSO and SO-8 packages and in die form.
