IMP52

The IMP527 is an Electroluminescent (EL) lamp driver designed for systems that must operate down to 1 volt and below. The input supply voltage range is 0.9V to 2.5V. Typical output lamp drive voltage is 180V. 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 components; 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 1µAtypical with a VDD of 1.5V. The chip can be disabled by connecting RSW, the oscillator frequency setting resistor, to ground. A disable pad (active low), 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 180V peak-to-peak. This conserves power and extends battery life.

The IMP527 is available in MicroSO and SO-8 packages and in die form.