EL Lamp Driver Delivers 60% More Drive Voltage

Combining 1.5V battery operation with high, 180V peak-to-peak ac drive, the IMP527 IC allows pager and cellular phone display screens to be brightly backlit by electroluminescent (EL) lamps. Its output voltage is said to be 60% higher than the existing IMP525, thereby increasing EL lamp brightness-IMP525 also operates from a single 1.5V battery. IMP527 incorporates four EL lamp driving functions on-chip: a boost switch-mode power supply, high-frequency oscillator, high-voltage H-bridge lamp driver, and a low-frequency oscillator. Few external components are needed: one inductor, one diode, one capacitor, and two resistors. The resistors allow independent adjustment of boost converter frequency and of EL lamp drive frequency. When not needed to drive the EL backlight, the device can be disabled.