General Description
The Supertex HV858 is a high voltage triple EL lamp driver designed for driving combined EL lamps of up to 3.0 in2 (1.0 in2 each). The input supply voltage range is from 1.8V to 6.5V. The device is designed such that the input voltage to the inductor can be different from the input voltage to the device (split supply). The device uses a single inductor and a minimum number of passive components. The nominal regulated output voltage that is applied to the EL lamp is ±95V. The HV858 has two internal oscillators, one for the internal switching MOSFET, and the other for the high voltage EL lamp driver. The EL lamp frequency is fi xed internally at 500Hz. The power converter oscillator runs 256 times faster than the EL lamp driver at 128kHz.

Features
❐ Tri-EL lamp driver with common terminal
❐ Independent brightness control for all 3 lamps
❐ 1.8V to 6.5V Operating Supply Voltage
❐ Output voltage regulation
❐ Two-pin serial data communication for control
❐ Linear brightness control with seven steps at constant effi ciency
❐ 128kHz Fixed Switching Frequency
❐ Split supply capability
❐ Patented high effi ciency EL lamp driver
❐ Single miniature inductor drives all 3 lamps
❐ Only 4 external components
❐ Burst mode power converter for best effi ciency
❐ CMOS compatible serial interface with noise rejection
❐ 150nA max. leakage current when disabled
❐ Power-on reset causes all outputs to be off when fi rst powered up
❐ Small 10-pin MSOP package
❐ 10-pin DFN/MLP package (0.8mm thickness)

Applications
❐ Mulit-segment, variable displays
❐ Cell phone keypads and displays
❐ MP3 players
❐ Watches