HV861

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Continuous operation of the device at the absolute rating level may affect device reliability. All voltages are referenced to device ground.

The Supertex HV861 is a low noise, dimmable, high voltage, dual EL Lamp driver designed for driving two electroluminescent (EL) Lamps with a combined area of 5.0 square inches. The input supply voltage range is from 2.5V to 4.5V. Enable input logic high can go as low as 1.5V, which allows logic interface operating from typical 1.8V supplies. The device is designed to minimize audible noise emitted by the EL Lamps.

The device HV861 uses a single inductor and a minimum number of passive components. Using the internal reference voltage, the regulated output voltage is at a nominal value of 90V. The EL Lamps will therefore see 90V. The two EL Lamps can be turned ON and OFF using two CMOS logic inputs, EN1 and EN2. The driver is disabled when both EN1 and EN2 are at logic low.

The HV861 has two internal oscillators, a switching MOSFET, and two high voltage EL Lamp driver H-bridges. Each driver has its own half bridge common output, COM1 and COM2, which signi cantly minimizes the DC offset seen by the EL Lamp. The frequency for the switching MOSFET is set by an external resistor connected between the RSW-osc pin and the supply pin VDD. The EL Lamp driver frequency is set by an external resistor connected between the REL-osc pin and the VDD pin. An external inductor is connected between the LX and VDD pins or VIN for split supply applications. Depending upon the EL Lamp sizes, a 1.0nF to 10.0nF capacitor is connected between the CS and ground.  As the switching MOSFET charges the external inductor and discharges it into the capacitor at CS, the voltage at CS will start to increase. Once the voltage at CS reaches a nominal value of 90V, the switching MOSFET is turned OFF to conserve power. 

EL Lamp dimming can be accomplished by applying a PWM logic signal to the PWM pin. The EL Lamp brightness will be proportional to the PWM duty cycle. The HV861 can also slowly turn the EL Lamp ON/OFF giving a fade ON/OFF appearance.