HV881

HV881 is a 16 channel EL lamp driver with a single common terminal. It can drive up to a 1nF EL lamp load (approx. 0.3in2 lamp size) on each of the sixteen channels.The input supply voltage range is 1.8 to 5.5V. The logic interface to the device can be as low as 1.7V. The device has an enable logic input pin to turn the device on or off.

The device is designed to minimize audible noise emitted by the EL lamp. The HV881 uses an external MOSFET, a single inductor and minimum number of passive components to drive all sixteen EL lamps. 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 HV881 has two internal oscillators and a high voltage EL lamp driver. An external MOSFET is driven by the switch oscillator to generate output voltage.

The frequency for the external switching MOSFET is set by an external resistor connected between the RSW-Osc pin and the VDD supply pin. The EL lamp driver frequency can be set by either an external logic signal frequency at the SEL pin or by an external resistor connected between the REL-Osc pin and VDD pin. If external frequency is input at the SEL pin, the REL-Osc pin should be connected to ground.

An external inductor is connected between the LX and VDD or VIN pins for split supply applications. Depending upon the EL lamp sizes, a 1.0 to 10.0nF capacitor is connected between the CS pin and ground. The CS capacitor is connected to the internal H-bridge, and the energy stored in the capacitor is therefore transferred to the EL lamp. One side of all the sixteen EL lamps is connected to the respective EL pins (EL1, EL2, etc.), and the other side is connected to the COM pin.

The external switching MOSFET charges the inductor and discharges it into the capacitor at CS. The voltage at CS will start to increase. Once the voltage at CS reaches the desired regulation limit, the external switching MOSFET is turned off to conserve power.

The HV881 allows for controlling the fall time of the EL1 - EL16 outputs by an external resistor from the RSLOPE pin to the VDD pin. This feature can be used to reduce the audible noise of the EL lamp or to increase the lamp brightness.

The brightness of each of the sixteen EL lamps can be independently controlled to have one of fifteen brightness levels or can be completely turned off by the serial data (SDA) input. The serial data input has a 4-bit binary code for each lamp, to control the brightness level from level 0 to level 15. The brightness is controlled by controlling the number of EL frequency cycles (from 0 to 15) in a group of 15 cycles.