Dual Electroluminescent Lamp Driver

The MAX14514 is a high-voltage DC-AC converter ideal for driving two electroluminescent (EL) lamps. The MAX14514 features a +2.7V to +5.5V input range that allows the device to accept a wide variety of voltage sources, including single-cell lithium-ion (Li+) batteries. The lamp outputs of the device generate up to 300VP-P for maximum lamp brightness.

The MAX14514 utilizes an inductor-based boost converter to generate the high voltage necessary to drive EL lamps and allows the use of a 220µH inductor to effectively drive total combined lamp sizes of up to 20nF.

The MAX14514 uses a high-voltage full-bridge output stage to convert the high voltage generated by the boost converter to an AC waveform suitable for driving the EL panels. An external resistor controls the slew-rate of the rising and falling edges of the AC drive waveform to reduce audible noise output. The high-voltage outputs are ESD protected up to ±15kV Human Body Model, ±4kV IEC 61000-4-2 Air Gap Discharge, and ±4kV IEC 61000-4-2 Contact Discharge.

The MAX14514 features dimming/enable controls (DIM1, DIM2) for each output to allow the user to set the peak-to-peak output voltage with a PWM signal, a DC analog voltage, or a resistor connected from DIM to GND. The MAX14514 also provides a slow turn-on/-off feature that slowly ramps the output voltage applied to the lamp when enabled or disabled.

The MAX14514 enters a low-power shutdown mode when the EN and DIM inputs are connected to GND. The device also features thermal shutdown if the die temperature exceeds +158°C (typ).

The MAX14514 is available in a space-saving, 14-pin, 3mm x 3mm TDFN package and is specified over the extended -40°C to +85°C operating temperature range.

Applications

* Keypad Backlighting * LCD Backlighting * PDAs/Smartphones

* Dual ±15kV ESD-Protected EL Lamp Outputs

* 300VP-P Maximum Output for Highest Brightness

* +2.7V to +5.5V Input Voltage Range

* Resistor Adjustable Slew-Rate Control

* Resistor Adjustable Lamp and Switching Converter Frequencies

* DIM Input for Controlling Output Voltage Through DC Analog Voltage, PWM, or Resistor to GND

* Capacitor Adjustable Soft Turn-On/Off

* Low 150nA Shutdown Current

* Thermal Shutdown

* Space-Saving, 14-Pin, 3mm x 3mm TDFN Package