Electroluminescent Driver IC Delivers Small and Silent Backlight Control

With a low parts count and internal wave-shaping to minimise audible noise, the Micrel MIC4833 dual-output Electroluminescent (EL) lamp driver improves display backlighting in handheld and portable devices.

The MIC4833 implements a boost converter and H-bridge network to generate two outputs for EL panels up to 4cm2. Two internal oscillators control the boost switching frequency and the H-bridge driver frequency, and both can be individually programmed to optimise EL efficiency and brightness. The MIC4833 also provides an independent Enable pin for each EL-driver output.

Driving both outputs from a single inductor saves component count and bill-of-materials costs, and reduces typical external components to the inductor, diode, three decoupling capacitors, and three programming resistors. Two resistors set the EL-driver and H-bridge frequencies, while the third can be used to adjust the output slew rate to further reduce audible noise. EL-lamp dimming can also be achieved, by applying a PWM signal to the H-bridge oscillator via an external pin.

As a further benefit of the MIC4833, the input-voltage range of 2.3V to 5.8V allows use with multiple battery configurations and chemistries, such as single-cell Li-ion and two- or three-cell alkaline, NiCd, or NiMH batteries. This allows use in a wide variety of consumer and professional equipment.

 

FEATURES 220V AC peak output voltage 152µA typical operating current 0.1µA typical shutdown current EL-output frequency range: 100Hz to 1500Hz 12-pin, 3mm x 3mm MLF® package

APPLICATIONS Remote controls Portable test equipment Instrumentation Domestic appliances GPS devices

 

 

Micrel Semiconductor / MIC4833