MIC4833: Low Noise 220Vp-p EL Driver - Micrel - #1

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MIC4833 Low Noise Dual 220 VPP EL Driver With Output Voltage Slew Rate Control MLF and MicroLead Frame are registered trademark of Amkor Technologies Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com General Description The MIC4833 is a low noise dual Electroluminescent (EL) Panel driver used in backlighting applications. The MIC4833 converts a low DC voltage to a high DC voltage using a boost converter and then alternates the high DC voltage across the EL panels using an H-bridge. The MIC4833 incorporates internal wave-shaping circuitry specifically designed to reduce audible noise emitted by EL panels. The two EL panels may be dimmed by applying a PWM signal to the device. The MIC4833 drives two outputs from a single inductor and requires a minimum number of passive components. It features an operating input voltage range of 2.3V to 5.8V, making it suitable for 1-cell Li-ion and 2- or 3-cell alkaline/NiCad/NiMH battery applications. An external resistor may be used to adjust the output voltage slew rate to reduce audible noise. The MIC4833 features separate oscillators for the boost and H-bridge stages to allow independent control. External resistors set the operating frequencies of each stage allowing the EL circuit to optimize efficiency and brightness. The MIC4833 is available in a 12 pin 3mmx3mm MLF® package, and has an operating junction temperature range of –40°C to +125°C. Features • Drives two EL panels, up to 4 in2 each at full brightness • Independent input control for each of the two panels and allows PWM dimming. • 220Vpp regulated AC output waveform • 2.3V to 5.8V DC input voltage • Wave-shaping circuit to reduce audible noise • Adjustable slew rate for audible noise reduction • Independently adjustable boost converter and EL panel frequency • Single inductor to power both panels • 0.1uA typical shutdown current • 12 pin 3mmx3mm MLF® package • –40oC to +125oC junction temperature range Applications • Mobile Phones • MP3s/Portable Media Players (PMP) • Clocks/ Watches • Remote Controls • Cordless Phones • GPS Devices • PDAs _________________________________________________________________________________________________ Typical Application ENAVDDRSWRELENB1.78M220ìHMIC4833332kGNDSLEWVINLi Ion3V to 4.2V0.01ìFELAELBCOMCSSW50k2.2nF250V10ìFVINLi Ion3V to 4.2VHighLowHighLowHighLowEL Lamp AEL Lamp B October 2008 M9999-100308 (408) 955-1690 Low Noise Dual EL Driver