MIC4827 Low Input Voltage, 180VPP Output Voltage, EL Driver - Micrel - #1

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MIC4827 Low Input Voltage, 180VPP Output Voltage, EL Driver General Description Micrel’s MIC4827 is a high output voltage, DC to AC con-verter, designed for driving EL (Electroluminescent) lamps. The device operates from an input voltage range of 1.8V to 5.5V, making it suitable for 1-cell Li-Ion and 2- or 3-cellalkaline/NiCad/NiMH battery applications. The MIC4827 converts a low voltage DC input to a 180VPP AC output signal that drives the EL lamp. The MIC4827 is comprised of two stages: a boost stage, and an H-bridge, lamp driver, stage. The boost stage steps the input voltage up to +90V. The H-bridge stage then alternately switches the +90V output to each terminal of the EL lamp, thus creating a 180VPP AC signal to drive the EL lamp and generate light. The MIC4827 features separate oscillators for the boost- and H-bridge stages. External resistors independently set the operating frequency of each stage. This flexibility allows the EL lamp circuit to be optimized for maximum efficiency and brightness. The MIC4827 uses a single inductor and a minimum number of external components, making it ideal for portable, space-sensitive applications. The MIC4827 is available in an 8-pin MSOP package with an ambient temperature range of –40°C to +85°C. Features • 1.8V to 5.5V DC input voltage • 180VPP regulated AC output waveform • Independently adjustable EL lamp frequency • Independently adjustable boost converter frequency • 0.1ìA shutdown current Applications • LCD panel backlight • Cellular phones • PDAs • Pager • Calculators • Remote controls • Portable phones Typical Application Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com July 2009 M9999-070709-A (408) 955-1690 332k3.32MCOUT0.033ìF/100VD1BAV20WSL1220ìH2in2 EL LAMP15687234SWCSVAVBVDDRSWRELGNDMIC4827CIN10ìFVIN TIME (2ms/div)VB(50V/div)VA(50V/div)VA—VB(50V/div) High Voltage EL Driver