MIC4827 Low Input Voltage, 180V Output Voltage, PP EL Driver General Description Features 1.8V to 5.5V DC input voltage Micrels MIC4827 is a high output voltage, DC to AC con- 180V regulated AC output waveform verter, designed for driving EL (Electroluminescent) lamps. PP The device operates from an input voltage range of 1.8V to Independently adjustable EL lamp frequency 5.5V, making it suitable for 1-cell Li-Ion and 2- or 3- Independently adjustable boost converter frequency cellalkaline/NiCad/NiMH battery applications. The 0.1A shutdown current MIC4827 converts a low voltage DC input to a 180V AC PP output signal that drives the EL lamp. The MIC4827 is comprised of two stages: a boost stage, Applications and an H-bridge, lamp driver, stage. The boost stage steps the input voltage up to +90V. The H-bridge stage then LCD panel backlight alternately switches the +90V output to each terminal of Cellular phones the EL lamp, thus creating a 180V AC signal to drive the PP PDAs EL lamp and generate light. Pager The MIC4827 features separate oscillators for the boost- Calculators and H-bridge stages. External resistors independently set the operating frequency of each stage. This flexibility Remote controls allows the EL lamp circuit to be optimized for maximum Portable phones 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 40C to +85C. Typical Application L1 D1 V 220H BAV20WS IN C OUT C IN 0.033F/100V MIC4827 10F 15 VDD SW 332k 2 6 RSW CS 3.32M 3 8 REL VA 4 7 GND VB TIME (2ms/div) 2 2in EL LAMP High Voltage EL Driver Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC4827 Ordering Information Part Number Ambient Temp. Range Package Standard Pb-Free MIC4827BMM MIC4827YMM 40 to +85C 8-Pin MSOP Pin Configuration 8-Pin MSOP (MM) Pin Description Pin Number Pin Name Pin Function 1 VDD Supply (Input): 1.8V to 5.5V. 2 RSW Switcher Resistor (External Component): Set switch frequency of the internal power MOSFET by connecting an external resistor to VDD. Connecting the external resistor to GND disables the switch oscillator and shuts down the device. 3 REL EL Resistor (External Component): Set EL frequency of the internal H-bridge driver by connecting an external resistor to VDD. Connecting the external resistor to GND disables the EL oscillator. 4 GND Ground Return. 5 SW Switch Node (Input): Internal high-voltage power MOSFET drain. Regulated Boost Output (External Component): Connect the output capacitor of 6 CS the boost regulator and connect to the cathode of the diode. 7 VB EL Output: Connect to one end of the EL lamp. Polarity is not important. 8 VA EL Output: Connect to the other end of the EL lamp. Polarity is not important. M9999-070709-A July 2009 2 (408) 955-1690