The SC4538 is designed to regulate current for a series string of white LEDs in LCD backlighting applications where small size and high effi ciency are priorities. This device integrates an 800kHz current-mode PWM boost converter and a 30mA programmable low dropout current sink regulator.
An external resistor sets the LED current up to 30mA. PWM dimming (100Hz to 50kHz) may be applied directly to the enable (EN) pin, or dimming can be controlled by applying an analog signal to the ISET circuit. The boost circuit can output up to 38V (guaranteed) to drive up to 10 LEDs in series. The current regulator protects against shorts between the BL and OUT pins and also eliminates backlight glow during shutdown when using LEDs with high leakage. Under-voltage lockout and thermal shutdown provide additional protection. A small external capacitor and series resistor control soft-start and loop compensation. Over-voltage detection protects the SC4538 if the BL pin is fl oating or shorted to ground.
The SC4538 is available in an MLPD-8 pin 2mm x 2mm x 0.6mm package, with a rated temperature range of -40°C to +85°C.

*Input voltage range — 2.8V to 5.5V
*Programmable LED current up to 30mA
*Current-mode PWM control — 800kHz
*Soft-start to reduce in-rush current
*PWM dimming — 100Hz to 50kHz
*PWM dimming at ISET — Analog and fi ltered
*Over-voltage protection — 38V (minimum)
*Under-voltage lockout (UVLO)
*Thermal shutdown
*Shutdown current — <0.1μA (typical)
*Ultra-thin package — 2mm x 2mm x 0.6mm
*Lead-free package, WEEE and RoHS compliant

*DSLR, DSC, and Video Cameras
*Cellular handsets
*Portable media players
*Personal navigation systems
*Satellite radio
*Handheld video games


댓글을 달아 주세요 Comment