Features • Drives up to 4 LEDs with up to 30mA each • Regulated current sources with 0.2%(typ.) matching • 3/2x, 1x Gain transition based on LED VF • Peak Efficiency Over 85% • Input Voltage Range: 2.8V to 5.5V • PWM Brightness Control • Very Small Solution Size - NO INDUCTOR • Fixed 750kHz Switching Frequency • <1µA Shutdown Current • 14-pin LLP Package: 4.0mm X 3.0mm X 0.8mm Description The LM27951 is a switched capacitor white-LED driver capable of driving up to 4 LEDs with 30mA through each LED. Its 4 tightly regulated current sources ensure excellent LED current and brightness matching. LED drive current is programmed by an external sense resistor. The LM27951 operates over an input voltage range from 2.8V to 5.5V and requires only four low-cost ceramic capacitors. The LM27951 provides excellent efficiency without the use of an inductor by operating the charge pump in a gain of 3/2, or in a gain of 1. Maximum efficiency is achieved over the input voltage range by actively selecting the proper gain based on the LED forward voltage requirements. The LM27951 uses constant frequency pre-regulation to minimize conducted noise on the input. It has a fixed 750kHz switching frequency optimized for portable applications. The LM27951 consumes less than 1µA of supply current when shut down. The LM27951 is available in a 14-pin No-Pullback Leadless Leadframe Package: LLP-14. Applications • White LED Display Backlights • White LED Keypad Backlights • General Purpose LED Lighting

MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application click for larger image	Block Diagram click for larger image
Typical Performance click for larger image

Datasheet

Title		Size	Date	Other Language
	LM27951 White LED Adaptive 1.5X/1X Switched Capacitor Current Driver	608 Kbytes	26-Apr-06

Featured Application Notes

Title		Size	Date	Other Language
	AN-1251: Application Note 1251 Switched Capacitor Circuits Provide Efficient and Functional White LED Drive	55 Kbytes	26-Sep-02
	AN-1218: Application Note 1218 LM2791/2/4/5 Evaluation Board	424 Kbytes	13-May-04

More Application Notes

Title		Size	Date	Other Language
	AN-1218: Application Note 1218 LM2791/2/4/5 Evaluation Board	424 Kbytes	13-May-04
	AN-1251: Application Note 1251 Switched Capacitor Circuits Provide Efficient and Functional White LED Drive	55 Kbytes	26-Sep-02

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM27951SD	CMOS7	0	18406	0	0	1089000	4	309006723
LM27951SDX	CMOS7	0	18406	0	0	1089000	4	309006723

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

For more information on Reliability Metrics, please click here.