LM27951 White LED Adaptive 1.5X/1X Switched Capacitor Current Driver | TI.com

LM27951
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White LED Adaptive 1.5X/1X Switched Capacitor Current Driver

 

Description

The LM27951 is a switched capacitor white-LED driver capable of driving up to four LEDs with 30 mA through each LED. Its four 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 2.8 V to 5.5 V 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 750-kHz switching frequency optimized for portable applications. The LM27951 consumes less than 1 µA of supply current when shut down.

The LM27951 is available in a 14-pin no-pullback WSON package.

For all available packages, see the orderable addendum at the end of the data sheet.

Features

  • Input Voltage Range: 2.8 V to 5.5 V
  • Drives up to Four LEDs With up to 30 mA each
  • Regulated Current Sources with 0.2% (Typical) Matching
  • 3/2×, 1× Gain Transition Based on LED Vƒ
  • Peak Efficiency Over 85%
  • PWM Brightness Control
  • Very Small Solution Size - No Inductor
  • Fixed 750-kHz Switching Frequency
  • < 1-µA Shutdown Current

Parametrics

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Part number Order Channels (#) Vin (Min) (V) Vin (Max) (V) Vout (Min) (V) Vout (Max) (V) Switching frequency (Max) (kHz) Type LED current per channel (mA) LED (#) Topology Shutdown current (Typ) (uA) Peak efficiency (%) LED configuration Features Operating temperature range (C) Package Group Package size: mm2:W x L (PKG)
LM27951 Order now 4     2.8     5.5     2.8     5.5     975     Capacitive     30     4     Boost     0.1     85     Parallel     Direct PWM Dimming     -40 to 85     WSON | 14     14WSON: 12 mm2: 3 x 4 (WSON | 14)