LM27952 Datasheet, PDF (1/17 Pages) National Semiconductor (TI) – White LED Adaptive 1.5X/1X Switched Capacitor Current Driver

LM27952
www.ti.com
SNVS364B – MAY 2005 – REVISED MAY 2013
LM27952 White LED Adaptive 1.5X/1X Switched Capacitor Current Driver
Check for Samples: LM27952
FEATURES
1
•2 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 V_F
• Peak Efficiency Over 85%
• Input Voltage Range: 3.0V to 5.5V
• PWM Brightness Control
• Very Small Solution Size - NO INDUCTOR
• Fixed 750kHz Switching Frequency
• <1µA Shutdown Current
• 14-pin WSON Package: 4.0mm X 3.0mm X
0.8mm
APPLICATIONS
• White LED Display Backlights
• White LED Keypad Backlights
• General Purpose LED Lighting
DESCRIPTION
The LM27952 is a switched capacitor white-LED
driver capable of driving up to 4 LEDs with 30mA
through each LED. Its 4 tightly regulated current sinks
ensure excellent LED current and brightness
matching. LED drive current is programmed by an
external sense resistor. The LM27952 operates over
an input voltage range from 3.0V to 5.5V and requires
only four low-cost ceramic capacitors.
The LM27952 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.
Typical Application Circuit
V_IN = 3.0V - 5.5V
V_IN
C₁+
C_IN
3.3 µF
C₁
1 µF
V_OUT
3.3 µF
C₁-
D4
C₂+
LM27952 _D3
C₂
1 µF
D2
C₂-
D1
I_SET
PWM
D₄
C_OUT
D₃
D₂
D₁
I_DX = 30 mA max
R_SET
GND
EN
Capacitors: 1 µF - TDK C1608X7R1A105K
3.3 µF - TDK C2012X7R1A335K
or equivalent
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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