LM3557 Datasheet, PDF (1/19 Pages) National Semiconductor (TI) – Step-Up Converter for White LED Applications

LM3557
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SNVS338B – NOVEMBER 2004 – REVISED FEBRUARY 2013
LM3557 Step-Up Converter for White LED Applications
Check for Samples: LM3557
FEATURES
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•2 V_IN Range: 2.7V–7.5V
• Small External Components
• 1.25 MHz Constant-Switching Frequency
• Output Over-Voltage Protection
• Input Under-Voltage Protection
• Cycle-By-Cycle Current Limit
• TRUE SHUTDOWN: No DC current paths to
ground during shutdown
• Low Profile Package: <1 mm Height -8 Pin
WSON
• No External Compensation
APPLICATIONS
• White LED Display Lighting
• Cellular Phones
• PDAs
DESCRIPTION
The LM3557 is a complete solution for white LED
drive applications. With minimal external component
count, no DC current leakage paths to ground, cycle-
by-cycle current limit protection, and output over-
voltage protection circuitry, the LM3557 offer superior
performance and cost savings over standard DC/DC
boost component implementations.
The LM3557 switches at a fixed-frequency of 1.25
MHz, which allows for the use of small external
components. Also, the LM3557 has a wide input
voltage range to take advantage of multi-cell input
applications. With small external components, high
fixed frequency operation, and wide input voltage
range, the LM3557 is the most optimal choice for
LED lighting applications.
Typical Application Circuit
L
2.2 PH
D
Vout
V_SUPPLY
Cin
4.7 PF
V_IN
Sw1 Ovp
LM3557 Fb
En
NC
Gnd Sw2
Cout
1 PF
R2
Figure 1. Backlight Configuration
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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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