LM2754 Datasheet, PDF (1/19 Pages) National Semiconductor (TI) – 800mA Switched Capacitor Flash LED Driver with Time-Out Protection

LM2754
www.ti.com
SNVS463A – SEPTEMBER 2006 – REVISED MAY 2013
LM2754 800mA Switched Capacitor Flash LED Driver with Time-Out Protection
Check for Samples: LM2754
FEATURES
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•2 Up to 800mA Output Current
• Wide Operating Input Voltage Range: 2.8V to
5.5V
• Drives 1, 2, 3 or 4 LEDs in Parallel
• Ability to Disable One Current Sink Via the
SEL Pin to Accommodate 3-LED Flash
Modules
• Time-Out Circuitry Limits Flash Duration to 1
Second
• TX Input Ensures Synchronization with RF
Power Amplifier Pulse
• Adaptive 1x, 1.5x and 2x Gains for Maximum
Efficiency
• 1MHz Constant Frequency Operation
• Output Current Limit
• True Shutdown Output Disconnect
• <1µA Shutdown Current
• Internal Soft-Start Limits Inrush Current
• No Inductor Required
• Total Solution Size without LED <28mm²
• Low Profile 24-Pin WQFN Package (4mm x
4mm x 0.8mm)
APPLICATIONS
• Camera Flash in Mobile Phones
• Flash for Digital Cameras
• Supplies for DSP’s, Microprocessors, Memory,
MP3 Players, Pagers, Other Portable Devices
DESCRIPTION
The LM2754 is an integrated low noise, high current
switched capacitor DC/DC converter with four
regulated current sinks. The device is optimized for
driving 1 to 4 high power white LEDs in parallel with a
maximum current of 800mA. Maximum efficiency is
achieved over the input voltage range by actively
selecting the proper gain based on the LED forward
voltage and current requirements.
Two external low power resistors set the desired
current for Torch and Flash modes. The TX pin
allows the device to be forced into Torch mode during
a Flash pulse, allowing for synchronization between
the RF power amplifier pulse and Flash/Torch modes.
To protect the device and Flash LEDs, internal Time-
Out circuitry turns off the LM2754 in case of a faulty
prolonged Flash mode. Internal soft-start circuitry
limits the amount of inrush current during start-up.
The LM2754 is available in a small 24-pin thermally
enhanced WQFN package.
Typical Application Circuit
V_IN = 3.0V - 5.5V
V_IN
C₁+
C_IN
2.2 µF
C₁
2.2 µF
I_F = 800 mA max
V_OUT
4.7 µF
C_OUT
D₁
D₂
D₃
D₄
C₂
R_SET1
C₁-
C₂+
LM2754
D₁
D₂
D₃
2.2 µF
D₄
C₂-
I_SET1
I_SET2
R_SET2
EN
T/F
TX
SEL
GND
TDK: 2.2 µF ± C1608X5R1C225
4.7 µF ± C2012X5R1C475
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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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