TPS61043
www.ti.com
SLVS465A – DECEMBER 2003 – REVISED DECEMBER 2003
CONSTANT CURRENT LED DRIVER
FEATURES
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Current Source with 18 V Overvoltage Protec-
tion
Powers Up to 4 LEDs in Series
Input Voltage Range . . 1.8 V to 6.0 V
Internal 30 V Switch
Up to 85% Efficiency
Precise Brightness Control Using PWM Signal
or Analog Signal
Switching Frequency . . Up to 1 MHz
Internal Power MOSFET Switch . . 400 mA
Operates With Small Output Capacitors Down
to 100 nF
Disconnects LEDs During Shutdown
No Load Quiescent Current . . 38 µA Typ
Shutdown Current . . 0.1 µA Typ
Available in a Small 3 mm
×
3 mm QFN
Package
DESCRIPTION
The TPS61043 is a high frequency boost converter
with constant current output that drives white LEDs or
similar. The LED current is set with the external
sense resistor (R
S
) and is directly regulated by the
feedback pin (FB) that regulates the voltage across
the sense resistor R
S
to 252 mV (typ). To control LED
brightness, the LED current can be pulsed by apply-
ing a PWM (pulse width modulated) signal with a
frequency range of 100 Hz to 50 kHz to the control
pin (CTRL). To allow higher flexibility, the device can
be configured where the brightness can be controlled
by an analog signal as well, as described in the
application information
section. To avoid possible
leakage currents through the LEDs during shutdown,
the control pin (CTRL) disables the device and
disconnects the LEDs from ground. For maximum
safety during operation, the output has integrated
overvoltage protection that prevents damage to the
device by limiting the output voltage to typically 18 V
in case of a high impedance output (e.g. faulty LED).
The TPS61042 device provides a solution for appli-
cations where higher LED currents or more than four
LEDs in series need to be powered.
APPLICATIONS
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White LED Supply for Display
Backlight/Sidelight in
– PDA, Pocket PC, Smart Phones
– Handheld Devices
– Cellular Phones
L1
4.7
mH
D1
C
O
100 nF
25 V
VIN
1.8 V to 6 V
C
IN
4.7
mF
3
5
VIN
SW
8
7
CTRL OVP
6 GND LED 1
4 FB
R 2
S
Enable/PWM Brightness
Control 100 Hz to 50 kHz
R
S
13
W
A.
Output capacitor values like 1 µF and larger, reduce the LED ripple current and improve line regulation.
Figure 1. Typical Application
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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.
Copyright © 2003, Texas Instruments Incorporated
TI [ TEXAS INSTRUMENTS ]
