TPS61043 Datasheet, PDF (1/21 Pages) Texas Instruments – CONSTANT CURRENT LED DRIVER

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TPS61043
SLVS465A – DECEMBER 2003 – REVISED DECEMBER 2003
CONSTANT CURRENT LED DRIVER
FEATURES
• 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
APPLICATIONS
• White LED Supply for Display
Backlight/Sidelight in
– PDA, Pocket PC, Smart Phones
– Handheld Devices
– Cellular Phones
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.
L1
4.7 mH
D1
VIN
1.8 V to 6 V
C_IN
4.7 mF
3 _{VIN SW} 8
5 _{CTRL OVP} 7
6 _{GND LED} 1
4 _FB
R_S ²
C_O
100 nF
25 V
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