TPS92560 Datasheet, PDF (15/23 Pages) Texas Instruments – SIMPLE LED DRIVER FOR MR16 AND AR111 APPLICATIONS

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8 Application and Implementation
TPS92560
SNVS900B – DECEMBER 2012 – REVISED DECEMBER 2015
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
In the applications that need true regulation of the LED current, the intrinsic input current control loop can be
changed to monitor the LED current by adding an external LED current sensing circuit. Figure 18 and Figure 23
show the example circuits for true LED current regulation in boost and SEPIC configurations respectively. In the
circuits, the U₃ (TL431) maintains a constant 2.5-V voltage drop on the resistors, R₃ and R₇. Because the U₂
(TL431) maintains a constant voltage drop on the R₃, the power dissipation on the output current sensing
resistor, R₇ can be minimized by setting a low voltage drop on the R₇. Because the change of the current flowing
through the R₇ reflects in the change of the cathode current of U₃ and eventually adjusts the ADJ pin voltage of
the TPS92560, the LED current is regulated independent of the change of the input voltage.
L₁
D₃
C₁
LED
R_ADJ1
R_ADJ2 C_ADJ
C_OUT
C_IN
L₂
Q₁
TPS92560
R₁
D₁
D₂
GATE AC1
C_VCC
SRC
VCC
PGND
AC2
R_SEN
SEN
VP
GND
ADJ
C_VP
Power
Source
D₄
Figure 16. Typical Application Circuit of the TPS92560 Using SEPIC Configuration
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