TLED2043 Datasheet, PDF (12/15 Pages) Texas Instruments – 4-CHANNEL WHITE LED DRIVER

TLED2043
4-CHANNEL WHITE LED DRIVER
SLDS147C – JUNE 2002 – REVISED NOVEMBER 2002
TYPICAL CHARACTERISTICS
example of a “digital” brightness control circuit
When using equipment such as cell phones, often it is desirable to adjust the brightness of the LCD display.
While variable resistors offer an easy means of adjusting the LED brightness as described above, they are not
economical if a digital potentiometer is required. Figure 9 shows a relatively simple and cost-effective means
of achieving “digital” control of the LED brightness using standard resistors and signal switches.
Using a simple dual signal switch such as the SN74LVC2G66, resistors R2A and R2B can be individually
paralleled to R2 to change the voltage divider being fed by V_REF. Doing so lowers the voltage applied to IN–
of the current-control amplifier, resulting in increased LED current and brightness.
VOUT2
VOUT1
TLED2043
SN74LVC2G66
R2B
R2A
R1
R3
R6
FB
R5
R7
R8
R2
R4
IN– _{_}
AMP1
+
IN+
Current-Control Amplifier
C1
Figure 9. Example of a “Digital” Brightness Control
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