TLC59208F Datasheet, PDF (25/37 Pages) Texas Instruments – 8-BIT FM+ I2C BUS LED DRIVER

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10 Application and Implementation
TLC59208F
SCLS715A – MARCH 2009 – REVISED NOVEMBER 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.
10.1 Application Information
10.1.1 Setting LED Current
The LED current is primarily dependent on the supply voltage, the forward voltage of the LED, and the series
resistor (R_SET). In many applications the supply voltage and LED forward voltage cannot be adjusted. Hence,
R_SET is utilized to adjust the LED current. This calculation is discussed in detail in the typical application example.
10.1.2 PWM Brightness Dimming
The perceived brightness of the LEDs can be adjusted by use of PWM dimming. For example, an LED driven at
50% duty cycle will appear less bright than it would at 100% duty cycle. The TLC59208F offers duty cycle control
for each individual channel and also offers group duty cycle control. Refer to the Register Map for details
regarding programmable duty cycle.
10.2 Typical Application
This application example provides guidance on how to set the LED current using the TLC59208F.
V_LED
3.3V or 5V
R_SET
SCL
SDA
RESET
Microcontroller
SCL
SDA
RESET
A0-A2
VDD
OUT7
OUT6
OUT5
TLC59208F
OUT1
OUT0
GND
Figure 20. Typical Application
10.2.1 Design Requirements
For this design example, use Table 12 the following as the input parameters.
V_LED
V_F
I_LED
R_ON
Table 12. Design Parameters
DESIGN PARAMETER
Supply voltage that powers the LED
Forward voltage across the LED
Current flowing through the LED
Resistance across open-drain output
EXAMPLE VALUE
5-V
3-V
6-mA
1.5-Ω
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