TLC5925 Datasheet, PDF (13/22 Pages) Texas Instruments – LOW-POWER 16-CHANNEL CONSTANT-CURRENT LED SINK DRIVER

TLC5925
www.ti.com .............................................................................................................................................................................................. SLVS765 – OCTOBER 2008
APPLICATION INFORMATION
Operating Principles
Constant Current
In LED display applications, TLC5925 provides nearly no current variations from channel to channel and from IC
to IC. While I_OUT ≤ 45 mA, the maximum current skew between channels is less than ±5% and between ICs is
less than ±6%.
Adjusting Output Current
TLC5925 sets I_OUT based on the external resistor R_ext. Users can follow the below formulas to calculate the
target output current I_OUT,target in the saturation region:
I_OUT,target = (1.21 V / R_ext) × 18, where R_ext is the external resistance connected between R-EXT and GND.
Therefore, the default current is approximately 26 mA at 840 Ω and 13 mA at 1680 Ω. The default relationship
after power on between I_OUT,target and R_ext is shown in Figure 5.
45
40
35
30
25
20
15
10
5
0
0
500 1000 1500 2000 2500 3000 3500 4000
R_ext – 8W
Figure 5. Default Relationship Curve Between I_OUT,target and R_ext After Power Up
Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): TLC5925
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