TLC5973 Datasheet, PDF (12/34 Pages) Texas Instruments – TLC5973 3-Channel, 12-Bit, PWM Constant-Current LED Driver with Single-Wire Interface (EasySet)

TLC5973
SBVS225B – MARCH 2013 – REVISED MAY 2014
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Feature Description (continued)
8.3.3 No Limit Cascading
This feature results in no limitation on the number of total cascaded devices used in series in an application. This
advantage is attained because a timing-adjusted pulse generator is implemented in the device.
8.3.4 Constant Sink Current Value
The output current value of each channel (I_OLC) is programmed by a single resistor (R_IREF) that is placed between
the IREF and GND pins. The current value can be calculated by Equation 1:
R_IREF (kW) =
V_IREF (V)
I_OLC (mA)
´ 43.4
where:
• V_IREF = the internal reference voltage on IREF (typically 1.20 V), and
• I_OLC = 2 mA to 50 mA
(1)
I_OLC is the current for each output. Each output sinks I_OLC current when it is turned on. R_IREF must be between
1 kΩ and 27 kΩ in order to hold I_OLC between 50 mA (typ) and 1.93 mA (typ). Otherwise, the output may be
unstable. Refer to Figure 1 and Table 1 for the constant-current sink values for specific external resistor values.
Table 1. Constant-Current Output versus
External Resistor Value
I_OLC (mA)
50
45
40
35
30
25
20
15
10
5
2
R_IREF (kΩ, typ)
1.04
1.16
1.30
1.49
1.74
2.08
2.60
3.47
5.21
10.4
26.0
12
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