TLC5947_17 Datasheet, PDF (19/33 Pages) Texas Instruments – 24-Channel, 12-Bit PWM LED Driver With Internal Oscillator

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TLC5947
SBVS114B – JULY 2008 – REVISED JANUARY 2015
9.2.2.2 Grayscale (GS) Data
There are a total of 24 sets of 12-bit GS data for the PWM control of each output. Select the GS data of each
LED lamp and write the GS data to the register following the signal timing.
9.2.2.3 Auto-Display Function
There are a total of 24 sets of 12-bit GS data for the PWM control of each output. Select the GS data of each
LED lamp and write the GS data to the register following the signal timing.
9.2.2.4 Setting for the Constant Sink Current Value
The constant-current value for all channels is set by an external resistor (R_IREF) placed between IREF and GND.
The resistor (R_IREF) value is calculated by Equation 2.
R_IREF (W) = 41 ´
V_IREF (V)
I_OLC (mA)
where
• V_IREF = the internal reference voltage on the IREF pin (typically 1.20 V).
(2)
I_OLC must be set in the range of 2 mA to 30 mA. The constant sink current characteristic for the external resistor
value is shown in Figure 4. Table 3 describes the constant-current output versus external resistor value.
Table 3. Constant-Current Output versus External Resistor Value
I_OLC (mA, Typical)
30
25
20
15
10
5
2
R_IREF (Ω)
1640
1968
2460
3280
4920
9840
24600
9.2.3 Application Curves
Figure 24. Output Waveform with GS Data Latch Input
Figure 25. Output Waveform without GS Data Latch Input
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