TLC59711 Datasheet, PDF (16/36 Pages) Texas Instruments – 12-Channel, 16-Bit, Enhanced Spectrum PWM, RGB, LED Driver

TLC59711
SBVS181 – OCTOBER 2011
www.ti.com
GLOBAL BRIGHTNESS CONTROL (BC) FUNCTION (SINK CURRENT CONTROL)
The TLC59711 has the capability to adjust all output currents of each color group (OUTR0-3, OUTG0-3, and
OUTB0-3) to the same current value. This function is called global brightness (BC) control. The BC data are
seven bits long, which allows each color group output current to be adjusted in 128 steps from 0% to 100% of
the maximum output current, I_OLCMax. The BC data are set via the serial interface. When the BC data are
changed, the output current is changed immediately.
When the IC is powered on, all outputs are forced off by BLANK (bit 213). BLANK initializes in the data latch but
the data in the 224-bit shift register and the 218-bit data latch are not set to a default value, except for the
BLANK bit. Therefore, BC data must be written to the data latch when BLANK is set to '0'.
Equation 2 determines each color group maximum output sink current:
BCX
I_OUT (mA) = I_OLCMax (mA) ´ _127d
Where:
I_OLCMax = the maximum channel current for each channel determined by R_IREF
BC = the global brightness control value in the data latch for the specific color group
(BCX = 0d to 127d, X = R/G/B)
(2)
Table 2 summarizes the BC data value versus the output current ratio and set current value.
BC DATA (Binary)
000 0000
000 0001
000 0010
—
111 1101
111 1110
111 1111
Table 2. BC Data versus Current Ratio and Set Current Value
BC DATA (Decimal)
0
1
2
—
125
126
127
BC DATA
(Hex)
00
01
02
—
7D
7E
7F
OUTPUT CURRENT
RATIO TO I_OLCMax
(%, Typical)
0
0.8
1.6
—
98.4
99.2
100
60 mA I_OLCMax
(mA, Typical)
0
0.47
0.94
—
59.06
59.53
60
2 mA I_OLCMax
(mA, Typical)
0
0.02
0.03
—
1.97
1.98
2
16
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