Datasheet

I I (mA)

OUT OLCMax

(mA)= ´

BCX

127d

TLC59711

SBVS181A –OCTOBER 2011–REVISED JULY 2012

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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:

Where:

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.

Table 2. BC Data versus Current Ratio and Set Current Value

OUTPUT CURRENT

BC DATA RATIO TO I

OLCMax

60 mA I

OLCMax

2 mA I

OLCMax

BC DATA (Binary) BC DATA (Decimal) (Hex) (%, Typical) (mA, Typical) (mA, Typical)

000 0000 0 00 0 0 0

000 0001 1 01 0.8 0.47 0.02

000 0010 2 02 1.6 0.94 0.03

— — — — — —

111 1101 125 7D 98.4 59.06 1.97

111 1110 126 7E 99.2 59.53 1.98

111 1111 127 7F 100 60 2

Product Folder Link(s): TLC59711