TLC5949 Datasheet, PDF (19/51 Pages) Texas Instruments – 16-Channel, 12-Bit, ES-PWM, Full Self-Diagnosis LED Driver for 7-Bit Global BC LED Lamp

TLC5949
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Table 2 summarizes the BC data versus the set current value.
SBVS219A – DECEMBER 2012 – REVISED DECEMBER 2012
BINARY
000 0000
000 0001
000 0010
—
111 1101
111 1110
111 1111
Table 2. BC Data versus Constant-Current Ratio and Set Current Value
BC DATA
DECIMAL
0
1
2
—
125
126
127
HEX
00h
01h
02h
—
7Dh
7Eh
7Fh
RATIO OF OUTPUT
CURRENT TO I_OLCMax(%)
25.0
25.6
26.2
—
98.8
99.4
100.0
I_OUT (mA)
(I_OLCMax= 45 mA, typ)
11.25
11.52
11.78
—
44.47
44.73
45.00
I_OUT (mA)
(I_OLCMax= 2 mA, typ)
0.50
0.51
0.52
—
1.98
1.99
2.00
GRAYSCALE (GS) FUNCTION (PWM CONTROL)
The TLC5949 can adjust the brightness of each output channel using a pulse width modulation (PWM) control
scheme. The architecture of 12 bits per channel results in 4096 brightness steps, from 0% up to 100%
brightness.
The PWM operation for OUTn is controlled by a 12-bit grayscale (GS) counter. The GS counter increments on
each GS reference clock (GSCLK) rising edge. The GS counter resets to 000h when the BLANK bit in the first
control data latch is set to '1'; the counter value is held at 000h while the BLANK bit is '1', even if the GS clock
input is toggled high and low.
The TLC5949 has two types of PWM control: conventional PWM control and enhanced spectrum (ES) PWM
control. The conventional PWM control can be selected when the ESPWM bit in the first control data latch is '0'.
The ES PWM control is selected when the ESPWM bit is '1'.
The on-time (t_{OUT_ON}) of each output (OUTn) can be calculated by Equation 3.
t_{OUT_ON} = t_GSCLK × GSn
(3)
Copyright © 2012, Texas Instruments Incorporated
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