TLC5911 Datasheet, PDF (16/30 Pages) Texas Instruments – LED DRIVER

TLC5911
LED DRIVER
SLLS402 – DECEMBER 1999
PRINCIPLES OF OPERATION
brightness control function
By writing data into the brightness control latch, current on all the constant current outputs can be adjusted to
control the variation of brightness between ICs. The division ratio for the gray scale clock can be set to control
the variation of brightness for the total panel system. Furthermore, by writing data into the dot correction latch,
current on each constant current output can be adjusted.
output current adjustment on all constant current outputs – brightness adjustment between ICs
By using the lower 6 bits of the brightness control latch, output current can be adjusted in 64 steps as 1 step
of 0.8% of the current ratio between 100% and 50.8% when the output current is set to 100% of an external
resistor (note that the current value is lower if the constant current output is corrected using the dot correction
function). By using this function, the brightness control between modules (ICs) can be adjusted sending the
desired data externally even if ICs are mounted on a print-circuit board. When BCENA is pulled low, the output
current is set to 100%.
Table 2. Relative Current Ratio For Total Constant Current Output
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ CURRENT RATIO
%
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _50.8
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _99.2
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ₁₀₀
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ † _{BCENA is low.}
20 (mA)
10.2
.
.
.
.
19.8
20.0
80 (mA)
40.6
.
.
.
.
79.7
80.0
CODE
MSB 000000 LSB
.
.
.
.
111110
111111†
VIREF
(TYP)
0.60
.
.
.
.
1.19
1.20
frequency division ratio setting for gray scale clock – panel brightness adjustment
By using the upper 4 bits of the brightness control latch, the gray scale clock can be divided into 1/1 to 1/16.
If the gray scale clock is set to 16 times the speed of frequency (1024×16=16384) during horizontal scanning
time, the brightness can be adjusted in 16 steps by selecting the frequency division ratio. By using this function,
the total panel brightness can be adjusted at once, and applied to the brightness of day or night. When BCENA
is pulled low, the gray scale clock is not divided. When BCENA is pulled high, the brightness can be adjusted
as shown in Table 3.
Table 3. Relative Brightness Ratio For Total Constant Current Output
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _CODE
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{MSB 0000 LSBâ€} 
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ 1110
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ¹¹¹¹
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ^{† BCENA is low.}
FREQUENCY DIVISION
RATIO
1/1
.
.
.
.
1/15
1/16
RELATIVE
BRIGHTNESS RATIO
(%)
6.3
.
.
.
.
93.8
100
16
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