TLC5910 Datasheet, PDF (16/30 Pages) Texas Instruments – LED DRIVER

TLC5910
LED DRIVER
SLLS392 – NOVEMBER 1999
PRINCIPLES OF OPERATION
brightness control function
By writting data into the brightness control latch, the current on all constant current outputs can be adjusted to
control the variation of brightness between ICs and the division ratio for the gray scale clock can be set to control
the variation of brigtness for the total panel system. Furthermore, by writing data into the dot correction latch,
the 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, the output current can be adjusted to 64 steps. 1 step
of 0.8% current ratio between 100% and 50.8% when the set output current is 100% by 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 the ICs are mounted on a print-circuit board. When BCENA is pulled low, output current is set
to 100%.
Table 2. Relative Current Ratio For Total Constant Current Output
CODE
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{MSB 000000 LSB}
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ 111110
111111†
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _{† BCENA is low.}
CURRENT RATIO
(%)
50.8
.
.
.
.
99.2
100
20
(mA)
10.2
.
.
.
.
19.8
20.0
80
(mA)
40.6
.
.
.
.
79.7
80.0
VIREF
(TYP)
0.61
.
.
.
.
1.20
1.21
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 (1024×16=16384) of frequency during horizontal scanning
time, the brightness can be adjusted to 16 steps selecting the frequency division ratio. By using this function,
the total panel brightness can be adjusted at once, and it applies to the brightness of day or night circumstances.
When BCENA is pulled low, the gray scale clock is not divided. When BCENA is pulled high, the brightness can
be adjusted (see Table 3).
Table 3. Relative Brightness Ratio For Total Constant Current Output
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _CODE
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ^{MSB 0000 LSBâ€} 
.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _.
.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ₁₁₁₀
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ₁₁₁₁
FREQUENCY
DIVISION RATIO
1/1
.
.
.
.
1/15
1/16
RELATIVE BRIGHTNESS RATIO
(%)
6.3
.
.
.
.
93.8
100
† _{BCENA is low.}
16
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