Datasheet

R (k )=W
IREF
V (V)
IREF
I (mA)
OLCMax
´ 41
TLC59711
www.ti.com SBVS181A –OCTOBER 2011–REVISED JULY 2012
APPLICATION INFORMATION
MAXIMUM CONSTANT SINK CURRENT SETTING
The maximum constant sink current value for each channel, I
OLCMax
, is programmed through a single resistor,
R
IREF
, placed between IREF and GND. The desired value can be calculated with Equation 1:
Where:
V
IREF
= the internal reference voltage on the IREF pin (1.21 V, typically, when the the global brightness
control data are at maximum),
I
OLCMax
= 2 mA to 60 mA. (1)
I
OLCMax
is the maximum current for each output. Each output sinks the I
OLCMax
current when it is turned on and
global brightness control data (BC) are set to the maximum value of 7Fh (127d).
R
IREF
must be between 0.82 kΩ and 24.8 kΩ to hold I
OLCMax
between 60 mA (typical) and 2 mA (typical).
Otherwise, the output may be unstable. Output currents lower than 2 mA can be achieved by setting I
OLCMax
to 2
mA or higher and then using global brightness control to lower the output current. The constant-current sink
values for specific external resistor values are shown in Figure 11 and Table 1.
Table 1. Maximum Constant-Current versus External Resistor Value
I
OLCMax
(mA) R
IREF
(kΩ, Typical)
60 0.827
55 0.902
50 0.992
45 1.1
40 1.24
35 1.42
30 1.65
25 1.98
20 2.48
15 3.31
10 4.96
5 9.92
2 24.8
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