TLC59282 Datasheet, PDF (13/21 Pages) Texas Instruments – 16-Channel, Constant-Current LED Driver with 4-Channel Grouped Delay

TLC59282
www.ti.com
SBVS152A – DECEMBER 2010 – REVISED DECEMBER 2010
DETAILED DESCRIPTION
SETTING FOR THE CONSTANT SINK CURRENT VALUE
The constant-current values are determined by an external resistor (R_IREF) placed between IREF and GND. The
resistor (R_IREF) value is calculated by Equation 1.
R_IREF (kW) =
V_IREF (V)
I_OLC (mA)
´ 41.9
Where:
V_IREF = the internal reference voltage on the IREF pin (typically 1.205 V)
(1)
I_OLC must be set in the range of 2 mA to 35 mA when V_CC is less than 3.6 V. Also, when V_CC is equal to 3.6 V or
greater, I_OLC must be set in the range of 2 mA to 45 mA. The constant sink current characteristic for the external
resistor value is shown in Figure 10. Table 1 describes the constant-current output versus external resistor value.
Table 1. Constant-Current Output versus External Resistor Value
I_OLC (mA, Typical)
45 (V_CC > 3.6 V only)
40 (V_CC > 3.6 V only)
35
30
25
20
15
10
5
2
R_IREF (kΩ)
1.12
1.26
1.44
1.68
2.02
2.52
3.37
5.05
10.1
25.2
CONSTANT-CURRENT DRIVER ON/OFF CONTROL
When BLANK is low, the corresponding output is turned on if the data in the on/off control data latch are '1' and
remains off if the data are '0'. When BLANK is high, all outputs are forced off. This control is shown in Table 2.
Table 2. On/Off Control Data Truth Table
OUTPUT ON/OFF DATA
0
1
CONSTANT-CURRENT OUTPUT
STATUS
Off
On
When the IC is initially powered on, the data in the 16-bit shift register and output on/off data latch are not set to
the respective default value. Therefore, the output on/off data must be written to the data latch before turning the
constant-current output on. BLANK should be at a high level when powered on because the constant-current
may be turned on as a result of random data in the output on/off data latch.
The output on/off data corresponding to any unconnected OUTn outputs should be set to '0' before turning on the
remaining outputs. Otherwise, the supply current (I_CC) increases while the LEDs are on.
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