TLC59283_15 Datasheet, PDF (14/29 Pages) Texas Instruments – 16-Channel, Constant-Current LED Driver with Pre-Charge FET

TLC59283
SBVS199B – JUNE 2012 – REVISED OCTOBER 2012
DETAILED DESCRIPTION
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CONSTANT SINK CURRENT VALUE SETTING
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)
´ 43.8
Where:
V_IREF = the internal reference voltage on the IREF pin (typically 1.208 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 illustrated in Figure 12. Table 1 describes the constant-current output versus external resistor
value.
Table 1. Constant-Current Output versus External Resistor Value
I_OLC (mA)
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, Typical)
1.18
1.32
1.51
1.76
2.12
2.65
3.53
5.29
10.6
26.5
CONSTANT-CURRENT DRIVER ON OR OFF CONTROL
When BLANK is low, the corresponding output is turned on if the data in the on or 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. Output On or Off Control Data Truth Table
OUTPUT ON OR OFF DATA
0
1
CONSTANT-CURRENT OUTPUT
STATUS
Off
On
When the device is initially powered on, the data in the 16-bit shift register and output on or off data latch are not
set to default values. Therefore, the output on or off data must be written to the data latch before turning the
constant-current output on. BLANK should be high when powered on because the constant-current may be
turned on as a result of random data in the output on or off data latch.
14
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