點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
新竹市科學園區展業一路9號7樓之1
9-7F-1, Prosperity RoadⅠ, Hsin-Chu, Taiwan, R.O.C.
DD312
Tel：886-3-5645656
Fax：886-3-5645626
Constant-Current Output
Constant-current value of each output channel is set by an external resistor connected between
the REXT pin and GND. Varying the resistor value can adjust the current up to 1A. Notice that the
output current is a little increasing or decreasing until the device temperature and ambient
temperature are balance. The maximum power dissipation of the determined external resistor should
be large enough than the actual power consumption: 0.5(V )× Iout(A) need to be considered.
Approximate output current value can be calculated by following equation:
Output Current as a Function of REXT value
1100
1000
900
Vout = 1.0 V
800
700
600
500
400
300
200
100
0
0
1
2
3
4
5
6
7
8
9
10
11
REXT( Ω )
Output Current as a Function of Output Voltage
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Vout (Volt)
HIGH CONSTANT CURRENT LED DRIVER
Version:A.001
Page 6
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