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.
DD311
Tel：886-3-5645656
Fax：886-3-5645626
Constant-Current Output
Constant-current value is set by the reference current input. The output current will be 100
times the input current value produced by an external resistor between the REXT pin and the bias
voltage*2 or, alternatively, force the low bias voltage to REXT pin. Varying the resistor or the bias
voltage value can adjust the current scale ranging up to 1A. Notice that the output current is a little
increasing or decreasing until the device temperature and ambient temperature are balance. The
output current value is calculated roughly by the following equation:
I
LED (A) ～ 100 × ( Vbias－ VREXT ) / REXT (ohm) = 100 × IREF (A)
*2 The variation of bias voltage influences the output stability directly.
HIGH CONSTANT CURRENT LED DRIVER
Version:A.002
Page 6
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