DD311 Datasheet, PDF (7/15 Pages) Silicon Touch Technology Inc. – HIGH CONSTANT CURRENT LED DRIVER

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.
Tel：886-3-5645656
Fax：886-3-5645626
Constant-Current Output
DD311
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 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 × ( V_bias－ V_REXT ) / R_EXT (ohm) = 100 × I_REF (A)
V_LED
V_bias
I_LED
I_REF
R_EXT
DD311
123 45
V_REXT
EN
1100
1000
900
800
700
600
500
400
300
200
100
0
100
Output Current as a Function of REXT value
Vbias=36V
Vbias=24V
Vbias=18V
Vbias=12V
Vbias=5V
1000
REXT (ohm)
10000
100000
HIGH CONSTANT CURRENT LED DRIVER
Version:PRE.001
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