Huawei MC509 Series Hardware Manual page 32

HUAWEI MC509 Series CDMA LGA Module
Hardware Guide
Figure 3-11 Driving circuit
For resistance of R placed on user board, choose the value such that it satisfies the
following equation:
I *R+V
F
V : Forward Voltage
F
I : Forward current
F
Take the LED 19-213/GVC-AMNB/3T as an example (its manufacturer is Everlight
Electronics., Ltd. And the website is http://www.everlight.com). Figure 3-12 shows its
I - V
F
then the voltage of the LED V
corresponding value for resistance of R is (3.8 - 1.5)/0.003 = 767 Ω.
The brightness of the LED depends on the current value, and for most of the
indicator lights the current from 2 mA to 5 mA is already enough.
Issue 02 (2013-05-06)
Module
(DCE)
LED_MODE
LED_STATUS
= VBAT
F
curves. If VBAT is 3.8 V and the desired current through the LED I
F
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Description of the Application Interfaces
D201
R
2
LED V
F
D202
R
2
LED V
F
is 1.5 V according to I
F
VBAT
1
I
F
1
I
F
is 3 mA,
F
-V curves, and the
F F
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