Semtech EB-GS3440, Руководство пользователя

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EB-GS3440
Evaluation Board User Guide
57964 - 0
June 2012
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1.5 Potentiometer Settings
Adjusting the potentiometers clockwise will decrease the voltage level at the SQ_ADJ
and OP_CTL pins. Adjusting the potentiometers counter-clockwise will increase the
voltage level at the SQ_ADJ and OP_CTL pins.
1.5.1 OP_CTL Potentiometer Settings
The output control potentiometer settings are described in Table 1-5 below:
1.5.2 Squelch Adjust (SQ_ADJ) Potentiometer Settings
There is one multi-turn potentiometer on the EB-GS3440 assigned for squelch adjust,
which adjusts the voltage seen at the SQ_ADJ pin. This input adjusts the threshold of the
CD pin. When the SQ_ADJ input is 0V, all cable lengths will be equalized. When the
SQ_ADJ input is 3.3V, there will be no equalization regardless of the cable length. Please
refer to the GS3440 Data Sheet for more details on carrier detect and squelch adjust.
1.6 LED Indicator
D1 is the Carrier Detect LED for the GS3440. D1 is on when no carrier is detected and
stays off otherwise. There is one LED_EN jumper which when disconnected, it disables
the LED. This is useful when measuring system power dissipation.
Table 1-5: OP_CTL Input Settings
Level Swing De-emphasis Mute Voltage
0 800mV Off N 0.000 - 0.083
1 800mV 2dB N 0.234 - 0.394
2 800mV 4dB N 0.545 - 0.704
3 800mV 6dB N 0.856 - 1.015
4 400mV Off N 1.166 - 1.333
5 400mV 2dB N 1.484 - 1.644
6 400mV 4dB N 1.795 - 1.954
7 400mV 6dB N 2.106 - 2.265
8 400mV N/A Y 2.416 - 2.500