ETS2228 Maintenance Manual
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Figure 4 Data receiving signal power level conversion circuit
Chapter 3 Detailed Introduction of Functional Module
3.1 Power Part
（
including power supply and power management
）
1 .DC/DC power protect module
This part is chosen joint circuit .the external power over voltage protection module protects the
input power. When the input voltage exceeds 30V, the protection circuit will function. Then the silicon
controlled thyristor is in the continuity status and the self-healing fuse F301/F302 (we only need to joint
one of them and now we joint F301) will be blown. Thus, the power protection circuit will be cut.
