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Tool/software:
现用Ti的TPS2378做交换机的PD接口芯片,按下面原理图做成PD设备。接PSE设备后,无法给该PD设备供电(PSE设备是好的,可以给摄像机供电),量得PD接口处电压在DC3V左右。请分析下原理图有啥问题!
We are currently using Ti's TPS2378 as the PD interface chip and making the PD device according to the following schematic diagram. After connecting the PSE device, the PD device cannot be powered (the PSE device is good and can power the camera), and the voltage at the PD interface is measured to be around DC3V. Please help check if there are any issues with the schematic diagram!
Hi Terry,
Thanks for reaching out! There could be 3 reason that cause the PD test failure:
1. The major issue: The RTN and VSS should not be connected. There is a hotswap between VSS and RTN, when PSE-PD negotiates successfully, this hotswap will be turned on.
2. PoE has a maintain power signature check, when PD consumption current is less than 10 mA, the PSE may turn off the port for low current PD. If you run the test without a real load, you can put a dummy load to maintain > 10mA current.
3. This PD could be only workable for PSE with mode B. Besides, could you share the H1602SG datasheet?
Best regards,
Diang