Under low temperature conditions, POE power supply is unstable, and in severe cases, it cannot output; Please help check the schematic design and analyze possible causes.
Hello Zhang,
Could you provide more information on the specific temperatures at which you are encountering problems at? The operating temperature for this device is –40°C to 125°C. Additionally, at the temperature you are encountering problems at, could you measure the voltage waveform of Vdd-Vss? The datasheet for the TPS23754 contains a graph of what this waveform would look like normally, which can be found at Figure 22 on Page 19, under 7.4.1.2 PoE Start-Up Sequence. I have included this graph below.
Furthermore, does the device operate normally under other temperature conditions?
One suggestion we have is to change the capacitance of the Vc capacitor to 40 μF to 50 μF and see if the same problems continue to occur. It is possible that the charge time for the capacitor is too short, which could lead to a delay that is not as long as the recommended delay time.
Best regards,
Nahiyan Muzaffar
