TPS2379 with Powerdesign PD9501G issue

nagaraju nerella

I was validating the detection and functionality of the TPS2379EVM(PWR106). I try to power on with 60W Power design POE model number PD9501G.

I observe the PSE port power is blinking. When i check the waveform with oscilloscope i observe the 48V is given by the PSE and again removes the power. Do you have any inputs?

The test is performed with EVM and keeping the J6, J7 not placed. I observe the T2p also not detected.

When i connect the oscilloscope probe after few cycles of that it detects and gives the power(This is some times) but the T2p LED is not turning on.

The above test are performed without any load to the circuit. Even connected load for the VDD, VSS nets and observe similar behavior.

please let me know.

Regards

Nagaraju

over 11 years ago

0 Darwin Fernandez over 11 years ago

TI__Mastermind 41760 points

Hi Nagaraju,

Try adding some load to the output. There needs to be at least 10mA of current after startup for the PSE to maintain power. This is called MPS and can be found in detail in the IEEE 802.3 standard.

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TPS2379 with Powerdesign PD9501G issue