TPS2379 T2P application

Sjef Koopmans

Other Parts Discussed in Thread: TPS2379, PMP7499

Dear all,

We are currently using the TPS2379 for our PoE system. In the Datasheet on page 21 stands a circuit for indicating if a high power source is available. I don’t understand a few things that are said on this page.

Where does Vc come from. In the whole datasheet, Vc is not mentioned. Does it come from my DC/DC converter?
Where does Vout come from?

We want to use it for giving us a signal via a LED to indicate is I have a type 2 PSE connected.

Kind regards,
Sjef Koopmans

over 11 years ago

0 Darwin Fernandez over 11 years ago

TI__Mastermind 41760 points

Sjef,

We apologize for the confusion. VC is typically what powers the controller of the converter. Please see PMP7499 reference design as an example.

Vout is the output voltage of the converter.

Regards,

Darwin

0 Sjef Koopmans over 11 years ago in reply to Darwin Fernandez

Prodigy 40 points

Darwin,

when i look into the schematic U suggest that I use the input voltage of the controller wich, in my case, is variabel between 44V en 57V (PoE). That is because I use the TPS2379 as controller of the converter.

Vout will be then the voltage of my converter.

Is this correct?

Regards,
Sjef

0 Darwin Fernandez over 11 years ago in reply to Sjef Koopmans

TI__Mastermind 41760 points

Sjef,

TPS2379 is a PD only device and does not have an integrated PWM controller.

What are your output power requirements?

0 RAHEEMBASHA SHAIK over 11 years ago in reply to Darwin Fernandez

Intellectual 295 points

Hi all,

I am using TPS2379-EVM PD device for 50W application with Phihong PSE (POE80U-560G). This PSE looks for a 12.5-kΩ detection signature and ensures that 720 mA of current are provided in each of the pair sets.

But its not detecting and its give result with LEDs: 1) Incorrect resistive signature , 2)Incorrect capacitive signature.

Please suggest me to solve this problem.

0 Sjef Koopmans over 11 years ago in reply to Darwin Fernandez

Prodigy 40 points

I have solved my problem.

Thank u for all the information and help!

Kind regards,
Sjef Koopmans

0 Sjef Koopmans over 11 years ago in reply to RAHEEMBASHA SHAIK

Prodigy 40 points

From the datasheet of the TPS2379-EVM u can see that the classification resistance is 63.4Ω so the 12.5-kΩ will not be detected. This is resistor R8 from the picture. Also Jumper 7 needs to be open.

If u look at table 1 (Class Resistor Selection) in the datasheet of the TPS2379. U can see which resistors can be provided and what currents go with it.

kind regards,
Sjef Koopmans5700.tps2379.pdf

0 Eric Wright over 11 years ago in reply to Sjef Koopmans

TI__Mastermind 42795 points

With the Phihong PSE, you can install a shunt on J6 to present the 12.5k detection resistance. Leave the shunt on J7 removed. Remember also to have some minimum load between J4-1 and J4-4 to keep the PSE on after it detects and powers up.

0 RAHEEMBASHA SHAIK over 11 years ago in reply to Eric Wright

Intellectual 295 points

Hi Eric Wright

I was connected Phihong PSE out -ethernet port to TPS2379-EVM-106 J1 port and remove R15 and also remove shunt of J5 ,J6,J7.

connected a load (led device) on J4-1pin and J4-4 pin.But its not connected with this device, still it in fault mode. The PSE Phihong 3 leds connected/fault/ On all are blinking continuously.

0 Darwin Fernandez over 11 years ago in reply to RAHEEMBASHA SHAIK

TI__Mastermind 41760 points

The EVM should have no problems starting up to the phihong high power PSE. Above you said you removed J6 shunt. This needs to be connected so that two 24.9k are in parallel for a 12.5k detection resistance.

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TPS2379 T2P application