PoE PD project controller selection

Calvin H

Prodigy 170 points

Other Parts Discussed in Thread: LM5070, TPS23753, TPS23753A, TPS23757, TPS23757EVM, PMP8923, PMP9175

Hi All,

I'm starting design a PD power supply unit, need output max 5.2V/2.4A. Could you please suggest an controller to start?

Thanks a lot.

over 8 years ago

0 Darwin Fernandez over 8 years ago

TI__Mastermind 40100 points

Hi Calvin,
I recommend looking into the TPS23753AEVM-235 to start. If you do any adjustments to the design, I recommend reading SLVA305 which is a step by step design guide.

0 Calvin H over 8 years ago in reply to Darwin Fernandez

Prodigy 170 points

Thank you Darwin.
Days ago I got a board with LM5070-50, coil craft C1585 transformer. I'm thinking to use LM5070, but not decided yet.
I was wondering, TPS23753 is better than LM5070 in my application?
Thanks.

0 Darwin Fernandez over 8 years ago in reply to Calvin H

TI__Mastermind 40100 points

Hi Calvin,
While LM5070 will work, it is from an older line of products. The TPS23753A is a newer and cost effective IC and as such is a more frequently used part with many app notes, a design guide, EVMs, and TI reference designs associated with it than the LM5070.

0 Todd Collin over 8 years ago in reply to Darwin Fernandez

Prodigy 75 points

Hello Darwin,
1. What's the key advantage of TPS23753A vs the TPS23757?
2. The TPS23753AEVM-235 uses the B1100/FDS89161 Half Mosfet Bridge. Seems the higher efficientcy of this design is because of the bridge (compared to say TPS23757EVM). Do you have and app note summary of all the Bridge options?
3. Do you have 23753 or 23757 reference designs done in Orcad DSN file to speed my process.

0 Darwin Fernandez over 8 years ago in reply to Todd Collin

TI__Mastermind 40100 points

Hi Todd,

1. TPS23753A is newer IC without the secondary gate driver for a more cost effective soltuion.

2. We currently do not have an app note regarding different bridge topologies. Typically, diode bridges are used. When higher efficiency is needed (+1-2%), different types ofFET bridges are used. For 13W range, half FET/diode bridge is good. At higher power levels, full FET bridges can be used. Such as in PMP8923.

3. Please see attached PMP9175 Orcad files. Which was exported from Altium. Below is a link to it's test report

http://www.ti.com/tool/PMP9175

ORCADexport.zip

0 Calvin H over 8 years ago in reply to Darwin Fernandez

Prodigy 170 points

Hi Darwin,

The ref design uses a PA6340-AL. I don't find it on Coilcraft website. I was wondering, if it can bought easily? Is there any replacements? Thanks.

0 Calvin H over 8 years ago in reply to Darwin Fernandez

Prodigy 170 points

Hi Darwin,
If change the R36 to set it Class 0, will the whole circuits still working well?
Thank you.

0 Darwin Fernandez over 8 years ago in reply to Calvin H

TI__Mastermind 40100 points

Hi Calvin,

I recommend contacting the coilcraft sales support or local coilcraft contact to obtain samples of the transformer as there is no online orderable transformer avialable for this part.

For the Class 0 resistance, it will work as well.

0 Todd Collin over 8 years ago in reply to Darwin Fernandez

Prodigy 75 points

Hello Darwin,

1. The Orcad file .dsn file did not work. Is there some special procedure to use those?

2. I noticed the TPS23753AEVM-235 (5V/2/A) rates the efficiency at 93% while the TPS23757EVM (5V/2.2A) rates the efficiency at 87% per your docs. So that's 6% difference which is big. So if 1-2% diff is related to the bridge what is other factor affecting the remaining effciency difference?

Thanks for the support!!

0 Calvin H over 8 years ago in reply to Darwin Fernandez

Prodigy 170 points

Thank you Darwin. I sent coil craft emails.
I have a question about Detection Resistor (R22) in PMP9175. It's a 27.4K instead of 24.9K between 23.75 kΩ and 26.25 kΩ. Is there special reason? Thanks.

0 Darwin Fernandez over 8 years ago in reply to Todd Collin

TI__Mastermind 40100 points

Hi Todd,
1. I think it will be better to give you the original Altium files. Is this okay?
2. Another large part of efficiency is the transformer design. TPS23757EVM may have been designed for this much efficiency. While TPS23753AEVM-235 is optimized for high efficiency.

0 Darwin Fernandez over 8 years ago in reply to Calvin H

TI__Mastermind 40100 points

For the detection resistor, depending on how the Half diode/FET Bridge is designed, there may be leakage that will effect the detection current. In this case, the detection resistor can be adjusted based on your design. The same goes for the TPS23753AEVM-235 design. You can try measuring the detection current by placing a voltage at the PD input RJ45 between 1.6V-10V and adjust the resistor as necessary to meet IEEE spec for your design.

0 Todd Collin over 8 years ago in reply to Darwin Fernandez

Prodigy 75 points

Hello Darwin,

The OrcadExport did work when loaded with older Orcad V9.1. I'll look at the transformer designs more closely.

Thanks!

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PoE PD project controller selection