About the issue of TWR-VF65GS10 power supply circuit

[george]

Hi,

Currently, my customer started the product design which used Vybrid.
They have TWR-VF65GS10 schematics (Rev.G) under NDA.
And they refers to that schematics for their product design.

They do not have TWR-VF65GS10 board yet.
That is because the supply schedule of TWR-VF65GS10 was delayed.
I heard the issue of the power supply circuit on TWR-VF65GS10.

My customer wishes to know that issue.
It is because their original board wishes to avoid it.

Please tell me the newest TWR-VF65GS10 schematics revision.
And, what kind of issue did the power supply circuit have?

It was urged to ask here although I asked the same question to techsupport.

Best Regards,
George

[george]

Dear Naoum & Karina,

Thank you for your quick response and clear answer.

Because it is a good opportunity, please let me know one more.

When a problem occurs using MIC2026, is it operation of only TWR-VF65GS10 board?

Or when using with TWR-SER2 and TWR-LCD-RGB, does a problem occur?

My customer thinks how many current margins of the power supply circuit are ensured.

And they want to get to know the operating current of TWR-VF65GS10 board.

If you have the information on the power consumption of TWR-VF65GS10 board, please let me know.

Best Regards,

George

[naoumgitnik]

Dear George,

1. The marginality has been observed for the entire Tower kit, i.e. including TWR-SER2 and TWR-LCD-RGB, and powered through both USB ports.
2. No problem when using TWR-SER instead, whose power consumption is ~70mA lower than that of TWR-SER2  .
3. Regarding the TWR-VF65GS10 board power consumption estimation:

• 2 USB ports together provide 1A @ 5V, i.e. 5W,
• The 5V-to-3.3V step-down switcher has efficiency of min. 80%, so  the 3.3V rail power is 4W,
• #1 power consumer, Vybrid, needs up to 0.5A @ 3.3V in such application, i.e. 1.65W,
• #2 power consumer, DDR3, needs up to 0.3A @ 3.3V in such application, i.e. 1.0W,
• Thus, for the 2 major power consumers, the total power equals 2.65W, way below 4W.

If the above data are insufficient, more detailed Vybrid power consumption data can be found on the below link (not sure, though, if you have access permission for that):

https://community.freescale.com/message/316584#316584.

Best regards, Naoum Gitnik.

[george]

Hello Naoum,

Thank you for supplying information more which I desired.

I will report my customer it.

It is very helpful information for my customer.

Best Regards,

George

[naoumgitnik · Accepted solution]

Dear George,

1. If your customer does not use USB as a power source, all the below information is irrelevant.
2. The issue was with a type of the previously used Switch IC controlling the USB power on the board - MIC2026, whose built-in current threshold appeared to be marginal for the latest SW applications, so it had to be replaced with a drop-in replacement, MIC2506, with a higher threshold.
3. The next schematic revision (in progress) with MIC2506 instead of MIC2026 will be G1.

Best regards, Naoum Gitnik.