AM4378: IDK schematics question

user4999129

Other Parts Discussed in Thread: TPS5402

Hello everyone:

I am going to start my design reference to AM437x' IDK. Its Power input shows as below:

I am not clear about the function of MBRS104T, Fuse4A and SMCJ26CA. I need advise on componet selection for these. Thanks !

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

D19 is reverse polarity protection.
F1 is overcurrent protection.
D21 is overvoltage protection.

0 user4999129 over 7 years ago in reply to Biser Gatchev-XID

Intellectual 550 points

Hi, Biser:
Could you give me some more detail suggestion on componet selection of these?

0 Biser Gatchev-XID over 7 years ago in reply to user4999129

TI__Guru**** 393215 points

The IDK board power input is rated for 24V DC, 4A. Therefore D19 should have at least 4A forward current. F1 is obviously chosen for 4A breakdown current, and D21 is chosen with 26V breakdown voltage.

0 user4999129 over 7 years ago in reply to Biser Gatchev-XID

Intellectual 550 points

Hi, Biser:

The MBRS140T 's forward current is only 1A instead of 4A. The attachment is the datasheet.

MBRS140T3G.pdf

0 Biser Gatchev-XID over 7 years ago in reply to user4999129

TI__Guru**** 393215 points

This is average current. Surge current is 40A, right below it.

0 user4999129 over 7 years ago in reply to Biser Gatchev-XID

Intellectual 550 points

Oh, I see.
You mean the IDK 's 4A input represent surge current, am I right?

0 Biser Gatchev-XID over 7 years ago in reply to user4999129

TI__Guru**** 393215 points

Yes, this is correct.

0 user4999129 over 7 years ago in reply to Biser Gatchev-XID

Intellectual 550 points

Thank you very much!

0 user4999129 over 7 years ago in reply to Biser Gatchev-XID

Intellectual 550 points

Hi, Biser:

The SMCJ26CA 's maximum clamping voltage is 42.1V.

While the VIN pin of TPS5402 's voltage range is at -0.3V to 30V,

which is powered by V24_0D

It seem that SMCJ26CA can not protect TPS5402 if surge voltage high enough.

0 Biser Gatchev-XID over 7 years ago in reply to user4999129

TI__Guru**** 393215 points

Choose a TVS that suits your input requirements.

0 user4999129 over 7 years ago in reply to Biser Gatchev-XID

Intellectual 550 points

All right, Thank you!

Processors

Processors forum

AM4378: IDK schematics question