LM5176-Q1: LM5176-Q1 and LM46000-Q1 : Request for schematic review

Jeffrey Chung1

Expert 2470 points

Part Number: LM5176-Q1
Other Parts Discussed in Thread: LM46000-Q1, LM5176, LM46000, LM46001

Dears,

I'd like to request the schematic review of BMS application included LM5176-Q1, LM46000-Q1, and OPAMPs.

The application details are as follows.

If you have additional questions, please reply me.

LM5176-Q1

VIN : 8~16V (Charging starts from 10V)

FSW : 300KHZ (Master / Slave)

2Phase Max Charging Current Limit 33A : 16.5A Per 1Phase

Charging Voltage : 12.6V

LM5176 2 Parallel Applications : Master 1EA / Slave 1EA

CC (Constant Current) Variable Control

LM46000-Q1

VIN : 8~16V, VOUT : 3.3V, FSW : 200KHZ

BMS_LM5176-Q1_LM46000-Q1.pdf

Regards,

Jeffrey

over 3 years ago

0 Youhao Xi over 3 years ago

TI__Guru 68595 points

Hi Jeffrey,

Thank you for using TI product in your design. I reviewed the LM5176 section of your schematic. I attach my markup here for your reference. Reviewed--BMS_LM5176-Q1_LM46000-Q1.pdf

Since the LM46000 belongs to a different product line, I am notifying our colleagues in that group about your thread. In the future, create two different posts, each with one part number in the subject, then you will have a fast path to reach the responsible team.

Again, thanks.

Youhao Xi, BCS Applications Engineering

0 Jeffrey Chung1 over 3 years ago in reply to Youhao Xi

Expert 2470 points

Hi Youhao,

Thanks for your support.

Let me check about design review of LM46000-Q1 through different post of your colleagues.

I'll post that if I have the additional questions.

Regards,

Jeffrey

0 Jeffrey Chung1 over 3 years ago in reply to Youhao Xi

Expert 2470 points

Hi Youhao,

I simulated two parallel configuration of LM5176 through PSPICE tool. But Vfb variation is between 785.6mV and 1.057V like attached pdf file. Is it ok or any problem?

Also there is no reference design guide(ex. layout design guide) for two parallel configuration of LM5176. Could you share it with me?

4300.Variation of feeback voltage.pdf

Regards,

Jeffrey

0 Andy Chen over 3 years ago

TI__Mastermind 27045 points

Hi Jeffrey,

For LM46000 section:

Add 22uF 50V Electrolytic cap parallel with C83
C102 is option, reserve position
Add 4.7 ohm in series C94 for lower EMI
If no strict requirement on light load efficiency, reduce R44 and R118 10X times smaller for better noise immunity.

B R

Andy

0 Jeffrey Chung1 over 3 years ago in reply to Andy Chen

Expert 2470 points

Hi Andy,

Thanks for your feedback. I'll ask some questions if I have some other issues.

Regards, Jeffrey

0 Jeffrey Chung1 over 3 years ago in reply to Andy Chen

Expert 2470 points

Hi Andy,

I'd like to request 2nd design review of LM46000-Q1 part. Please refer to the below link file.

BMS_LM5176_LM46000_2nd.pdf

Regards, Jeffrey

0 Jeffrey Chung1 over 3 years ago in reply to Youhao Xi

Expert 2470 points

Hi Youhao,

I'd like to request 2nd design review. Please refer to the below link file.

2018.BMS_LM5176_LM46000_2nd.pdf

Also, Do you have any updates on my previous post? I know you're very busy but I'd like to get a quick your answer.

Regards, Jeffrey

0 Youhao Xi over 3 years ago in reply to Jeffrey Chung1

TI__Guru 68595 points

Hi Jeffrey,

Sorry I did not see your previous msg questioning on the current sharing circuit. This is why I suggested you to create separate e2e thread, with one addressing one part. Once I forward your post to Andy, I would not automatically see your new post.

Here, let me answer your question first: The Vfb variation looks normal. The actual sharing circuit may need to adjust Rc value to be effective.

We tested the concept by creating a small daughter board controlling two LM5176 EVMs. The key in layout is to make the sharing circuit including the sensing resistor symmetrically. The symmetry also includes the grounding of the Op-Amp with respect to the sense resistors. A smaller voltage difference would cause remarkable sharing errors, because you are working with small sense voltage. The error caused by asymmetry is due to the PCB trace resistance. So please keep this in mind.

Finally, I reviewed your updated schematic, and seemingly you did not follow all my recommendations. Anyway, it's up to you and the circuit should work.

Thanks,

Youhao

0 Jeffrey Chung1 over 3 years ago in reply to Youhao Xi

Expert 2470 points

Hi Youhao,

I didn't know the separate e2e thread process. Now I know that. Thanks for your sharing.

I understood the layout guide that you told me. Is there any other layout guide document for two parallel configuration of LM5176?

Also, I had already updated a schematic as you recommended. Could you check it again?

Regards, Jeffrey

0 Andy Chen over 3 years ago in reply to Jeffrey Chung1

TI__Mastermind 27045 points

Hi Jeffrey,

On LM46001 circuit:

1. Suggest to change R44 to 10K and R118 to 4.42K

2. Connect upper terminal of R44 and C102 together, then connect it to VCC_3.3V by a 47ohm resistor, this is for testing loop response.

B R

Andy

0 Jeffrey Chung1 over 3 years ago in reply to Andy Chen

Expert 2470 points

Hi Andy,

Your comment of No.2 is different from typical application for VOUT ≥ 3.3 V. Is it a recommended or necessary application?

Also, please forward to your colleague Youhao my previous post.

Regards, Jeffrey

0 Andy Chen over 3 years ago in reply to Jeffrey Chung1

TI__Mastermind 27045 points

Hi Jeffrey,

The output capacitors include bulk electrolytic cap and ceramic cap, so it's better to verify loop response on prototype building, this resistor has no impact on 3.3V output and can be removed on mass production circuit.

B R

Andy

0 Jeffrey Chung1 over 3 years ago in reply to Andy Chen

Expert 2470 points

Hi Andy,

I understood what you mean about verifying loop response. I'll apply on feedback circuit of LM46000-Q1.

Also, as I told you, please forward to Youhao my previous post.

Regards, Jeffrey

0 Jeffrey Chung1 over 3 years ago in reply to Youhao Xi

Expert 2470 points

Hi Youhao,

Did you check my last post? Please check it again.

Regards, Jeffrey

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LM5176-Q1: LM5176-Q1 and LM46000-Q1 : Request for schematic review