LM5160A: LM5160ADNT || Heat Issue || 48V TO 24V || 2A LOAD

RAHUL RAI

Prodigy 55 points

Part Number: LM5160A

Tool/software:

We are using LM5160A in our design.

Below is our design requirement which we done in Design.

Vinput = 48V

V(OUTPUT)= 24V

I(LOAD) = 2A

Below are issue we are facing in our PCB:-

1. We are getting 18V instead of 24V.

2. After removing R9(130mohm) and Adding zero Ohm resistor in R9. We are getting proper 24V. But we are getting some heating issues. below are mentioned:-

a) with load current = 1A, LM5160A & Inductor(120uH) getting heated.

b) With Load current = 2A, LM5160A & Inductor(120uH). its get repaid heated & output voltage are varing(10-24V).

After done some change from switching frequency side . We are getting same issue.

1. bydefault 192khz (Ron= 1.24M)

2. 292khz (Ron= 480K)

Inductor part no :- MSS1210-124KEB

5 months ago

0 RAHUL RAI 5 months ago

Prodigy 55 points

Below is the attached layout for your reference:-

This is 2 layer board. above image is for bottom layer.

0 David Baba 5 months ago in reply to RAHUL RAI

TI__Mastermind 33240 points

Hello Rahul,

please can you fill out design spreadhseet. thanks.

LM5160DNTBK-CALC Calculation tool | TI.com

David.

0 RAHUL RAI 5 months ago in reply to David Baba

Prodigy 55 points

Hi David,

Please find the filled design Spreadsheet.

PFA

Copy of LM5160BKQuickStartCalculator - FinalVersion_FILL_DATA.xls

Thanks

Rahul Rai

0 David Baba 5 months ago in reply to RAHUL RAI

TI__Mastermind 33240 points

Hello Rahul,

According to the spreadsheet, recommend an effective COUT of 40uF min. using Type 2 ripple injection recommends 0.06ohm RESR and Cff = 10nF.

Also, layout: boot cap is not following datasheet recommendations for layout. if you need further feedback on the layout, please identify, C11, this should be by the device, like C9. also most critical is C7 placement. please follow DS guidelines very closely for said components.

Hope this helps,

David.

0 RAHUL RAI 5 months ago in reply to David Baba

Prodigy 55 points

Hi David,

I have change below input. still I am getting heat issue on buck.

Cff= 10nF

Cout = 40uF

Thanks

Rahul

0 David Baba 5 months ago in reply to RAHUL RAI

TI__Mastermind 33240 points

Hello Rahul,

Can you confirm the switching is stable and switching at 300kHz? is heating happening while loaded?

If so, looking at the layout, looks like you have minimal polygon pour area for the VIN, this connects internally to the Drain of the HS FET. You will need to increase the area of this to help reduce temp rise.

Hope this helps.

David,

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LM5160A: LM5160ADNT || Heat Issue || 48V TO 24V || 2A LOAD