TPS55160-Q1: Vout >9V , Inductor DCR

Shinji Tsuji

Genius 12718 points

Part Number: TPS55160-Q1

Hi team,

1. If the resister divider or internal FB reference voltage drift and Vout setting unintentionally goes above 9V,

what does occur to the device, system?

In other word, what does limit the maximum output voltage?

2. DC resistance of inductor is recommended to be less than 40mohm in the datasheet.

I would like to use the inductor which is >40mohm.

What does limit the maximum DCR of the inductor?

regards,

over 2 years ago

0 Zack Liu over 2 years ago

TI__Mastermind 34201 points

Hi Shinji,

Thank you for reaching out on E2E.

1. The device is internal compensated. Beyond the limitation on maximum output voltage would lead to instability issue.

2. It's recommended to follow the datasheet 40mohm DCR suggestion. A bigger DCR causes higher power loss. Otherwise the device performance cannot be guaranteed as EC table.

0 Shinji Tsuji over 2 years ago in reply to Zack Liu

TI__Genius 12718 points

Hi Liu,

Zack Liu said:
2. It's recommended to follow the datasheet 40mohm DCR suggestion. A bigger DCR causes higher power loss. Otherwise the device performance cannot be guaranteed as EC table.

Since the system load current is not that high as below, the power consumption should not be a concern for my design.

The major issue is power consumption and there is no instability issue, is my understanding correct?

If there is any other concern please advise.

LQH32PH4R7NNCL (DCR=0.155ohm +/-20%)

search.murata.co.jp/.../JLF243A-0145.pdf

System load current.

Typ : 205mA

Max : 312.6mA

regards,

0 Zack Liu over 2 years ago in reply to Shinji Tsuji

TI__Mastermind 34201 points

Hi Shinji,

May I know the system input voltage range, Vout?

LQH32PH4R7NNCL saturation current level is 1.6A, which is less than TPS55160-Q1 switch current limit 3.5A typ. If there is overload or short circuit condition happening, the inductor will be saturated.

0 Shinji Tsuji over 2 years ago in reply to Zack Liu

TI__Genius 12718 points

Hi Liu,

Input voltage range : 5.4V to 17.8V at IC input

Output voltage : 8.8V (typ) (8.175V to 9V)

For the output short circuit event, there is an external safety mechanism to monitor and protect from output short to GND,

so the saturation current is fine.

regards,

0 Zack Liu over 2 years ago in reply to Shinji Tsuji

TI__Mastermind 34201 points

Hi Shinji,

Thank you for the information.

Please let customer evaluate the inductor on bench. If there is no obvious loop stability issue, it should be OK to use.

0 Shinji Tsuji over 2 years ago in reply to Zack Liu

TI__Genius 12718 points

Hi Liu,

Thank you. Yes, I will check the stability.

But I don't think the DCR of the inductor affect the stability of the loop, does it?

regards,

+1 Zack Liu over 2 years ago in reply to Shinji Tsuji

TI__Mastermind 34201 points

Hi Shinji,

Normally if DCR is not very big, it won't affect.

Bigger DCR will affect the power loss, efficiency, maximum output current capability.

0 Shinji Tsuji over 2 years ago in reply to Zack Liu

TI__Genius 12718 points

Thank you.

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TPS55160-Q1: Vout >9V , Inductor DCR