TPS55289: About TPS55289 Inductor

Li YuanKan

Prodigy 200 points

Part Number: TPS55289
Other Parts Discussed in Thread: TPS55288

Tool/software:

Vin:3.2V

Vout : 3.4V+-10%

Vout(max):4.2V

Iout(max)=8A

Vout p-p=+-20mV

A. Assuming the use of Vin 3.3V to convert to Vout 3.4V or 3.1V, is it still necessary to use a 4.7uH inductor? According to Excel calculations, the minimum inductance that can be used is 32.9nH?

B. Can you please confirm if the following circuit settings are correct? Are there any suggested modifications?

Setting:

TPS55289-CALCULATION-TOOL-V1.0 (1).xlsx

10 months ago

0 Brigitte 10 months ago

TI__Guru 67355 points

Hello Li,

The expert team has a public holiday today. Please expect an answer tomorrow.

Best regards,

Brigitte

0 Mulin Yuan 10 months ago

TI__Genius 16570 points

Hi Yuankan,

Thank you for reaching out. 4.7uH inductor is needed for internal stability.

With 8A maximum output current, maximum input current will be 4.2*8/0.95/3.2=11A. TPS55289 cannot support this input current because it is 8A average current limit. Recommend to use TPS55288.

Regards,

Mulin

0 Li YuanKan 10 months ago in reply to Mulin Yuan

Prodigy 200 points

Change condition as below

Vin:3.2V

Vout : 3.3V+-10%

Vout(max):3.63V

Iout(max)=7A (100us/peak) 5A (average)

Vout p-p=+-20mV

Peak:3.63*7/0.95/3.2=8.35A

Average:3.63*5/0.95/3.2=5.97A

Is this setup possible using the TPS55289?

0 Mulin Yuan 10 months ago in reply to Li YuanKan

TI__Genius 16570 points

Hi Yuankan,

Due to bandwidth limitation, I will reply to you next week. Thanks for your patience.

Regards,

Mulin

0 Mulin Yuan 10 months ago in reply to Li YuanKan

TI__Genius 16570 points

Hi YuanKan,

100us is already steady state for the device because switching frequency is 2.5us. 8.35A is over spec for TPS55289. Is there any possibility that you reduce the load current? Otherwise TPS55288 is more recommended.

Regards,

Mulin

Power management

Power management forum

TPS55289: About TPS55289 Inductor