using TPS40170 to generate a negative 15 v

noura zogheb

Other Parts Discussed in Thread: TPS54260, TPS40170

Hi,

i am really confused here. For sometime, i was thinking using TPS54260 as an inverting buck boost and now, i found out that the output current is not the rated current of the TPS542560 (2.5Amps) . the real output of the device is decreased by (1-Duty cycle).

Can i use "TPS40170 " to generate a negative 15V using 'inverting buck-boost topology'? my requirement is Vin-min=19V, Vin _max=45V, Output voltage=-15V, iout=2.5A. is there an application note that will help me to design it?

Thank you

Sara

over 14 years ago

0 Na Kong over 14 years ago

TI__Genius 17240 points

Hi Sara,

You can find the app notes from the following links:

http://www.ti.com/lit/an/slyt286/slyt286.pdf

http://focus.ti.com/analog/docs/litabsmultiplefilelist.tsp?literatureNumber=slva257a&docCategoryId=1&familyId=64

Regards,

0 noura el-ouafi over 14 years ago

Prodigy 30 points

Hi Na,

Thank you very much for your suggestions. I did read those those applications notes and they both have an asynchronous buck converter where you have a catch diode not a synchronous FET. In my application, I am considering to use TPS40170 in a synchronous buck-boost converter. Is there any application note that talk about it.

Thanks again for your help

Sara

0 Na Kong over 14 years ago in reply to noura el-ouafi

TI__Genius 17240 points

Hi Sara,

Please find the app note of Creating an Inverting Power Supply Using a Synchronous Step-Down Regulator below.

http://www.ti.com/litv/pdf/slva458

Regards,

0 noura el-ouafi over 14 years ago in reply to Na Kong

Prodigy 30 points

Hi Na,

The application note SLVA458 assume that the two mosfet are included in the module. Is it correct to say that, the TPS40170 controller using two external mosfets in a synchronuous topology will work the same way and generate a negative output? or is there other consideration that I should be aware off.

I appreciate very much your feedback. Thank you.

Sara

0 Na Kong over 14 years ago in reply to noura el-ouafi

TI__Genius 17240 points

Hi Sara,

You're right. You'll need to pick up two external mosfets for your design. The circuit will work the same way as the one wih integrated FETs to generate a negative output using the synchronous buck controller. I don't have much experience using TPS40170. I will suggest you read the datasheet carefully, especially the Design Hints on page 30 and work closely with our local FAE from paper design to PCB layout. If you need more help, please let me know.

Regards,

0 noura el-ouafi over 14 years ago in reply to Na Kong

Prodigy 30 points

Hi Na,

Thank you very much. It was a big help. Have a great day.

Power management

Power management forum

using TPS40170 to generate a negative 15 v