TPS92643-Q1: Synchronous Mosfet

Dustin Yim

Intellectual 2140 points

Part Number: TPS92643-Q1
Other Parts Discussed in Thread: LM3409

Hi Expert,

I wonder about Synchronous Mosfet in TPS92643-Q1.

- Why It is called by "Synchronous Mosfet"?

- It's role

- What happen it does not exist and examlpe device. How can it do same fuction with TPS92643-Q1.

If you give me any advice to study about it, it will be very helpfull.

Thank you.

over 1 year ago

+1 fhoude over 1 year ago

TI__Genius 17205 points

Hello Dustin,

In a BUCK converter you need a HS FET/TOP mosfet to start the power transfer with the inductor. This mosfet is called the control fet. In a traditional BUCK there is a diode that automatically conducted due to the inductor when the TOP fet is OFF. In a synchronous BUCK we replace that DIODE with a FET but it has to be synchronized with the off time of the TOP mosfet so that it isn't turned on at the same time. Thus the synchronous mosfet, sometimes called low side mosfet or catch mosfet.

Here is a app note talking about the advantagaes of synchronous mosfet:

https://www.ti.com/lit/an/slyt358/slyt358.pdf?ts=1658157397848&ref_url=https%253A%252F%252Fwww.google.com%252F

An example of a non-synchronous buck is the LM3409.

if you know nothing about power electronics that I highly recommend the power classes from Colorado University, which you can do using Coursera,

https://www.coursera.org/learn/power-electronics

There are also lots of app notes out there that can help learn about the basics of power converters.

TI has lots of training videos if you prefer to app notes.

https://training.ti.com/search-catalog/field_language/EN/categories/dcdc-switching-regulators

here are training videos for LED drivers:

https://training.ti.com/search-catalog/field_language/EN/categories/led-drivers

I think these material will get you started.

-fhoude