TPS55340-Q1: about Pulse Skip Mode in light load

taichi

Expert 1395 points

Part Number: TPS55340-Q1
Other Parts Discussed in Thread: TPS61175, TPS55340

Hi, Team

My customer were considering TPS61175, but they plan to revisit TPS55340-Q1 as a result of errata sheets being issued.

So there is a question, Pulse skip mode of TPS55340-Q1 is similar to TPS61175's it.

Does the output voltage become uncontrollable at light load depending on the switching frequency?

【specification】

Vin: 5~6V

Vout:8V

Iout : 1A max

SWF:2MHz

Regards

over 7 years ago

0 Helen chen over 7 years ago

TI__Mastermind 40080 points

TPS55340 and TPS61175 has the same errata sheet. when fs=2MHz, need add an external sync signal to the freq pin or add a minimum load at the output side. or the output voltage may rise higher than the target.

what is the minimum load in your system? if there's a 20mA minimum load, then everything should be OK! They need add nothing.

0 taichi over 7 years ago in reply to Helen chen

Expert 1395 points

Hi, Helen-san

Thank you for your reply.
There is a 4mA minimum current , so if they use tps55340 or tps61175, it need resistors to add load.
In this case, Light load efficiency is down. It is very important for their application.

Is there any other device that I can suggest?

Regards,
Taichi Nakamura

0 Helen chen over 7 years ago in reply to taichi

TI__Mastermind 40080 points

20mA is based on the 10uH inductor, if they use 22uh inductor, then 9.35mA load is OK, that is : they need to add (9.35-4)=5.35mA extra load at the output side. is 5.35mA load acceptable?

0 Helen chen over 7 years ago in reply to taichi

TI__Mastermind 40080 points

Lower the operation frequency also helps, could they lower the operation frequency?

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TPS55340-Q1: about Pulse Skip Mode in light load