TPS61372EVM-033: Load regulation characteristics is not good.

Miyanaga

Prodigy 190 points

Part Number: TPS61372EVM-033

I changed R3 to 200k and R4 to 10k to set output is 7.9V.

Load regulation characteristics is not good to exceed 50mA.

Could you please let me know the suggestions for improving?

over 5 years ago

0 Miyanaga over 5 years ago

Prodigy 190 points

I set as J7's EN is High and J8's MODE is low.

0 Miyanaga over 5 years ago in reply to Miyanaga

Prodigy 190 points

This result is according to your specifications?

If so, could you please introduce your substitute product?

4.2Vin

7.9Vout

Up to 500mAout

Load regulation is good(0.6%/A).

0 Miyanaga over 5 years ago in reply to Miyanaga

Prodigy 190 points

Efficiency at light load(below 1 to 50mA) is above 80 to 90%.

0 Minqiu Xie over 5 years ago in reply to Miyanaga

TI__Mastermind 21565 points

Hi Miyanaga:

The converter is setup at PFM mode right?

It will be 1.1.6% (typ) higher than normal operation during the PFM mode. That's why you see the Vout is 7.9 V with light load, and it will "decrease" a little with load. The issues will be gone if set it with FPWM mode, but with low efficiency at light load. It's a trade off for efficiency and Vout accuracy.

Besides, the Vref peak-peak tolerance is +- 0.008V. It will bring the Vout tolerance. But I think you are not facing this, only PFM mode.

0 Miyanaga over 5 years ago in reply to Minqiu Xie

Prodigy 190 points

Hi Minqiu san.

Thank you for your comment.

I measured at Forced PWM mode.

This result is as follows.

There is nothing for it?

Best regards,

Miyanaga

0 Minqiu Xie over 5 years ago in reply to Miyanaga

TI__Mastermind 21565 points

Hi Miyanaga:

It seems the voltage "drop" is caused by PFM mode, and the actually target is around 7.8V.

It's hard to use single PFM mode or FPWM mode to have good efficiency and accuracy Vout at same time. What's your requirement for the Vout range? Does it need so accuracy during whole load range?

0 Miyanaga over 5 years ago in reply to Minqiu Xie

Prodigy 190 points

Hi, Minqiu san,

The Vout range is 7V to 8V.

7.9V is typical.

I need the accuracy whole load range, so as you told me, there is nothing for it to use as Forced PWM mode.

Best regards,

Miyanaga

0 Minqiu Xie over 5 years ago in reply to Miyanaga

TI__Mastermind 21565 points

Hi Miyanage-san:

I'm unclear about the sentence "there is nothing for it to use as Forced PWM mode." You could use the Forced PWM to have a accuracy Vout, but the efficiency won't be good enough. There are some figures about "Efficiency vs. Load" in datasheet, you could check it for reference.

Actually, the Vout should be around 7.8V according to your divided resistance if the converter doesn't enter into PFM mode.

Power management

Power management forum

TPS61372EVM-033: Load regulation characteristics is not good.