TPS65263-Q1: tolerance of switching frequency

Shinji Tsuji

Genius 12358 points

Part Number: TPS65263-Q1
Other Parts Discussed in Thread: TPS65263

Hi team,

I have a question about a tolerance of the switching frequency of TPS65263-Q1.

I would like to set the switching frequency min 1.8MHz to avoid AM band interference.

Vin=5V+/-150mV

Vout=1.2V

Since minimum on time of this device is 110ns maximum, maximum allowable switching frequency is 1.983MHz.

Isn't it possible to set the switching frequency 1.8MHz minimum and 1.983MHz maximum?

regards,

over 6 years ago

0 Zhao Ma over 6 years ago

TI__Genius 15135 points

Hi,

How do you calculate the max Fsw=1.983MHz?

My calculation:

When Vin=5.15V，Vo=1.2V, ON time=110nS --> Max Fsw= ~2.12MHz.

0 Shinji Tsuji over 6 years ago in reply to Zhao Ma

TI__Genius 12358 points

Sorry I used the Vinmax=5.5V (+10%).

Actually Vinmax = 5.25V (+5%)

In that case Fsw max = 2.078MHz.

regards,

0 Zhao Ma over 6 years ago in reply to Shinji Tsuji

TI__Genius 15135 points

Hi, Tsuji-san

So, the min Fsw=1.8MHz, the Max Fsw=2.078MHz.
The range is too narrow, TPS65263-Q1 Fsw accuracy cannot match this application.

0 Shinji Tsuji over 6 years ago in reply to Zhao Ma

TI__Genius 12358 points

How much is the frequency tolerance if Min Fsw = 1.8MHz?

There are multiple power rails and I can change power tree configuration to generate 1.2V by other regulator but instead TPS65263 must generate 1.35V.

I wonder if Vout=1.35V can be used or not.

Vin max = 5.25V

Vout = 1.35V

Fsw = 2.338MHz

Is that possible to set Fsw min = 1.8MHz and maximum 2.338MHz?

regards,

0 Zhao Ma over 6 years ago in reply to Shinji Tsuji

TI__Genius 15135 points

Hi,

From EC table, there is trim for Fsw=500kHz, the tolerance is from 430kHz to 560kHz, variation is -14% to 12%.
If set Fsw to high frequency, eg. Fsw=(1.8+2.338)/2=2.069MHz, the variation range will become bigger. (maybe +/-20%, i need to double check with test engineer.)
So I think it still cannot support your application.

0 Zhao Ma over 6 years ago in reply to Shinji Tsuji

TI__Genius 15135 points

Hi, Tsuji -san

I have checked the ATE test data.

If set Fsw=(1.8+2.338)/2=2.069MHz(ROSC=20Kohm), the variation is about +/-200kHz, so i think the TPS65263-Q1 can support your application.

Besides, the accuracy of ROSC will also affect the Fsw variation, suggest to use resistor accuracy<=1%.

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TPS65263-Q1: tolerance of switching frequency