CLK / RT mode change

PAN-M

Other Parts Discussed in Thread: TPS54320, TPS54310, TPS54350, TPS54824, TPS54424, TLV62130

Dear all.

The following comments are written in datasheet of TPS54320;
"TI does not recommend to switch from the CLK mode back to the RT mode, because the internal switching frequency drops to 100 kHz first before returning to the switching frequency set by RT resistor."
Is there the device which such a phenomenon does not occur even if we change a mode?

VIN=8.4V(2cell)

VOUT=4.5V
IOUT=1A to 3A

Regards,
PAN-M

over 6 years ago

0 JohnTucker over 6 years ago

TI__Guru**** 191445 points

Pan,

Depending on your input voltage you could look at TPS54310 or TPS54350. Neither of these use a PLL for the SYNC clock. Let us know if one of those will work. They are both 3 A solutions.

0 PAN-M over 6 years ago in reply to JohnTucker

Mastermind 8375 points

Thank you, John.
I added the input voltage to my question.
My customer will try TPS54350.
Thanks,
PAN-M

0 Anthony F over 6 years ago in reply to PAN-M

TI__Mastermind 35165 points

Hi PAN-M,

I'd like to add one more suggestion. In the TPS54424/TPS54824 we have improved the transition from CLK mode to RT mode. Instead of waiting for the switching frequency to decay to the minimum 100 kHz, these parts wait for a fixed time period of 10µs typical without a clock edge to transition back to RT mode. Figure 34 in the current TPS54424 datasheet shows the improved transition with this change. There is still a small undershoot and overshoot on the output when the transition occurs but it is typically no larger than the undershoot and overshoot after a load step.

Anthony

0 PAN-M over 6 years ago in reply to Anthony F

Mastermind 8375 points

Thank you for detailed information, Anthony.
I will check these devices sequentially.
Thanks,
PAN-M

0 PAN-M over 6 years ago in reply to PAN-M

Mastermind 8375 points

John, Anthony,

I got an opinion from our customer.
TPS54350->Total size(IC, L) is big.
TPS54424->Cost is high (An evaluation whether or not 10us influences picture is necessary.)

They say that they want evaluate TLV62130 which seems to be able to satisfied on a cost side.
This device may be usable because the clock rate is high.

Thanks,
PAN-M

0 JohnTucker over 6 years ago in reply to PAN-M

TI__Guru**** 191445 points

PAN-M,

OK, let us know what they find.

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CLK / RT mode change