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The voltage precision of TPS63061 in PFM mode.

Tomoaki Yoshida
Expert 2200 points
Other Parts Discussed in Thread: TPS63061

Hi,

 

I'm considering to use  Buck-boost DCDC converter  by TPS63061.

The condition is as follows.

  Input voltage  :  4～7V

  output voltage : 5V

  load current : 100mA(Typ) / 500mA(Max)

The PS/SYNC pin is connected to GND directly by PCB wire.

A load current is little and it's ｄriving in PFM mode , and the output voltage is 5.15V.

At first, the range of output voltage in PFM mode.

In the datasheet, threshold voltage are 2.5% and 3.5% at typical condition.

But , it's not written at worst condition.

I would like to know the threshold voltage of ripple at PFM mode.

 

I'd like to improve the output voltage precision, so I'd like to make them drive by a PWM mode.

But, it's impossible to re-connect the PS/SYNC pin to VIN.

Is it possible TPS63061 operate in  PWM mode or like a PWM mode while the PS/SYNC pin isconnected to GND?

I'd like to know that if there is a way .

 

Thanks.

  • 0
    TI__Expert 7110 points
    The absolute deviation is stated in the electrical specification table. It is -0.6% to 5% in PFM Mode.

    Basically, the only way to manually force device in PWM operation is the level of the Pin PS/SYNC.
    However, the device automatically switches in PWM operation once the load gets higher. Once your load is at least approx. 400mA, the device will always operate in PWM Mode.
    Is your circuit a prototype or already for production?
  • 0 in reply to Florian Feckl
    Expert 2200 points

    Hi Florian,

     

    Thank you for your reply.

    It's difficult to force the Pin PS/SYNC to Vin.

    I think only I'll increase a load current and confirm the voltage in PWM mode.

    The PCB layout is almost mass production, it's difficult to change it by the temporal restrictions.

     

    When the accuracy of output voltage is within the 5% in PFM mode, it may be no problem.

    I'll try again to consider specification.

     

    thaks.