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TPS62110 sync pin

S.Satoshi
Guru 21685 points
Other Parts Discussed in Thread: TPS62110, TPS62140, TPS62160

Hi,

Now our customer evaluating TPS62110 and then we received questions about sync pin as below. Can you please confirm them?

1, Can customer float sync pin? Which mode does TPS62110 operate with PWM forced or PWM/PFM if floating will be acceptable ?

2, Can customer tied sync pin through pull-down resistor ? They plan to switch sync pin VIN to GND through pull-down resistor dynamically。

Best Regards,

Sonoki / Japan Disty

  • 0
    TI__Guru**** 150790 points

    Floating the SYNC pin is not recommended.

    You can tie it to ground through a resistor.  

    Instead of using these older devices, we have the new TPS62140 and TPS62160 families that offer much better, lower noise power save mode performance.  They should be used for new designs.

  • 0 in reply to Chris Glaser
    Guru 21685 points

    Hi Chris-san,

    I appreciate for your quick response.

    I will answer our customer to not float SYNC pin, and they can tie it to ground through a pull-down resistor.

    And thank you for propose TPS62140 and TPS62160

    I show them as new devices and have better performance than TPS62110.


    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    Prodigy 170 points

    Hello,

    Does it matter if the SYNC pin is tied high or low if the SYNC pin is always driven with 1 MHz clock?  Or, is it still required to tie the SYNC pin either high or low even though the clock is always present?

     

    Thanks,

    Eric

  • 0 in reply to Eric Hooker1
    TI__Guru**** 150790 points

    I'm not sure that I understand your question.  If you are always driving it with a clock source, then you are tying it either high or low through the clock.

    The key point is that if the pin is left floating, we don't know what state the pin is in and so don't know whether we have forced PWM mode or PFM mode.

  • 0 in reply to Chris Glaser
    Prodigy 170 points

    Chris,

    Thanks for your reply and sorry I wasn't clearer.

    The TPS62110 data sheet describes (on page 5) the SYNC (pin 5) as follows:

    Input for synchronization to external clock signal. Synchronizes the converter switching frequency to an external clock signal with CMOS level. Also controls power save mode by being tied high or low:

    SYNC = HIGH: Low-noise mode enabled, fixed frequency PWM operation is forced

    SYNC = LOW (GND): Power save mode enabled, PFM/PWM Mode enabled

    My application is a two-way radio so I need all dc-dc converters synchronized to the same external clock (1 MHz in my case).  Since I use a constant frequency, do I still need to connect a resistor to the SYNC pin?  My thinking is no but I wanted someone at TI to confirm this.

    Thanks,

    Eric   

  • 0 in reply to Eric Hooker1
    TI__Guru**** 150790 points

    No, if your SYNC signal is always present and driving high and low, then no resistor is needed.

    The resistor is only needed to keep the SYNC pin in a known state when there is no input clock source to the pin.