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TPS63030 Power save doesn't work

BOUQUET Hugo
Prodigy 130 points
Other Parts Discussed in Thread: TPS63030

Hello,

I've design a power supply board to supply a RF module with the TPS63030 but I've a problem. When power save is disable I've no problem but when it is enable I can't detect my RF module unless the output voltage is 3,3V. I think that TPS63030 doesn't suplly enough current in power save disable but I don't understand why.

The power consumption of this module is 3,3V and 20mA every second during 100µs and 10µA during in the rest of the time. The transmission of the data is 80mA during 200ms.

So the power consumption seems to be less than the maximum current that the TPS63030 can supply in power save mode

My power supply board can accept 2 power supply, one with an external 5V supply and the other with a 3,6V LiSoCl2 battery.

Find below my scheme. R3 and R4 is the couple of resistor I change when to change power save disable and enable.

Is it possible to help me to understand why it doesn't work in power save enable ?

  • 0
    TI__Guru*** 145780 points

    The device automatically transitions between power save mode and PWM mode, so it is not limiting your output current.  At 80 mA load, you are likely in power save mode always.

    It is more likely that the increased ripple in power save mode is interfering with your RF system.  Does your system have a supply voltage ripple requirement?  Adjusting the inductance and output capacitance on the TPS63030 will affect the ripple.  Increasing either will reduce it.  Another option is an LDO after the TPS63030 to filter out the ripple and provide a clean voltage to the RF system. 

  • 0 in reply to Chris Glaser
    Prodigy 130 points

    Thank yo for your answer. It seems that you have right, a ripple interfer with my RF System. Every second, when my RF system is listen (and so a current consumption) I have a ripple of 70mV on my 3,3V.

    I don't want to use a LDO because it have a bad efficiency and it will highly reduce the life time of my product on battery. Tell me if what I say is wrong !

    What is a supply voltage requirement ? What way i've to follow ? It's the first we design a power supply for RF.

  • 0 in reply to BOUQUET Hugo
    TI__Guru*** 145780 points

    I mean what is your RF device's required power supply noise?  What does it require for its voltage?  It should spec a maximum ripple voltage for a desired performance.

    I would try adding more output capacitance to your TPS63030 to reduce the ripple in power save mode.

    Another thing to look for is how many pins the RF device has for its input voltage.  It may have an analog Vin and a power Vin.  An RC filter on the analog Vin may help it perform better.  You should consult your RF device's datasheet for its power supply recommendations.