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TPS61230: No startup from dc/dc -> output voltage not reached

Part Number: TPS61230

I tested the circuit and the TPS61230 don't startup. The output voltage freezes between 1-1.5V. The voltage at Css is about 300mV. In the datasheet the Css should be loaded till 0.5V and after this the soft starting is over and it will be charged to the regulated output voltage. The pin En is shortcuted to Vin. 
Sometimes it happens that after some time I get the regulated output voltage of 4.2V and everything is ok.
Do you have any hint, to find the issue?

Thanks Andi


  • Hi Andreas,

    The phenomenon looks really strange. You can debug this circuit following below steps:

    1. Check the input voltage VCC is correct.

    2. Share the layout to me. We used to see many similar cases that the IC doesn't work if the layout didn't follow TI's suggestion.

    3. Check IC and passive components are soldered well. If the input voltage, layout are good, replace the IC with a new one.

    4. Probe the the Vin, SW, Vout pin waveforms. 

  • Hi, thanks for your help,

    1.) I have a Lipo as input voltage with about 4V named VCC_SYS at the circuit

    2.) The enable pin is connected to a solder pad because I didn't know if I activate the TPS61230 via controller but now it is shortcutted to VCC_SYS. Should this be as near as possible at the chip?

    3.) Solderings looks good (industrial soldering). I also have 5 similar boards but the other one have also the some behaviour. Sometimes it works well, sometimes not. Could it be that the load (GSM-Modul) at Vout is a problem?
    Replacing the chip is not that easy for me :-), but with the other boards a have a change to check.

    4.) In progress

    Is there a modul like the PTN04050CAH which i can use instead of the TPS61230?

    Thanks for your help


    I added the BOM. Maybe the inductance isn't fit well?

  • Hi Andi,

    The layout looks good. The chosen inductor is also OK.

    Can you change the softstart capacitor C47 to 100nF. The 2.2uF is too big. Using below equation, a 2.2uF Css sets the tss 62ms.

    Just one reminder, during the soft start, there is a pre-charge phase and the current limit is 550mA typically. so the output load cannot exceed 500mA during softstart.

  • Hi, 

    I changed the C47 to 47nF (I don't have a 100nF) yesterday with same fault. Today the board started several times good. I changed nothing. 
    Is there a dependency from the load possible? 

    Thanks for you help. If you search a fault it is always good to here that the layout should fit ;-).

    Bests Andi

  • Hi Andreas,

    Yes. This device cannot startup with heavy load. Please startup with no load connected to make sure it's OK.

  • Hi Andreas,

    Any update about this case?

  • Hi,
    I tested it several times and now the TPS61230 starts well and I got the 4.2V output voltage. I assume some problems with the shutdown and starting with the load. Now I fully shutdown the load and now it works.
    Thanks for your help