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Original question:

TPS61094: No Charge

TPS61094: Does not charge

Andris Igaunis
Prodigy 10 points
Part Number: TPS61094

Tool/software:

Dear Sir or Madam, 

I have the same issue as another person in this forum - my implementation of TPS61094 sometimes does not charge the supercap. Significantly, it often stops at ~0.7V and would not go higher. 

My setup:

Vin = 3.3V from solar panel

Vout = 3.3V

Vchg = 2.6V

Ichg = 350mA

EN = MODE = HIGH through diodes from Vin and Vout. 

I have absolutely verified that V_solar = 6.5V, Vin = 3.34V, Vout = 3.34V, EN = Mode = 3.28V, Vsupercap = 0.799V, and there is no charging for many minutes, without any sign that it would resume. Even if I unplug Solar panel, essentially making Vin = 0, and re-plugging. Also, I have put 3mF electrolytic capacitors in parallel with solar, and with Vin, and it worked better, but at a load transient of 100mA on output, the TPS61094 hang again, and stopped charging, and could not be re-forced into buck mode even with Vin = 0. It was again when Vsupercap = ~0.7V. 

Can you please check out what is going on, and if such unstable operation is to be expected? 

Best regards, 
Andris Igaunis

  • 0
    TI__Guru 66350 points

    Hello Andris,

    The supercap value is 200F. Is this correct? I am not an expert for this device (the expert is out on public holiday until next week). Let me try to help debug.

    Did you observe the same issue if you keep the 3mF connected and reduce the supercap to 50F?

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Prodigy 10 points

    I removed 1 supercap to access components, so now it was 150F. Yes, capacitance is large (200F usually) to survive 24h. 

    Right now it is evening here, so I will continue tests tomorrow. But we designed v1 of this device 1 year ago, and from wall power supply it always worked. It seems like the device cannot handle weak source or something. It seems like if this TPS61094 senses a weak input, it does not charge supercap, and does not recover. But that is just my guess. I have a rather large charging current of 350mA, because at direct sunlight the solar panel produces plenty of energy. But of course at dim light it is not that powerful. 

    Andris

  • 0 in reply to Andris Igaunis
    TI__Guru 66350 points

    Hello Andris,

    It might be an impedance matching problem on the input side, but please expect a better help end of next week from the expert.

    Best regards,
    Brigitte