TPS61094: Facing issue with boost mode operation

Hi Mitesh,

Please check my several questions below,

1.In the duration of charging super caps, there is always no load in VOUT pin?

2.What's input source(5V) type? Is it a USB port or some other power supply? 

3.how does customer measure the 2A current which is drawing from super cap?

4.how does customer set the ICHG VCHG, could customer provide their schematic?

And more, it'd  better if customer could provide VSUP VOUT SW node voltage waveforms when "device  is drawing more than 2A current from super cap".

Thanks.

Best Regards,

Nathan

Nathan,

As I mentioned while input is present device is working fine, however pls. find my inputs.

1.In the duration of charging super caps, there is always no load in VOUT pin?

Response - Load is present, load is MCU & display.

2.What's input source(5V) type? Is it a USB port or some other power supply? 

Response - Power Supply

3.how does customer measure the 2A current which is drawing from super cap?

Response - Using multimeter placed in series.

4.how does customer set the ICHG VCHG, could customer provide their schematic?

Response - Kindly find the schematic.

We have also requested for Switching node waveform, as soon as it is available to us I will share it with you.

MiteshSUPCAP_MANAGEMENT_2.pdf

Hi Mitesh,

Very thanks for your sharing. 

Miteshkumar Dalabhai Patel said:

while input is present device is working fine

      So the problem is only appeared when input is not present, there is only a super cap to power supply output. Is this right?

And what is the state of SUPCAP_ENA_TGR signal during the 2A drawing current appeared? Is it logic high or low?

And more, about the waveforms, could customer please add EN waveforms? Thanks.

Regards,

Nathan

Nathan,

Kindly find attached waveforms for switching node while working in boost mode.

First 2 waveforms are for boost mode operation & waveforms showing burst operation is in buck mode.

Hi Mitesh,

Could you please provide the test condition in these 3 figure? And which one is the condition that "device  is drawing more than 2A current from super cap when super cap voltage > 2.0V" ? These three results is seemed to be normal.

Regards,

Nathan

Nathan,

Waveforms shown previously are with the lower voltage with which device is working fine but whenever voltage from super cap is above 2.0V device is start drawing  > 2A of current even if there is no load at output.

customer has shared the waveform & you can see the duty cycle is very wide for no load condition.

Mitesh

Hi Mitesh,

It seems the device is triggered valley current limit (about 2A), so it can't regulate VOUT to target value. And this may because there is large load current although customer said there is no load but it would be better customer could double check this. 

And more, did customer try another chip? Did this problem appear each time? Or customer could also have a try in our EVM to see if there is a same problem.

Thanks.

Regards,

Nathan

Nathan,

We have doubled check with customer about the load & they confirmed that there is no load connected at output & voltage at output terminal is also not as per the set voltage & still device is drawing 2A. Once supercap voltage come down below 2V, device is operating normally & that is most baffling behaviour.

On EVM device is working fine but then why device is not working in only boost mode operation & that too above 2V input?

Mitesh

Hello Mitesh,

As we did not hear back from you, I expect the problem is solved and will now close the thread. If you have further questions, please post below or start a new thread.

Best regards,
Brigitte