TPS61030: TPS61030 enable pin causing high battery state of charge cutoff or irregular operation

Hi Ibrahim,

Why is you VBat waveform not stable, even when there is no load? Is VBat the real supply voltage on your EVM? As I mentioned before, the comparator should trigger EN pin to low when VBat is 3.2V. And the voltage of your power supply could be higher since there is resistance on the cable. To make the showed voltage on your power supply is exactly the voltage on EVM, you can use 4 wires to connect. You need additional 2 wires used as sense wire connecting sense pins on EVM. Could you give me a picture of your bench setup including power supply? You can draw a block diagram as well to let me know how you connect power supply and your EVMs. It is strange that your VBat waveform not stable.

Best Regards,

Yichen

Hi Ibrahim,

These pictures below shows what 4 wire connection is. There are 2 sense wires connecting power supply and EVM which can make sure the real input voltage is the same as setting value on screen of power supply. You can add a capacitor between the red wire and yellow wire if it is unstable.

BR,

Yichen

Hello,

Yes VBat is the real supply voltage of my EVM, and I'm not sure why the waveforms are so unstable. All the images sent were tests done with a YH-605D DC power supply and there were projects in the past which showed that this supply is not the most stable. So I have attached a waveform image with an actual 6000 mah battery whose capacity indicates a voltage level 3.9V:

Mind you that this is for a battery at a voltage far from the threshold. I suspect that as the capacity of the battery drains, the influence of the enable pin may take effect on the stability of the voltage source.

Images of my test bench supply as well as a rough block diagram are attached below here:

Thanks as always,

Ibrahim

Hi Ibrahim,

One possible reason for unstable VBat is that TPS61030 works in PSM and the current pulse is high and discontinuous. Due to internal resistance of your battery, the output voltage will decrease when there is an inrush current and increase back when the current is zero. You can check the current waveform if you have current probe. If not, you can set SYNC pin to high and disable PSM to see if there are any differences. And you can use TPS61030 alone first to avoid the influence of comparator.

If the internal resistance of your power supply is low enough, the power supply voltage should be stable. Please set the current limit of your power supply to maximum and use only TPS61030.

Best Regards,

Yichen 

Hello Yichen,

I currently do not have a current probe and I do not have a designated pin for the SYNC pin on my board. Would it possible to solder my SYNC pin to my VBat?? Also I am slightly concerned of short circuiting my TPS61030 by doing this since my SYNC pin is connected to my analog GND which is indirectly connected to my power ground PGND. 

I have done a test to check if the power supply and 5V regulator output function properly without the influence of the comparator EVM. I have done what I did previously where I would monitor the waveform at the same 3 different voltages with and without the load. This time, the blue waveform represents the 5V output and the yellow waveform represents VBat. The images with no load are attached below:

TPS61030_Noload.pdf

The images with the 1 A load are attached below:

TPS61030_Withload.pdf

Hi Ibrahim,

From your waveforms it is obvious that the TPS61030 is working normally. It works in PSM without load and PWM with load. And VBat is stable with load, the internal resistance of your power supply is large so there is a obvious voltage drop when inrush current occurs in PSM.

You can not solder SYNC pin to my VBat since it will cause shorting. 

Please check the waveforms of VBat, 5V Vout and EN when both comparator and boost are connecting to power supply, but the EN pin is not connected to VOUTA. 

Best Regards,

Yichen

Hello Yichen,

Please find attached below the waveforms of the 3 previously mentioned pins at the same 3 voltage levels measured previously. In these waveforms, the yellow represents VBat, the blue represents the 5V output, and the pink represents the EN pin which is not attached to the comparator's Vout.

With 1 A load:

61030_WithLoad.pdf

Without 1 A load:

61030_NoLoad.pdf

Thanks,

Ibrahim

Hi Ibrahim,

Sorry, my mistake. I should say VOUTA without connecting to EN pin. I want to know if comparator can work well when EN and VOUTA are not connected. If not, we should focus on comparator. From previous waveforms we know Boost works well without comparator, and we need to find the reason of this strange waveform:

And put a large capacitor with low ESR may be helpful for battery input, which could make VBat stable. Besides, you can make base line of your CH1 higher so I can find the value better. These Avg, Max, Min are not always accurate.

Best Regards,

Yichen 

Hi Ibrahim,

Is there any update?

BR,

Yichen

Hello Yichen,

The screenshots i sent you in my last post are in fact without the EN connecting to VoutA. Are you suggesting that I send CH3 at the VOUTA pin instead of the EN pin?? Also I'm not so sure what you mean by setting the CH1 baseline higher, can you please clarify upon that?? Also, I have designed my PCB board and had it fabricated and I have noticed that there is a high pitched audible ringing coming from my inductor when attaching a 1A load. Is there a way of reducing this or is there a flaw in my design shown below??

Schematic:

Schematic_FIXED final base model copy_2020-12-11_10-38-15.pdf

PCB design:

PCBdesign.pdf

The BQ24650 charger, comparator, and battery are found on the far left and the two TPS61030 converters are found in the middle and top right of the board. The 1A USB load is found in the far bottom right of the board.

Thanks,

Ibrahim

Hi Ibrahim,

Yes, I want to know if the comparator can work well alone. I mean you can put the horizontal position of CH1 higher like CH2. Is the old issue solved?
It seems that TPS61030 is not working stable. You can check the waveform of output voltage to verify it. What inductor and output capacitor do you use? Do they have the same inductance and capacitance like schematic? You can provide the part number.

Best Regards,

Yichen

Hello Yichen,

Yes, they are the same as the schematic. I have provided links to my inductors and capacitors used for the TPS61030:

- lcsc.com/.../Multilayer-Ceramic-Capacitors-MLCC-SMD-SMT_FH-Guangdong-Fenghua-Advanced-Tech-0805X225K250NT_C105486.html

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The TPS61030 works well with low loads such as the arduino and bluetooth module. There is a high intermittent load coming from the serial addressable LEDs (the WS2812B-B) but that only occurs when triggering the push button. I did however notice that when the load is continuously pulling 1 A from the battery, it turns off suddenly and does not turn back on again. I fear that the TPS61030 chip is being burned for some reason. This issue usually never occurs when using the model is on its own as adafruit have done with their powerboost 1000 basic which utilizes the TPS61030 chip here:  

I fear that the old issue might still not be resolved.

Thank you,

Ibrahim

Hi Ibrahim,

It could be over current because of low input voltage on powerboost 1000 basic. You can test the input voltage right via the input capacitor on the board. As we discussed before, the cable could bring voltage drop.

Best Regards,

Yichen