BQ25606: BQ25606RGER charging status problem

Hi,

We will check and get back to you.

Thanks,

Ning.

Thanks for your reply!! 

Let me know if you have any query.

Hi,

Which pin voltage of the BQ25616 is your scope waveform showing?

Thanks,

Ning.

Thanks for Your reply!!

This is BQ25606 IC. Not BQ25616.

And in this this charging status waveform is showing.

 Thanks!!

Hi,

Let's debug step by step. 

1. The waveform shown is the STAT pin voltage, right?

2. What rail support the STAT pin pull-up?

3. Please double-check your schematic per https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/890626/faq-bq25606-schematic-review-and-pcb-layout-design-tips for BQ25606: Schematic Review and PCB Layout Design Tips. Additional Information including FAQs is available http://www.ti.com/lit/an/slva924/slva924.pdf 

Thanks,

Ning.

1. Yes it's voltage waveform of STAT pin.

2. STAT pin is connect with an LED indicator in series with current limiting resistor.

3. Thanks for sharing this file. I check and compare this points with my schematic, its all good.

Thanks!

Hi, 

For your second case it appears the BQ25606 is detecting the connected battery as fully charged. STAT stays high to indicate this. This is why it is not observed with Vbat = 3.65V, but it is when you have an almost fully charged battery. 

I can replicate you observation when connecting Vbat = 4.15V as shown below. Although I am unable to replicate when connecting a Vbat = 4.05. Are you able to provide a waveform capture of Vbat/Ibat during the test with Vbat = 4.01-4.05V?

Regards,

Garrett

Hi,

Thanks for reply!!

Here I attach the waveform of STAT pin at Vbat 4.01v.

Let me know if you have any query.

As you mention that you also face the same issue at 4.15v. So this is inappropriate behavior of IC.

So what is the solution of this?

Thanks!

Hi,

We will check and let you know.

Thanks,

Ning.

Hi,

Thanks for reply!!

I am waiting for your answer.

Thanks!

Hi,

What is the battery charge voltage set by the VSET in your circuitry?

Thanks,

Ning.

Hi,

In our design we set the VSET pin as float.

So the VSET is 4.208v.

Hi,

What is the charge termination current set by the ICHG pin in your circuitry?

Thanks,

Ning.

Hi,

We set the ICHG is 2A.

Thanks!

Hi,

Referring to 9.3.5.1 Autonomous Charging Cycle on the d/s,

1. The charger device automatically terminates the charging cycle when the charging current is below termination threshold, battery voltage is above recharge threshold, and device not is in DPM mode or thermal regulation. Please note that the recharge threshold is lower than the battery charge voltage set by the VSET pin.
2. When a fully charged battery is discharged below recharge threshold, the device automatically starts a new charging cycle.

Thanks,

Ning.

Hi,

I already check the both scenario in our circuit but none of this is applicable.

Charging termination is automatically off by some unknown reason.

Thanks.

Hi,

Will get back to you on the next business day.

Thanks,

Ning.

Hi,

I am waiting for your reply.

Thanks!!

Hi,

The BQ25606 enables charge termination by default. If the VBAT (the BAT pin voltage) decreases (i.e. the battery voltage decreases when discharging), will the device start recharging?

Thanks,

Ning.

Hi,

Here I little confuse what you say?

Yes if battery is connected to PCB so VBAT voltage is obvious decreases because its discharging.

When you say device start recharging?

Hi Harsh, 

The recharge threshold is on the datasheet (VRECHG), typically is 121mV. When you said the device is not terminating: 

1. Is the battery voltage above the recharge threshold? Is the battery close to the charger on your design? 
2. Is the device in DPM mode? Any big load connected to SYS? 
3. Is the device is thermal regulation?
4. Is the device in cool or warm region? 

These could make the device not terminate, as termination is disable on those cases. 

Regards, 

Arelis Guerrero 

Hi,

I think you miss-understood my problem. I have issue that my battery is terminate at 4.01v instead of 4.2v. Its mean that my device is early terminate the battery .

1. Yes at terminate time my battery voltage is 4.01v above the recharge threshold. Yes  battery is near design.

2. No we are not use DPM mode. No any load is connected to SYS.

3. No we are not use thermal regulation .

4. No we have not any kind of region .

Hi Harsh, 

Apologies, I understood the device was not terminating. It looks like the device is terminating prematurely. Termination will happen whenever the charger observe the current is below the termination threshold, and not necessary by battery voltage. The termination current will be ~5% of your ICHG setting, but you also have to consider the termination accuracy specs. 

In order to better debug the possible root cause of why the current is lower than expected at 4.01V can you answer the following: 

1. Are you using a real battery to perform the test? Or is a battery simulator used?
2. If using a battery simulator, what capacitance do you have on the battery pin?  
3. If using a real battery, is the configuration for termination current matching the real battery specs? 
4. Have you tried a different battery or battery simulator? 
5. Have you measure the termination current, does it seems to be correct whenever it terminates at 4.01V? 

Regards, 

Arelis G. Guerrero 

Hi Arelis,

1. Yes we are use the real 3.7v 5000mAh battery.

2. No we are not use the battery simulator.

3.  As per datasheet 5% of ICHG termination current is 100mA and as per battery datasheet the charging shall be terminate when the charging current has tapered to 50mA(0.01C). 

4.Yes we have 3 different battery. we check with all battery result is same.

5. As I early mention termination current is 100mA and when our battery is terminate the charging current is 180mA. So its not kindly same.

Thanks.!!

Hi,

Did you measure the battery voltage (e.g. 4.01V) at the battery terminal after the charge is terminated?

Thanks,

Ning.

Hi,

Yes I continuous measure the voltage of battery.

when charging ic terminate the battery voltage is in 4.01v~4.1 range.

Thanks!!

Hi,

Since Monday (9/5/22) is a federal holiday, we will get back to you on Tuesday.

Thank you very much for your understanding,

Ning.

Hi,

Thanks for inform.

I'm looking forward to your reply.

Thanks!

Hi Harsh, 

Sounds good, we'll get back to you on Tuesday. 

Regards, 

Arelis Guerrero 

Hi Arelis,

Thanks, Waiting for further assist.

Hi,

When the battery terminal voltage is 4.01V, what is the BAT pin voltage of the BQ25606?

Thanks,

Ning.

Hi Ning,

When the battery terminal voltage is 4.01V, then BAT pin voltage is 4.21v.

Thanks.

Hi,

Since the battery charge voltage set by the VSET is 4.208V, the charger should terminate charge when the BAT pin voltage is 4.21V. Please note that the charger IC can only sense the BAT pin voltage (not the battery terminal voltage) and control charging accordingly.

Thanks,

Ning.

Hi Ning,

I check earlier when battery in charging then BAT pin voltage is 4.21~4.22v but battery still charging. The battery is not terminate.

This is my observation.

Thanks!!

Hi,

In the previous response below, you mentioned your battery is terminate at 4.01V. In the follow-up response, you mentioned "the battery terminal voltage is 4.01V, then BAT pin voltage is 4.21v.". The 4.21v BAT pin voltage basically matches your expectation below (4.2v to terminate). Could you please double-check?

Thanks,

Ning.

Hi Ning,

My meaning is battery is in charge, battery voltage is below 4.01v and the BAT pin voltage is 4.21~4.22v when charging. Then battery is not terminating. Its in charging.

Sorry I forget to mention battery voltage.

Thanks!!

Hi,

We will get back to you on the next business day.

Thanks,

Ning.

Hi,

Please note the 4.208V is typical battery charge voltage, it may vary to 4.21V~4.22V. So it is normal that the charger still charges when the BAT pin voltage is 4.21V~4.22V.

Thanks,

Ning.

Hi,

Thanks For Information.

So that's our query, now in some scenario what happen:-

1) Bat voltage 4.15v then sometime charging.

2) Bat voltage 4.01v then battery is not charging.  

So I notice that our charging ic make malfunctioning.

One thing is weird that but, we use this IC over the last one year and we cannot face any issue. But after this we face this issue in last one month.

So that's kind annoying and we cannot solve whats happen suddenly.

Hi,

Based on the previous discussions, there's nothing wrong with the device. Let's check again step by step.

For 1) Bat voltage 4.15v then sometime charging, it looks like there are two steps.

1a) When "Bat voltage 4.15v", what are VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS? 

1b) when "then sometime charging", what are VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS? 

Thanks,

Ning.

Hi Ning,

I check all point voltage and current is accurate as per datasheet there is no issue, but problem is why we face this issue if all is correct?

Any more suggestion which we implement in circuit side?

Thanks!!

Hi,

We have to know what is going on before we may provide suggestion. The following info is needed in order to debug.

For 1) Bat voltage 4.15v then sometime charging, it looks like there are two steps.

1a) When "Bat voltage 4.15v", what are VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS? 

1b) when "then sometime charging", what are VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS? 

Thanks,

Ning.

Hi Ning,

Following Reading I measure.

1a) VBus = 0v,IVBUS =0A, VBat=4.15v,IBAT= 6mA, VSys=4.15v,

2b) VBus=  11.7v, IVBus= 600ma, Vbat= 4.15v, IVbat= 552mA. VSys= 4.21v.

I have no option to measure the ISYS.

Hi Harsh, 

For cases:

1a) the VBUS =0V, therefore the battery would not charge as there is not a valid adapter to provide charge to the battery. 

2b) the VBUS is present and valid (11.7V), therefore the device can charge the battery, as VBAT (4.15V) < VBATREG . 

In both scenarios the charger is operating normally and shows the expected results. 

Best regards, 

Arelis Guerrero 

Hi Arelis,

Yes with this in both case we have right outcome but after this when battery voltage is 4.01v then also we get the almost same value as above case 2a.

but in that case our battery is terminating charging rather charge the battery.

Hi Harsh, 

In order to optimize the support:

1. Can you please provide only the cases where you don't see the right outcome, as examples above show the charger operating normally. What do you mean by later you get the same case as 2a? What are the values at this later time (VBUS, IBUS, VBAT, IBAT, VSYS, ISYS)? At this later time is there an active fault (DPM, TREG, Warm/Cool, etc..)? 
2. Is the charger terminating or not terminating? 
3. You mentioned you used this IC for over a year, and just recently started seeing problems? Did anything changed on your design? Have you tried a different unit? 

Regards, 

Arelis Guerrero 

Hi Arelis,

1. I get problem when bat voltage 4.01v. so that time the value of VBUS= 11.87v, IBUS= 0mA, VBAT= 4.01v, IBAT= 0mA, VSYS= 4.19v.

2. When bat voltage 4.01v reach then battery charging automatic terminating. This is the our issue.

3. Yes this is right before this issue we have not any kind of this behaviour happen with us our battery terminate at 4.19v~4.20v. we are not change in our design. yes we have 300 units here and i check with almost 30+ units but same case happen with all that. 

Hi,

Harsh Bhatt said:

1. I get problem when bat voltage 4.01v. so that time the value of VBUS= 11.87v, IBUS= 0mA, VBAT= 4.01v, IBAT= 0mA, VSYS= 4.19v.

For the statement above, what was the BAT pin voltage right before IBAT drop to 0mA?

Thanks,

Ning.

Hi Ning,

When IBAT 0mA before that Bat pin voltage is 3.9~4.0 v.                                                                              

Hi,

What are VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS right before IBAT drops to 0mA?

Thanks,

Ning.