BQ25622: Battery Charging Issue

we are still waiting for your valuable response 

Hi Margub, 

We are working to review your schematic and will get back to you with further comment today. 

Best Regards,

Garrett 

Hi Margub, 

Thank you for your patience. I have reviewed your schematic and have the following comments. 

-Given resistor selection C11 (330nF capacitor) is not necessary at ILIM pin. It can be removed.

-Do you have any resistors connected at TS pin? TS cannot be left floating unless you set TS_IGNORE = 1 (REG0x1A[7]). With TS floating and default register configuration the BQ25622 will not start charge. Please refer to datasheet section 8.3.5.4.2 on TS pin configuration. 

Beyond these comments I see no other issues in the provided schematic. 

Margub Aalam said:

2) In our schematic when we connect VBAT to VSYS load it will work and I2C is Detect but it gives garbage value in12bit ADC.

In this case are you connecting BAT to SYS load external to the BQ25622 IC? Expectation is you connect battery to BAT pin and battery will discharge to SYS output pin to support SYS load even when VBUS is not connected. 

Margub Aalam said:

 3) When we give input voltage at VBUS and also connect the battery in VBAT and load VSYS in this case we cant get any output voltage and IC is Heated Extremely.

This would typically indicate there is some layout or soldering issue on the board you are testing. With a 1A current limit set by ILIM pin resistor I would not expect "extreme heating". Have you measured the current draw at VBUS in this case? What voltage do you measure at VBUS and BAT pins?

Also unexpected for this case is your claim of no voltage at SYS even though battery is connected. Even if buck converter is not on for 1 reason or another expectation is BQ25622 will connect BAT pin to SYS pin through internal Q4 BATFET. What is expected current draw of your system load? 

Best Regards,

Garrett 

Dear Sir,

As per your suggestion we did the changes in schematic  C11 (330nF capacitor) we removed and we added some resistor in TS and TS bias pin for configuration.

Also we checked BQ25620EVM User's Guide (Rev. A) and we doing the same schematic as per show in document but we cant read I2C and we don't understand how to connect Battery Management Studio (BQStudio) without EV2400 Adapter.

So current situation is we are not sure how to connect our schematic board to host the Charging peripherals.

Voltage at this schematic design VBUS =5v,VSYS=3.78v,VBAT=1.3v,BTST=8.2v & SDA,SCL,INT,CE is pullup.

And please suggest for this problem and provide full working schematic while BQ25622 communicate with I2C to any Microcontroller. 

Dear Sir,

We attached Schematic file for your reference. As per your guide we changed SCL and SDA lines connected to a pullup rail via a resistor10K and I2C got detected. In this case VBUS-5V/3A,VSYS-3.78V,VBAT-0.600V, BTST-7.7V

But we need to now start VBAT for Battery charging so as per datasheet we can do CE pin then VBAT voltage is 0V and IC shorted.

so please guide us for Battery Charging issue and please check schematic if there any changes needed.

AE175_DT.pdf

Hi Margub, 

Great to hear that you now have functioning I2C communication to the charger IC. Please see my comments below on schematic review. 

-I recommend using a larger resistor value for pullup for STAT and PG pins. TI recommends using 1kohm or larger resistor. 

-Your design needs to have the ability to pull CE pin to GND. If CE is always pulled up to logic high charge will never be allowed to start.

Beyond these comments I see no other issues with your schematic. 

Margub Aalam said:

But we need to now start VBAT for Battery charging so as per datasheet we can do CE pin then VBAT voltage is 0V and IC shorted.

Please help to further explain what you mean by 'IC shorted". What specifically is being shorted? To start charge you need to connect /CE pin to GND. 

Best Regards,

Garrett 

Dear Sir,

We test as per your comment larger resistor value for pullup for STAT and PG pins we use 1K and CE pin to GND. But we found 2Cases and there details in below:

Case 1: As per your comment changes.

1) we can start VBUS and CE pin GND then result is VSYS =0V and VBAT = 0V and PG LED OFF.

so we can try with CE pin high and see the Result.

2) we got some voltages on overall pins:   BTST-7.7V, REGN-4.9V, PG-0V, ILIM-0V, TS_BIAS-0V, TS-0V, QON-3.3V, VBAT-0.6V, VSYS-3.78V, STAT-1.6V, INT-3.78V, SDA-3.78V, SCL-3.78V, CE-3.78V, GND-0V, SW-3.78V, PMID-4.9V, VBUS-4.9V. 

Now we don't know is that correct value or not and also we cant connect I2C with MCU. And after connect I2C we got scanned I2C address on serial please find the attached photo.

After we got I2C address we thought we can start for VBAT for battery Charge because we got still VBAT-0.6V.But before we write VBAT internal register on code but our VSYS voltage drop and PG LED is low and now create Case-2.

Case 2:VSYS Voltage drop 3.78V to 0V.

1) we think suddenly what happened and we find not only VSYS but some other pins voltage has been low. BTST-3.1V, REGN-3.6V, PG-0V, ILIM-0V, TS_BIAS-0V, TS-0V, QON-3.3V, VBAT-0V, VSYS-0V, STAT-0V to 0.150V, INT-0.002V, SDA-0.002V, SCL-0.002V, CE-0.002V, GND-0V, SW-0V, PMID-4V, VBUS-4.9V. 

Please find the yellow highlight pins voltage has been changed and now we cant read I2C address as before case 1 read.

2) Now we tray to connect second as per case 1 but there is no change. And we connect VBAT 4V 1cell Battery and we got VSYS -3.8V. In this situation we can read I2C address and able to write charging register and show in image for your reference.

After write charging bit we check VBAT voltage is still same 0V.

So please guide for this problems and tell us proper way to testing this charging IC and IC part no. BQ25622RYKR. Also we test this whole things on General Purpose Board but for IC we use proper PCB board as per exact foot print.

Please sir guide us for our problems and share proper flow for our application and this is really important for our company future large scale production.

AE175_DT_.pdf

Hi Margub, 

Thank you for the further detail on your test cases. Please see my comments below.

Margub Aalam said:

1) we think suddenly what happened and we find not only VSYS but some other pins voltage has been low. BTST-3.1V, REGN-3.6V, PG-0V, ILIM-0V, TS_BIAS-0V, TS-0V, QON-3.3V, VBAT-0V, VSYS-0V, STAT-0V to 0.150V, INT-0.002V, SDA-0.002V, SCL-0.002V, CE-0.002V, GND-0V, SW-0V, PMID-4V, VBUS-4.9V. 

After review of these voltage measurements the value which stands out to me is PMID = 4V while VBUS = 4.9V. PMID voltage is expected to be much closer to VBUS, similar to the 1st voltage measurements you took. 

If you remove all power sources from board then reconnect 5V VBUS do you still see a low PMID voltage? 

Margub Aalam said:

But before we write VBAT internal register on code but our VSYS voltage drop and PG LED is low and now create Case-2.

Ideally, if you are able to replicate this behavior I recommend capturing a waveform of VBUS, SW, VSYS, VBAT which triggers on VSYS dropping in an attempt to debug exactly what is leading to issue where SYS output is no longer able to be regulated normally. 

Nothing in your schematic should be preventing SYS regulation when charge is disabled. We need to understand what event is causing VSYS drop. For example, is there a sharp current increase observed? Your test results up to this point still appear to show you have a board issue. What do you mean by you are using a "general purpose board"? 

Best Regards,

Garrett 

Dear Sir,

Thank you for your support.

 If you remove all power sources from board then reconnect 5V VBUS do you still see a low PMID voltage? 

Yes we check multiple time and PMID voltage is the same.

if you are able to replicate this behaviour I recommend capturing a waveform of VBUS, SW, VSYS, VBAT which triggers on VSYS dropping in an attempt to debug exactly what is leading to issue where SYS output is no longer able to be regulated normally. 

Yes sir we capture waveform and details in below:

1) VBUS - 5V/3A and VSYS Voltage checked in scope.CH1 is VSYS Signal and CH2 is VBUS Signal

2) VBUS - 5V/3A and SW Voltage checked in scope.CH1 is SW Signal and CH2 is VBUS Signal

3) VBUS - 5V/3A and VBAT Voltage checked in scope.CH1 is VBAT Signal and CH2 is VBUS Signal 

4) VBAT - 3.78V/2A and SW Voltage checked in scope.CH1 is VBAT Signal and CH2 is SW Signal 

5) VBAT - 3.78V/2A connect VSYS Voltage and SW Voltage checked in scope.CH1 is SW Signal and CH2 is VSYS Signal 

6) VBAT - 3.78V/2A and VSYS Voltage checked in scope.CH1 is VBAT Signal and CH2 is VSYS Signal 

All upper case is test on yesterday IC condition and still the same conditions.

What do you mean by you are using a "general purpose board"? 

...

See we are testing on this type GP Board so is it okay and if is it okay then why we cant get proper result.

please sir provide better solution for the same.

Dear Sir,

we test first on yesterday IC and there waveform we have already send on previous reply. And after we test on fresh new IC and the waveform result on below:

1) VBUS - 5V/3A and SW Voltage and CE pin is low and waveform checked in scope.CH1 is SW Signal and CH2 is VBUS Signal.

2) VBUS - 5V/3A and VSYS Voltage and CE pin is low and waveform checked in scope.CH1 is VSYS Signal and CH2 is VBUS Signal.

3) VBUS - 5V/3A and VBAT Voltage and CE pin is low and waveform checked in scope.CH1 is VBAT Signal and CH2 is VBUS Signal.

4) VBUS - 5V/3A and SW Voltage and CE pin is high and waveform checked in scope.CH1 is SW Signal and CH2 is VBUS Signal.

5) VBUS - 5V/3A and VSYS Voltage and CE pin is high and waveform checked in scope.CH1 is VSYS Signal and CH2 is VBUS Signal.

6) VBUS - 5V/3A and VBAT Voltage and CE pin is high and waveform checked in scope.CH1 is VBAT Signal and CH2 is VBUS Signal.

After Checking waveform of VSYS,SW,VBAT and VBUS in CE high and low both condition we check all pins individual voltages.

 --when CE pin low overall pins voltage is BTST-8.5V, REGN-5V, PG-0.007V LED is ON, ILIM-0.0075V, TS_BIAS-0.0075-0.0086V, TS-0.0044-0.0050V, QON-4V, VBAT-2.6V, VSYS-3.78V, STAT-0-0.006V LED is ON, INT-3.78V, SDA-3.78V, SCL-3.78V, CE-0.050V, GND-0V, SW-3.78V, PMID-4.9V, VBUS-4.9V. 

In this case we connect I2C and charging register enable so we got ADC value of VBAT on serial is 2.6V and physically check on pin we got same value2.6V show in below image.

--when CE pin High overall pins voltage is BTST-8.5V, REGN-5V, PG-0.006V LED is ON, ILIM-0.0075V, TS_BIAS-0.0075V, TS-0.0044-0.0050V, QON-4V, VBAT-2.6V, VSYS-3.78V, STAT-2.33V LED is OFF, INT-3.78V, SDA-3.78V, SCL-3.78V, CE-3.78V, GND-0V, SW-3.78V, PMID-4.9V, VBUS-4.9V. 

In this case we connect I2C and charging register enable so we don't got ADC value of VBAT on serial is 0V and physically check on pin we got 2.6V show in below image.

Now we can see upper all case I2C read but CE pin high ADC is internally high that's why we got serial value. 

so please guide us for VBAT how we can increase and start testing for the same.0763.AE175_DT_.pdf

Hi Margub, 

Please see my comments below. 

1)Waveforms from your 1st post on old IC do appear to indicate IC was damaged. Do you have confidence the general purpose board and wires you are using can handle the expected current draw during fast charge portion? From the image the trace width on the PCB the IC is on appear quite narrow.

2)In the waveform which includes SW expectation is SW voltage should be transitioning between 5V and 0V, similar to what is shown in Figure 9-10 in the BQ25622 datasheet. If you use a smaller time division are you able to see expected SW waveform? Given you do see SYS regulated to 3.78V it would appear buck converter is functioning. 

3)

Margub Aalam said:

when CE pin low overall pins voltage is BTST-8.5V, REGN-5V, PG-0.007V LED is ON, ILIM-0.0075V, TS_BIAS-0.0075-0.0086V, TS-0.0044-0.0050V, QON-4V, VBAT-2.6V, VSYS-3.78V, STAT-0-0.006V LED is ON, INT-3.78V, SDA-3.78V, SCL-3.78V, CE-0.050V, GND-0V, SW-3.78V, PMID-4.9V, VBUS-4.9V. 

For this case device appears to be behaving as expected. With VBAT=2.6V device will be charging in precharge phase (default precharge current is 100mA). Are you using a real battery or a simulator in your test? 

You ask how to increase VBAT if you are using a real battery then voltage at BAT pin should naturally increase as charging is in progress. If you are using a simulator you can increase the voltage and when VBAT > 3V device will transition to fast charge and expected charge current will increase to 1.04A. 

Best Regards,

Garrett 

Dear Sir,

As per your 3rd comment we are not using any simulator but we use 3.7V /2A single cell rechargeable battery. And we cant charge this battery with 2.6V and when we connect IC got heat up and damaged.so please give us proper solution for the same .

Hi Margub, 

Thank you for your response. Please see my comment below. 

Margub Aalam said:

And we cant charge this battery with 2.6V and when we connect IC got heat up and damaged

In your testing is the voltage measured at the battery terminals before connecting to charger IC 2.6V? 

Please understand the BQ25622 performs constant current mode charging for both pre-charge and fast charge phase of charge. In other words the voltage at BAT output is dictated by the battery connected not the charger IC. If BQ25622 measures voltage at BAT pin as 2.6V the device will source IPRECHG to battery, which is 100mA by default. 

Again I will reiterate the device is designed to function with both a battery and input adapter connected. This should not cause overheating and damage considering I see no issues in your schematic and your most recent voltage measurements matched expectation. For your test case of VBUS = 4.9V and VBAT = 2.6V how are you determining device is damaged? Are you seeing abnormally high current at either VBUS or BAT? 

Best Regards,

Garrett

Dear Sir,

we make fresh all circuit on General Purpose Board as per schematic and now this time we place input signal component so much near to as per guideline.

now we got I2C ,VSYS and give VBUS with 5V/3A, But problem is when we connect Battery on VBAT our battery not charged.

so please guide for the how to enable constant current for charging mode.

Hi Margub, 

Thank you for your reply. To address your report of not charging with battery connected can you please try the following experiment. Please test if BAT pin output voltage will increase to approx. 4.2V with charge enabled and no battery actually connected?

Expectation is BQ25622 will charge the 10 uF output capacitor at BAT to 4.2V, then charge will terminate, voltage will decay some and then charge up to 4.2V again similar to the waveform capture shown below. 

If BQ25622 works as expected in this test then it confirms all IC configuration is okay and there is something specifically related to your battery pack preventing charge. If device still does not charge with no battery connected then you will need to double check whether other pins have appropriate connections. 

Best Regards,

Garrett