BQ24232: CHRG LED some PCB ON some OFF for same battery

Hi,

Haim Rodrik said:

In some of them the LED is ON some of them the LED

Just to clarify, this is in reference to the LED_CHARGE LED?

Can you please share the input voltage, battery voltage, and OUT pin voltage when the LED is on and off? 

Additionally, can you please share the specifications (part number or Resistance + Beta value) of the Battery NTC as well as the temperature at which the tests take place.

Best Regards,

Juan Ospina

Hola Juan,

I will be at the site around next week, then I will test and reply.

Have a great weekend 

Note: Yes, LED_CHARGE LED. Power-good LED, ON state when connected to the USB port.

Hi,

Great, I'll await your response.

Best Regards,

Juan Ospina

Input Voltage of the IC 4.38V then Voltage on the battery 4V
when input shutdown to 0V, battery 3.98V

One cell standard LiPo battery

Cheers,

Hi Haim,

Your input voltage seems pretty low. It is close to the VINDPM minimum voltage so it is possible that the device is not charging because of it.

Can you try a higher input voltage to see if you can achieve more consistent charging behavior?

Best Regards,

Juan Ospina

Weird, because the LDO should be 5V

Are the values of all the resistors in the schematic OK? Single-cell LiPo batteries. I am using the same circuit on various battery sizes from 500mAh to 10Ah 

ChatGPT reply:

chat.openai.com/.../789706f0-de1a-4119-a9df-280022e46f68

Hi, I replaced the LDO. Now Vin Pin# 13 measured Vin 5.02V , same  as before. when input 0V , the battery switched to feed the Vcc. I asked about internal TS resistor value to the vendor. They don't have any clue. I hope they reply in some stage.

Found this 

Hi,

With a 5V at the IN pin was the charger able to charge normally?

Can you confirm if your IC is the BQ24232 or BQ24230? The schematic label indicates BQ24232however the pin 15 is labeled "TD" rather than ITERM. This pin can behave as either the Termination disable pin (BQ24230) or the Termination input pin. If this is the BQ24232 then I recommend a resistor to more accurately determine termination current.

Based on your resistor values ILIM is 463 mA, ICHG is 395 mA, and fast charge timer is set to 6.3 hours.

The TS NTC calculator you provided can be used to calculate compensation resistors for your NTC. These may be valid depending on your Battery's NTC characteristics. Typically, if your battery has a 103AT then it does not need compensation resistors and can be directly connected to the pin for normal TS behavior. If you do not need to use the TS function then you can directly connect the TS pin to ground with only a 10kOhm resistor.

Best Regards,

Juan Ospina

I started to use BQ24230 and BQ24232 , But next batches will use only BQ24232

Hi,

As mentioned, with the pin difference, if you will use BQ24232s going forward then I recommend a resistor to accurately determine Termination current. I don't believe shorting to ground is a valid configuration for ITERM.

Best Regards,

Juan Ospina

Hi, TD shorted to ground enabling terminator. 

Hi,

This is ok for BQ24230. For the BQ24232, Pin 15 is not TD but it is ITERM.

Best Regards,

Juan Ospina

Hi Juan, 

Now you hit me strongly. :) I need to ask you elementary questions. 
1, Why do I need termination? What's the purpose?
2. I thought that USB 100mA or USB 500mA is the maximum charging current of the battery
3. I understand the capacity of the battery does not affect the charging current value. 

Now I am going to change all logic, I will use BQ24230 for the same capacity of the batteries with devices that charge from the USB (O.V. protection 6.6V)
BQ24232 solar panel charger 4 to 7.2 depending on the Sunlight strength 

I prefer to select one of the chips for all types of devices because inventory BQ24232 is for both options, but termination ITERM is not clear to me

Thank you. 

Hi Halm,

Haim Rodrik said:

1, Why do I need termination? What's the purpose?

The resistance between the BAT pin and battery cell (R) will cause a voltage drop R x I where I is the charge current. So when the BAT pin voltage rises as the battery gets charged, the device enters Constant Voltage mode to finish charging the battery. In this mode the BAT pin will be equal to the regulation. As the battery cell voltage continues to rise, the charge current is reduced and the R x I voltage drop gets smaller. The charge current would continue to reduce and infinitely approach 0 mA. In order to indicate charging has stopped Termination allows us to set a charge current at which to stop. So once the charge current, in Constant Voltage mode, has reduced the charge current to ITERM, the charge will stop charging and indicate charge is done.

Setting ITERM to GND can have unexpected behavior and it is better to provide a resistor value to program ITERM.

Haim Rodrik said:

2. I thought that USB 100mA or USB 500mA is the maximum charging current of the battery

This is the input current limit so if your charge current is set to 200 mA but your input current limit is set to USB 100mA, then you will only have 100 mA of charge current. If your input current limit is set to USB 500 mA but your charge current is set to 200 mA, then you will have 200 mA of charge current.

Based on your schematic, (EN2 = 1, EN1 = 0) your input current limit is actually set by your ILIM pin. Based on the ILIM pin resistance you have an input current limit of about 463 mA (not USB 100 mA or USB 500 mA), based on your ISET pin your charge current is 395 mA.

Haim Rodrik said:

3. I understand the capacity of the battery does not affect the charging current value. 

This is right, battery capacity won't affect charge current value, only how long it takes to charge.

I don't think termination impacts the behavior you described before, but its helpful to distinguish the pin definition for the device used (BQ24232 or BQ24230). Has device been able to charge as expected?

Best Regards,

Juan Ospina

Hi,

I received a new batch of PCB manufactured, sam circuit but the PCB shape is different. I am using the same Altium schematic for all circuits, with no errors, and the PCB layout is proper, with no bugs. I have the same Vin at Vout.

The only change is the POWER GOOD and CHRG LEDS Vcc connected to Vin (Vusb). The circuit is powered only by batteries, the idea was when no USB input voltage from the USB source, the LEDs would not powered to save battery consumption. Please see the schematics above.

thank you 

Conclusion Based on your explanations from 31/1/2024, going to fix the circuit. I have only two scenarios:

1. Vin=5V from the voltage regulator or USB (PC or standard Charger) input voltage source.
2. Solar panel input maximum 7V@2.8A when a nice sunny day.

To cover the current limit,  100mA, and 500mA options first I will use bq24232 for both scenarios.
https://www.ti.com/lit/ds/symlink/bq24232.pdf?ts=1706993459346&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ24232 resistor values as on page# 30. I will only use close standard resistor values to the original resistor values. timers and current charge can be very close,

What do you think? is it ok?

Thank you

This is the last version of the scematics if you will confirm, going to production.

Thank you

Note: I am still waiting for the NTC datasheet from the battery manufacture 

Sounds good Haim. The Schematic looks good, the device should terminate around 25 mA.