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I want to identify this battery level indicator SOP-8 IC that has no marking on it. Please see the following images with some extra information added to them in red markings.

enter image description here

enter image description here

enter image description here

enter image description here

Here is what we know:

  1. Battery is single cell 18650 lithium 3.7v.
  2. Every pair of LEDs are connected in reverse polarity (LED5 <-> LED4 and LED3 <-> LED2) (See attached image.)
  3. While charging, the last LED (the one that indicates the battery level) flashes.
  4. LED5 indicates LOW and LED2 is HIGH.
  5. LED1 in the circuit has nothing to do with battery level indicator.
  6. The left hand IC is an AP5056 charge controller.
  7. Pin 7 the IC is connected to pin 7 of the AP5056 through a 1K resistor. Pin 7 of the AP5056 according to datasheet is cathode of charge indicator LED (see attached image.)

Please let me know if there are any extra information that I can obtain and provide to help with identification.

Edit: The following images show how the IC controls LED using PWM:

Common pin of all LEDs when there is no flashing LEDs: enter image description here

The Common pin of all LEDs when there is a flashing LED: enter image description here

The other pin is always like this: enter image description here

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    \$\begingroup\$ It's likely some microcontroller with analog input and program that reads voltage and charlieplexes those LEDs. Even if you knew what the chip is, you will only know what chip it is and will not have the program it runs, so why is knowing which chip it is important? \$\endgroup\$
    – Justme
    May 20, 2023 at 12:11
  • \$\begingroup\$ @Justme Thanks. Even in that case, I think I can handle programming it. So it is still valuable to know what chip it is. \$\endgroup\$
    – AKTanara
    May 20, 2023 at 12:27
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    \$\begingroup\$ As it can be any MCU and you think you can handle programming any MCU, why bother determining which MCU this is? Just buy any MCU which has matching pinout if you intend to replace it. If you intend to make a new PCB anyway, any MCU can be used as the pinout does not matter. Also you can make an adapter PCB so pinout does not matter in any case. \$\endgroup\$
    – Justme
    May 20, 2023 at 12:34
  • \$\begingroup\$ @Justme, Yep, All you said is right, but even though improbable, if there is a specific chip in the market that does this, it would be the ideal choice. Other than that I have to evaluate those options in order of ease of access and execution \$\endgroup\$
    – AKTanara
    May 20, 2023 at 13:27

1 Answer 1

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It could be any MCU which has pin 1 for VDD and pin 8 for GND.

Such as ATtiny202.

There is no way to know which exact MCU it is unless you decapsulate it and try to identify it from the silicon die structures.

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  • \$\begingroup\$ Thanks, Why is VDD pin connected to input voltage through a 10 ohm resistor? Is it something obvious that I do not know? Is it just an RC filter for noise? \$\endgroup\$
    – AKTanara
    May 20, 2023 at 15:11
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    \$\begingroup\$ It might just be an RC filter for noise. \$\endgroup\$
    – Justme
    May 20, 2023 at 16:03
  • \$\begingroup\$ And one another question if you could help me out. How it that reverse polarity of LEDs work? For example while LED3 is constant on, LED2 flashes @ 1Hz yet they are connected to the same two wires just in reverse!!! \$\endgroup\$
    – AKTanara
    May 20, 2023 at 17:54
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    \$\begingroup\$ @AKTanara The IO pins alternate polarity so that any two LEDs can be turned on at any given time instance. Pin 6 will be high to allow turning on two LEDs, low to allow turning on the other two. Multiplexing is done at hundress or thousands of times per second, so a normal person can't see them blinking. If you wave the LEDs around rapidly before your eyes, you might see that they are not 100% of the time on and don't leave a continuous line due to persistence of vision, but a dotted line because they are pulsed on and off. \$\endgroup\$
    – Justme
    May 20, 2023 at 18:32
  • \$\begingroup\$ I do confirm according to what you said that micro controller uses PWM to turn LEDs on and off. So I have added some oscilloscope images of LED pins to demonstrate that to my question for educational purposes. Thanks again \$\endgroup\$
    – AKTanara
    May 21, 2023 at 11:02

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