Teardown of a Pulse Oximeter

Today I did a teardown of BPL SmartOxy pulse oximeter and wanted to share amazing images I took which reveals a lot about interesting details about the product.

It is always great to see how different companies are designing products, their choice of microcontrollers, ICs and the over all construction.

You learn a lot by looking at someone else design, you get to know their perspective.

I have been a big fan of teardowns and started watching teardown videos on EEVblog YouTube channel some 15 years back 🙂

  • Teardown of a Pulse Oximeter 1
  • Teardown of a Pulse Oximeter 2
  • Teardown of a Pulse Oximeter 3
  • Teardown of a Pulse Oximeter 4
  • Teardown of a Pulse Oximeter 5
  • Teardown of a Pulse Oximeter 6
  • Teardown of a Pulse Oximeter 7
  • Teardown of a Pulse Oximeter 8
  • Teardown of a Pulse Oximeter 9
  • Teardown of a Pulse Oximeter 10
  • Teardown of a Pulse Oximeter 11
  • Teardown of a Pulse Oximeter 12
  • Teardown of a Pulse Oximeter 13
  • Teardown of a Pulse Oximeter 14
  • Teardown of a Pulse Oximeter 15

Details about various ICs used on the PCB:

  1. U101, OLED 128×64 0.96″ Display used with yellow and blue color pixels.
  2. U6, Microcontroller used is GD32E230C8T6, Cortext M-23, 64KB Flash, 8KB RAM, running at 72Mhz, LQFP48 package.
  3. U8, Quad Opamp RS624, probably for amplification and conditioning of signal from photodiode
  4. U5 (RS2105 ) looks like an Analog Switch
  5. Q3, N-Channel Mosfet NM2302B
  6. U2(marking Bp13) seems to be a boost converter which converts 3V battery voltage to probably 5V, I did not test the voltage yet. Test pad VH also indicates that higher voltage is getting generated from battery voltage. I am guessing may be SX1308 or something similar.
  7. U3 (marking LB33 C5U1) seems to be 3.3V LDO Some hint about LB33 marking.
  8. U10 is not populated, Antenna on the PCB indicates it to be Bluetooth circuit, which will be populated in the Bluetooth modem of the device.
  9. S100 switch is used to power on the device and then if user presses it changes the display formats. If the device is kept idle without finger, it gets power off to save battery.


Hope you have enjoyed the teardown pictures and learned something new.

If you have any further question you ask in the comments section, I will try to respond as soon as possible.


I am currently working as an embedded systems design consultant and helping companies build custom embedded products, develop test automation solution for their PCB.

If you have any feedback about the blog, you can share in the comments below or you can also contact me directly.

Read more interesting articles on Embedded Systems Design.


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