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I am looking for a specific chips datasheet but am not having much luck in my search. The chip is used in a trigger mechanism, and although the chip is apparently widely available, no vendor has a proper datasheet for it. The chip is an CPX94 SOP8, with 9221 written below the CPX94. It connects to a MOSFET so I was looking to get its pinout. I'm not sure if this chip is now considered obsolete and that's why it's so hard to locate.

enter image description here

enter image description here

In the circuit below, the resistors between the pads are rheostats. enter image description here

Below is the mostly complete setup, less the MOSFET and switch.

enter image description here enter image description here

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    \$\begingroup\$ Is there any way to get a more clear picture? Right now the picture is too blurry and doesn't help at all. \$\endgroup\$
    – snowmanemperor
    Commented Nov 5, 2021 at 18:24
  • \$\begingroup\$ I had to crop the picture to keep it under the 2mb limit, but honestly, the writing is faded, it only get picked up with a glare, I'll update with what I believe the circuitry is around based on what I got from my multimeter. \$\endgroup\$
    – JTH828
    Commented Nov 5, 2021 at 18:35
  • \$\begingroup\$ "Today we are announcing that effective June 30, 2012, production will end for the CPX, XPX, SCC, and SX Series products with pressure ranges of 1 psi and higher." kynix.com/Detail/327344/CPX94.html \$\endgroup\$
    – Michael Harvey
    Commented Nov 5, 2021 at 18:43
  • \$\begingroup\$ Cropping isn’t the issue, focus is. \$\endgroup\$
    – winny
    Commented Nov 5, 2021 at 18:48
  • \$\begingroup\$ You're right @winny, I updated the image with a more clear picture of the chip. And I figured it was out of production, but I was unaware if there was a replacement chip that had the same pinout or if the spec sheet for this chip was out there somewhere. \$\endgroup\$
    – JTH828
    Commented Nov 5, 2021 at 19:12

2 Answers 2

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My guess is the part is a dual op-amp chip, like this one:

here.

I'm also guessing there are additional traces (such as under the chip) that are not reflected in your diagram which would account for the IN1(-) pin on the A-side amplifier. For example, there appears to be a trace connecting pins 3 to 4 in your photo, but so fuzzy its difficult to confirm.

If my guess is correct, then candidate parts such as the MC4558 come to mind.

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  • \$\begingroup\$ I updated the image if it helps at all, I believe that chip is correct since I believe the CPX94 was also an ST chip. I removed the chip and updated the post, I'm not sure if the A side of the opamp is even used. \$\endgroup\$
    – JTH828
    Commented Nov 5, 2021 at 19:48
  • \$\begingroup\$ I agree, the A side amp may not be used. I mistakenly interpreted the Out1 (pin 1) connecting to the MOSFET gate. It was difficult to see the yellow net from your diagram. Very nice pics the second round. \$\endgroup\$
    – icodeplenty
    Commented Nov 5, 2021 at 20:06
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I would guess it's a simple ASIC designed for just this purpose. Here, for example, is a similar ASIC from Wuxi ASIC Microelectronics:

enter image description here

enter image description here

enter image description here

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