Hello folks,
I decided to open the can of a cheap OCXO marked OSC5A2B02.
I must admit I am quite puzzled with the circuit. Is the "501" IC a micro, or ASIC? I think it is something programmable, because the controll loop of heater transistor seems like good PID. But I am puzzled by the oscillator circuit between pin 6 and 14 almost as much as that strange LLC thingy connected to pin 15 and 16. And why the 4V (reference?) is connected to two pins of the IC?
The output to the base of the power transistor is purely analog, no PWM, so if it is a micro, it must have an DAC able to source a couple of milliamps.
Any opinion will be welcome.
![Teardown and RE of a cheap OCXO](http://<img src=)
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