crystal oscilator

Posted by: @atlestroms

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Hi whats the point having 2 clocks in this pcb, and also the grounding of the can 

 

 

 

ReplyQuote

The cylindrical one is usually an 32.768kHz crystal for the internal RTC.

The other one is the main crystal for det microcontroller.

@morten Thanks for replay, first thing is it normal to have 4 pin on the microprocess in that size, and  one of them are  connected from the cap of oscillator to minus side on a open capacitator place on the pcb.

It depends on the microcontroller, wats the number on the chip?

I dont know they have brushed it away, but the thing i dont understand is that bought oscillators have their own 2 port input and at the same time serie connected throw a capasitator. I think this picture is better

the crystal below is indeed a 32kHz crystal, the above with the grounded cap is the main clock provider for the uP  which is really unusally looks also like a crystal not like an oscillator (which has 4 pins gnd vcc enable and out). and the two caps at the crystal  are the  3-10pF caps used as it is usually defined in the datasheet so the crystal works at its spec. I dont think the two leds of the crystal go though an additioal cap to the uP, usually they are connected directly, but one of the tweo pins can also be an output of the driver, there might be a cap to feed out the oscillation to additional circuit, — may please provide additional enlargement of the part. for example the stm32f series has those 4 pins but there are many more cpus.

Hello, thank you for the response. The reason for my question is that the op-amp was burnt out. I have been thinking that they have expanded the board with an audio amplifier output or simular, and then they inserted the 32kHz crystal. I have seen a picture of the same board with an inductor placed in the same spot. It could also be a new design that requires stronger oscillation?

But i still have no ide if its ok like that or what i can do