Linked Questions
11 questions linked to/from Crystal oscillator load capacitance, again
0
votes
3answers
531 views
What is the purpose of capacitors parallel to crystal? [duplicate]
In many schematics, we have two capacitors connected in parallel to a crystal?
Why do we have capacitors parallel to crystal? Whats the purpose?
How are the capacitor values determined ?
8
votes
4answers
4k views
Different (15 and 10 pF) load capacitors on 32.768 Hz quartz crystal
I've got some random chinese electronic desktop clock/alarm.
It turned out that it's completely missing any capacitors on crystal. That was the reason why the clock were going faster ~5 min each month....
1
vote
4answers
2k views
Resistor symbol in a schematic with zero value
I can't figure out the purpose of the 0Ohm resistor in bellow schematic. It's crystal oscillator configuration and why the designer have included a resistor there with 0ohms ?
Any idea ?
8
votes
3answers
1k views
Why do MCU crystal oscillators not fry the crystals?
I am trying to better understand crystal oscillators. I have been reading ST's AN2867, where they explain that, depending on the crystal, a series resistor (R2 in the diagram below) on the output side ...
3
votes
3answers
2k views
Capacitive load - Matching Right Crystal and Caps for oscillator circuit - DS1302 RTC - cut and trim
CL = (C1 * C2) / (C1 + C2) + Cstray
I have a 12.5pf crystal. DS1302 is happy with 6pf.
what is trim capacitors to make him happy using 12.5pf?
12.5-6=6.5pf
(6.5*6.5) / (6.5+6.5) + cstray= 3.25pf + ...
5
votes
3answers
2k views
What actually is the load capacitance of a quartz crystal?
I'm having hard time understanding the principles of piezoelectric crystal oscillators.
I've found this picture:
I understand that "load capacitance" is something you have to connect to a crystal. I ...
2
votes
2answers
2k views
Crystal's datasheet give load capacitance is 20pF, do I need external load capacitors?
I use external crystal for HSE of STM32F0. I plan to use 8MHz Cylinder Crystals. Datasheet of this crystal below
Datasheet give crystal load capacitance is 20pF
My questions:
1/ Do I need to add 2 ...
1
vote
2answers
879 views
What is the influence of an asymetric load capacitance on a crystal duty cycle
I have a crystal oscillating at 25MHz (datasheet). The recommanded load capacitance is 18pF according to the datasheet.
The crystal is connected to a component where the capacitance on the pin are ...
2
votes
2answers
674 views
Crystal oscillator on custom ATMega2560 board is at the wrong frequency
I have designed a custom board using an ATMega2560. The board works fine when configured to use the internal oscillator. The board stops working when I configure it to use the the external 16MHz ...
1
vote
1answer
531 views
How do I deal with different XTAL pin capacitance when selecting XTAL and load capacitors
I'm trying to select a 32kHz crystal and appropriate load capacitors for Atmega48A MCU.
Atmega48A specifies different capacitances for Xtal1 and Xtal2 pins:
18pF for Xtal1
8pF for Xtal2
The ...
0
votes
2answers
49 views
Can you explain the operation of this RC network for a crystal oscillator? [duplicate]
I am trying to work out what the RC network in the circuit below does and how it works. The circuit output is fed as input to a CD4060 binary counter. According to what I have read, the signal from ...