Crystal Resonator / Oscillator for Aurix MCU

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abhishek-2138
Level 3
Level 3
First like received 10 likes given 10 replies posted

For AURIX MCU we are considering Murata ceramic resonator & optional crystal resonator.

The 20 MHz Ceramic resonator is - Murata Crystal Resonator.

And the crystal oscillator is (supply voltage = 3.3V) - Crystal Oscillator.

Are the above parts are compatible with TC364 AURIX MCU ?

Vext supply = 5V. Also, we have 3.3V supply for Flash memory. 

 

Regards,

Abhishek D.

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4 Replies
MoD
Employee
Employee
50 likes received 500 replies posted 100 solutions authored

When you use Vext supply = 5V then the crystal oscillator must be also supplied with 5V. On TC3xx the XTAL pins are connected to VEXT (3,3V or 5V).

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Yes, when the output of crystal oscillator is high, Vext = 5V will be connected to XTAL1 or XTAL2 pins.

So, is it needed to add series resistor with XTAL1/2 ?

abhishek2138_0-1676605618000.png

The max current = 70uA as per datasheet above. So, series R = 5 / 70uA <= 71.42kohm.

Can you please comment on above?

 

Regards,

Abhishek D.

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Di_W
Moderator
Moderator
Moderator
500 solutions authored 1000 replies posted 250 solutions authored

Abhishek D.

Based on the TC3XX user manual, there are two clocking system modes: the external input clock mode and the external crystal/ceramic resonator mode. For the CMOS XO (Crystal Oscillator) option, I conducted a search on https://www.diodes.com/products/connectivity-and-timing/crystal-and-crystal-oscillator/crystal-oscil... and noticed that it differs from the crystal unit used in the Triboard.

The CMOS XO has four pins - OE , GND , OUTPUT, and Vdd. To operate the CMOS XO correctly, it is necessary to provide Vdd with a voltage of 3.3V. The input amplitude (peak to peak) should be greater than 0.35 * Vext according to the datasheet(refer to the section 3.9 "MHz Oscillator" in the TC3XX datasheet). So no resistor is needed between XTAL1 and OUTPUT of the CMOS XO, and it would degrade the waveform quality.

When using active crystal oscillators, it is important to take into account factors such as power consumption, cost, and other relevant elements.

 

Best regards,

dw

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Di_W
Moderator
Moderator
Moderator
500 solutions authored 1000 replies posted 250 solutions authored

Please refer to AP56002 AP32369 AP32214 for Crystal Oscillator Configuration and Basics.

In summary, while both quartz crystals and ceramic resonators are used as resonant circuits in electronic devices, quartz crystals are more accurate, stable, and temperature-resistant than ceramic resonators. However, ceramic resonators are less expensive and easier to manufacture. 

Please find below a list of crystal units utilized by the Triboard for your reference:

  1. NDK NX3225SA-vehicle: Link
  2. NDK NX3225GA-vehicle: Link
  3. NDK NX8045GB-vehicle: Link

About resonators, please kindly request an resonator evaluation report for TC3XX from the 3rd party vendor - MuRata.

dw

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