Can't find the X3 crystal recommended by ST from any supplier, nor can I find an equivalent that is in stock from any supplier.

[CLH]

Hi,

I have a STMF32446ZE board and require an external crystal that isn't using the STLINK crystal.

For x3 ST recommend the following: NX3225GD-8.000MEXS00A-CG04874

The specs of this crystal are:

Frequency Stability ±50ppm

Frequency Tolerance ±20ppm

Load Capacitance 8pF

Operating Temperature -40°C ~ 85°C

Mounting Type Surface Mount

Size / Dimension 0.126" L x 0.098" W (3.20mm x 2.50mm)

Frequency 8 MHz

ESR (Equivalent Series Resistance) 500 Ohms

Does anyone know of a crystal that can be used?

Thanks in advance, much appreciated!

[Bouraoui Chemli · Accepted solution]

Hi @CLH​ 

You can refer to STM32F446, "Table 39. HSE 4-26 MHz oscillator characteristics", Gm_crit_max equal to 1 mA/V.

Then, refer to application note AN2867 "Oscillator design guide for STM8AF/AL/S, STM32 MCUs and MPUs", especial focus on section "3.4 Oscillator transconductance" to calculate gm_crit of the crystal. Also, as mentioned in section "5 Recommended resonators for STM32 MCUs / MPUs", STM32 microcontrollers is compatible with almost all the resonators available on the market.

For the crystal selection and compatibility with your MCU, make sure that Gm_crit_max (MCU) > gm_cirt (crystal).

Bouraoui