AM62P: AM62P crystal

hello Jhon, 

Thank you for the query.

Jhon Q said:

1.  I went over the AM62P datasheet section requirements listed in Table 6-21 but it is not clear if Cshunt requirement will be met, can you check if Q22FA1280071000 meets the crystal requirements?

2. Selection of CL1,CL2 caps - The PROC164E1-1 reference schematics shows using XRCGB25M000F3A00R0 which has Load Capacitance of 6pF and the CL1/CL2 caps used with it C47,C50 are 18pF.

The values in the AM62P schematics may need to be updated.

Jhon Q said:

What would be the recommended baseline for CL1/CL2 when using Q22FA1280071000?

For a 6 pF crystal considering PCB capacitance or ~4 pF, an 8 pF load cap could be considered.

Regards,

Sreenivasa

Hi,

Thank you for your reply.

Can you address Q1 if Q22FA1280071000 meets the crystal requirements with emphasis on Cshunt assuming PCB capacitance or ~4 pF?

Thank you for the support

Jhon

Hhello Jhon, 

Thank you.

Jhon Q said:

We wish to use crystal P/N: Q22FA1280071000 [ FA-128 case 2016 25MHz 6pF 10ppm , 30ppm -40+85C , 80 Ohm ESR] (datasheet attached) for our AM62P design.

1.  I went over the AM62P datasheet section requirements listed in Table 6-21 but it is not clear if Cshunt requirement will be met, can you check if Q22FA1280071000 meets the crystal requirements?

I done see the 80 Ohm spec called in the data sheet. This looks higher. 

Any reason to choose this crystal.

Are you not bale to source crustal as per the data sheet specs ?

Regards,

Sreenivasa

Hi Sreenivasa,

In terms of pricing and availability we and also specs Q22FA1280071000 seems to be better.

AM62P datasheet states Cshunt only for ESR=30/40/50 Ohm 

However, the P/N used on EVK XRCGB25M000F3A00R0 has 100 ESR from section 5 in datasheet

https://www.murata.com/products/productdata/8801076543518/SPEC-XRCGB25M000F3A00R0.pdf?1680492618000 

Q22FA1280071000 has 80 ESR see below:

How was Cshunt max value obtained for XRCGB25M000F3A00R0 with ESR=100Ohm ?

in a similar manner, what would be the value for Q22FA1280071000 with ESR=80Ohm? will this value satisfy the requirement listed in datasheet

Cshunt ≥ CO + CPCBXIXO + CXIXO?

Thank you,

Jhon

Hello Jhon, 

Thank you.

The AM62P is configured for crystal oscillator.

Here is an example crystal part number:

ABM11W-25.0000MHZ-8-D1X-T3

AM62P doesn’t support any crystal that has an ESR over 50 Ohms.

The recommendation is to select a different crystal, one that meets all of the AM62P data sheet requirements.

Regards,

Sreenivasa

Hi Sreenivasa,

I have not seen specs for the oscillator in the datasheet so thought it would be safer to use a crystal.

1. is there any reason not to use a crystal?

2. Thank you very much for your recommendation, I will check this part.

Also, can you advise if this part will suit: https://download.epsondevice.com/td/pdf/td_xtal_mhz/TSX-3225_X1E0000210136_en.pdf

Thank you,

Jhon

Hello Jhon, 

Thank you.

We have configured the clock on the SK to Oscillator. 

We do not see any concerns with using crystal provided the recommendations in the data sheet are followed.

We are working on adding the oscillator specs.

Regards,

Sreenivasa