• State Resolved
  • Replies 2 replies
  • Subscribers 22 subscribers
  • Views 37 views
  • Users 0 members are here
Support feedback
Options
Options
Related

BQ32002: Crystal resonator selection

hiroshi.yamada
Intellectual 575 points

Part Number: BQ32002

We are currently using the NDK crystal resonator NX3215SE-32.768K-STD-MUA-17.

According to the results of a matching test conducted by the manufacturer (NDK), the required negative resistance is 180 kohm, whereas our circuit only achieves approximately 40 kohm, which is insufficient to ensure proper operation.

We are using 18 pF external load capacitors for the crystal. Even when these capacitors are removed, the negative resistance only increases to about 130 kohm, which is still below the required level.

Do you have any recommended crystal resonators that are better matched to the BQ32002D?

Currently, the operating conditions are as follows:

  • Drive level: 0.1 µW
  • Frequency deviation: −89 dF/F (×10⁻⁶)
  • +1
    TI__Guru** 119790 points

    Hi There,

    Usually customers pick their crystal, we don't have recommendation on this. 

  • 0 in reply to Noel Fung
    Intellectual 575 points

    Hi Noel,

    Thank you for your previous response.

    I shared the information with the manufacturer, NDK.

    After reviewing it, NDK requested that we confirm once again whether there is any way to modify or optimize the effective load capacitance through the configuration or settings of the BQ32002.

    In particular, they are referring to the 12 pF load capacitance specified in the datasheet.

    Could this 12 pF load capacitance increase under certain conditions or due to any external/internal factors?

    If there is such a possibility, could you please advise on the potential causes and any recommended corrective actions or countermeasures?

    Thank you for your support.

    Best regards,

    Hiroshi Yamada