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Can I set ODR (sampling) > 6 kHz for use as a contact microphone?

Thread Summary

The user wants to use the ADXL367 as a contact microphone but requires a high sampling rate (> 6 kHz). The ADXL367's maximum output data rate (ODR) is 625 Hz, and its bandwidth cannot exceed 200 Hz, making it unsuitable for audio recording. The engineer recommends the ADXL382 as an alternative, which is larger but better suited for higher bandwidth applications.
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Category: Hardware
Product Number: ADXL367

I want to use an accelerometer as a contact microphone. It needs to be very small. The ADXL367, with its dimensions of 2.2 × 2.3 × 0.87 mm, is about the largest size that would be suitable.

I am confused by the sampling/ODR for the ADXL367. The data sheet states:

ODR and bandwidth scale proportionally with the clock. The ADXL367 provides a discrete number of options for ODR, such as 100 Hz, 50 Hz, and 25 Hz, in factors of 2. To achieve data rates other than those provided, an external clock can be used at the appropriate clock frequency.

The, later on: 

The ADXL367 can operate with external clock frequencies ranging from the nominal 102.4 kHz down to 51.2 kHz to allow the user to achieve any desired output data rate.

I cannot see how to obtain the high (> 6 kHz) sampling/ODR I require.

Am I missing something? If not, is there an alternative small accelerometer that might suit my requirements?

Parents
  • Hello  The BW for this XL can not be greater than 200Hz, it was designed to work as an ULP tilt sensor or motion switch. Audio recording is out of the capabilities of this device unless your BW of interest is really close to DC... For this subject I would recommend ADXL382 Datasheet and Product Info | Analog Devices even if it is larger than ADXL367.

    The external clock configuration aims to give the user more control on which SPS do receive for applications in which timing is really sensitive, or an specific ODR is needed outside of the ones available by default. This is achieved by decimating the external input. But, it does not allow to increase ODR further than 625Hz, or change the BW configuration defined in the reg. FILTER_CTL.

    Please refer to page 68 of ADXL366 (Rev.0), I will add this info to ADXL367 DS in the next revision.



    hope this solves your inquiry,

    Mario SM

Reply
  • Hello  The BW for this XL can not be greater than 200Hz, it was designed to work as an ULP tilt sensor or motion switch. Audio recording is out of the capabilities of this device unless your BW of interest is really close to DC... For this subject I would recommend ADXL382 Datasheet and Product Info | Analog Devices even if it is larger than ADXL367.

    The external clock configuration aims to give the user more control on which SPS do receive for applications in which timing is really sensitive, or an specific ODR is needed outside of the ones available by default. This is achieved by decimating the external input. But, it does not allow to increase ODR further than 625Hz, or change the BW configuration defined in the reg. FILTER_CTL.

    Please refer to page 68 of ADXL366 (Rev.0), I will add this info to ADXL367 DS in the next revision.



    hope this solves your inquiry,

    Mario SM

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