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[FAQ] ADS7883: Is there a minimum sampling rate or maximum idle time?

Part Number: ADS7883

What is the minimum sampling rate that the ADS7883 device can support?

Or, what is the maximum time the device can be left idle, not converting?

  • The ADS7883 is a higher sampling SAR device, supporting up to 3MSPS sampling rate and the device is generally meant to be used in applications requiring higher sampling rates.

    The device is not designed to support long periods of idle time and the power down mode should be enabled for the applications requiring longer delays between conversions.

    Power down mode is enabled by a rising CS edge between the 2nd SCLK falling edge and the 10th SCLK falling edge. In power down, SDO is in tri-stated and current consumption is decreased to hundreds of micro-amps. To exit power down mode, the device needs a full conversion cycle to enter normal operation. The conversion results from this dummy conversion should be thrown out. A conversion cycle requires a falling and rising edge of CS.

    If the device is left idle without enabling power down, then the device will enter an unwanted state of operation. The device will appear to be in power down mode except without the benefits of power savings. Therefore, if the device is left in an idle state for over completing a conversion cycle (sampling rates <=2.5kSPS), then device should be put in power down mode between conversions.

    A dummy conversion will be required for the device to return to normal operation if power-down mode is not activated before entering a long idle state. This is similar to exiting power down mode as described above and the conversion result after the dummy conversion will result in correct output measurements.