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ADS1293

vengadesh uthirapathy
Intellectual 770 points
Other Parts Discussed in Thread: ADS1293

HI Sir /Madam,

This is vengat here from Avnet India , one of my customer planning to do BLE based 3 Lead ECG Application .

They do have below Query , can you please revert back with feedback ASAP  .

1. Possible gain setting available

2. Can we use fourth analog channel both for Pace detection and RLD ?

 3. Whether AFE is compliant with regulatory standard like IEC  60601-1, IEC 60601-2-25, IEC 60601-2-27, IEC 60601-2-47 

4. Actual power consumption while using at higher sampling rate (1000 sample/second/channel).

Thanks in Advance .

Rgds/

Vengat.

  • 0
    TI__Expert 3835 points

    Hello Vengat,

    I'll try to address your questions.

    1. The instrumentation amplifiers in the ADS1293 have a fixed gain of 3.5 V/V.

    2. No, channel 4 can't be used for RLD, but the ADS1293 has a dedicated amplifier to be used in an RLD circuit ("RLD Amp." in the block diagram). The output of channel 4 can be routed to the WCT pin or to the RLDIN pin. If the output of channel 4 is routed to the RLDIN pin, the positive input of the RLD amplifier is connected internally to the RLD reference via a switch.

    3. The AFE is not tested for IEC compliance.

    4. The power consumption is determined by the configuration used (which blocks are ON and which are OFF). The electrical characteristics table provides values for a couple of arrangements, and a table in the datasheet called "Typical Current Consumption Per Block" summarizes the typical current consumption per block in different modes of operation.

    The analog power consumption of the AFE blocks is independent of the output data rate, because the system is running at the same speed (102.4kHz or 204.8kHz). The parameter that sets the output data rate is the decimation value of filters, and this is just how many times the reading is decimated before updating the value in the data registers.

    The output data rate (1000 sampes/second/channel) will impact the IO power consumption in the sense that it determines the rate at which they access the SPI bus to read data. Some of the factors that can  impact the power consumption are the IO voltage, frequency, switching speed, loading,  and the access duration (SPI is not accessed continuously), but it's hard to quantify.

    Best regards,

    Sergio

  • 0 in reply to Sergio
    Prodigy 10 points

    Hi Sergio,

    I have similar questions, but rephrased them... we would like to get more clarity before finalizing on ADS1293 for our application. Our application calls for a low power ECG monitoring and hence would like the following clarified....

    1. If the IN AMP gain is fixed at 3.5x, is there any other mechanism to change the gain post the IN AMP ? Or should we do it in software / firmware as part of back end operation ? 

    2. Your answer "No, channel 4 can't be used for RLD, but the ADS1293 has a dedicated amplifier to be used in an RLD circuit ("RLD Amp." in the block diagram). The output of channel 4 can be routed to the WCT pin or to the RLDIN pin. If the output of channel 4 is routed to the RLDIN pin, the positive input of the RLD amplifier is connected internally to the RLD reference via a switch." ..... so does this imply that Channel 4 can be used for PACE detect as well as routing its output to RLDIN or WCT ? We would like to confirm that both RLD and Pace detect can be implemented simultaneously. Is this possible ? If yes, what internal switch routing do you recommend ?

    3. Your answer "The AFE is not tested for IEC compliance."... Can you confirm  or give reference to products which have used ADS1293 and met the applicable IEC compliance as a finished product ? Do you know of any known issues that we need to consider when the product goes for compliance testing ?

    4. Can you share some data on total consumption of the ADS1293 as a complete device at a known SPI clock speed ? 

    Appreciate your help in getting these queries clarified.

    regards,

    Prakash

     

  • 0 in reply to Sergio
    Intellectual 770 points

    Hi Sergio , Thanks for your feedback  , appreciate.

  • 0 in reply to Prakash Sonwalkar22
    TI__Expert 3835 points

    Hello Prakash,

    Can you please give me more details about your application? What type of ECG are you planing to build and why do you need the additional gain in the front-end?

    1. The gain of the instrumentation amplifier (INA) is fixed and there is no other mechanism in the ADS1293 to change the gain post INA.

    2. Yes, both the RLD feedback and Pace detect can be implemented simultaneously because they use different amplifiers. Keep in mind that channel 4 is just an INA, with characteristics given in the datasheet, and you would have to implement the Pace detection off-chip. By default, channel 4 is shut-down and its output is not connected to any pin. At your convenience, you can route the output of channel 4 to the RLDIN pin or to the WTC pin. This can be done by setting bit [2] or [1] in register 0x17. Channel 4 is powered up by reseting bit [0] in register 0x17.

    3. Let me ask and see what I can find.

    4. I am afraid we don't have this information readily available. As I mentioned already, the EC table provides supply current values for various configurations. I know that these do not include the VDDIO current, but I would expect this to be negligible compared to the analog current consumption (few uA).

    Best regards,

    Sergio

  • 0 in reply to Sergio
    Prodigy 70 points

    Hi Sergio,

    Could you please provide info on the point 3 above. It would be important to understand this before using this as platform.

    Regards,

    Ravi

  • 0 in reply to RBM
    TI__Expert 3835 points

    Hi Ravi,

    I am not aware of products that have hit the market with the ADS1293 in them yet.

    Regards,

    Sergio