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Some questions about using ADS1293

Tom Fighter
Prodigy 35 points
Other Parts Discussed in Thread: ADS1293, ADS1298R

Hello!

I'm Working on a project about Holter monitor using ADS1293 and I have some questions and I think this is the best place to ask them.

first of all I want to use a '28-pin plcc to dip adapter' for ADS1293 to make it possible to use it on bread board,so the question here is that: is it safe to do it or it will be dangerous for ADS1293? because in datasheet is writing "The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates."

the second question is about filters.ADS1293 has programmable low-pass filters,but should I design some High-pass filters for preventing DC voltage?

the third question is about input resistance.Should I put a resistant between lead and ADS1293 channel inputs for protection?

I want to use LPC1768 Cortex-M3 Header Board to program the ADS1293 and read data from it. Is it ok? 

the reasons for choosing LPC1768 Cortex-M3 Header Board are availability and being able to use on bread board.

I've searched the forum and read previous topics about ADS1293,and I'll be happy if some one answer my questions and give me some schematics and source codes for my project.

regards

Tom

  • 0
    TI__Expert 3835 points

    Hi Tom,

    Welcome to the E2E forum!

    It's safe to use the ADS1293 with a socket/adapter. The quoted statement refers to ESD precautions when handling/storing the devices. Keep in mind that the additional lead inductance due to the adapter can make your design susceptible to noise pickup, and that the bread board would not provide a nice ground plane for the system.

    You can add external high-pass filters. The requirement of the high-pass filters is driven by the ECG standards and not by the ADS1293. The right-leg drive circuit of the chip is used to bias the DC level of the system within the operating range.

    Typically 100k safety resistors are used between the leads and the ECG front-ends for protection.

    You should be able to use the microcontroller of your like as long as it can implement the SPI protocol of the ADS1293.

    As far as resources, there is a schematic of the EVM in the user's guide and a reference design of a wireless hear monitor here. I am not aware of source code references for your micro though.

     Regards,

    Sergio

  • 0 in reply to Sergio
    Prodigy 35 points

    Hi Sergio,

    Thank you for your hospitality and answer.

    You know the package of ADS1293 is QFN and its hard to solder it on board, so are you aware of any socket for this kind of IC?

    I know that but is there any way except bread board for testing my design? 

    Is it essential or optional? Can it been done with software?

    So you mean there is no need for adding extra resistors at input pins? But I saw some 0 ohm resistors in schematic of EVM,what are they for?

    Did you work on ADS1293 or do you know anybody who could get right ECG output with ADS1293? Because I want to get some practical tips!

    Thank you again for your complete answer

    Regards,

    Tom

  • 0 in reply to Tom Fighter
    TI__Expert 3835 points

    Hi Tom,

    I worked on the characterization of the ADS1293, so I can help you with settings and configurations of the device and other questions you may have from the datasheet. Such work is done with standard lab equipment and ECG simulators. 

    There is a company by the name of Plastronics that makes sockets for this type of package, and they list them under QFN sockets. I used a through-hole socket, but the footprint is not bread-board friendly. You may still want to contact them to ask if they have something like what you need.

    The DC filtering is essential for commercial products to comply with ECG standards. I assume software filters can be implemented, but we have not done so in the GUI or sample code.

    The resistors at the inputs are needed for patient protection. The EVM is not intended for use with a patient, so I am not sure why the resistors are there. I think they were inherited from the original characterization board design.

    Best regards,

    Sergio

  • 0
    Prodigy 210 points
    Dear Tom and Sergio,

    I have order the ADS1293 and ADS1298R Microchips from TI but i CAN NOT USE them on my BREADBOARD,
    since they come WITHOUT ANY PINS or LEGS to be TESTED.

    TOM said: ''I want to use a '28-pin plcc to dip adapter' for ADS1293 to make it possible to use it on bread board''
    Is this '28-pin plcc to dip adapter' a UNIVERSAL BREAKOUT BOARD and can be USED for ADS1293 and ADS1298R?

    Are there ANY SPECIFIC BREAKOUT BOARDS for ADS1293 and ADS1298R Microchips to be USED for BREADBOARD, TESTING, PROGRAMMING.

    The problem is that with the Corresponding 1293 and 1298R EVM these ADS1293 and 1298R Microchips are FIXED on the board, and CAN NOT BE TAKEN OUT to REUSE them on ANY OTHER PROTOTYPE DESING.

    Can you please send me an ANALYTICAL TECHNICAL SUPPORT, and LINKS of BREAKOUT BOARDS for the ADS1293 and ADS1298R to PURCHASE.

    TEXAS INSTRUMENTS SHOULD HAVE THESE since are USEFUL for DESIGN, PROTOTYPING, PROGRAMMING, and TESTING.

    Many thanks.

    ---Lakis

    lakis.christodoulou@gmail.com
  • 0 in reply to Lakis Christodoulou
    TI__Expert 3835 points
    Hi Lakis,

    I am not aware of specific breakout boards for the ADS1293 or ADS1298R. You can find the package information for these devices in the last few pages of their respective datasheets. Your best bet is to search the web for breakout boards compatible with the packages of your devices.

    Most EVMs come with the devices soldered on them. If you need extra devices to test in your own prototype, you can order just the ICs.

    Regards,
    Sergio
  • 0 in reply to Sergio
    Prodigy 210 points
    Hi Sergio,

    thanks for the fast response.
    No there are no Breakout boards for the ADS1298R.
    I have found the Breakout Board for the ADS1293 which is the 28-pin plcc to dip adapter
    www.proto-advantage.com/.../PA0106SOCKET_0.JPG.

    Yes you are RIGHT the ADS1293 and ADS1298R are devices soldered on their CORRESPONDING EVMs.

    What do you mean i can just order the ICs? (Integrated Circuits)

    Does Texas Instruments has the ADS1293 and ADS1298R with Larger size and PINS-LEGS?
    How do engineers TEST-PROGRAM these devices without PINS-LEGS?

    Can you please send me your email and phone number to contact you now?

    Many thanks.

    ---Lakis
  • 0 in reply to Lakis Christodoulou
    TI__Expert 3835 points
    Hi Lakis,

    Check with the vendor if the socket is compatible with the ADS1293 package (WQFN). Judging by the picture, the socket seems to make contact with the IC pins on the sides, and it may not make contact with the WQFN pins, with sit more at the bottom of the IC.

    The ADS1293 only comes in the WQFN package, which is a leadless package (no legs). What I meant by ordering only the ICs, is that you can purchase ICs without EVMs, and then you can solder them as you wish.

    I think what others do with leadless ICs is create prototype PCBs, where they can solder down the devices. I have not used them on breadboards.

    Regards,
    Sergio
  • 0 in reply to Sergio
    Prodigy 210 points
    Hi Sergio,

    the ADS1293 package (WQFN) Without Pins-Legs but comes with contact Pins on the Side 7x4
    should work with the PA0106SOCKET

    www.proto-advantage.com/.../PA0106SOCKET_0.JPG

    the other Breakout Board i found for the ADS1293 is the
    PA0065-ND
    QFN-28 TO DIP-28 SMT ADAPTER
    www.digikey.com/.../5014780
    that has the contact surface on the bottom (but i am not sure if this will work)

    For the ADS1298R the contact Pins come on the Bottom Surface 8x8 points, this is why i need a Breakout Board for this to use it.

    Now when you mentioned what Others do with leadless ICs is create prototype PCBs, where they can solder down the devices,
    there should be a machine for PCB soldering since this needs dedicated small printing.

    But first before you go for Prototype you need to test them and program them.

    Any more comments and information on how to solder these ICs to create PCBs would be more than welcome.

    Thanks.

    ---Lakis