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part selection issues

David DeMeglio
Prodigy 40 points
Other Parts Discussed in Thread: ADS1118, ADS1115, ADS1100, ADS1201, ADS1203

I am new to TI parts. My project involves monitoring an input voltage and setting up an output based on the input voltage. My supply voltage is between 3.2V and 4.2V (battery power), the input to sample is .5V to 3 V. I would like a small package, 6 to 8 pins. When I use the various part selection tools TI has I come up with large chips, maybe 32 pins.

I'm sure it is just my inexperience using the tools that is the main problem. I have tried several times but can't seem to find what I want. I have done this project with a microchip but really want to move to TI.

Can someone recommend some ADC parts for this?

thanks in advance

  • 0
    TI__Mastermind 23275 points
    Hi David,

    welcome to TI and to our E2E forum.
    Do you have any other constraints for your project, such as data rate, resolution, interface preference, etc.

    I would start looking at our ADS1115 (I2C) and ADS1118 (SPI) first. They would seem to fit your requirements.

    Regards,
  • 0 in reply to Joachim Wuerker
    Prodigy 40 points
    thanks for the response. This is a controller project and the input voltage is set with a potentiometer by the end user. Data rate and resolution requirements are easily met with any of the TI products. Both parts you specify are great. Is there one with 6 or 8 pins? If not either of these are fine and I will order a few up and get started.
  • 0 in reply to David DeMeglio
    TI__Mastermind 23275 points
    Hi David,

    if you need a 6 or 8 pin ADC then you could look at ADS1100.
    However on this device the supply voltage acts as the voltage reference for the device. If your battery/supply voltage is not constant then this might not be a good fit.

    The nice thing about ADS1115 and ADS1118 is that you can measure signals as large as the supply voltage.
    Many of our other ADCs have an internal 2.048V or 2.5V reference. Means you could not measure signals up to 3V unless you would use an external voltage reference which is larger than 3V.

    Also the 10 pin QFN package of ADS1115/ADS1118 is smaller then most other 6 pin packages on the market.

    Regards,
  • 0 in reply to Joachim Wuerker
    Prodigy 40 points

    Thanks for the info. I bought a couple of ADS1118 chips. Downloaded Code Composer and it didn't run on my box. Is there other software I can use instead? Can you point me to an explanation of how you connect the chip to program it? Are there tutorials out there? 

    My apologies for asking such basic questions but I have a hard time finding this stuff.

    thanks

  • 0 in reply to David DeMeglio
    TI__Mastermind 23275 points

    Hi David,

    you cannot program the ADS1118 directly using Code Composer. You will have to connect the SPI interface of the ADS1118 to an MCU as shown in section 10 of the datasheet and then program the MCU accordingly.

    As a first step I would study the information provided in the datasheet (sections 9.5 and 10) to give you an idea of how the interface works and how a program flow could look like.

    Regards,

  • 0 in reply to Joachim Wuerker
    Prodigy 40 points
    So I may be going about this wrong. Based on a user input voltage (a potentiometer as part of a voltage divider) I want to have different pulses as output (a do it yourself pwm). I can do it with other mcu chips. Is there a single TI chip that I can use which will read in a voltage and respond with a programmable output pulse.
    thanks
  • 0 in reply to David DeMeglio
    TI__Mastermind 23275 points

    Hi David,

    alright, understand.

    Our MCU's could certainly do that as well but in the end what they do internally is probably sample the input signal with the integrated ADC and then calculate and output the PWM signal based on the conversion result. I am not an MCU expert and therefore don't know all their capabilities.

    You will get something like that in a single-chip device with our delta-sigma modulators, e.g. ADS1203 or ADS1201. However you cannot 'program' how the output pulses will look like.

    Regards,