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TMS320F28069: Need C2000 device with ADC 24 channels?

ian cartwright
Intellectual 540 points
Part Number: TMS320F28069


Hi, I need some advive on device C2000 selection.

Currently using a TMS320F28069 device but I have a new project that requires a minimum of 24 (maybe 26) ADC channels (12 or 16bit).

Looks like the TMS320F28069 is limited to 16 ADC channels.

Ive looked at the TMS320F28379 which has 24 ADC channels, problem is its in a 337 bga package and not a QFP which will cause layout and build issues.

Ideally are there any parts in the C2000 range with a conventional QFP package with 24 (or more) ADC channels or am I stuck with TMS320F2837x parts in a 337 bga package?

Also if I have to use a part limited to 24 ADC channels, how could I increase this by 2 channels?

Thanks

  • 0
    TI__Guru* 81560 points

    Ian,

    I'd suggest looking at the https://www.ti.com/product/TMS320F280049 device, as it has 21 ADC inputs using a 100 pin QFP type package.  This has all the latest IP that exists on the F2837x and from a next gen device is the successor to the F2806x device you mentioned in your post.

    You also mentioned needed 24 ADC inputs, I think there are a few options here:

    1)External Sigma Delta ADC, the F28004x device has 4 Sigma Delta input channels with the demodulator logic on chip.  Typically Sigma Delta ADCs are slower/higher resolution than the internal ADC on this device as well as isolated since only a digital bit stream is passed to the C2000; depending on your application need this could be a good fit.

    2)External analog mux, basically we would increase the channels and use a GPIO to determine which analog channel would route to the F28004x ADCIN pin.  Assuming you have some signals that have a slower update rate this could be a very cost effective option.

    Let me know if you have additional thoughts/questions on the above, I will be happy to brainstorm on a soln.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Intellectual 540 points

    Many thanks for the details.

    I'll take a look at your suggestions.

  • 0 in reply to ian cartwright
    Intellectual 540 points

    Hi, Ive decided to use the TMS320F28379SZWTT part as 24 ADC channels is just enough.

    I just wanted to clarify a few things.

    I need to connect four temperature sensor parts (TMP05BKS) to the TMS320 GPIO pins and the TMP05BKS part has a PWM o/p that changes with temperature. To read this I think I would need the eCAP feature or maybe there is a better way? Am I correct in saying that the six eCAP channels are available through the CLB/Xbar feature on any GPIO pin? Ive currectly connetced them to GPIO18/19/20/21 so hopefully this will be ok?

    Also my other Digital o/ps are all connected on GPIOs 0 to 17 which will all just be simple digital o/ps controlled by CAN.

    Assume these should be ok on these pins?

    Many thanks.

  • 0 in reply to ian cartwright
    TI__Guru* 81560 points

    Ian,

    You are correct, you'll want to use the eCAP to measure pulse widths of the TMP05BKS device.  Additionally as you mentioned any GPIO can route to the eCAP via the setup in the X-bar logic.  Below is from the TRM, giving some options and care-bouts when routing to the eCAP

    16.4 Configuring Device Pins for the eCAP

    To connect the device input pins to the module, the Input X-BAR must be used. Any GPIO on the device can be configured as an input. The GPIO input qualification can be set to synchronous or asynchronous mode by setting the GPxQSELn register bits. Using synchronized inputs can help with noise immunity but will affect the eCAP's accuracy by ±2 cycles. The internal pull-ups can be configured in the GPyPUD register. Since the GPIO mode is used, the GPyINV register can invert the signals.

    Best,
    Matthew

  • 0 in reply to MatthewPate
    Intellectual 540 points

    Many thanks...

    I'll carry on with this part then and hopefully will find more info in ref manual.