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Piccolo TMS320F28023 General Questions

CraigHB
Prodigy 215 points

Other Parts Discussed in Thread: TMS320F28023

I'm thinking about using the TMS320F28023 in a design.  I'd like to use it to provide the PWM signal for a DC-DC converter in a hand-held battery powered device. 

Looking at the data sheet I see a sleep mode that brings current draw down to about 60uA.  This is a little high for the battery I would be using.  Is there a way to further reduce current draw when the microcontroller goes to sleep.

The data sheet shows a current demand about 90mA with most things running which is pretty high for my device. What would roughly be the current demand at 50MHz with only one HRPWM clock, two ADC clocks, and three core timers.

The HRPWM module is only required when there's output power demand which is not full time for this device.  Can the MCU switch clock speeds on the fly to reduce current demand when the higher speed is not required?

I didn't see off-hand in the data sheet if the processor has the ability to wake on input change.  For example, if a user pushes a button, the MCU wakes up to service the request. Can this MCU wake on input change?

The LCD for this utilizes the SPI module, but only communicates one way and requires a GPIO to control the CE input (there's other stuff attached to it).  So, I only need the SPI data out and clock lines.  Is it possible to use the SPI module with the chip enable and master receive pins disabled through the mux registers or will that cause a problem for the SPI module?

That's all I'm concerned with at this point, but I'll probably run into more questions about features and function if I actually start a design with it.

TIA, Craig

  • 0
    Guru 192875 points

    Hi Craig,

    CraigHB said:
    Looking at the data sheet I see a sleep mode that brings current draw down to about 60uA.  This is a little high for the battery I would be using.  Is there a way to further reduce current draw when the microcontroller goes to sleep.

    If I've to share my experience with you, I would say "C2000 mcus are power hungry devices!". Battery based applications would not be recommended with these devices unless your Battery capacity is high enough to meet the power requirements.

    CraigHB said:
    The data sheet shows a current demand about 90mA with most things running which is pretty high for my device. What would roughly be the current demand at 50MHz with only one HRPWM clock, two ADC clocks, and three core timers.

    Yup, its going to be around/more than 100mA for sure.

    CraigHB said:
    The HRPWM module is only required when there's output power demand which is not full time for this device.  Can the MCU switch clock speeds on the fly to reduce current demand when the higher speed is not required?

    C2000 has a number of ways to reduce power consumption - the easiest being disabling most of the peripherals (the ones not in use).  And there are also low power modes as well.

    As you mentioned above reducing clock speeds does decrease the current consumption but have not tried personally.

    CraigHB said:
    I didn't see off-hand in the data sheet if the processor has the ability to wake on input change.  For example, if a user pushes a button, the MCU wakes up to service the request. Can this MCU wake on input change?

    Here are difference ways to exit the low power modes:

    CraigHB said:
    The LCD for this utilizes the SPI module, but only communicates one way and requires a GPIO to control the CE input (there's other stuff attached to it).  So, I only need the SPI data out and clock lines.  Is it possible to use the SPI module with the chip enable and master receive pins disabled through the mux registers or will that cause a problem for the SPI module?

    Its always suggested to use chip enable/SS pin for SPI comm; you can ignore the receive pin if you're not expecting any acknowledgement signals.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Prodigy 215 points

    Thanks, I think that covers it.  It's a powerful controller, but it looks it's going to consume too much power for what I want to do.  I'll have to look at something else.

  • 0 in reply to CraigHB
    Guru 192875 points

    CraigHB said:
    Thanks, I think that covers it.  It's a powerful controller, but it looks it's going to consume too much power for what I want to do.  I'll have to look at something else.

    No problem. You can try out the MSP430 line-up though.

    Regards,

    Gautam