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MSP430FR5043: Maximum frequency for PWM output possible for MSP430 IC

Bivin George
Expert 1017 points
Part Number: MSP430FR5043

Hi

What is the maximum PWM frequency that can be generated using MSP430 devices. Can it be increased by using HF CLK input ?

  • 0
    TI__Guru 56685 points

    Hello Bivin,

    It really depends on the resolution you need for your PWM. The formula is as follows: FrequencyTimer = frequencyPWM X 2N , where N is resolution in bits of PWM. You are mainly going to be limited by the frequency of the MCU for Frequency into the Timer. You also have a output frequency limit on the pins, but you won't hit that on MSP430 as you can't go higher than device speed. 

    So say for an example, you run the timer full out @ 16MHz, and you want 8-bits (256 counts) of resolution; Then you would have a PWM frequency of 62.5kHz. 

  • 0 in reply to Jace H
    Expert 1017 points

    Hi Jace

    Here are you referring resolution to the voltage level or duty cycle ? Can i estimate PWM frequency as 8MHz if the resolution required is only 1 bit  (High/Low) with 16MHz input clock .

    You mentioned " You are mainly going to be limited by the frequency of the MCU for Frequency into the Timer.", Confirm PWM frequency can be 12MHz with 24MHz HF clock input .

    You mentioned " You also have a output frequency limit on the pins, but you won't hit that on MSP430 as you can't go higher than device speed.", what is this limit. Is a 2MHz PWM possible.

    Thanks

    Bivin

  • +1 in reply to Bivin George
    TI__Guru 56685 points

    Hello Bivin,

    I was speaking about resolution of the duty cycle, which if you put a filter on it could translate as resolution of voltage, but let's keep it on the digital side for this discussion. 

    Your question about HFXtal sourcing the Timer is dependant on your clock path. That being said, look at the Timer specifications in the datasheet as well (Section 8.13.7), as it has a limit of 16MHz operation on this device. 

    See section 8.3.5.2 in the datasheet for I/O speed limit.

    You could output a 2MHz PWM, while have the timer at 16MHz, that makes for 8 steps or 3 bits of resolution to your duty cycle. 

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