PWM SIGNAL GENERATION ON LPC54628

[aajithkumarr]

Hi NXP TEAM,

I am currently working on a OM13098LPCxpresso54628 board. I am working on a PWM generation.

I have just created the example sdk file sctimer_simple_pwm in mcuxpresso ide. I have got the pwm output of 50% duty cycle and 24KHz pwm_freq. 

What is the maximum and minimum range of the pwm output. In user guide they have mentioned that the pwm output maximum will be 100MHz and not mentioned the minimum value. When I am practically implementing i can see the maximum output of 56MHz.and minimum of the 1Hz.

In user guide CLK_IN source is 12MHz and the PLL frequency = ((CLK_IN * M)/N)/2P.As mentioned in the user guide output frequency will be 4.3MHz to 550MHz.But the pwm maximum output will be 100MHz.

What is the mistake i have made with the calculation.What is the proper way to do this so and what is the maximum and minimum pwm output frequency.

Please guide me,

Thanks and regards,

A.Ajith Kumar.

[Alice_Yang · Accepted solution]

Hello @aajithkumarr 

Do you mean "The maximum frequency for the SCTimer/PWM clock is 100 MHz." in UM as below?

There are two type of input for SCT, the the 100MHz clock limitation is only valid for the clock source inputted from external pads (SCT_IN7), if you use system clock as the SCTimer/PWM clock source, the system clock frequency can be greater than 100MHz.

The PWM output frequency can calculated after you choose source clock.

BR

Alice