dead time generation of 24 micro seconds

[Srinath_03]

hi I'm using NUCLEOG4 series controller. configuring TIM1 in both normal and complimentary PWM. PWM is generating, no problem in that. but i want 24 micro seconds of dead time between top and bottom pwm. but i can able to achieve maximum of 6 micro seconds only. As per the datasheet and calculation, dead time insertion value for 24 micro seconds is 244, but output dead time is maximum 6 micro seconds.

can anyone suggest how to achieve 24 us deadtime in nucleog4 and I'm running at 170MHZ.

[unsigned_char_array]

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@Srinath_03 wrote:

I'm using NUCLEOG4 series controller

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Which one. Please provide exact product name or a link.

 

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@Srinath_03 wrote:

dead time insertion value for 24 micro seconds is 244, but output dead time is maximum 6 micro seconds.

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Please upload your ioc file and user code.

[Srinath_03]

nucleog4 stm32g474ret6 controller at 170MHZ

I'm just directly keeping the calculated 244 value in deadtime configuration section in IOC file. 

[unsigned_char_array]

That's not the full ioc file, just a screenshot of a single value.

From what I read in RM0440 the dead time value is a 10 bits value, so it should work from 0 to 1023. So 244 ticks should work.

DTG is 3 bits and has 4 possible values: 1,2,8,16 * DTS

Can you post the register values?
Can you post an oscilloscope/logic analyzer capture? Pick a sane duty cycle. Use several values for dead time.

[unsigned_char_array]

I think I figured it out. I didn't know anything about this particular MCU or how these timers worked, but after reading the reference manual (RM0440) I think I found it:

 

/*
from RM0440 Rev 8:
"Bits 9:8 CKD[1:0]: Clock division
This bitfield indicates the division ratio between the timer clock (tim_ker_ck) frequency and
the dead-time and sampling clock (tDTS )used by the dead-time generators and the digital
filters (tim_etr_in, tim_tix)"
*/

 

looking at the block diagram you will see tim_ker_ck, tim_psc_ck and tim_cnt_ck
The prescaler divides tim_psc_ck and outputs tim_cnt_ck, but the dead time uses tim_ker_ck.
You generally want tiny dead time values, even with high prescaler values, so it makes sense the dead time block is clocked separately. So set Internal Clock Division in STM32CubeMX.