UCC28070: Synchronization with external pulse

Sankar Selvakumar

Prodigy 60 points

Part Number: UCC28070

Hi,

Does the PWM frequency is same as external pulse or the internal clock obtained from Rt resistor?

Regards,

Sankar S

over 3 years ago

0 Sankar Selvakumar over 3 years ago

Prodigy 60 points

The datasheet says that the external pulse should be twice that of the internal pwm. I guess if it not then the phase shift between the switch 1 and 2 may not have 180deg. The phase shift error depends on the difference of internal clock to the 1/2 times of external clock.

0 Sankar Selvakumar over 3 years ago

Prodigy 60 points

The PWM frequency is same that of the internal clock..

0 Ray DiCecco over 3 years ago in reply to Sankar Selvakumar

TI__Genius 11350 points

If there is no external SYNC, then fPWM = internal clock. If there is ext SYNC, then fPWM = 1/2 fSYNC , as long as fSYNC > fRT by about +10%.
There is never any phase-shift error. Always 180 due to logic.

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UCC28070: Synchronization with external pulse