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UC2843A: Synchronization question

AJ Cheng
Genius 3615 points
Part Number: UC2843A
Other Parts Discussed in Thread: UC2843,

Dear Sir.

Good day. Can the UC2843A be used synchronously circuit? For example, the UC2843 non-A version of the description. UC2843A SPEC does not see the synchronization information.

Please help confirm if the sync schematic is correct as follows.

  • 0
    TI__Genius 13660 points
    Hi AJ Cheng，
    I will get back to soon.
    Thanks,
    Teng
  • 0 in reply to Teng Feng
    Genius 3615 points

    Dear Teng.

    Good day.

    One more question. Are we making produc PWM frequency range are within the UC2843A internal accuracy range + R + C accuracy range? Thanks for kindly help~

     UC2843A internal accuracy range

    R + C accuracy range

  • 0 in reply to Teng Feng
    Genius 3615 points

    Dear Teng.

    Good day.

    We need to know how the synchronization architecture is calculated. Thanks for kindly help~

  • 0 in reply to AJ Cheng
    TI__Genius 13660 points

    Hi AJ Cheng,

    The date just shows the the accurate of Oscillator.  The  oscillator frequency range is from 47 kHz to 57 kHz at the condition RT = 10 kΩ; CT = 3.3 nF.
    But oscillator frequency of UC2843A can operate up to 500 kHz, so we can set up its oscillator frequency below 500 kHz.

    Regards,
    Teng

  • 0
    TI__Genius 13660 points

    Hi AJ Cheng,

    The UCx84xA family of control devices is a pin-for-pin compatible improved version of the UCx84x family. So UC2843A should has all features of UC2843.
    May I know which did this schematic refer to or designed by yourself, since we have not provided the reference design for sync functionality of UC2843.
    According to section 8.3.7 in UC2843 datasheet, the sync pulse should set to 20% higher than oscillator frequency, and the amplitude is 0.5 V. From figure 19, the sync pulse directly connects to the Cct, without a small coupling capacitor and resister. which obviously is in conflict with your schematic.
    Besides, in the schematic, a output signal of IC is used as sync signal of another IC, why did not use a same sync signal for sync functionality of both ICs?

    Regards,
    Teng

  • 0 in reply to Teng Feng
    TI__Genius 13660 points

    Hi AJ Cheng, I haven’t heard back from you, I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out) – thanks, Teng

  • 0 in reply to Teng Feng
    Genius 3615 points

    Dear Teng.

    Good day. There are no other problems with the customer. Thank you very much for your help~