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ucc28704 vs ucc28703

Other Parts Discussed in Thread: UCC28704, UCC28703, UCC28740



Are there other benefits to the UCC28704 vs. UCC28703?


We know that the UCC28704 has improved load transient regulation but a lower switching frequency.

thank you



  • Kamal,

    The UCC28704 is the newest device in the UCC287xx family of PSR flyback controllers. It incorporates many new features and internal upgrades, and would be the recommended part to use instead of UCC28703 in most applications.

    This blog highlights the major differences and benefits of UCC28740:

    To list the main features and differences:

    - Improved transient response for repeating dynamic load (as you already mentioned above)

    - CCUV protection - in CC mode, the controller will shut down for output UV at a defined output voltage level (~60% of Vonom), assuming that the VDD rail is high enough to keep the IC functioning. On the other hand, the UCC28703 relies on the VDD pin UV protection in deep CC mode, which is not always correlated to the output voltage level, due to transformer leakage inductance

    - Fmax 85 kHz for UCC28704 vs. 130 kHz for UCC28703

    - AM gain 4:1 for UCC28704 vs 3:1 for UCC28703

    - Dmagcc 475.% for UCC28704 vs. 42.5% for UCC28703 - wider secondary side conduction angle reduces secondary peak and rms currents

    - NTC/SU pin - the NTC pin can also be used to control an external depletion-mode startup FET for faster startup and lower standby power compared to resistor-only startup.

    - Minimum output capacitance for loop stability - per eqn 5 in the UCC28704, a certain minimum value of output capacitance is required to ensure stability of the PSR voltage loop. Due to internal IC improvements, the UCC28704 can use smaller values of output capacitance for stability.

    I hope this answers your questions. If so, please click the "verify answer" button.