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UCC2803: Which IC to be used from UCC28xx series.

ANURAG LOKHANDE
Prodigy 70 points
Part Number: UCC2803
Other Parts Discussed in Thread: UCC2800, , UCC2802, UCC2804

Tool/software:

HI,

I have to build isolated power supply.

AC/DC converter with

Input DC 20V to 60V

Input AC 20V to 265V

Output 12V 0.1A

I came across UCC28xx series. 

I confirm about duty.

but not of TURNON THRESHOLD and TURNOFF THRESHOLD.

Which IC to choose from UCC2800, UCC2802, UCC2803?

I have UCC2803, It seems it does not drive Power MOSFET(IRF840), or I am missing something. 

Please also suggest if any low cost solution is available from TI.

Regards,

Anurag

  • 0
    TI__Expert 7473 points

    Hi there,

    These devices are general purpose PWM controllers, and as you mentioned the main difference is max duty cycle, Vref voltage and different turn ON and turn OFF thresholds, which depends on the VDD voltage. Based on that you can pick any one of them.

    ANURAG LOKHANDE said:
    I have UCC2803, It seems it does not drive Power MOSFET(IRF840), or I am missing something.

    It should be able to, can you provide more details please.

    Best,

    Pratik A.

  • 0 in reply to Pratik Adibatla
    Prodigy 70 points

    Hi,

    When input voltage to AC/DC converter is 20V AC.

    UCC2803 starts providing pulses(burst) to MOSFET of 4V. But when I see, MOSFET does not fully ON.

    Series gate R = 3E to 10E.

    What is purpose of different duty cycle IC available in UCC28xx series like 50% and 100%, where it affects particularly and what's purpose. 

    Regards,

    Anurag 

  • 0 in reply to ANURAG LOKHANDE
    TI__Expert 7473 points

    Hi Anurag,

    That's because the Vgs is low enough to turn on the MOSFET, what's the VCC you're providing to the IC? The OUT will follow VCC.

    Some PWM controllers have a maximum 50% duty cycle due to microcontroller timer limitations, where the timer's design or firmware logic divides the cycle into a fixed number of time slots. Hence, we provide customers the option of 50% or 100% max duty cycle with diff turn ON and turn OFF thresholds.

    Hope this helps.

    Best,

    Pratik A.

  • 0 in reply to Pratik Adibatla
    Prodigy 70 points

    Hi,

    Then where UCC2803, IC to be used. Or need to find MOSFET that works under 4V Vgs?

    For application, 

    AC/DC converter with

    Input DC 20V to 60V

    Input AC 20V to 265V

    Output 12V 0.1A

    UCC2800 will work?

    Regards,

    Anurag

  • 0 in reply to ANURAG LOKHANDE
    TI__Expert 7473 points

    Hi Anurag,

    There are general purpose PWM controller with lots of variants fitting specific needs and different topologies like buck, boost, SEPIC, flyback, etc.

    UCC2803 will turn OFF below 3.6V and turns ON above 4.1V, so any MOSFET which has Vgs over 4.1V will work.

    For that AC/DC converter they can pick any device expect UCC2802 and UCC2804 as their turn ON voltage is 12.5V.

    Best,

    Pratik A.