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UCC38C43: VOH of UCC38C43 is really up to 6.8V?

treez
Intellectual 970 points
Part Number: UCC38C43

Hello,
The reference voltage inside the UCC38C43 controller is said to range between 4.9V to 5.1V.
The internal error amplifier of the UCC38C43 is presumably supplied from this reference voltage, so how is it that near the bottom of page 5 of the UCC238C43 datasheet, it states that the output high voltage (VOH) of the COMP pin ranges up to 6.8V?

The “Test Conditions” for this voltage (6.8V) is said to be…….

“VFB = 2.7 V, RCOMP = 15 kΩ COMP to GND”

…however, if the FB pin had 2.7V on it, and there was a 15k resistor to ground connected to the COMP pin, then the COMP pin voltage would tend to be near zero volts.
Also, page 2 says that the COMP pin's "Absolute Maximum" voltage is just 6.3V.....so how can it have 6.8V on it like on page 5?

Do you know what’s going on?

UCC38C43 datasheet:
http://www.ti.com/lit/ds/symlink/ucc38c43.pdf

  • 0
    TI__Mastermind 26700 points
    Hello Treez,

    Thank you for pointing out some inconsistencies in our datasheet. At VOH, for COMP to go high, I believe the test condition on FB should read "VFB = 2.3V, RCOMP = 15 kΩ COMP to GND”. Ironically, the very next parameter VOL, for COMP to go low has the same test conditions as for VOH, and in this case they are correct. As for the 6.8V typical "high level" exceeding the 6.3V absolute maximum rating, I believe this is another typographical error. I don't know whether the typical number is incorrect or the abs max number is incorrect, but I will bring these errors to the attention of the documentation team to have them corrected.

    Despite the typos, I assure you that the COMP voltage is guaranteed to exceed 5V when the voltage at FB is less than 2.5V (in an open-loop test condition) and the part behaves as expected in a closed-loop application.
    Thanks again for bringing this to our attention.

    Regards,
    Ulrich