UCC27614: Equivalent Ron for temperature rise estimation

Jimmy Palmer

Part Number: UCC27614

Tool/software:

Hello,

I would like to use the SON-8 version of this device due to its smaller size, but I need to make sure it's capable of handling the gate-drive power loss. I understand that the total Ploss = Qg*Vdd*Fsw and that this loss is then proportional to the size of the resistor in the gate-drive path. For turn-off it's clear to me, but for turn-on, I don't know what the equivalent turn on resistance is for the UCC27614 due to the NFET and PFET structure. The datasheet mentions an "Ron" but I didn't see it referenced anywhere else in the datasheet.

over 1 year ago

0 Rubas Khalid over 1 year ago

TI__Expert 8460 points

Hi Jimmy,

In our devices with hybrid output structure (including UCC27614), there's a pull-up NMOS in parallel with the PMOS. This NMOS briefly turns on when the gate driver output switches from low to high, which significantly reduces the pull-up resistance. This reduced pull-up resistance is known as "Ron". The pull-up resistance listed in the electrical characteristics table is the Rds(on) of the PMOS only.

This FAQ explains further on output resistance: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1082569/faq-ucc27624-what-is-the-output-resistance-of-a-gate-driver

With the approximation given from the FAQ, the Ron for the UCC27614 is about 0.51Ω typical.

Thanks,
Rubas

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UCC27614: Equivalent Ron for temperature rise estimation