- Ask a related questionWhat is a related question?A related question is a question created from another question. When the related question is created, it will be automatically linked to the original question.
Hi, TI experts
The customer is currently reviewing the use of UCC27614 for N-channel MOSFET drive ON/OFF control
1.MCU GPIO -> TI UCC27614 -> N-channel FET Gate control must be performed.
First of all, if you press and hold the POWER OFF button on the product, the N-channel FET should be turned off, but if you look at the attached circuit diagram, it doesn't seem to be turned off accurately.
Q1) We request a review of the attached circuit for identification of any issues and suggestions for improvement.
Your assistance in assessing potential problems and providing recommendations would be greatly appreciated.
Q2) Is it possible to control ON/OFF of N-channel FET using UCC27614?
For reference, the function control configuration diagram is as follows.
[Function control diagram]
Please check. Thank you.
Hi Grady,
The UCC27614 will pull out to VDD when on, and pull to GND when off.
This setup essentially makes a voltage divider, where 4.7K is in parallel with R5 when a high signal is sent, and in parallel with R6 when the low signal is sent. This results in a gate voltage of 17.2V when high, and 11.4V when low. I simulated this and got the same result. By removing that voltage divider in simulation, the FET was able to be turned off.
However, the main problem (for Q2) is the source voltage. The FET is only on when Vgs is > Vth. UCC27614 is a low-side gate driver, intended to be used to drive a FET with a source referenced to GND. This is a high-side switch, and the UCC27614 does not have any level-shifting ability to adjust for the source voltage not being 0V.
Here are three options:
Thanks,
Alex M.
