I would like to use the example circuit, from TL5001's guide, for a wider voltage range. I need it to work with almost 50V input.
Here's the circuit:
Now, the problem with this is that Q3 pulls the MOSFET's gate to GND. While the source voltage is around 40-50V, and this would destroy the gate. How can I limit this voltage?
As a secondary question: TL5001 max input voltage is 40V. Will a simple shunt regulator, with a zener diode, be enough to supply it?
I know this isn't the ideal IC to do this job, and I know that there are easier ways to drive a MOSFET gate nowadays, but please, I'd like to avoid answers suggesting the use os MOSFET driver ICs or other controller chips. There are reasons why I need to work with this particular IC.
Best Answer
Well, your choices are limited. You could use a TVS diode from gate to source, and a resistor in series with the gate to clamp Vgs. Of course that will slow down the switching and you'll have higher switching losses. Same goes with the supply voltage- The TL5001 only draws a couple of mA, so a shunt regulator could work at the cost of more power dissipation.
John