Buck Converter Mosfet Driver Circuit
Driver circuit. In a buck converter based on an N-channel MOSFET, the source terminal of the MOSFET is not connected to the circuit ground (not ground-referenced) and is floating. The N-channel MOSFET of a buck converter is a high-side switch. Drive circuits for the high-side switches are called. Why is this design preferred over a low side, N-Mosfet buck converter? Simulate this circuit – Schematic created using CircuitLab. Would this design work? The load is a 12V Fan, 3.6W The Mosfet would be driven directly from the microcontroller in PWM, 5V logic, 32 Khz carrier frequency.
I am working on developing a 20 Watt power buck converter and want to know the available drive IC and modules to control and switch the IRF720 MOSFET.
Are you using an IRF540 as you say in your text, or an IRF510 as shown on your schematic?In either case, it's an N-channel MOSFET. To turn it ON strongly, you need to bring the gate about 10V more positive than the source.
But when the MOSFET is ON, its source will be at +24V. So you need a way to generate a voltage of about 34V to drive the gate.
You need a 'high-side MOSFET driver' IC.The International Rectifier IR2111 will do what you want. It uses a technique called bootstrapping to generate the gate drive voltage, using an external diode and capacitor.
The IR2111 actually has a high side and a low side driver; you don't need the low side driver. Are you using an IRF540 as you say in your text, or an IRF510 as shown on your schematic?In either case, it's an N-channel MOSFET. To turn it ON strongly, you need to bring the gate about 10V more positive than the source. But when the MOSFET is ON, its source will be at +24V. So you need a way to generate a voltage of about 34V to drive the gate. You need a 'high-side MOSFET driver' IC.The International Rectifier IR2111 will do what you want.
It uses a technique called bootstrapping to generate the gate drive voltage, using an external diode and capacitor. The IR2111 actually has a high side and a low side driver; you don't need the low side driver. The IR2101 will work fine. You will need another supply voltage of around +12V for it - you can use a 7812 supplied from the 24V input. You don't use the low-side switch.The bootstrap circuit (diode and capacitor) around the IR2101 will ensure that the MOSFET gate is pulled up to about +34V to turn it ON. You don't need to provide that voltage.The circuit input voltage should still be 24V.Edit: I added CD, a 1 µF low-ESR ceramic, as shown to provide a solid firm voltage rail for M1 to switch against.
The IR2101 will work fine. You will need another supply voltage of around +12V for it - you can use a 7812 supplied from the 24V input. You don't use the low-side switch.The bootstrap circuit (diode and capacitor) around the IR2101 will ensure that the MOSFET gate is pulled up to about +34V to turn it ON. You don't need to provide that voltage.The circuit input voltage should still be 24V.Edit: I added CD, a 1 µF low-ESR ceramic, as shown to provide a solid firm voltage rail for M1 to switch against. For schematics I use a very old program called OrCAD/SDT III.
Buck Converter Mosfet Driver Circuit High Side
It is an MS-DOS app and runs under DOSbox under Windows. It was commercial software and is not available for download.You need to control the duty cycle to achieve regulation. That means you need to monitor the output voltage, compare it to the desired output voltage, and adjust the duty cycle as necessary to achieve the desired output voltage. But I guess you knew that. If you want to know how to do it, I guess that depends on the capabilities of your MCU, including the resolution of the PWM output. There are quite a few variables here and I have no experience with using MCUs to directly generate control signals for regulators.Someone else may be able to help. I think BobK has done this before.
The IR2101 will work fine. You will need another supply voltage of around +12V for it - you can use a 7812 supplied from the 24V input.
Mosfet Application Circuits
You don't use the low-side switch.The bootstrap circuit (diode and capacitor) around the IR2101 will ensure that the MOSFET gate is pulled up to about +34V to turn it ON. You don't need to provide that voltage.The circuit input voltage should still be 24V.Edit: I added CD, a 1 µF low-ESR ceramic, as shown to provide a solid firm voltage rail for M1 to switch against.