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Feather Wing Isolated MOSFET driver

Drive MOSFET with proper signal and power isolation with any Feather boards

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Drive MOSFETs like a pro. This feather wing helps you drive both N and P MOSFET with Isolated 12 Volts Gate drive signals which is optically coupled with pwm pin of the mcu on Feature board. 12 volt is generated with boost converter from a LiPo Battery. Then Isolated 12 volts is made with DC-DC isolation converter.

Isolated DC does not share common Ground with the rest of the Feather system, essentially allowing user to use MOSFET to switch any floating system with voltage below Vds of the MOSFET. Maximum switching frequency 250 kHz. User can choose to use any TO-220 MOSFET (either N or P type but only one) simply by soldering it on the respective unpopulated pads. MOSFET pads are placed in such a way that big heat sinks can be attached easily.

https://easyeda.com/suntop/featherwing-isolated-fet-gate-drive

To enable this wing, a digital high is applied to pin 13 of mcu, which will enable the ap3012ktr DC-DC converter to power up and get the wing ready to operate.

Then enabling pwm to pin 12 of the mcu from code, the MOSFET can be driven.

It only requires 2 pins of Feather boards, rest of the pins can be brought up with long male/female pin headers !

Working Principle :

B1212S-1WR2 has a tiny flyback converter consists of switching element, tiny transformer and rectifier, which turns 12 volts into isolated 12 volts. This kind of isolation is galvanic isolation.

Flyback Isolated DC-DC converter (source: Wikipedia)

Flyback Isolated DC-DC converter (source: Wikipedia)

This isolated 12 volts is supplied to power the FOD3182 opto isolated gate drive IC. Inside this IC, there is an IR LED which can be turned on/off directly from 3.3 volts mcu GPIO pin through a current limiting resistor. The IR light will turn on or off the pull-push output drive transistors which will connect the gate drive pin to Isolated 12 Volts or Isolated Ground.

                                                     Fig: FOD3182 guts

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  • 2 × 10uF 25v Electrolyte
  • 1 × AP3012KTR-G1 SOT-23-5 Power Management ICs / Switching Regulators and Controllers
  • 2 × 4.7uF 0603 Ceramic Capacitor
  • 1 × 10uH Inductor-SMD_L6.0-W6.0
  • 1 × 0.1UF-25V 0603-CAP

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