Hello
Not having designed a mosfet bridge module before I am in need of some help please. searching through various drivers and mosfets I decided to use the UC3637N controller as it is a current device and the application note U-102 had a circuit for an 8A bridge circuit. I have bought all the bits and built up a module for test. I am trying to understand the various voltage and switching levels but having difficulty.
I need to design a throttle actuator output module to drive exsisting actuators using a printed circuit motor with 100:1 ratio gearbox fitted for positional travel in range 0..90 degrees. Also I am looking to use this UC3637N based circuit to drive a car 12V or 24V wiper motor also configured for positional control. Both have a 1K Ohm feedback pot for position sensing. The from part of the circuit is based on an old design to accept demand and feedback and sum into an error amp before going to IR2110 drivers and single rail mosfet output.
I have chosen the U-102 design as a possible base for a half bridge design for positional control of a wiper motor in the future as normally one of the brushes is tied to the casing/ earth/ ground. So switching +- 15V to the high side brush would be good.
The current problem is how to modify the U-102 circuit on page 3.77 to have a higher bridge voltage that the 15V used for the UC3637N. The high current pSU I have is a 15-0-15 7.9A transformer with bridge and 3300uF smoothing giving an off load voltage of around 21V DC. This I think is too high for the UC3637N and I would like to seperate the control ic supplies from the high current motor supply.
I have attached a PDF drawing of the basic idea circuit and if you could advise on PSU seperation and any other help that would be much appreciated.
Thank you
Vic Oliver