in short,
For layout,
Just place the outputs somewhere I can solder a header. Pcf8574 Inputs same thing.
I want to place diodes on the mosfet outputs, pullup resistors on the analog inputs.
Anything else that can help reduce noise and improve reliability. Special care must be taken to improve EMI/RF noise immunity by design of PCB and component layout.
Please give me a quote
If you don't give more details you risk getting something which doesn't match you needs. Best would be to provide a schematic which would also clarify points like what power supply/ supplies are available, whether the mosferts are P or N channel etc. Then you may get alternative suggestions also, say for your choice of port expanders.
What is your application?
Do you have the schematics ready?
Also is there a way to contact you since your profile is hidden.
You can write to me at info@ed3services.com.
put in short, 3 pcf8574s will operate a series of relays and mosfets through means of optocouplers. 2 pcf8591 will receive input from a photo resistor and 6, 2 wire float sensors. My design currently with 2 pcf8574 and no pcf8591 is picking up way too much noise from the environment. the noise is coming from HID digital switching ballasts.
i think the first step to a functional device needs to be a proper PCB with grounding planes and attention within reason to EMI anf RF noise.
there should be 5, 30 amp relays for switching 120v. these relays would be operated by some pcf8574 pins. the rest of the outputs from the pcf8574s would control mosfet gates through optocouplers. the mosfets should handle around 9-24vdc @ 10amp
Use stronger i2c pull up resistors or shorter wires ? Anyway, it would be best to get the detail of the design sorted out before proceeding to the pcb stage. If you already have something built, although not a full match for your requirements, then show the schematic.
N mosfets or P Mosfets? I think you need to specify connectors for those and the relays. A random 0.1in header pin isn’t good for 10A, much less 30A. What is the coil voltage of the relays? (Is there 12V available, for instance?). Have you particular relays or mosfets in mind?
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