Hello,
I'm experiencing problems to drive relays with MCP23S17 over ULN2803.
The MCP23S17 is 3.3V powered.
When i set an output of MCP23S17 at high state : "1",
i can properly measure 3.3V voltage on the MCP23S17 pin but the voltage measured at the input of the ULN2803 falls down and relay can't be driven.
Do you think MCP23S17 (when 3.3V powered) can't drive ULN2803 (common pin set to +5V)
Should i have to place a level converter : MAX3002 between MCP23S17 and ULN2803 to shift the levels ?
If so will a MAX3002 or 74LVC07A deliver enough current to drive ULN2803 ?
Attached below the schematic i use so far.
Thank you for your help,