I would like to connect various MCP23S17 datasheet devices to the Raspberry Pi3 MB SPI port. But first I would like to start making some test with a single connection: only one chip. After this I will add more than one expanser to the SPI net. First I will try to connect a LED to the output pins (aprox 20mA).
I have some questions regardless electrical characteristics of this device. About outputs there are two instructions:
1."output current sourced by any output pin.. 25mA"
2.and "output clamp current, IOK...20mA".
What is the difference between 2 both expressions? If 20mA is a damaging value how is it possible that they could give until 25mA?
Could I connect a load to these output pins when current load requirements are closer or bigger than 20mA?
If not, How could I do it? Things I was thinking as a solution for this:
- using current drivers
- single transistors working in active zone
Have you any other option suggestion?