Current drawn with uln2003 together with mcp23017 or PCF8575

[acroscene]

Im using uln2003a for driving 28BYJ-48 on my esp32. SInce I need many motors I need to multiplex. Im going to use either MCP23017 or PCF8575. Ive read however that MCP23017 has a maximum current per pin rating of around 25mA.

The 28BYJ-48, it's typically around 150-200mA per phase according to specs. The uln2003a can handle this since ULN2003A can handle up to 500mA per output.

The main concern is the current drawn by the ULN2003A's input pins, which are connected to the MCP23017 output pins. Will MCP23017 be alright with driving this? Will it currentwise be ok to drive four uln2003a with 28BYJ-48

[JCA34F]

The ULN2003 INPUT current is only about 1 mA.
From the datasheet:

https://www.ti.com/lit/ds/symlink/uln2003a.pdf

You might consider the tpic6b595, an 8 channel power shift register that can drive 2 28BYJ-48s.

https://www.ti.com/lit/ds/symlink/tpic6b595.pdf

[acroscene]

Ok thanks. So no problem then. Im going to use 4 uln2003a on mcp23017 so all 16 possible pins will be used

[JCA34F]

See my edited post.

[JCA34F]

[quote="JCA34F, post:2, topic:1253075"]
You might consider the tpic6b595, an 8 channel power shift register that can drive 2 28BYJ-48s.

tpic6b595.pdf

[acroscene]

@JCA34F

tpic6b595

Thanks. But using 4 uln2003a on mcp23017 for driving 4 28byj-48 will also work right?

[JCA34F]

Oh sure, just keep in mind, the Darlington transistor outputs will drop about 1.4 volts from your 5.

[acroscene]

I made this quick sketch in fritzing. Think it should be ok

[JCA34F]

Let us know, good luck.