Hi all,
I am beginning to despair with electronics as I hate keep asking what I feel are stupid questions! but here I go again.
The EL7232 is a push pull line driver capable of sourcing / sinking 2A between 4.5v and 16v but the inputs can be operated from 3.3v
Here is what I do:
1A 5v regulator MC7805CDTRKG
EL7232
Atxmega running at 3.3v
The 5v regulator supplies only the EL7232, I have a separate regulator for the MCU
Set pin 1 (3-STATE for line A) high at (3.3v)
Cycle PIN 2 high and low at 3 second intervals, this should drive the output, pin 7, high / low (inverted)
To test the "PULL UP" I connect the output it to ground via 6ohm resistor, I see the output drop from 5v to 1.73v and it see it drawing 290ma approx
To test the "PULL DOWN" I connect the same resistor to the output of the 5v regulator and I see 3.54v and drawing again 290ma approx.
View attachment 93011
So here are my questions
- Why does the EL7232 not pull harder and keep the line high / low as it cycles
- Why do I only see 290ma through the resistor when it should be 833ma approx (5v/6ohm = 0.8333)
Steve