Driving a Powermax II stepper motor with a L298. Approx 22vdc at 2.0 amps. The L298 gets very hot. Is this normal ?. Currently have it on a 3x2" heatsink and it is running at around 65 Celcius.
According to the data sheet it can drop 4.9V maximum at 2A. That's nearly 10W, so yes the device will get hot with a 3x2" heatsink. The device thermal resistance is 3C/W junction to case, so at 10W and a 65C heatsink temperature, the junction is at 95C, which is below it's absolute maximum junction temperature rating of 130C.
get a different chip ... the L297 is an antique piece of garbage! ditch it and it's darlington output stage for a FET part that can do synchronous rectifying for you.
Sorry yes, the L298. The L297 is the controller typically used with it.
Vsat on the thing is 3-5V. At 2A that is 6-10W if you do not add external diodes.
The Allegro **broken link removed** is a FET output 2.5A driver with 0.9Ω total for 1.8W total losses with synchronous rectifier outputs and micro stepping built in.