HP Paintjet stepper motor driver IC

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sun Nov 28 13:33:28 2004

I've got an HP Paintjet printer on the bench (this is on-topic, it seems
to have been made in 1986 or so). I've figured out most of it (even the
PSU section with a complex custom DIL resistor pack), but I can't
indentify the driver chip for the linefeed motor, which is a 4-input
unipolar stepper motor.
 
Anyway, the driver chip is marked 1820-4864 (too late for my equivalents
list). It would seem to be a quad power driver chip rather than a stepprr
motor controller, as it takes in 4 bits from one of the microocntroller
ports. The pins, as I've traced them seem to be :

1 Input
2 +5V
3 Output
4 N/C
5 Input
6 +5V
7 Output
8 Ground
9 Clamp
10 Output
11 Input
12 +5V
13 Output
14 Input
15 +5V
16 +5V
 
It's a normal 16 pin DIL package (no heatsink tabs or anything).
 
I usspect, without prood, that it's actually 4 separate stages, AND or
NAND functionality, : 1 & 2 -> 3, 5 * 6 -> 7, 12 & 11 -> 10, 15 & 14 -> 13
 
Does that pinout ring any bells with anyone? It's not any of the chips in
my TI Interface Databook..
 
-tony
Received on Sun Nov 28 2004 - 13:33:28 GMT