3977
MICROSTEPPING DMOS DRIVER
WITH TRANSLATOR
Half-Step Operation
MS
1
= H, MS
2
= L, DIR = H
STEP
INPUT
HOME
OUTPUT
MIXED
DECAY
SLOW
DECAY
SLOW
DECAY
SLOW
DECAY
MIXED
DECAY
MIXED
DECAY
SLOW
DECAY
MIXED
DECAY
MIXED
DECAY
SLOW
DECAY
100%
70.7%
PHASE 1
CURRENT
–70.7%
–100%
SLOW
DECAY
MIXED
DECAY
MIXED
DECAY
SLOW
DECAY
MIXED
DECAY
SLOW
DECAY
100%
70.7%
PHASE 2
CURRENT
–70.7%
–100%
Dwg. WK-004-14
The mixed-decay mode is controlled by the percent fast
decay voltage (V
PFD
). If the voltage at the PFD input is
greater than 0.6V
DD
then slow-decay mode is selected. If
the voltage on the PFD input is less than 0.21V
DD
then
fast-decay mode is selected. Mixed decay is between
these two levels.
12
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
