3977 Datasheet, PDF (13/18 Pages) Allegro MicroSystems – MICROSTEPPING DMOS DRIVER WITH TRANSLATOR

3977
MICROSTEPPING DMOS DRIVER
WITH TRANSLATOR
STEP
INPUT
HOME
OUTPUT
100%
70.7%
38.3%
PHASE 1
CURRENT
–38.3%
–70.7%
–100%
100%
70.7%
38.3%
PHASE 2
CURRENT
–38.3%
–70.7%
–100%
Quarter-Step Operation
MS₁ = L, MS₂ = H, DIR = H
SLOW
DECAY
MIXED
DECAY
SLOW
DECAY
MIXED
DECAY
SLOW
DECAY
MIXED
DECAY
MIXED
DECAY
SLOW
DECAY
Dwg. WK-004-13
www.allegromicro.com
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.
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