A3981 Allegro Micro Systems, Inc., A3981 Datasheet - Page 17

• Manufacturer Part Number: A3981
• Manufacturer: Allegro Micro Systems, Inc.

A3981
Configuration Register 0
SYR
MS[1..0]
MXI[1..0]
PFD[2..0]
TBK[1..0]
PFD2
TBK1
MXI1
SYR
MS1
0
1
0
0
1
1
0
0
1
1
0
0
0
0
1
1
1
1
0
0
1
1
CONFIG 0
Synchronous rectification
Synchronous Rectification
Diode recirculation
Synchronous
Microstep mode for external STEP input control
Max phase current as a percentage of I
Fast decay time for mixed decay
Assumes 4-MHz clock
Blank Time
Assumes 4-MHz clock
PFD1
TBK0
MXI0
MS0
0
1
0
1
0
1
0
1
0
0
1
1
0
0
1
1
0
1
0
1
Microstep Mode
Maximum Current
Blank Time
Full Step
Half Step
Quarter Step
Sixteenth Step
PFD0
100%
0
1
0
1
0
1
0
1
25%
50%
75%
1.5 μs
2.5 μs
3.5 μs
1 μs
15
0
Fast Decay Time
10 μs
14 μs
20 μs
2 μs
3 μs
4 μs
6 μs
8 μs
14
0
SYR
13
1
MS1
12
0
Automotive, Programmable Stepper Driver
Default
Default
SMAX
Default
Default
Default
MS0
11
0
D
D
D
D
D
MXI1
10
1
MXI0
9
1
PWM
TOF[2..0]
FRQ[2..0]
PFD2
8
1
PWM
TOF2
FRQ2
0
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
PFD1
7
0
PWM configuration
MODE
Fixed off-time
Fixed frequency
Off time (only valid when PWM bit = 0)
Replaces FRQ bits
Assumes 4-MHz clock
Frequency (only valid when PWM bit = 1)
Replace TOF bits
Assumes 4-MHz clock
TOF1
FRQ1
PFD0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
6
0
FRQ0
TOF0
TBK1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
5
0
TBK0
Off Time
Period / Frequency
24 μs / 41.7 kHz
32 μs / 31.3 kHz
40 μs / 25.0 kHz
46 μs / 21.7 kHz
52 μs / 19.2 kHz
56 μs / 17.9 kHz
60 μs / 16.7 kHz
64 μs / 15.6 kHz
4
1
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
20 μs
24 μs
28 μs
32 μs
36 μs
40 μs
44 μs
48 μs
TOF2
FRQ2
3
1
TOF1
FRQ1
2
1
TOF0
FRQ0
1
0
Default
Default
Default
D
PWM
D
D
0
0
17