A3981KLPTR-T Allegro Microsystems Inc, A3981KLPTR-T Datasheet - Page 23

• Manufacturer Part Number: A3981KLPTR-T
• Description: AUTOMOTIVE PROGRAMMABLE STEPPER DRVR
• Manufacturer: Allegro Microsystems Inc

Specifications of A3981KLPTR-T

• Applications: Stepper Motor Driver, 2 Phase
• Number Of Outputs: 1
• Voltage - Load: 7 V ~ 28 V
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A3981
arithmetic operators to be used, within the microcontroller, to
determine the size of the next step increment. Table 6 shows the
binary equivalent of each decimal number between –16 and +16.
Each increase in the Step Angle Number represents a forwards
movement of one-sixteenth microstep. Each decrease in the Step
Angle Number represents a reverse movement of one-sixteenth
microstep.
To move the motor one full step, the Step Angle Number must be
increased or decreased by 16. To move the motor one half step,
the Step Angle Number must be increased or decreased by 8. For
quarter step the increase or decrease is 4 and for eighth step, 2.
So, for example, to continuously move the motor forwards in
quarter-step increments, the number 4 (000100) is repeatedly
written to SC[5..0] through the serial interface Run register (see
figure 10). To move the motor backwards in quarter step incre-
ments, the number -4 (111100) is repeatedly written to SC[5..0]
(see figure 11). The remaining bits in the Run register should be
set for the required configuration and sent with the step change
number each time.
The step rate is controlled by the timing of the serial interface.
It is the inverse of the step time, t
motor step only takes place when the STRn goes from low to
SDI
SCK
STRn
SDI
SCK
STRn
Figure 8. Serial interface sequence for quarter step in forward direction
Figure 9. Serial interface sequence for quarter step in reverse direction
STEP
, shown in figure 10. The
1 0 1 0
1 0 1 0
Automotive, Programmable Stepper Driver
t
STEP
1 0 1 0
1 0 1 0
1 0 0 0 0 1 0 0
1 0 1 1 1 1 0 0
Table 6. Binary Equivalents
Decimal
10
12
13
14
15
16
11
0
1
2
3
4
5
6
7
8
9
+4
-4
Complement
000000
000001
000010
000100
000101
001000
001001
001010
010000
000011
000110
000111
001011
001100
001101
001110
001111
2’s
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
Decimal
–10
–12
–13
–14
–15
–16
–11
–1
–2
–3
–4
–5
–6
–7
–8
–9
Complement
110101
110100
110010
110001
110000
111101
111100
111011
111010
111001
111000
110111
110110
110011
111111
111110
2’s
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