lm9831 National Semiconductor Corporation, lm9831 Datasheet - Page 40

• Manufacturer Part Number: lm9831
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• Manufacturer: National Semiconductor Corporation

Stepper Motor Current Controller Block Diagram
CR
CR
DAC code for
DAC code for
B
B
A
A
phase A
phase B
8
6
Generator
÷1 to 256
Phase A
high time
0/64 to
12MHz
Invert
PWM
63/64
Phase B
÷64
Invert
3
3
TriState Stepper
Motor Outputs
DAC A:
0.110V,
0.175V,
0.325V,
0.425V,
DAC B:
0.110V,
0.175V,
0.325V,
0.425V,
0.465V
0.465V
Comparators need no hysteresis. SR flipflops are set periodi-
cally by pulse from PWM Generator. Flipflops can only be reset
after SR goes low when Reset (comparator output) is high
(V
Reset is level sensitive, not edge sensitive.
SENSE
–
+
+
–
> V
DAC
).
Reset
Reset
Set-Dominant
Set-Dominant
Set
Set
S/R Flipflop
S/R Flipflop
Q
Q
40
LM9831
HIGH CURRENT
GND SENSE
SENSE1
SENSE2
A
A
B
B
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Phase A
Phase B
Stepper
Stepper
External Components
1
1
+Vmotor
+Vmotor
Phase A
Phase B
Stepper
Stepper