A3992SBT- Allegro MicroSystems, Inc., A3992SBT- Datasheet - Page 5

• Manufacturer Part Number: A3992SBT-
• Description: DMOS Dual Full-Bridge Microstepping PWM Motor Driver
• Manufacturer: Allegro MicroSystems, Inc.

A3992
The A3992 is controlled via a 3 wire serial port. The
programmable functions allow maximum fl exibility in
confi guring the PWM to the motor drive requirements.
The serial data is written as two 19 bit words, 1 bit
to select which word (referred to here as Word 0 and
Word 1) and 18 bits of data. The serial port is defi ned
in the following tables and text descriptions.
Word 0 Bit Assignments
Word 0 is selected by setting D0 = 0. Assignments are
summarized in the following table, and desribed in
detail in the remainder of this section.
D1 – D6 Bridge 1, Linear DAC.
sired current level for bridge 1. Setting all bits to zero
disables Full Bridge 1, all drivers off. (See Current
Regulation in the Functional Description section.)
D10
D11
D12
D13
D14
D15
D16
D17
D18
Bit
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
Word 0 Bit Assignments
Word Select = 0
Bridge 1, DAC, LSB
Bridge 1, DAC, Bit2
Bridge 1, DAC, Bit3
Bridge 1, DAC, Bit4
Bridge 1, DAC, Bit 5
Bridge 1, DAC, MSB
Bridge 2, DAC, LSB
Bridge 2, DAC, Bit2
Bridge 2, DAC, Bit3
Bridge 2, DAC, Bit4
Bridge 2, DAC, Bit 5
Bridge 2, DAC, MSB
Bridge 1 Phase
Bridge 2 Phase
Bridge 1 Mode
Bridge 2 Mode
Reference Select
Range Select
Function
6 bit word to set de-
Serial Interface Description
Microstepping PWM Motor Driver
D7 – 12 Bridge 2 Linear DAC.
desired current level for bridge 2. Setting all bits to
zero disables Full Bridge 2, all drivers off. (See Cur-
rent Regulation in the Functional Description section.)
D13 Bridge 1 Phase.
of current for motor phase 1 as defi ned below:
D14 Bridge 2 Phase.
of current for motor phase 2 as defi ned below:
D15 Bridge 1 Mode.
for Full Bridge 1 as defi ned below:
D16 Bridge 2 Mode.
for Full Bridge 2 as defi ned below:
D17 Ref Select.
input for the two 6 bit linear DACs. Logic low selects
internal 2 V reference voltage, logic high selects ex-
ternal reference input on the REF pin.
D18 G
factor used is 4 or 8:
D18
0
1
m
Range Select.
D15
D16
DMOS Dual Full-Bridge
D13
0
1
0
1
Divider
0
1
D14
÷ 8
÷ 4
This bit determines the reference
0
1
This bit determines the decay
This bit determines the decay
This bit controls the direction
This bit controls the direction
OUT1A
OUT2A
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
D18 determines if the scaling
H
L
H
Mixed Decay
Mixed Decay
L
Slow Decay
Slow Decay
I
I
Mode
Mode
TRIP
TRIP
6 bit word to set the
Load Current
= V
= V
OUT2B
OUT1B
DAC
DAC
H
L
H
L
/(R
/(R
SENSE
SENSE
× 8)
× 4)
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