A3973(2007) Просмотр технического описания (PDF) - Allegro MicroSystems
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A3973 Datasheet PDF : 10 Pages
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A3973
Dual DMOS Full-Bridge
Microstepping PWM Motor Driver
FUNCTIONAL DESCRIPTION
Serial Interface. The A3973SB/SLB is controlled via a
3-wire (clock, data, strobe) serial port. The programmable func-
tions allow maximum flexibility in configuring the PWM to the
motor drive requirements. The serial data is written as two
19-bit words: 1 bit to select the word and 18 bits of data. The
serial data is clocked in starting with D18.
Word 0 Bit Assignments
Bit
Function
D0
Word select = 0
D1
Bridge 1, DAC, LSB
D2
Bridge 1, DAC, bit 2
D3
Bridge 1, DAC, bit 3
D4
Bridge 1, DAC, bit 4
D5
Bridge 1, DAC, bit 5
D6
Bridge 1, DAC, MSB
D7
Bridge 2, DAC, LSB
D8
Bridge 2, DAC, bit 2
D9
Bridge 2, DAC, bit 3
D10
Bridge 2, DAC, bit 4
D11
Bridge 2, DAC, bit 5
D12
Bridge 2, DAC, MSB
D13
Bridge 1 phase
D14
Bridge 2 phase
D15
Bridge 1 mode
D16
Bridge 2 mode
D17
REF select
D18
Range select
D1 – D6 Bridge 1 Linear DAC. Six-bit word sets desired
current level for Bridge 1. Setting all six bits to zero disables
Bridge 1, with all drivers off (See current regulation section of
functional description).
D7 – D12 Bridge 2 Linear DAC. Six-bit word sets desired
current level for Bridge 2. Setting all six bits to zero disables
Bridge 2, with all drivers off (See current regulation section of
functional description).
D13 Bridge 1 Phase. This bit controls the direction of output
current for Load 1.
D13
OUT1A
OUT1B
0
L
H
1
H
L
D14 Bridge 2 Phase. This bit controls the direction of output
current for Load 2.
D14
OUT2A
OUT2B
0
L
H
1
H
L
D15 Bridge 1 Mode.
D15
0
1
Mode
Mixed-decay
Slow-decay
D16 Bridge 2 Mode.
D16
0
1
Mode
Mixed-decay
Slow-decay
D17 REF Select. This bit determines the reference input for
the 6-bit linear DACs.
D17
Reference Voltage
0
Internal 2 V
1
External (3 V max)
D18 Gm Range Select. This bit determines the scaling factor
(4 or 8) used.
D18 Divider
Load Current
0
1/8
1
1/4
ITRIP = VDAC/8RS
ITRIP = VDAC/4RS
continued next page ...
Allegro MicroSystems, Inc.
6
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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