MODE
PHASE
ENABLE
SLEEP
A3949
DMOS Full-Bridge Motor Driver
Functional Block Diagram
.22 μF
25 V
VREG
0.1 μF
CP1
CP2
Low Side
Gate Supply
OSC
Charge
Pump
VCP
VBB
0.1 μF
Load
Supply
0.1 μF
100 μF
Control
Logic
DMOS Full Bridge
OUTA
OUTB
SENSE
GND
GND
Control Logic Table
PHASE ENABLE MODE SLEEP OUTA OUTB
Function
1
1
X
1
H
L
Forward
0
1
X
1
L
H
Reverse
X
0
1
1
L
L
Brake (slow decay)
1
0
0
1
L
H
Fast decay SR*
0
0
0
1
H
L
Fast decay SR*
X
X
X
0
Hi-Z
Hi-Z
Sleep mode
* To prevent reversal of current during fast decay SR (synchronous rectification), the outputs
go to the high impedance state as the current approaches zero.
2
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