a2919 Allegro MicroSystems, Inc., a2919 Datasheet - Page 6

• Manufacturer Part Number: a2919
• Description: Dual Full-bridge Pwm Motor Driver
• Manufacturer: Allegro MicroSystems, Inc.

LOGIC CONTROL OF OUTPUT CURRENT
of the motor winding current at 100%, 67%, 41%, or 0% of
the maximum level per the table. The 0% output current
condition turns OFF all drivers in the bridge and can be
used as an OUTPUT ENABLE function.
entation of P-controlled drive formats.
control the motor at a constant torque between all posi-
tions in an eight-step sequence. This is accomplished by
digitally selecting 100% drive current when only one phase
is ON and 67% drive current when two phases are ON.
Logic highs on both l
rapid current decay.
control the motor position in a sixteen-step sequence.
This is accomplished by digitally selecting drive current as
shown in the table (for one quadrant of operation). Logic
highs on both I
current decay.
reduced current level (and reduced power dissipation) for
‘hold’ conditions and/or increased current (and available
torque) for start-up conditions.
2919
DUAL FULL-BRIDGE
MOTOR DRIVER
QUARTER-STEPPING CURRENT CONTROL
Two logic level inputs (l
These logic level inputs greatly enhance the implem-
During half-step operations, l
During quarter-step operation, I
The logic control inputs can also be used to select a
l
H
H
L
L
CURRENT-CONTROL TRUTH TABLE
0
Current Level
Phase 1
100%
100%
67%
41%
0%
0
and I
I
L
L
H
H
1
0
1
and l
turn OFF all drivers to allow rapid
1
0
turn OFF all drivers to allow
and I
V
V
V
REF
0
REF
REF
1
and l
) allow digital selection
Output Current
Current Level
/24.4 R
0
/10 R
/15 R
and I
Phase 2
1
100%
100%
41%
67%
allow the P to
0%
S
S
1
S
0
= 100% I
allow the P to
= 67% I
= 41% I
TRIP
TRIP
TRIP
GENERAL
direction motor winding current flows. An internally
generated deadtime (approximately 2 s) prevents cross-
over currents that can occur when switching the PHASE
input.
between steps (l
decay through the internal output clamp and flyback
diodes. The fast current decay is desirable in half-step and
high-speed applications. The PHASE, l
float high.
ous control of the peak load current for micro-stepping
applications.
the junction temperature reaches +170 C. It is only
intended to protect the device from failures due to exces-
sive junction temperature and should not imply that output
short circuits are permitted. The output drivers are re-
enabled when the junction temperature cools to +145 C.
low output saturation voltages—less than 1.8 V total
(source plus sink) at 500 mA. Under normal operating
conditions, when combined with the excellent thermal
properties of the batwing package design, this allows
continuous operation of both bridges simultaneously at
500 mA.
The PHASE input to each bridge determines the
All four drivers in the bridge output can be turned OFF
Varying the reference voltage (V
Thermal protection circuitry turns OFF all drivers when
The A2919SB/SLB output drivers are optimized for
0
= l
1
2.4 V) resulting in a fast current
REF
0
) provides continu-
, and I
1
inputs