L6219DS
Dual Full-Bridge PWM Motor Driver
Logic Control of Output Current
Two logic level inputs (I
0
and I
1
) allow digital selection of
the motor winding current at 100%, 67%, 33%, or 0% of the
maximum level per the table below. The 0% output current
condition turns off all drivers in the bridge and can be used as an
OUTPUT ENABLE function.
These logic level inputs greatly enhance the implementation of
μP-controlled
drive formats.
During half-step operations, the I
0
and I
1
allow the
μP
to control
the motor at a constant torque between all positions 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 I
0
and I
1
turn off all
drivers to allow rapid current decay when switching phases. This
helps to ensure proper motor operation at high step rates.
The logic control inputs can also be used to select a reduced
current level (and reduced power dissipation) for ‘hold’
conditions and/or increased current (and available torque) for
start-up conditions.
Current-Control Truth Table
l
0
L
H
L
H
I
1
L
L
H
H
Output Current
V
REF
/10 R
S
= I
TRIP
V
REF
/15 R
S
= 2/3 I
TRIP
V
REF
/30 R
S
= 1/3 I
TRIP
0
General
The PHASE input to each bridge determines the direction
motor winding current
fl
ows. An internally generated dead time
(approximately 2
μs)
prevents crossover currents that can occur
when switching the PHASE input.
All four drivers in the bridge output can be turned off between
steps (I
0
= I
1
≥
2.4 V) resulting in a fast current decay through the
internal output clamp and
fl
yback diodes. The fast current decay
is desirable in half-step and high-speed applications. The PHASE,
I
0
,and I
1
inputs
fl
oat high.
Varying the reference voltage (V
REF
) provides continuous control
of the peak load current for microstepping applications.
Thermal protection circuitry turns off all drivers when the
junction temperature reaches 170°C. It is only intended to protect
the device from failures due to excessive 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.
The L6219DS output drivers are optimized for 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 fused internal lead
package design, this allows continuous operation of both bridges
simultaneously at 500 mA.
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
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