A3961SLB Allegro, A3961SLB Datasheet - Page 7

• Manufacturer Part Number: A3961SLB
• Description: Dual Full Bridge PWM Motor Driver 24-Pin SOIC W
• Manufacturer: Allegro
• Type: Dual Full Bridge PWM Motor Driverr

Specifications of A3961SLB

• Package: 24SOIC W
• Maximum Operating Current: 85 mA
• Operating Temperature: -20 to 85 °C

by placing a capacitor from REF
return for this capacitor as well as R
dent from the high-current power-ground trace to avoid
changes in REF
Thermal Considerations. For reliable operation it is
recommended that the maximum junction temperature be
kept below 110 to 125 C. The junction temperature can
be measured best by attaching a thermocouple to the
power tab/batwing of the device and measuring the tab
temperature, T
approximated by using the formula:
where V
table for the given level of I
given in the package thermal resistance table for the
appropriate package.
be improved by 20 to 30% by adding a section of printed
circuit board copper (typically 6 to 18 square centimeters)
connected to the batwing terminals of the device.
high load currents and/or high duty cycles can be im-
proved by adding external diodes from each output to
ground in parallel with the internal diodes. Fast recovery
( 200 ns) diodes should be used to minimize switching
losses.
with an electrolytic capacitor ( 47 F is recommended)
placed as close to the device as is physically practical.
To minimize the effect of system ground IR drops on the
logic and reference input signals the system ground should
have a low-resistance return to the motor supply voltage.
ations” above.
Fixed Off-Time Selection. With increasing values of t
switching losses will decrease, low-level load current
regulation will improve, EMI will be reduced, the PWM
frequency will decrease, and ripple current will increase.
The value of t
parameters. For applications where audible noise is a
concern, typical values of t
range of 15 to 35 s.
3961
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
If desired, the reference input voltage can be filtered
The power dissipation of the batwing packages can
The thermal performance in applications that run at
The load supply terminal, V
See also “Current Sensing” and “Thermal Consider-
F
can be chosen from the electrical specification
OFF
TAB
IN
T
can be chosen for optimization of these
due to IR drops.
. The junction temperature can then be
J
T
TAB
OFF
LOAD
+ (I
are chosen to be in the
LOAD
. The value for R
BB
IN
, should be decoupled
to ground. The ground
2 V
2
should be indepen-
F
R
JT
)
JT
is
OFF
,