A3964SLBTR Просмотр технического описания (PDF) - Allegro MicroSystems

Номер в каталоге

Компоненты Описание

производитель

A3964SLBTR

DUAL FULL-BRIDGE PWM MOTOR DRIVER

Allegro MicroSystems 

3964

DUAL FULL-BRIDGE

PWM MOTOR DRIVER

If desired, the reference input voltage can be filtered

by placing a capacitor from REFIN to ground. The ground

return for this capacitor as well as RB should be indepen-

dent from the high-current power-ground trace to avoid

changes in REFIN due to IR drops.

Thermal Considerations. For reliable operation, it is

recommended that the maximum junction temperature be

kept below 110°C 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, TTAB . The junction temperature can then be

approximated by using the formula:

TJ ≈ TTAB + (2 ILOAD VF RθJT)

where VF can be chosen from the electrical specification

table for the given level of ILOAD. The value for RθJT is

approximately 6°C/W for both package styles.

The power dissipation of the batwing packages can 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.

The thermal performance in applications that run at

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.

The load supply terminal, VBB, should be decoupled

with an electrolytic capacitor (≥47 µF 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 load supply voltage.

See also “Current Sensing” and “Thermal Consider-

ations” above.

Fixed Off-Time Selection. With increasing values of tOFF,

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 tOFF can be chosen for optimization of these

parameters. For applications where audible noise is a

concern, typical values of tOFF are chosen to be in the

range of 15 to 35 µs.

The products described here are manufactured under one or more

U.S. patents or U.S. patents pending.

Allegro MicroSystems, Inc. reserves the right to make, from time to

time, such departures from the detail specifications as may be required

to permit improvements in the performance, reliability, or

manufacturability of its products. Before placing an order, the user is

cautioned to verify that the information being relied upon is current.

Allegro products are not authorized for use as critical components

in life-support devices or systems without express written approval.

The information included herein is believed to be accurate and

reliable. However, Allegro MicroSystems, Inc. assumes no responsi-

bility for its use; nor for any infringement of patents or other rights of

third parties which may result from its use.

www.allegromicro.com

7

Share Link: