A4950ELJTR-T Allegro Microsystems Inc, A4950ELJTR-T Datasheet - Page 7

• Manufacturer Part Number: A4950ELJTR-T
• Description: DMOS FULL-BRIDGE MOTOR DRIVER IC
• Manufacturer: Allegro Microsystems Inc

Specifications of A4950ELJTR-T

• Applications: DC Motor Driver
• Number Of Outputs: 1
• Voltage - Load: 8 V ~ 40 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Supply: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 620-1400-2

A4950
Sense Pin (LSS)
In order to use PWM current control, a low-value resistor is
placed between the LSS pin and ground for current sensing pur-
poses. To minimize ground-trace IR drops in sensing the output
current level, the current sensing resistor should have an indepen-
dent ground return to the star ground point. This trace should be
as short as possible. For low-value sense resistors, the IR drops in
the PCB can be significant, and should be taken into account.
When selecting a value for the sense resistor be sure not to
exceed the maximum voltage on the LSS pin of ±500 mV at
maximum load. During overcurrent events, this rating may be
exceeded for short durations.
Ground
A star ground should be located as close to the A4950 as possible.
The copper ground plane directly under the exposed thermal pad
GND
GND
Bill of Materials
Item
1
2
3
C1
Reference
CAPACITANCE
RS
BULK
C1
C2
C2
RS
(for V
GND
REF
Application Information
GND
= 5 V, I
Value
0.25
0.22
100
OUT2
OUT1
Full-Bridge DMOS PWM Motor Driver
VBB
OUT
= 2 A)
of the device makes a good location for the star ground point. The
exposed pad can be connected to ground for this purpose.
Layout
The PCB should have a thick ground plane. For optimum
electrical and thermal performance, the A4950 must be soldered
directly onto the board. On the underside of the A4950 package is
an exposed pad, which provides a path for enhanced thermal dis-
sipation. The thermal pad must be soldered directly to an exposed
surface on the PCB in order to achieve optimal thermal conduc-
tion. Thermal vias are used to transfer heat to other layers of the
PCB.
The load supply pin, VBB, should be decoupled with an electro-
lytic capacitor (typically 100 μF) in parallel with a lower valued
ceramic capacitor placed as close as practicable to the device.
Units
μF
μF
Ω
Thermal Vias
1
GND
IN2
IN1
VREF
PCB
X5R minimum, 50 V or greater
Electrolytic, 50 V or greater
A4950
2512, 1 W, 1% or better,
carbon film chip resistor
A4950
PAD
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
Description
OUT2
OUT1
VBB
LSS
Solder
Trace (2 oz.)
Signal (1 oz.)
Ground (1 oz.)
Thermal (2 oz.)
R
C1
S
C2
V
BB
7