a4403geu-t Allegro MicroSystems, Inc., a4403geu-t Datasheet - Page 14

• Manufacturer Part Number: a4403geu-t
• Description: Valley Current Mode Control Buck Converter
• Manufacturer: Allegro MicroSystems, Inc.

A4403
In terms of grounding the power components, a star connection
should be made to minimize the ground loop impedances. Note
that, although a ground plane may be required to meet the ther-
mal characteristics of the solution, it is still imperative to imple-
ment a star ground connection for the power components.
Figures 5 and 6 illustrate the importance of keeping the ground
connections as short as possible and forming good star connec-
tions.
Figure 5 also illustrates the current conduction paths during the
on-cycle of the switching FET. The following points should be
noted:
• The capacitor C
VIN terminal.
V
9 to 46 V
Figure 7. Typical application
IN
IN
Switching Frequency = 1 MHz
All capacitors are X5R or X7R ceramic
Resistors R3 and R4 should be surface mount, low inductance type, rated at 250 mW at 70°C
100 kΩ
R1
should be placed as close as possible to the
C5
47 nF
2.2 μF
100 V
C1
VIN
TON
DIS
SS
NC
A 4403
GND
Valley Current Mode Control Buck Converter
BOOT
SGND
ISEN
LX
FB
1 nF
C7
• The inductor L should placed as close as possible to the LX
• Good separation should exist between the LX connection and
Figure 6 shows the current conduction path during the off-cycle
of the switching FET. The following points should be noted:
• The diode D should be placed as close as possible to both the
• The boostrap capacitor, C2, and the soft start capacitor, C5,
terminal and to the output capacitors C
any adjacent components or traces.
switching FET and to the inductor. The resistor R should be
placed as close as possible to the diode D.
should be located as close as possible to their respective termi-
nal connections. The ground reference of the soft start capacitor
should be connected as close to the GND terminal as possible.
22 nF
R3
100 mΩ
C2
47 Ω
R2
D1
100 mΩ
R4
6.3 μH
L
1
10 μF
C3
6.3 V
10 μF
C4
6.3 V
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
3.92 kΩ
R5
750 Ω
R6
V
5.0 V
3 A
OUT
OUT
C6
10 nF
.
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