RT9921PQV View Datasheet(PDF) - Richtek Technology
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Description
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RT9921PQV Datasheet PDF : 15 Pages
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RT9921
Preliminary
z The analog ground (AGND) consists of the grounds of compensation, soft-stat capacitor, FB divider, and OP divider.
The AGND should be separated from PGND and connected to the ground of the input capacitor.
z The exposed pad of the chip should be connected to analog ground plane for thermal consideration.
Placing the power
components as
close as possible.
The traces should
be wide and short
especially for the
high-current
output loop.
Minimize the size
of the Lx node
and keep it wide
and Shorter.
Keep the Lx node
away from the FB
and analog
ground.
The feedback
voltage-divider
resistors must near
the Feedback pin.
The divider center
trace must be
shorter and avoid
the trace near any
switching nodes.
The power ground (PGND) consists of
input and output Capacitor grounds,
the components' ground of charge
Pump and GPM. The PGND should
be wide and short enough to connect
to a ground plane.
The feedback voltage-divider
resistors must near the
Feedback pin. The divider
center trace must be shorter
and avoid the trace near any
switching nodes.
PGND
AGND
VIN
C2
R2
C3
R3
R1
AVDD
C1
D1
24 23 22 21 20 19
LX 1
L1
VIN 2
R5
SS 3
AGND 4
ADJ 5
LDOO 6
R4
C9
AGND
http://www.DataSheet4U.net/
18 AVDD
17 DRVP
16 FBP
15 VGH PGND
14 VGHM
13 RE
7 8 9 10 11 12
PGND
PGND
The analog ground (AGND)
consists of the grounds of
Compensation, soft-stat
capacitor, FB divider, and OP
divider. The AGND should be
separated from PGND and
connected to the ground of
the input capacitor.
The compensation circuit
should be kept away from The
power loops and should be
shielded with a ground trace to
prevent any noise coupling.
The exposed pad of the chip
should be connected to analog
ground plane for thermal
consideration.
www.richtek.com
14
DS9921-00 November 2007
datasheet pdf - http://www.DataSheet4U.net/
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