Preliminary
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8
9
10
Pin Name
FB
COMP
GND
EN
LX
VOUT
VDD
PGND
LDRI
LFB
Feedback Input Pin.
Feedback Compensation Pin.
Ground.
Enable Input Pin
Switch Node.
Output Pin
Device Input Power Pin.
Power Ground.
Linear Controller Driver Output.
Linear Controller Feedback Input.
Pin Function
RT9278
Exposed Pad (11) GND
The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Function Block Diagram
COMP
Error
AMPLIFIER
-
V
REF
= 0.8V
VDD
GND
Oscillator
and
Shutdown
Control
Slope
Compen-
sation
Current
Sense
+
Error
Comparator
-
+
VOUT
FB
Control
and
Driver
Logic
LX
EN
PGND
LDRI
LFB
V
REF
= 0.2V
-
+
DS9278-04 August 2007
www.richtek.com
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