RT8005
Functional Pin Description
Pin No.
1
2, 3
4
5
Pin Name
LX
PVDD
VDD
EN
Pin Function
Internal Power MOSFET Switches Output. Connect this pin to the inductor.
Power Input Supply. Decouple this pin to PGND with a capacitor.
Signal Input Supply. Decouple this pin to GND with a capacitor. Normally VDD is
equal to PVDD.
Chip Enable (Active High). Logic low shuts down the converter. Floating this pin is
forbidden.
Switcher Feedback Voltage. This pin is the inverting input of the error amplifier.
FB senses the switcher output through an external resistor divider network. FB
regulation voltage is 0.5V.
Compensation Input. This pin is the output of the internal error amplifier. Connect
an external capacitor to compensate the regulator controlled loop.
Signal Ground. All small-signal components, compensation components and the
exposed pad on the bottom side of the IC should connect to this ground, which in
turn connects to PGND at one point. The exposed pad must be soldered to a
large PCB and connected to GND for maximum power dissipation.
Power Ground. Connect this pin close to the terminal of C
IN
and C
OUT
.
6
FB
7
8,
Exposed Pad (11)
9, 10
COMP
GND
PGND
Function Block Diagram
EN
VDD
PVDD
Shutdown
Control
Oscillator
COMP
V
REF
Slope
Compensation
Current Limit
Detector
Over
Temperature
Detector
Current
Sense
-
PWM
Comparator
+
Error
Amplifier
+
Control
Logic
Driver
LX
FB
-
Zero
Detector
GND
PGND
DS8005-08 August 2007
www.richtek.com
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RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
