RT8003
Functional Pin Description
Pin No.
1
2
3, 4
5
6
7
Pin Name
LX
VDD
NC
EN
FB
COMP
Pin Function
Internal Power MOSFET Switches Output. Connect this pin to the inductor.
Power Input Supply. Input voltage which supplies current to the output pin. Connect
this pin with a low-ESR capacitor to GND
No Internal Connection
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.
Ties the pin directly to the cathode terminal of C
IN
and C
OUT
and ground plane with
the lowest impedance. Signal and Common Ground (The exposed pad must be
soldered to a large PCB and connected to GND for maximum power dissipation).
The GND pad area should be as large as possible and using many vias to conduct
the heat into the buried GND plate of PCB layer. All small-signal, compensation and
feedback components should connect to this pin.
8, 9, 10, 11
(Exposed Pad)
GND
Function Block Diagram
EN
VDD
Shutdown
Control
Oscillator
COMP
V
REF
Slope
Compensation
Current Limit
Detector
Over
Temperature
Detector
Current
Sense
PWM
Comparator
-
+
-
+
Control
Logic
Driver
LX
Error
Amplifier
FB
Zero
Detector
GND
DS8003-08 March 2011
www.richtek.com
3
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
