RT8271
Functional Pin Description
Pin No.
PMSOP-10
1, 3
2
SOP-8
--
1
NC
BOOT
No Internal Connection.
High Side Gate Drive Boost Input. BOOT supplies the drive for the
high side N-MOSFET switch. Connect a 10nF or greater capacitor
from SW to BOOT to power the high side switch.
Power Input. V
IN
supplies the power to the IC, as well as the
step-down converter switches. Bypass VIN to GND with a suitable
large capacitor to eliminate noise on the input to the IC.
Power Switching Output. SW is the switching node that supplies
power to the output. Connect the output LC filter from SW to the
output load. Note that a capacitor is required from SW to BOOT to
power the high side switch.
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
Feedback Input. FB senses the output voltage to regulate said
voltage. The feedback reference voltage is 0.92V typically.
Compensation Node. COMP is used to compensate the regulation
control loop. Connect a series RC network from COMP to GND to
compensate the regulation control loop. In some cases, an additional
capacitor from COMP to GND is required.
Enable Input. EN is a digital input that turns the regulator on or off.
Drive EN higher than 1.4V to turn on the regulator, lower than 0.4V to
turn it off. If the EN pin is open, it will be pulled to high by internal
circuit.
Soft-Start Control Input. SS controls the soft start period. Connect a
capacitor from SS to GND to set the soft-start period. A 10nF
capacitor sets the soft-start period to 1ms.
Pin Name
Pin Function
4
2
VIN
5
6,
11 (Exposed Pad)
7
3
SW
4
5
GND
FB
8
6
COMP
9
7
EN
10
8
SS
DS8271-02 March 2011
www.richtek.com
3
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
