RT2805A
Pin Configurations
(TOP VIEW)
BOOT
NC
8
SW
VIN
GND
EN
2
3
4
7
6
5
GND
NC
9
FB
SOP-8 (Exposed Pad)
Functional Pin Description
Pin No.
Pin Name
Pin Function
Bootstrap Input for High Side Gate Driver. Connect a 10nF or greater capacitor
from SW to BOOT to power the high side switch.
1
BOOT
2, 3
4
NC
FB
No Internal Connection.
Feedback Input. The feedback threshold is 1.222V.
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. For
automatic startup, leave EN unconnected.
5
EN
6,
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
GND
VIN
9 (Exposed Pad)
Power Input. A suitable large capacitor should be connected from the VIN to
GND to eliminate noise on the input to the IC.
7
8
Switch Node. Note that a capacitor is required from SW to BOOT to power the
high side switch.
SW
Function Block Diagram
VIN
Current Sense
Amplifier
-
+
Ramp
Generator
BOOT
Oscillator
500kHz
S
R
Regulator
EN
FB
Q
Driver
+
-
Error
Reference
12k
Current
SW
Amplifier
+
Comparator
-
Bootstrap
Control
30pF
400k
GND
13pF
Copyright 2012 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS2805A-00 November 2012
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
