RT8284N
Typical Application Circuit
1
3
V
2
IN
VIN
BOOT
RT8284N
4.5V to 23V
C
C
BOOT
10nF
IN
L
10µF
10µH
V
OUT
SW
3.3V/2A
R
100k
EN
R1
7
8
EN
SS
26.1k
C
OUT
22µF x 2
5
6
FB
C
C
C
0.1µF
R
SS
C
R2
3.3nF
13k
10k
4, 9 (Exposed Pad)
COMP
GND
C
P
Open
Recommended Component Selection
(V) R1 (kΩ) R2 (kΩ) R (kΩ) C (nF) L (μH)
V
OUT
C
OUT
(μF)
C
C
8
5
3.3
2.5
1.8
1.2
76.8
45.3
26.1
16.9
9.53
3
10
10
10
10
10
10
27
20
13
9.1
5.6
3.6
3.3
22
15
10
6.8
4.7
3.6
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
3.3
3.3
3.3
3.3
3.3
Functional Pin Description
Pin No.
Pin Name
Pin Function
SOP-8
(Exposed Pad)
SOP-8
Bootstrap for High Side Gate Driver. Connect a 10nF or greater
ceramic capacitor from BOOT to SW pins.
1
1
BOOT
Input Supply Voltage, 4.5V to 23V. Must bypass with a suitably large
ceramic capacitor.
2
3
4
2
3
VIN
SW
Phase Node. Connect this pin to external L-C filter.
4,
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
GND
9 (Exposed Pad)
Feedback Input Pin. This pin is connected to the converter output. It
is used to set the output of the converter to regulate to the desired
value via an internal resistive voltage divider. For an adjustable
output, an external resistive voltage divider is connected to this pin.
5
6
7
8
5
6
7
8
FB
Compensation Node. COMP is used to compensate the regulation
control loop. Connect a series RC network from COMP to GND. In
some cases, an additional capacitor from COMP to GND is required.
COMP
EN
Enable Input pin. A logic high enables the converter; a logic low
forces the RT8284N into shutdown mode reducing the supply current
to less than 3μA. Attach this pin to VIN with a 100kΩ pull up resistor
for automatic startup.
Soft-Start Control Input. SS controls the soft-start period. Connect a
capacitor from SS to GND to set the soft-start period. A 0.1μF
capacitor sets the soft-start period to 15.5ms .
SS
Copyright 2012 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8284N-03 May 2012
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
