RT8279 RICHTEK [Richtek Technology Corporation], RT8279 Datasheet - Page 2

• Manufacturer Part Number: RT8279
• Description: 5A, 36V, 500kHz Step-Down Converter
• Manufacturer: RICHTEK [Richtek Technology Corporation]

RT8279
Typical Application Circuit
www.richtek.com
2
Functional Pin Description
9 (Exposed Pad)
Pin No.
2, 3
6,
1
4
5
7
8
V
OUT
2.5
3.3
5
8
(V)
5.5V to 36V
Chip Enable
BOOT
NC
FB
EN
GND
VIN
SW
Pin Name
Open = Automatic
V
IN
Startup
6, 9 (Exposed Pad)
R1 (kΩ)
100
100
100
100
Table 1. Recommended Component Selection
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.
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.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Power Input. A suitable large capacitor should be bypassed from VIN to GND to
eliminate noise on the input to the IC.
Power Switching Output. Note that a capacitor is required from SW to BOOT to
power the high side switch.
4.7µF/
50V x 2
C
IN
7
5
VIN
EN
GND
R2 (kΩ)
58.6
31.6
100
18
RT8279
BOOT
SW
FB
1
8
4
C
FF
82
82
82
82
(pF)
C
B550A
10nF
D1
Pin Function
BOOT
L1
C
FF
L (μH)
6.8
10
15
22
R2
R1
DS8279-01
C
22µF x 2
OUT
C
V
OUT
OUT
22 x 2
22 x 2
22 x 2
22 x 2
(μF)
December 2011