RT8253B RICHTEK [Richtek Technology Corporation], RT8253B Datasheet - Page 2

• Manufacturer Part Number: RT8253B
• Description: 3A, 23V, 1.2MHz Synchronous Step-Down Converter
• Manufacturer: RICHTEK [Richtek Technology Corporation]

RT8253B
Typical Application Circuit
Recommended Component Selection
www.richtek.com
2
Functional Pin Description
9 (Exposed Pad)
V
OUT
3.3
2.5
1.5
1.2
8
5
1
Pin No.
(V) R1 (kΩ)
4,
1
2
3
5
6
7
8
4.5V to 23V
25.5
10.5
27
62
75
12
3
0.1µF
V
C
IN
BOOT
VIN
SW
GND
FB
COMP
EN
SS
Pin Name
SS
R2 (kΩ)
11.8
24
12
12
24
12
3
4, Exposed Pad (9)
R
EN
10µF x 2
C
R
Bootstrap for High Side Gate Driver. Connect a 0.1μF or greater ceramic
capacitor from BOOT to SW pins.
Input Supply Voltage, 4.5V to 23V. Must bypass with a suitably large ceramic
capacitor.
Switch Node--Connect this pin to an external L-C filter.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Feedback Input. 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 divider. For an adjustable output, an external resistive divider is
connected to this pin.
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.
Chip Enable (Active High). A logic low forces the RT8253B 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 13.5ms.
IN
100k
C
8.2
6.8
51
33
22
16
10
(kΩ)
2
7
8
VIN
EN
SS
GND
C
C
2.2
2.2
2.2
2.2
2.2
2.2
2.2
RT8253B
(nF)
COMP
BOOT
L (μH)
SW
FB
6.8
3.6
3.6
10
2
2
2
1
3
5
6
2.2nF
C
C
100nF
Pin Function
C
BOOT
C
Open
OUT
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
C
P
22k
R
3.6µH
C
(μF)
L
R1
75k
24k
R2
DS8253B-02 March 2011
C
22µF x 2
OUT
V
3.3V/3A
OUT