RT8015D
Typical Application Circuit
V
IN
5V
C
IN
22µF
R4
100k
RT8015D
6 PVDD
R3
1
C1
0.1µF
R
OSC
332k
7 VDD
8
LX
3, 4
L1
2.2µH
C
F
22pF
FB 9
R
COMP
C
COMP
1nF
27k
COMP 10
GND
PGND
2
5
R2
240k
R1
510k
V
OUT
2.5V/3A
C
OUT
22µF x 2
PGOOD
PGOOD
1 SHDN/RT
Note : Using all Ceramic Capacitors
Table 1. Recommended Component Selection
V
OUT
(V)
3.3
2.5
1.8
1.5
1.2
1.0
R1 (kΩ )
750
510
300
210
120
60
R2 (kΩ )
240
240
240
240
240
240
R
COMP
(kΩ) C
COMP
(nF)
30
27
22
18
15
13
1
1
1
1
1
1
L1 (μH)
2.2
2.2
2.2
2.2
1.0
1.0
C
OUT
(μF)
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
Functional Pin Description
Pin No.
1
2
3, 4
5
6
7
8
9
Pin Name
SHDN/RT
GND
LX
PGND
PVDD
VDD
PGOOD
FB
Pin Function
Oscillator Resistor Input. Connecting a resistor to ground from this pin sets the
switching frequency. Forcing this pin to V
DD
causes the device to be shut down.
Signal Ground. All small-signal components and compensation components should
connect to this ground, which in turn connects to PGND at one point.
Internal Power MOSFET Switches Output. Connect this pin to the inductor.
Power Ground. Connect this pin close to the negative terminal of C
IN
and C
OUT
.
Power Input Supply. Decouple this pin to PGND with a capacitor.
Signal Input Supply. Decouple this pin to GND with a capacitor. Normally V
DD
is equal
to PVDD.
Power Good Indicator. This pin is open-drain logic output that is pulled to ground
when the output voltage is not within ±12.5% of regulation point.
Feedback Pin. This pin receives the feedback voltage from a resistive divider
connected across the output.
Error Amplifier Compensation Point. The current comparator threshold increases with
10
COMP
this control voltage. Connect external compensation elements to this pin to stabilize
the control loop.
11
Exposed Pad
No Internal Connection. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
DS8015D-02 March 2011
www.richtek.com
2
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
