RT8015 Datasheet, PDF (14/15 Pages) Richtek Technology Corporation – 2A, 2MHz, Synchronous Step-Down Regulator

RT8015
Layout Considerations
Follow the PCB layout guidelines for optimal performance of RT8015.
} A ground plane is recommended. If a ground plane layer is not used, the signal and power grounds should be segregated
with all small-signal components returning to the GND pin at one point that is then connected to the PGND pin close
to the IC. The exposed pad should be connected to GND.
} Connect the terminal of the input capacitor(s), C_IN, as close as possible to the PVDD pin. This capacitor provides the
AC current into the internal power MOSFETs.
} LX node is with high frequency voltage swing and should be kept small area. Keep all sensitive small-signal nodes
away from LX node to prevent stray capacitive noise pick-up.
} Flood all unused areas on all layers with copper. Flooding with copper will reduce the temperature rise of power
components. You can connect the copper areas to any DC net (PVDD, VDD, VOUT, PGND, GND, or any other DC rail
in your system).
} Connect the FB pin directly to the feedback resistors. The resistor divider must be connected between VOUT and
GND.
C_IN must be placed between V_DD and
GND as closer as possible
Output capacitor must be
near RT8015
V_IN
C_IN
GND
C_OUT ^VOUT
PVDD
RT8015
5
4
L1
PGND
LX should be
connected to
Inductor by wide
and short trace,
keep sensitive
compontents away
from this trace
VDD
6
3
LX
FB
7
2
GND
COMP
8
R1
C_F
R2 RCOMP
1
SHDN/RT
R_OSC
V_OUT
C_COMP
GND
Connect the FB pin directly to feedback resistors. The
resistor divider must be connected between V_OUT and GND.
Figure 5
Table 1. Recommended Inductor
Component Supplier
Series
Inductance (uH) DCR (mΩ) Current Rating (mA) Dimensions (mm)
TAIYO YUDEN
NR 4018
2.2
60
2700
4.00 x 4.00 x 1.80
Sumida
CDRH4D28
2.2
31.3
2040
4.50 x 4.50 x 3.00
GOTREND
GTSD53
2.2
29
2410
5.00x 5.00 x 2.80
TAIYO YUDEN
NR 4018
1.0
30
4000
4.00 x 4.00 x 1.80
Sumida
CDRH4D28C/LD
1.0
17.5
3000
4.50 x 4.50 x 3.00
GOTREND
GTSD53
1.0
15
4000
5.00x 5.00 x 2.80
Component Supplier
TDK
TDK
Panasonic
Panasonic
TAIYO YUDEN
TAIYO YUDEN
Table 2. Recommended Capacitor
Part No.
C3225X5R0J226M
C3225X5R0J226M
ECJ4YB0J226M
ECJ4YB1A226M
LMK325BJ226ML
JMK316BJ226ML
Capacitance (uF)
22
22
22
22
22
22
Case Size
1210
1210
1210
1210
1210
1206
www.richtek.com
14
DS8015-03 March 2011