RT8009
` Connect feedback network behind the output capacitors.
Keep the loop area small. Place the feedback
components near the RT8009.
` Connect all analog grounds to a command node and
then connect the command node to the power ground
behind the output capacitors.
` An example of 2-layer PCB layout is shown in Figure 7
and Figure 8 for reference.
Figure 7. Top Layer
V
V
IN
OUT
L1
RT8009
1
5
4
VIN
EN
LX
FB
4.7uH
C1
C2
R3
R1
3
C4
10uF
C3
4.7uF
R2
GND
2
Figure 6. EVB Schematic
Figure 8. Bottom Layer
Recommended component selection for Typical Application
Table 1. Inductors
Inductance (uH) DCR (mΩ) Current Rating (mA) Dimensions (mm)
Component Supplier
TAIYO YUDEN
TAIYO YUDEN
Sumida
Series
NR 3015
NR 3015
CDRH2D14
CDRH2D14
GTSD32
2.2
4.7
2.2
4.7
2.2
4.7
60
120
75
135
58
1480
1020
1500
1000
1500
1100
3x3x1.5
3x3x1.5
4.5x3.2x1.55
4.5x3.2x1.55
3.85x3.85x1.8
3.85x3.85x1.8
Sumida
GOTREND
GOTREND
GTSD32
146
Table 2. Capacitors for CIN and COUT
Component Supplier
TDK
Part No.
C1608JB0J475M
C2012JB0J106M
Capacitance (uF)
Case Size
0603
4.7
10
TDK
0805
MURATA
MURATA
MURATA
GRM188R60J475KE19
GRM219R60J106ME19
GRM219R60J106KE19
JMK107BJ475RA
JMK107BJ106MA
JMK212BJ106RD
4.7
10
10
4.7
10
10
0603
0805
0805
0603
0603
0805
TAIYO YUDEN
TAIYO YUDEN
TAIYO YUDEN
DS8009-03 March 2007
www.richtek.com
11
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
