RN5T566A PCB LAYOUT GUIDE
RN5T566A
PCB Layout Guide
Version 1.1
August 31, 2012
RICOH COMPANY, LTD.
Electronic Devices Company
©2012
RN5T566A PCB LAYOUT GUIDE
Abstract
This document describes the constraints and points when designing the PCB layout with RN5T566A.
This guide provides examples to explain of how it can be done.
The PCB layout example is helpful to achieve optimal RN5T566A performance.
Contents
1.
Basic Policy and Examples of Board Pattern ............................................................................................. 3
1.1
<DCDC block>..................................................................................................................................... 3
1.2
<LDO block>........................................................................................................................................ 5
2.
Recommended External Parts List ............................................................................................................. 6
3.
Example of Parts Layout............................................................................................................................. 8
©2012
Page 2
RN5T566A PCB LAYOUT GUIDE
1. Basic Policy and Examples of Board Pattern
1.1 <DCDC block>
■ DCDC Simple Schematic
VIN
RN5T566A
Cin_A
R
1
Buffer
Power
Supply
Analog
Power
Supply
Cin_B
Cf
L
VFB
VREF
+
Control
and
Analog
Vout
BUF
LX
R2
Cout
Analog
GND
Buffer
GND
GND
Current Loop
Fig.1-1: DCDC Simple Schematic
RN5T566A Pin Names
DCDC1
DCDC2
VCCA
Analog power supply
Buffer power supply
VCCP1
VCCP2
VFB
VFB1
VFB2
LX
LX1
LX2
Table 1-1: RN5T566A Pin Names
©2012
Page 3
RN5T566A PCB LAYOUT GUIDE
(3) (4)
(8)
VFB2
(7)
Cf
R1
R2
Cout
L
(5)
VCCP2
(2)
(1)
LX2
Cin
GND
(6)
VCCP1
LX1
VFB1
Fig.1-2: DCDC Block Evaluation Board Pattern (Top Layer)
■PCB Layout Procedure for DCDC
(1) Place the parts to minimize the switching current loop (Figure 1-1: blue line, Figure 1-2: red line).
(2) Route the LX line between RN5T566A and an inductor as short and wide as possible,
and yet should not add other redundant lines on it
(3) Connect the GND line of “Cout” directly to the internal GND plane with multiple vias, in order to reduce
impedance as small as possible. (Target: 50mΩ or less)
(4) Begin to route the VOUT line from near not “L” but “Cout”.
(5) Place “Cin” as close as possible to RN5T566A. (Higher priority level is “Cin” < L < “Cout” in the close
distance order with RN5T566A.)
Note: For evaluations being compliant with each DCDC specifications, the PCB layout shown in Fig.1-2
provides the routing for VCCP1 and VCCP2 separately.
But, the routing for them is permitted to unity when designing a PCB layout in actually.
(6) Place inductors for DCDC1 and DCDC2 without becoming too close between them, in order to avoid
the electromagnetic interference.
©2012
Page 4
RN5T566A PCB LAYOUT GUIDE
(7) Route the VFB line to be not the parallel routing to other lines, which may cause noise, because of being
easily influenced by noise. Route the VFB line as possible and put some distance from the other lines if
need the parallel routing due to limitations of terminal configuration.
To maintain a stable operation, note against extra parasitic capacitance.
(8) Place R1, R2, and Cf as close as possible in the same layer, and connect GND of R2 to a stable GND.
1.2 <LDO block>
Vout
VFBLDO2
Cout R1
(1)
(2)
R2
R3
Fig.1-3: LDO Block Evaluation Board Pattern (Top Layer)
■PCB Layout Procedure for LDO
(1) Place “Cout” as close as possible to RN5T566A to get better a load regulation.
(2) Route the VFBLDO line output from LDO (LDO2 and LDO4), which can change the output voltage by
external resistors, not to be the parallel routing to the source of noise. In this time, place external
resistors as close as possible to the VFBLDO line, and thereby the extra parasitic capacitance is not
required.
Note: In the evaluation board shown in Fig.1-3, two resistors are placed for the resistance value in the
upper side, in order to control the output easily at the evaluation.
©2012
Page 5
RN5T566A PCB LAYOUT GUIDE
2. Recommended External Parts List
RN5T566A External Parts
Block
Pin Name
PMU
LDO
VCCL1
VO1
VO2
Parts
Model value
0.1uF
1.0uF
2.2uF
R1(VO2)
VFBLDO2
R2(VO2)
VCCL3
VIN
VO3
1.0uF
VO4
1.0uF
R1(VO4)
VFBLDO4
R2(VO4)
VCCL5
VIN
VO5
1.0uF
VCCA
1.0uF
VREFO
1.0uF
INT18
1.0uF
DET
R1(DET)
VD1IN
R2(DET)
VD1HYS R3(DET)
DCDC VCCP1
22uF
VCCP2
LX1
2.2uH
47uF
R1(DC1)
VFB1
R2(DC1)
Cf(DC1)
LX2
2.2uH
47uF
R1(DC2)
VFB2
R2(DC2)
Cf(DC2)
RN5T566A
GRM155B31E104KA87
C1005JB1C105K
C1608JB0J225K
(Refer to Table 2-2)
GRM155B31E104KA87
C1005JB1C105K
C1005JB1C105K
(Refer to Table 2-2)
GRM155B31E104KA87
C1005JB1C105K
C1005JB1C105K
C1005JB1C105K
C1005JB1C105K
(Refer to Figure 2-1)
GRM21BB30J226ME38
MIPSZ2012D2R2
C2012X5R0J476M
(Refer to Table 2-3)
MIPSZ2012D2R2
C2012X5R0J476M
(Refer to Table 2-4)
Vender Num
RICOH
Murata
TDK
TDK
Murata
TDK
TDK
Murata
TDK
TDK
TDK
TDK
Murata
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
FDK
TDK
FDK
TDK
-
1
1
1
1
1
1
1
1
1
1
Total Num 30
Parts Size [mm]
X Size Y Size Z Size [mm2]
6.00 6.00 0.90
36
1.00 0.50 0.50
0.5
1.00 0.50 0.50
0.5
1.60 0.80 0.80
1.28
1.00 0.50 0.35
0.5
1.00 0.50 0.35
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.35
0.5
1.00 0.50 0.35
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.50
0.5
1.00 0.50 0.35
0.5
1.00 0.50 0.35
0.5
1.00 0.50 0.35
0.5
2.00 1.25 1.25
2.5
2.00
2.00
1.00
1.00
1.00
2.00
2.00
1.00
1.00
1.00
1.25
1.25
0.50
0.50
0.50
1.25
1.25
0.50
0.50
0.50
1.00
1.25
0.35
0.35
0.50
1.00
1.25
0.35
0.35
0.50
2.5
2.5
0.5
0.5
0.5
2.5
2.5
0.5
0.5
0.5
Total Parts size 61.28
Table 2-1: External Parts list
R1
R2
Output Voltage
3.30V
230kΩ
100kΩ
3.00V
200kΩ
100kΩ
2.85V
185kΩ
100kΩ
2.80V
180kΩ
100kΩ
1.80V
80kΩ
100kΩ
Table 2-2: LDO2 and LDO4 External Resistor
©2012
Page 6
RN5T566A PCB LAYOUT GUIDE
Example:
VH=3.4V, VL=3.3V
:R1=240kΩ, R2=100kΩ, R3=4.3kΩ
VL=(R1+R2+R3)/(R2+R3)×Vref
VH=(R1+R2)/R2×Vref
VH = Higher voltage threshold
VL=lower voltage threshold
Vref=reference voltage
Fig.2-1: Voltage Detection1 Timing
Output Voltage
R1
R2
Cf
1.775V
47kΩ
24kΩ
100pF
1.5V
36kΩ
24kΩ
100pF
1.2V
30kΩ
30kΩ
220pF
Table 2-3: Step-down DCDC Converter1 External Components
Output Voltage
R1
R2
Cf
1.2V
30kΩ
30kΩ
220pF
1.1V
30kΩ
36kΩ
220pF
1.0V
22kΩ
33kΩ
220pF
Table 2-4: Step-down DCDC Converter2 External Components
©2012
Page 7
RN5T566A PCB LAYOUT GUIDE
3. Example of Parts Layout
This layout is one example of parts layout with RN5T566A
12 mm
10.4 mm
2.1 mm
RN5T
566A
5.7 mm
3.4 mm
Total Parts Area 139.49mm2
0.8 mm
Fig.3-1: Example of Parts Layout
Note: Connect Exposed Paddle (Tab on the bottom side) to GND.
©2012
Page 8