RN5T566A - Ricoh

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 ..................................................................................................................................... 3
1.2 ........................................................................................................................................ 5
2. Recommended External Parts List ............................................................................................................. 6
3. Example of Parts Layout............................................................................................................................. 8
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RN5T566A PCB LAYOUT GUIDE
1. Basic Policy and Examples of Board Pattern
1.1
■ DCDC Simple Schematic
VIN
RN5T566A
Analog
Power
Supply
Buffer
Power
Supply
Cin_A
R
1
R2
Cf
VFB
VREF
-
+
Control
and
Analog
BUF
LX
Cin_B
L
Cout
Vout
Analog
GND
Buffer
GND
GND
Current Loop
Fig.1-1: DCDC Simple Schematic
RN5T566A Pin Names
DCDC1
DCDC2
Analog power supply
VCCA
Buffer power supply VCCP1 VCCP2
VFB VFB1 VFB2
LX LX1 LX2
Table 1-1: RN5T566A Pin Names
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RN5T566A PCB LAYOUT GUIDE
(3)
(4) (8)
Cf
VFB2
(7)
R1
R2
(5)
GND
Cout
VCCP2
Cin
L
(1)
LX2
(6)
(2)
VCCP1
LX1
VFB1
■PCB Layout Procedure for DCDC
Fig.1-2: DCDC Block Evaluation Board Pattern (Top Layer)
(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.
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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
(1)
Vout
Cout
R1
R2
(2)
VFBLDO2
R3
■PCB Layout Procedure for LDO
Fig.1-3: LDO Block Evaluation Board Pattern (Top Layer)
(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.
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RN5T566A PCB LAYOUT GUIDE
2. Recommended External Parts List
RN5T566A External Parts
Block Pin Name
Parts Size [mm]
Parts Model value Vender Num
X Size Y Size Z Size [mm2]
PMU - - RN5T566A RICOH 1 6.00 6.00 0.90 36
LDO VCCL1 0.1uF GRM155B31E104KA87 Murata 1 1.00 0.50 0.50 0.5
VO1 1.0uF C1005JB1C105K TDK 1 1.00 0.50 0.50 0.5
VO2 2.2uF C1608JB0J225K TDK 1 1.60 0.80 0.80 1.28
VFBLDO2
R1(VO2) - 1 1.00 0.50 0.35 0.5
(Refer to Table 2-2)
R2(VO2) - 1 1.00 0.50 0.35 0.5
VCCL3 VIN GRM155B31E104KA87 Murata 1 1.00 0.50 0.50 0.5
VO3 1.0uF C1005JB1C105K TDK 1 1.00 0.50 0.50 0.5
VO4 1.0uF C1005JB1C105K TDK 1 1.00 0.50 0.50 0.5
VFBLDO4
R1(VO4) - 1 1.00 0.50 0.35 0.5
(Refer to Table 2-2)
R2(VO4) - 1 1.00 0.50 0.35 0.5
VCCL5 VIN GRM155B31E104KA87 Murata 1 1.00 0.50 0.50 0.5
VO5 1.0uF C1005JB1C105K TDK 1 1.00 0.50 0.50 0.5
VCCA 1.0uF C1005JB1C105K TDK 1 1.00 0.50 0.50 0.5
VREFO 1.0uF C1005JB1C105K TDK 1 1.00 0.50 0.50 0.5
INT18 1.0uF C1005JB1C105K TDK 1 1.00 0.50 0.50 0.5
DET R1(DET) - 1 1.00 0.50 0.35 0.5
VD1IN
R2(DET) (Refer to Figure 2-1) - 1 1.00 0.50 0.35 0.5
VD1HYS R3(DET) - 1 1.00 0.50 0.35 0.5
DCDC VCCP1 22uF GRM21BB30J226ME38 Murata 1 2.00 1.25 1.25 2.5
VCCP2
LX1 2.2uH MIPSZ2012D2R2 FDK 1 2.00 1.25 1.00 2.5
47uF C2012X5R0J476M TDK 1 2.00 1.25 1.25 2.5
VFB1
R1(DC1) - 1 1.00 0.50 0.35 0.5
R2(DC1) (Refer to Table 2-3) - 1 1.00 0.50 0.35 0.5
Cf(DC1) - 1 1.00 0.50 0.50 0.5
LX2 2.2uH MIPSZ2012D2R2 FDK 1 2.00 1.25 1.00 2.5
47uF C2012X5R0J476M TDK 1 2.00 1.25 1.25 2.5
VFB2
R1(DC2) - 1 1.00 0.50 0.35 0.5
R2(DC2) (Refer to Table 2-4) - 1 1.00 0.50 0.35 0.5
Cf(DC2) - 1 1.00 0.50 0.50 0.5
Total Num 30 Total Parts size 61.28
Table 2-1: External Parts list
Output Voltage R1 R2
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
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RN5T566A PCB LAYOUT GUIDE
VH = Higher voltage threshold
VL=lower voltage threshold
Vref=reference voltage
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
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
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RN5T566A PCB LAYOUT GUIDE
3. Example of Parts Layout
This layout is one example of parts layout with RN5T566A
12 mm
2.1 mm
10.4 mm
RN5T
566A
5.7 mm
Total Parts Area 139.49mm 2
3.4 mm
0.8 mm
Fig.3-1: Example of Parts Layout
Note: Connect Exposed Paddle (Tab on the bottom side) to GND.
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