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中小型面板之电源管理器件 及应用介绍. 郑刚 专案副理 http://www.richtek.com. LDO Linear Regulators for Mobile Phone Application LED Drivers for Display Backlighting PCB Layout Considerations for Mobile Phone Power Circuit. Outline. Back. LDO Linear Regulators for Mobile Phone Application. Back. Outline. - PowerPoint PPT Presentation
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中小型面板之电源管理器件及应用介绍
郑刚 专案副理 http://www.richtek.com
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OutlineOutline
LDO Linear Regulators for Mobile Phone Application
LED Drivers for Display Backlighting
PCB Layout Considerations for Mobile Phone Power Circuit
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LDO Linear Regulators for Mobile Phone Application
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Outline Outline
Fundamental Introduction of LDO
Important Characteristic of LDO
Richtek LDOs for Cellular Phone Applications
LDO Topologies
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Low Drop Out: A linear voltage regulator that will operate even when the input voltage barely exceeds the desired output voltage.
Applications: Cellular Phones Notebook PCMCIA Cards Mother Board Power Supply Cable Modems Wireless LAN ……………………
Fundamental Introduction of LDOFundamental Introduction of LDOWhat is LDO ?
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I-V Characteristic of N-channel MOSFETI-V Characteristic of N-channel MOSFET
VIN
RLOAD
ControlCircuit
+ VDS -
D S
GR1
R2
NMOSSlop=1/Ri
Cutoff Region : VGS < Vt
Linear Region : VDS < VGS-Vt
Saturation Region: VDS > VGS-Vt
Vds=VIN - Vo
+
Vo
-
2
2
1DSoxnDS vCi Boundary:
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LDO TopologiesLDO Topologies
1. The reference
2. The pass element
3. The sampling resistor
4. The error amplifier
Four basic functional blocks:
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Load RegulationLoad Regulation Load regulation is a measure of the circuit’s ability to maintain the specified output voltage under varying load conditions.
Load regulation is defined as:
O
O
I
VregulationLoad
RT9182
Vo
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Line regulation is a measure of the circuit’s ability to maintain the specified output voltage with varying input voltage.
Line regulation is defined as:
Line RegulationLine Regulation
I
O
V
VregulationLine
RT9182
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Transient ResponseTransient ResponseThe transient response is an important specification, which is the maximum allowable output voltage variation for a load current step change.
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PSRR (Power Supply Rejection Ratio)PSRR (Power Supply Rejection Ratio)This specification is the measure of how well the regulator rejects an AC signal riding on a nominal input DC voltage
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Improved PSRRImproved PSRR
LC filter An additional linear regulator
One or more cascades of external RC filters
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Output Noise VoltageOutput Noise VoltageOutput noise voltage is the RMS output noise voltage over a bandwidth (10Hz to 100KHz) under the conditions of a constant output current and a ripple-free input voltage. The noise generated only by the LDO itself.
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The LDO output noise can be reduced by effective LDO internal design and external bypass and compensation
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Thermal ResistanceThermal Resistance
QDOI PPPP OID PPP
JAAJD TTP /)(
DAJJA PTT /)(
max DD PP or max JAJA Back
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VI-max= 4.2V
Design ExampleDesign Example
Vo= 2.5V
1. 100mA duty cycle D1 = 0.378/4.61=8.2%; 60mA duty cycle D2=91.8%
2. PD(100mA) = (Vi-Vo)Io+(Vi x Iq)
= (4.2V-2.5V)100mA + (4.2V x 130uA) = 170.55mW
PD(60mA) = (4.2V-2.5V)60mA + (4.2 x 130uA)= 102.55mW
3. PD(total) = PD(100mA) x D1 + PD(60mA) x D2 = 170.55mW x 8.2% +
102.55mW x 91.8% =108.13 mW
The maximum power dissipation for RT9198 operating at an ambient temperature of 70 : SOT-25: 220mW, SC-70: 165mW
Selecting SC-70 package
ILoa
d (m
A) 100mA
T(ms)
60mA
4.61ms
0.378ms
A 2.5V system using RT9198 to supply
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CMOS Camera Module PowerCMOS Camera Module Power
CIF
Array Size 640X480 ( VGA )
Digital 2.5VDC ± 10%
Analog 2.5VDC ± 4%
DOVDD is 2.8~3.0V sensor digital IO power
Dropout is not critical. ( Li-ion battery range from 3.2V to 4.2V) Require low-noise and high PSRR LDOs for AVDD. This LDO is not on all the time, so the quiescent current is not care. Small package.
VDD
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RT9167/A Low-Noise, 300mA/500mA LDO Regulator Feature Shutdown function Low-Dropout: 350mV at 300mA Low Noise Output Short circuit and thermal protection function SOT-25 package
RT9178 Ultra Low Noise, High PSRR LDO Regulator Feature 50uV Ultra-Low Output Noise Quick Start-up ( Typical 100us) Low-Dropout: 200mV at 200mA High PSRR SOT-25 package
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RT9182 Dual, Low-Noise, 200mA LDO Regulator Feature Dual shutdown pin control each output Low-Dropout: 120mV at 100mA 124uVrms Low Noise Output Short circuit and thermal protection function SOT-26 package
RT9198 300mA, High PSRR LDO Regulator Feature <0.01uA quiescent current when shutdown Low-Dropout: 220mV at 300mA High PSRR and ultra-low-noise for phone application SOT25/SC-70 package
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LED Drivers for Display Backlighting
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Outline
Features of White LEDFeatures of White LED Driver Solutions for WLEDDriver Solutions for WLED Efficiency AnalysisEfficiency Analysis RichTek Solutions for WLED DriverRichTek Solutions for WLED Driver
Backlight Driver Solutions for Dual PanelsBacklight Driver Solutions for Dual Panels
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White LED Background Info
Brightness is proportional to CURRENT Most popular LED currents (ILED) for backlight:10~15mA
(for camera flash: 50~120mA) LED forward voltage (VLED): Can range from 3V to 4Vtypically. Most
common: 3.3V~3.6V Forward voltage is a measure of efficiency of the LED… does not affect
brightness much
The LED with the higher VLED for a given current burns more power (VxI)
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White LED Connection
Parallel Connection No inductor requirement Low EMI
Series Connection Lighting uniformity Higher efficiency Higher current capability Easy layout
EXTVDD
CE
WLED Driver
GND
Charge Pump Topology
Panel
LXVDD
CE
WLED Driver FB
GND
Boost Topology
Panel
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WLED Driver Solution for Backlight
LX
VDD
CE
Boost FB
GND
Boost Topology RT9271
Panel
Charge Pump with RT9362Current source Topology RT9360
VDD
CE
Panel
CP
CS
VDD
CE
CS
Current source Topology RT9300
Panel
Low VF LED
VDD
CE
CP
Charge Pump Topology RT9361
Panel
Same VF LED
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WLED Driver Solution - Boost Converter
CS R
+
Vo
-V s
L
+ V L -
D IoLI
CCMCCM SS on , 0 on , 0 << tt << ttonon
CV s
L
R
+ V L - +
-
IL
Vo
SS off , t off , tonon << tt << ttoffoff
C
L
R
+ V L - +
Vo
-
IL
V s
From volt-second balance principle
so
os
sos
VD
V
TVDTV
TDVVDTV
1
1
)1(
)1)((
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WLED Driver Solution - Boost Converter
S
)(tiL
Ia
Ib 2
baL
III
DT (1-D)T
T
)(tVL
Vs-Vo
Vs
ton toff
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WLED Driver Solution - Boost Converter
DCMDCM
SS on , 0 on , 0 << tt << t1t1
SS off , t1 off , t1 << tt << t2t2
SS off , off , D offD off, t2, t2 << tt << TT
CV s
L
R
+ V L - +
Vo
-
IL
CV s
L
R
+ V L - +
-
IL
Vo
C
L
R
+ V L - +
Vo
-
IL
V s
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WLED Driver Solution - Boost Converter
S
)(tiL
Ib
T
)(tVL
Vs-Vo
Vs
t1 t2 t3
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WLED Driver Solution - Charge PumpOn StateOn State
Off StateOff State
During the on state, Q1 and Q4 are closed, which charge C1 to VIN
During the off state, Q3 and Q2 are closed.The output voltage is VIN plus VC1, that is 2VIN
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LED Driver Efficiency vs. Converter Efficiency
LED Driver Efficiency LED Driver Efficiency
= “Power delivered to the LEDs” ÷ “Power drawn by the Input”= “Power delivered to the LEDs” ÷ “Power drawn by the Input”
LED Driver LED Driver Efficiency = PLED ÷ PIN = (NxVLEDxILED) ÷ (VINxIIN)
Converter EfficiencyConverter Efficiency
= “Power delivered to the Output pin” ÷ “Power drawn by the Input”= “Power delivered to the Output pin” ÷ “Power drawn by the Input”
Converter Efficiency= POUT ÷ PIN = (VOUTxIOUT) ÷ (VINxIIN)
Converter Efficiency does not account for Power losses of external ballast resistors
LED Driver Efficiency & Converter Efficiency confusion can always be avoided by comparing “INPUT POWER”
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Efficiency - Example
Parallel Connection – Charge Parallel Connection – Charge PumpPump
LED Power (PLED)
= VF * IOUT * 3
= 3.5 * 20mA * 3
= 210mW
Input Power (PIN)
= VOUT * IOUT / Converter
Efficiency = 5V * 20mA * 3 / 0.85 = 352.9mW
LED Driver Efficiency
= PLED / PIN
= 59.5%
Series Connection – BoostSeries Connection – Boost
LED Power (PLED)
= VF * 3 * IOUT
= 3.5 * 3 * 20mA = 210mW
Input Power (PIN)
= VOUT * IOUT / Converter
Efficiency = (3.5 * 3 + 0.25)V * 20mA / 0.85 = 252.9mW
LED Driver Efficiency
= PLED / PIN
= 83% AssumptionAssumption
Test Condition is in 3 WLEDs – Mobile phone application Forward voltage of WLED is 3.5V and output current is 20mA The converter efficiency of boost and charge pump is the same as
85% The output of charge pump is about 5V The feedback of boost is 0.25V
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WLED Driver Solution - Charge Pump
The amount of charge flowing into C1 during on state is equal to that flowing out of C1 at off state
The efficiency of charge pump is given below:
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LCM Power Solution
White LED DriverWhite LED Driver Single PanelSingle Panel
- RT9271 (Boost DC/DC Converter)
- RT9360 (Charge Pump + Current Source)
- RT9362 (Charge Pump + Current Source)
- RT9361 (Charge Pump)
- RT9300 (Current Source)
Dual PanelDual Panel
- RT9272 (TFT/CSTN + TFT/CSTN)
- RT9273 (TFT/CSTN + OLED)
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Power Solution
RT9271White LED Boost converter with OVP
Feature High Efficiency: 85% typical 20V Internal Switch Fast 1.1MHz Switching Frequency Requires Only 1uF Input/Output Capacitor Low FB Voltage - 0.25V Optional 15V Over Voltage Protection Support camera flash application Low Profile SOT-25/26 Package Typical Application
Up to 80mA peak
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Power Solution
RT9271White LED Boost converter with OVP
Function Block Diagram
VDD
CE
OVP
FB
CE
GND
VCC
LX
Panel
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Power Solution
RT9271White LED Boost converter with OVP
Dimming Control
RT9271RT9271 FBFB
Using a DC VoltageUsing a DC Voltage
Using a Logic SignalUsing a Logic Signal
Using a Filtered PWM ControlUsing a Filtered PWM Control
RT9271RT9271 FBFB
RT9271RT9271 FBFB
200~1KHz
RT9271RT9271CECE FBFB
Using a PWM ControlUsing a PWM Control
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Power Solution
Inductor Selection
Inductance valueInductance value ESR: copper lossESR: copper loss Magnetic loss Magnetic loss SaturationSaturation Current RatingCurrent Rating Operation Operation
frequencyfrequency Leakage & NoiseLeakage & Noise HeightHeight
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Power Solution
RT9360High Efficiency Charge Pump WLED Driver
Feature Peak efficiency over 92% Current Regulation for up to 4WLEDs Digital 3 bit output control logic Soft-start, short circuit protection function Three charge pump modes of operation Support camera flash application QFN-4x4 package
Typical Application
Up to 200mA peak
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Power Solution
RT9362High Efficiency Charge Pump WLED Driver
Feature Everything is the same as RT9360 But has smaller size and different pin definition
QFN-3x3 package
Typical Application
Up to 200mA peak
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Power Solution
RT9360High Efficiency Charge Pump WLED Driver
Function Block Diagram
EN
VDD
Panel
Control Inputs
EN
GND
VIN VOUT
CTRL0CTRL1CTRL2
LED1LED2LED3LED4
ISET
C2P C2NC1P C1N
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Power Solution
RT9360High Efficiency Charge Pump WLED Driver
Efficiency
RT9360 (1x, 1.5x 2x CP+CS)Efficiency: 85%~95%
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Power Solution
RT9360High Efficiency Charge Pump WLED Driver
Dimming Control
Using a DC VoltageUsing a DC Voltage Using a PWM ControlUsing a PWM Control
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Power Solution
RT9360High Efficiency Charge Pump WLED Driver
Dimming Control
Using a Logic SignalUsing a Logic SignalBack
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White LED for Backlight
RT9361120mA, Regulated Charge Pump
Feature Useful for Same VF WLED Application ( VF difference < 0.1V) Step Up type Voltage Converter 1Mhz Frequency Operation Allows Small Capacitor Short Circuit and Over Temperature Protection Tiny Small Package SOT-26
VOUTVDD
GNDCECIN
COUT
C+ C-
Ccp
VOUT= 5VVIN= 2.8~4.5V
2.2uF2.2uF
0.22uF/
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White LED for Backlight
RT930080mA, Current Regulator
Feature Useful for Low VF WLED Application No External Components Very Low Internal Dropout Voltage(60mV) Initial Current Sink 20mA/15mA Tiny Small Package SOT-26 PWM Dimming Control
VMBAT
GNDCE
LED1 LED2 LED3 LED4
PWM
NoNoExternalExternalComponentsComponents!!
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Dual Panel Solution
CSTN/TFT + CSTN/TFT
CSTN/TFT + OLED
Dual Channel Dual Channel powerspowers
Main and Sub-DisplaysMain and Sub-Displays
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Power Solution
RT9272Constant Current WLED Driver for Dual Panel Mobile Phone
Feature Low Vin operating range: 2.4~6V Maximum output voltage up to 16V 1.4MHz Switching Frequency Share one set of inductor and Schottky diode for 2 channel Complete protection: OVP, OCP, OTP and SS
DFN3x3-10 PackageTypical Application
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Power Solution
RT9273OLED + WLED Driver for Dual Panel Mobile Phone
Feature Low Vin operating range: 2.7~4.5V Maximum output voltage up to 16V 1.1MHz Switching Frequency Share one set of inductor and Schottky diode for 2 channel Complete protection: OVP, OCP, OTP and SS
DFN3x3-10 PackageTypical Application
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PCB Layout Considerations for Mobile Phone Power Circuit
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OutlinesOutlines
Routing the DC/DC Converter Power StageRouting the DC/DC Converter Power Stage
Other Considerations Other Considerations
IntroductionIntroduction
The Right Connection of IC ControllerThe Right Connection of IC Controller
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Because of rapid charges in voltages and currents (dV/dt, di/dt)
within a switching converter, switching power supply is a
source of EMI.
IntroductionIntroduction
EMI Source
Equipment or device affected by
EMIConducted
radiated
• Conduction Propagation
• Space Conduction (Radiation)
• Capacitive Coupling (E field)
• Inductive Coupling (B field)
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A
V
t
T
tr
H
trf
2AH/T
f1 f2
-20dB/dec
-40dB/dec
Reduction of EMIReduction of EMI
EMI Filter
Consideration of driver design.
Using Snubber-circuit
Using soft-switching technology.
Proper PCB layout of power circuit
1/πH 1/πtr
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Boost ConverterBoost Converter
Vin
I o Lv + - v D +-
L F
i S
i L
V o
+
-
i D
S v S
+
- C F
i in
R L
D OFF ON ON
S
v D
i L
v S
I o
i D
T on T off
Vin / LF slopes
- (V -V ) o / LF
I in
V o
OFF
in
V o
VL
Vin
Vo-Vin
DV
VM
in
o
1
1
CCM
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Model of Boost Converter LayoutModel of Boost Converter Layout
L= LfT + LfD + LfC
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RT9271 PCB LayoutRT9271 PCB Layout
CinLDiodeCout : trace as short and thick as possible
L RT9271’s Lx pinRT9271’s GND pin : trace as short and thick as possible.
The through hole of RT9271’s GND pin as large and many as possible
The Inductor is far away receiver and microphone The voice trace is far away RT9271 The embedded antenna is far away and different side
RT9271 R2 as close as RT9271 Reduce Cout value or use VDC brightness control to
avoid audio noise Higher PWM frequency to avoid the flicker of LCM.
VCC
EN
GND
LX
FB
RT9271CE
DimmingControl
C11uF
C21uF
D1SS0520
L110uH
R212
OVP
D2
D5
D4
D3
Vin2.4 to 6V
Grounding
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Example layout for Buck Converter power stage
Any PCB trace can act as an antenna. To cancel radiated fields, take care to minimize the area of the AC current loop
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Grounds are important
Control Ground is the ground connected to the control IC and all
of its associated passive components. This ground is extremely
sensitive. Place it only after the other AC current loops are placed.
The Right Connection of IC ControllerThe Right Connection of IC Controller
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Connections of IC ControllerConnections of IC Controller
(a). Improper connection of Vcc.
Cause the voltage bounce on Vcc.
(b). Proper connection of Vcc.
dt
tdiLtVL
)()(
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Routing of Capacitor TracesRouting of Capacitor Traces
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Voltage DividerVoltage Divider
The path from resistor divider to error amplifier should be as short as possible and consists of parallel paths to reduce noise pick-up.
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LDO PCB LayoutLDO PCB Layout
Recommended LDO Regulator Layout
Common LDO Regulator Layout
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LED
4
LED
3
EN
LED
1
LED
2
CTRL2
CTRL1
CTRL0
GND
C2+
C2N
C1N
C1+ VIN
VO
UT
ISE
T
RT9360
1
2
3
4
5678
9
10
11
12
13 14 15 16
VIN
C1
1uF
C2
1uF
COUT
1uF
RSET
VADJRADJ
The Charge Pump is a high-frequency switched-capacitor voltage regulator. For best circuit performance, use a solid ground plane and place CIN and COUT as close to the IC as possible.
Charge Pump PCB LayoutCharge Pump PCB Layout
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Other Considerations Other Considerations Reduce RF EMI Issue
Keep HF and RF tracks as short as possible
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Avoid track stubs, these cause reflection and harmonics
On sensitive components and terminations use surrounding guard ring and ground fill where possible
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System Board
Avoid noise coupling
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The Copper Loss of PCBThe Copper Loss of PCB
The resistance of one square mm of PCB trace is 0.5~0.6 mΩ.(1 oz thickness)
From experience, 1mm width can stand 0.5A DC current. (1 oz thickness) (J=14.3A/mm2)
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Taiwan TOP 1 Power Management Solution ProviderTaiwan TOP 1 Power Management Solution Provider
Strongly Technical SupportStrongly Technical Support
Fast Delivery TimeFast Delivery Time
Aggressive BOM CostAggressive BOM Cost
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