- Chapter 1-Capacitor

Impedance Characteristics of Capacitor
Impedance equivalent circuit with capacitor is the same as the RLC series model.
Changes in Frequency

ESR: Increase

Impedance

Frequency

Frequency

ESL: Decrease
Frequency

Impedance

Impedance

ESL increases

CapacitanceFrequency

Impedance

ESR is constant

ESL

Changes in Element
Impedance

ESR

Impedance

Elements in Capacitor

Cap. : Increase

Frequency

Capacitance decreases

Frequency

What happens to the impedance level when connected in series?

Impedance Characteristics of Capacitor

Impedance for series connection

Impedance with different elements10010010インピーダンス
Impedance [Ω]インピーダンス [Ω]Impedance

10Impedance
depends on ESL

Impedance depends
on capacitance

10.1Resonance
Point

0.010.001
0.001

0.01

0.1

Impedance
depends onESR1

100.1

0.01

100

周波数 [MHz]
Frequency• At resonance point, no impedance
for Capacitor & ESL(Impedance for ESR only)• The frequency at resonance point depends
on Capacitor & ESL

Cap. : Increase

10.001
0.001

Resonance Point→Cap. : Increase,
ESL: Increase
0.01

0.1
1Frequency
周波数 [MHz]

ESL:
Decrease
ESR:
Decrease
10Impedance characteristics varydepended on each element.

100Reliabilities of Multi-Layered Ceramic Capacitor
1. Operational condition comparison chart for Circuit
Ripple CU.

Solvent

HeatPolarity De-rating Limitation ResistanceResistance

MLCC

Ta Cap.

No◎◎◎

Al Capacitor《Leaded》

What’s Electrolytic Capacitor?

LoadingTest◎

AlfoilAl foil◎Alfoil×△×△

Al foilElectrolytic paper
Dielectric<Surface mounted>

Yes

Electrolytic paper（Al2O3 )Vertical style×Electrolysis solution
LaDaDkCaCkRa

Al Cap.

Horizontal styleYes∗Layout

Application
Problems×∗Operational∗Polarity exam

limitation for rated
voltage

When mounting(70～50%level)

×∗Have margin
capacity for
ripple current∗Less reliableassociated fromself heating∗Reverse voltage
Consideration△∗Limitation
for reflow
molding anddegrading
advancement

×△∗Liquid solution
flooding except
block structure
MLCC∗Al capacitor:
decreasing incapacitance fromelectrolysis loss

Ta Capacitor《Leaded》∗Ta capacitor:
diffusion of Ag,
short circuit fromdegrading of
insulating layer

Rk

Ca, Ck: positive/negative pole cap.
Da,Dk: rectification from negativepole’s oxidization coatingLa,Lk: Inductance for +,- leads
R: resistance of electrolsis solution
and paper
Ra,Rk: Inside resistance of forward
direction from +,-poles’ oxidization
coating<Surface mounted>

Dielectric（Ta2O５）

MnO2Graphite

Ceramic Capacitor

TantalArgentum paste
SolderDa
La

Dielectric：
Barium Titanate

Lx

Ca

Lx

Ra

Breakdown Voltage (V)500

Breakdown voltage level comparison: rated voltage 10V
MLCC

400
300
200
1000Electrode: Ni

Ta Capacitor

Backward
direction

Forwarddirection

１０uF

212F475
4.7uF

316Ｆ１０６１０uF

212ＢＪ１０５１uF

316ＢＪ２２５2.2uF

Characteristics Comparison for the Different Type of Capacitors
Ripple Current Characteristics

Ripple current characteristics
for the different type of capacitors
リップル電流対部品温度上昇の比較

Temperature rise characteristic due to ripple current

HeatCapacitor
Ripplecurrent

Heat
ESR

ESL Capacitor

Temperature rise (degree)

Electrical energy is converted to heat
when current goes through resistance.

100

M LCC47uF
積層コン４７μF
Tant.Cap47uF
タンタル４７μF
Polymer100uF

10

1

0.1
00.5

1

1.5

22.5

3

リップル電流（Aｒｍｓ）
Ripplecurrent(Arms)

3.5

4

Given the same amount of calorific power,
ripple current goes through MLCC
the most because of its low ESR.

Electrical energy is converted
to heat when ripple current(AC) goes through capacitor.
(DC does not go through it)

Operational recommendation of heat releasevalue for MLCC is within 10℃.
There is no limitation of allowed ripple current for MLCC.

Heat shortens capacitor’sdurability.

Operational recommendation of heat releasevalue for electrolytic capacitor is within 5℃.
Allowed ripple current is regulated by makers.

The Basic Knowledge ofCircuits

The Functions of Bypass (decoupling) Capacitor
The Role of Bypass Capacitor
Noise + Load current

Power supply line

Necessary Characteristics for Bypass Capacitor
It has low impedance.

LoadCurrent

NoiseCurrent(low prevention of an electric current)

ICTo connect
the noisecurrent tothe earth(grounding)It electrifies an electric current well.
It efficiently grounds the noise current.
It effectively decreases the noise current.

The principle of operation for Bypass Capacitor

DC does not go through the capacitor(Impedance:∞)

DC is supplied directly to IC

AC (noise) does go through the capacitor
AC (noise) is grounded

Noise Suppression → Stabilize IC operation

Noise: more

Noise: less

Low ImpedanceHigh Impedance

Impedance

LowHigh

Noise effect ofdecreasing

Moreeffective

Lesseffective

The Functions of Bypass (decoupling) Capacitor
Selection Criteria for Capacitor
Impedance,ESR Freq.-Temperature Characteristic
1000

Increasing in noise
suppression effectiveness

Impedance,ESR[Ω]100RZ

10Decreasing in noise
suppression effectiveness1Several kinds of Noise Frequencies

Select a Capacitor based on noise
frequency needs to be eliminated

0.1

0.01

0.001
0.11Maximum level for noise
suppression effectiveness

101001000
Frequency[KHz]

10000100000

The Functions of Backup Capacitor

Load current doesn’t stay constant.

Load current:
smallIC

Operatingat low-speed

Load current:
largeIC

Operatingat high-speed

High-speed load change

Load current

When IC’s operational speed changes rapidly,
large load current is quickly needed.
Low-speed
operationHigh-speed
operation

Power line for high-speed load changing
The current can’t flow
Large load current isto IC quickly enough.
quickly needed.

Linevoltage

ICLinevoltage

Line voltage can’t bemaintained, therefore
voltage is dropped.
Voltage
droppedLinevoltageIC

Low-speed
operationIC

High-speed
operationCircuit voltage,
Load current

Load current to IC

Minimum
requiredoperationalvoltagefor ICTime
Line voltage decreases below the required
operational voltage for IC.

TimeThe IC stops its operation.

The Functions of Backup Capacitor
Capacitor’s actual(considering equivalent circuit)

The Role of Backup Capacitor
Electric current delays

ICLinevoltageLine voltage,needed load current,
Discharge current fromCapacitor

Voltage dropped
by electric current

ESR

Low-speed
operationMaintainingLinevoltageICCapacitor

Minimum required
operational voltage
for IC

Voltage dropped
by discharge
current

Line voltage
droppedVoltage fluctuation occurs
when capacitor charging

High-speed
operationLine voltage

Voltage
dropped∗This is a simplified version, so disregard ESL

Making up for electric
current shortage

Voltage dropped
by ESR
Voltage dropped
by electric
discharge

Voltage risen bycapacitor charging

Voltage risen by ESR

Time

Keeping the minimum required
operational voltage for IC

Maintaining
stable operation

Capacitor and ESR decide the amountof voltage dropped

The Functions of Backup Capacitor
Experimental
circuit

To oscilloscope

R = 1ΩPower
SupplyVoltage=5V

Experimental result for Capacitance and ESR

Loadresistance
R=5Ω

タンタル１００μFのリップル電圧
RippleVoltage of 100uF Ta Cap

Ripple Voltage of 22uF X5R 10v

ESR による電圧変動
Voltagefluctuation by ESR

Pulse generator
1945 (NF)
MLCC
47µF∗7２０ｍV／Div

RatingCapacitor

２０ｍV／Div

2SK2684

Current
probe

Voltagefluctuation
容量による電圧変動
by capacitance

Switching frequency =1000KHz
１μS／Div

ESR comparison

１μS／Div

ＥＳＲの比較

10MLCC
22uF
積層コン２２μＦ
Ta Cap
100uF
タンタル１００μＦＥＳＲ（Ω）

1High ValueLow ESR

The fluctuation band ofline becomes narrower.

0.1

Merits of MLCC
0.01

It enables to replace Ta capacitor with asmaller value of MLCC.

0.001
0.1

1

10100
1000
周波数（ＫＨｚ）
Frequency (KHz)

10000

100000The effectiveness of MLCC’s voltage fluctuation
depressing effect is greater than that of Ta capacitor.

The Basic Knowledge of Power
Supply Circuit

Series Regulator (3 Terminal Regulator)

Load current fluctuation

Loadcurrent

Producing output voltage bylowering certain amount of inputvoltage

Step-down power supplyControlling element(transistor)
Inputvoltage

Outputvoltage

Input
voltage

Controlling element(transistor)

Outputvoltage

Circuit operation (water gate model)

Loadcurrent

Controlling water gate to keep
the water level constantControlling load current with transistor
Output voltage stays constant.

Series Regulator (3 Terminal Regulator)
Circuit structure

Effects of input capacitor

Input voltage > Output voltage
Regulator

Add alternate current to input voltage
purposely to measure input current
amount with or without input capacitor

ICInput Capacitor

ICOutput Capacitor

IC

Consisting of IC, input and output capacitors.

Function of input capacitor

Noise current

Without capacitors

ICConnecting the line
noise to the ground.

Input Voltage Vin

Noise + Load current

Loadcurrent

With capacitors (MLCC)

2000

2000

1000

1000

00-1000-1000-2000-2000-101-1

Vertical: mV

Same as the function ofBypass Capacitor

01

Horizontal: u sec

Input voltage is stabilized as
input capacitor is connected.

Series Regulator (3 Terminal Regulator)
Effects of output capacitor

Unable to supply
current immediately

ICVoltage
droppedCover the current
shortageICLine
voltage

Measuring the voltage fluctuation when load change
is occurred with/without output capacitor.
Load Current Iout

Function of output capacitor

Keeping line
voltage200150100500-10-50IC

Same as the function ofBackup Capacitor

10IC

Without capacitors
Output fluctuation
ΔVout

Supply current to control voltage
fluctuation for rapid load change

5With capacitors (MLCC)

1000

1000

00-1000-1000-2000-2000-2-1012-10-50510Output voltage is stabilized as output
capacitor is connected.

Step-Down Converter
Transistor for switching power supply
has only ON or OFF signal.

Producing output voltage by lowering
input voltage with transistor

Switching operation

Outputvoltage

Controlling element(transistor)

Load current

Controlling element(transistor)
Outputvoltage

Input
voltage

Input
voltage

Circuit operation (water gate model)

Load current

Controlling output voltage
by switching
Turn-on cycle

Constant

Time to be ON

ChangesTurn-on cycle

ChangesTime to be ON

Constant

Turn-on cycle of the switch
ControlON

PWM
methodPFM
methodSwitching frequency
ControlON

PWMONTimeONONPFMONTimeStep-Down ConverterOperation of input capacitor

Circuit structure
Choke coil
FET1
Control IC

FET2

heat

heat

Heat generated by ESR

FET(2)

Necessary characteristics of input capacitor

Inputcapacitor

Outputcapacitor

Input side current
Inputcurrent

Ripple current flows
into input capacitor.

Ripple current

High tolerance for ripple current
Example: Permissible ripple current of a capacitor is 1A.
Ripple current: 6A

6capacitors

1A

FET1

FET1

FET1

ONONONTime

Large amount of alternating current(ripple current) flows.

1A

1A

1A

1A

1A

ReducedExample: Permissible ripple current of acapacitor is 2A.
Ripple current: 6A

32A2A

2A

capacitors

Step-Down Converter
Points of output voltage to remember

Output side operation
Choke coil

Keeping higher voltage than the lowest operating
voltage of load IC.

Ripple voltage
Rated output voltage

Voltage

Voltage

Outputcapacitor
Input voltage

ONON

Outputvoltage

ONThe lowest
operating voltage

Keep the band ofripple voltage within
the rated value.

Rapid load voltage fluctuation
TimeInput voltage is controlled
by an on-off switching.

TimeRated output voltage

It is smoothed with achoke coil and an output
capacitor.
The lowest
operating voltage

Ripple voltage is included.

Control voltage drop by
rapid load voltage
fluctuation

Step-Down Converter
Factor for determining voltage drop by
rapid load voltage fluctuation

Factor for determining ripple voltage
Repeating an on-off switching signal

Operation at rapid load change

Charge and discharge are repeated with
output capacitor.
Voltage is fluctuated by current flowing inand out.

Same as Backup Capacitor
Necessary characteristics for capacitor
when rapid load fluctuation occurred

Ripple voltage
When charging

When discharging

Charging
Current

Discharging
current

High capacitance
Supply capacitor of high electronic charge

ESR

Low ESR

Voltage rise

RepeatESR

Voltage drop

Charging

Reducing voltage drop when supplying
electronic charge

Capacity

Capacity
Voltage riseHigh Value MLCC

SuitableHigh capacitance and low ESR
reduce ripple voltage.

Discharging
Voltage dropCharge Pump (Boost)
Circuitry of charge pump(example: double boost)

Operation of charge pump (image)
Charging 2 capacitors separatelyCharging

C1VInCharging

VVC2V

Output capacitor(smoothing capacitor)

C1C2IC

Outputcapacitor

Capacitors for charging
Required characteristics of capacitor

VConnectInputcapacitor

Out2VLoadV

Connecting charged capacitors

Charging capacitor and output capacitor
Lowering voltage fluctuation
occurred by charging/discharging
Backup Capacitor
Same as step-down output capacitor

Output double amount of voltage than input
Smoothing with output capacitor (Switching)
Output voltage is determined by the number ofcapacitors connected. (integral multiple)

High capacitance and low ESRare required.

Comparison of Various Input Capacitors

Summary

Vertical mV, Horizontal µsec

Without Capacitor
コンデンサ未挿入
Input
fluctuation ΔVin
OutputfluctuationΔVout
入力変動
出力変動
100

Measuring the noise absorption and the output voltage
fluctuation by adding sine wave on input line

2000

Z1Regulator

Vs:1Vrms

Vs Z2

7.5V

ICΔVin00-1000-50-2000

ΔVout-100-101-1

Input fluctuation of 1Vrms

ΔVin =Z2
Vs
Z1 + Z 2

Capacitor (Z2) has low impedance.
Effect of noise suppression: large

Vertical mV, Horizontal µsec250250000-250-250-250250-500-500-10-500-1101-11000

With Capacitor
入力コンデンサ挿入時の出力変動
ΔVout
AlAl電解1μＦ
Cap
積層1μＦ
MLCCTaCap
Ｔａ電解1μＦ
202020100

10101010000-10-10-10

ML R
ML Z
Ta R
Ta Z
Al R
Al Z

0.10.01

1

Vertical mV, Horizontal µsec

各種コンデンサ周波数特性（1μF)
Frequency
Characteristics

10

MLCC is excellent in noise suppression (low impedance).

Constant IC input voltage
10000

1

入力コンデンサ挿入時の入力変動
ΔVin
With Capacitor
AlCapTaCap
Al電解1μＦ
Ｔａ電解1μＦ
MLCC
積層1μＦ
500500500(Z1:Line impedance)

0Output fluctuation of 35Vrms

Input capacitor inserted

IC used:NJM78L05(JRC)
Capacitor used:MLCC X5R 1uF 10v, Ta1uF, A11uF

Z・ESR [Ω]50

1000-20-20-20-1

0

1-10

1-10

1Output fluctuation becomes smaller as IC input voltage stays constant.

0.001
1101001000
Freq. [kHz]10000

100000MLCC has lower impedance than that of Ta for a wide range of frequency.

MLCC is suitable for input capacitor.

Summary Operation Analysis of Output Capacitor

Vout

150
100
500-10-505時間 μsec
Time

Waveform observation: Iout, Vout
(Observing by the type of output capacitors)
IC used: R1112N331B (Ricoh)
Input Cap: MLCC 4.7uF X5R 10v
Input V: 5V
Switching frequency: 100Hz
Load current: 150mA
1000

JMK212BJ475KG
Ta4.7μF

ESR [Ω]100

2000

WithoutCapacitor
未挿入
Ta 4.7uF
Ta 4.7μF
MLCC 4.7uF

0-2000-4000-10-505
時間μsecTime10Vout
Fluctuation
出力電圧変動ΔV

MLCC 4.7μF

Ta 4.7μF
505000-50-50-100-100-150-150-10

Taコンと積層コンのESR-周波数特性比較
FrequencyCharacteristics Comparison

10VoutFluctuation ΔV mV
出力電圧変動Regulator
IC200
負荷電流
LoadCurrent Iout mAIout

Vout Fluctuation
出力電圧変動Load負荷電流波形
Current Waveform

Observation of output voltage fluctuation-505Variable
ESR: Large
ESRの変動分：大ESR：Large

10-10-50510Variable
ESR: Small
ESRの変動分：小ESR：Small

Vertical mV, Horizontal µsec

10Using output capacitor with low ESR
reduces the output voltage dropwhen load fluctuation occurred.

10.1
0.01
0.001
1101001000
Freq. [kHz]10000 100000

MLCC with low ESR is well-suitable for output capacitor.

Development Method Direction for ML Lineups and Proposals

Market demand
Circuit segment

Digital circuit
Analog circuit

Capacitor application segment

Required performance

Focusing on impedance andESR characteristics

It is for circuit noise suppression and often usedin digital circuits.
Low Impedance, Low ESR
MLCC with Y5V characteristic and 0.1-10uF is best
suitedDecoupling
BackupSmoothing

Amplifier

It may also be used for a circuit with large loadchange (CPU), stability of power line andprotection of IC.
Low ESR, Low ESL, Low Impedance
MLCC with characteristics of Y5V,X5R,X7R
and 0.1-10uF is best suited.

ArithmeticOscillation

High pressure

ModemLogicDigital

High frequency

Power supply

Power supply
AudioOthers

FilterCoupling
Time constant,Resonance
Focusing on the stability of realcapacitance, temperature and bias

It is for in/output of power supply circuit and moreused as the miniaturization of equipment.
Real capacitance, Low ESR, Low ESL, Low Impedance
Rated Voltage and Reliability
MLCC with characteristics of X5R, X7R
and 1- tens of uF is best suited.
It is for amplifier, arithmetic, modem andfilter circuits.
Stability of capacitance temperature and bias
is important.
Temperature compensating dielectric type
MLCC is best suited.
(CFCAP, TC type multilayer)