SimSurfing
DC-DC Converter Design
Support Tool
Operation Manual

August, 2019
Murata Manufacturing Co., Ltd.
09 September 2019
Copyright © Murata Manufacturing Co., Ltd. All rights reserved. 2019

IndexPage
1. About This Tool
1-1. Outline
1-2. Notes for Use

34

2. Quick Operation Guide
2-1. Screen Configuration
2-2. How to Use Each Component

57

3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices

10

4. Details of Operation
4-1. Circuit Selection Field
4-2. Input Function of Circuit Operating Conditions
4-3. Part Number Selection Function
4-4. Graph Output Function
4-5. [Supplement] PFM Mode and PWM Mode

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21
24
26
36

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1. About This Tool
1-1. Outline
 This tool supports the selection of power inductors and multilayer ceramic capacitors of Murata
suitable for the desired operating conditions of DC-DC converter circuits.

[Basic Function]
The following outputs can be acquired by selecting the circuit of a DC-DC converter, entering each
operating condition, and selecting the part number of a power inductor.
Ripple current-> Inductor Current - Time

Output voltage-> Output Voltage - Time

Efficiency-> Efficiency - Output Current

Power inductors suitable for a DC-DC converter can be narrowed down based on these outputs.
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1. About This Tool
1-2. Notes for Use Characteristics graph of a power inductor displayed by the software

Each of the measurement systems differs in the following data measurements.
 Characteristics data of the power inductor used by the tool (see p.32)
 Characteristics data used in the power inductors of the SimSurfing characteristics viewer

Note that a difference may occur between both characteristics data due to the above
differences.

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2. Quick Operation Guide
2-1. Screen Configuration (1/2)

(1)
Graph
outputfunction(2)
Circuitselection
field /
input functionof circuit
operatingconditions(3)
Part number
selectionfunction(Powerinductor)-> The screen consists of three functional blocks including (1) Graph output,(2) Circuit selection field / input of circuit operating conditions, and (3) part number selection.
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2. Quick Operation Guide
2-1. Screen Configuration (2/2)(3)
Part number
selectionfunction(MLCC)-> A list of power inductors is displayed in (3) functional block of the part number selection.
Changing the tab will display a list of multilayer ceramic capacitors (hereinafter, MLCC).
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2. Quick Operation Guide
2-2. How to Use Each Component (1/3)(1) Graph output function-> The graphs of (1)-1 are output based on the settings and various conditions indicated p.8 and p.9.
Changing these settings and conditions allows for the basic operation of the software.
See the following for the detailed operation.
- Examples of use: p.10 to p.19
- Operation of each functional block: p.20 to p.35(1)-2 Selection of display graph(1)-1 Calculation results graph(1)-3 Graph optional functions<Default settings>- (1)-1 and (1)-2 display graph -> <Inductor Current (IL)>, <Output Voltage (Vout)>, <Efficiency>- (1)-3 Graph Options -> Not checked

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2. Quick Operation Guide
2-2. How to Use Each Component (2/3)(2) Input function of circuit selection field / circuit operating conditions(2)-1 Selection of DC-DC converter circuit<Default settings>(2)-1 Convert Type(2)-2 Setup Condition
Modulation- Input DC Voltage (Vin)- Output DC Voltage (Vout)- Output DC Current (Idc)- Switching Frequency(2)-2 Input of circuit operating conditions-> <Buck>: Buck circuit-> <Simple>:-> <PFM&PWM>-> 3.6 [V]-> 1.8 [V]-> 1 [A]-> 2 [MHz]8
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2. Quick Operation Guide
2-2. How to Use Each Component (3/3)(3) Part number selection function (Power inductors/MLCC)(3)-1 Selection for General/Automotive(3)-2 Changes list of power inductors/MLCC<Default settings>(3)-1 General/Automotive -> Both checked(3)-2 Inductor Selection-> Part No.: DFE201610P-1R0M
Capacitor Selection -> Part No.: GRM186R60G226ME15
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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (1/10)<Design of DC-DC converters for mobile devices>

Operating conditions of DC-DC converter:- Buck circuit- Low current: PFM, Normal operation: PWM- Input voltage: 3.6V, Output voltage: 1.0V
- Output current: 1.5A
- Switching frequency: 1MHz
I want to select a power inductor with an inductance of 1.0µH, size 2016 (mm) / height 1.0 mm max
in which the efficiency and ripple are optimized for a DC-DC converter with the above conditions.

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (2/10)-> Set the conditions on the previous page to narrow down the part number of the power inductors
suitable for the conditions.

Buck circuit

Output voltage (Vout)
1.8 -> 1V

PFM/PWM

Output current (Idc)
1.8 -> 1.5A

SW frequency
2 -> 1MHz

InductanceBlank -> 1µH

Size 2016 (mm)check

Height8 -> 1mm
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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (3/10)-> While "DFE201610P-1R0M" (and MLCC "GRM186R60G226ME15") are selected, the ripple
current, output voltage and efficiency graphs will be displayed.

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (4/10)-> The graph shows that there is no great difference in the ripple current for all of the part numbers.
Next, look at the efficiency graph.

Click

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (5/10)-> Expands the efficiency graph only. In this graph, "DFE201610P-1R0M" and "DFE201610E-1R0M"
can be selected as a high efficiency power inductor which satisfies the initial conditions.
Remove the check

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (6/10)

Next, it was determined to evaluate a high frequency DC-DC converter aiming for downsizing.
I want to select a power inductor in which the efficiency and ripple current are optimized whensome of the conditions are changed as follows.
- Switching frequency 1MHz -> 4MHz
- Inductance 1µH -> 0.47µH

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (7/10)-> Click theof

to delete all the graph curves.

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (8/10)-> Change the inductance and switching frequency.

Switching frequency
1 -> 4MHz
Inductance1 -> 0.47µH

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (9/10)-> The graph shows that there is no great difference in the ripple current for all of the part numbers inthis case as well. Similarly, look at the efficiency graph.

Click

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3. Use Cases
3-1. Design of DC-DC Converter for Mobile Devices (10/10)-> The same as p.13, expands the efficiency graph only. In this graph, "DFE201610E-R47M" and"LQM2MPNR47MGH" can be selected as high efficiency power inductors which satisfies theinitial conditions.

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4. Details of Operation
4-1. Circuit Selection Field-> Select Buck (Buck type) or Boost (Boost type) as the type of DC-DC converter circuit.
The operation when "Buck" is selected is described in the following.

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4. Details of Operation
4-2. Input Function of Circuit Operating Conditions (1/3)-> There are two types of modes including "Simple" and "Standard" as the input items. The tablebelow shows the items that can be input in each mode.

Input DC Voltage (Vin)
Output DC Voltage (Vout)
Output DC Current (Idc)

Input
Mode
unit Simple Standard
Ｖ
✔
✔
Ｖ
✔
✔
Ａ
✔
✔

Switching Frequency
SW1 ON Resistance
SW2 ON Resistance
IC Standby Current

MHz
Ω
Ω
μA

✔
-

✔
✔
✔
✔

IC Switching Transition Time

ns

-

✔

Input item

Remarks"Iout" is indicated dependingon the IC
ON resistance of IC, etc.
ON resistance of IC, etc.
Self-consumption current of
PMIC
Time for SW to be in ON state
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4. Details of Operation
4-2. Input Function of Circuit Operating Conditions (2/3)

Input DC Voltage (Vin)
Output DC Voltage (Vout)
Output DC Current (Idc)

Input
Mode
unit Simple Standard
Ｖ
✔
✔
Ｖ
✔
✔
Ａ
✔
✔

Switching Frequency
SW1 ON Resistance
SW2 ON Resistance
IC Standby Current

MHz
Ω
Ω
μA

✔
-

✔
✔
✔
✔

IC Switching Transition Time

ns

-

✔

Input item

Remarks"Iout" is indicated dependingon the IC
ON resistance of IC, etc.
ON resistance of IC, etc.
Self-consumption current of
PMIC
Time for SW to be in ON state-> Advanced calculation can be set by selecting the Standard mode and entering the basic characteristicsof the PMIC (red check mark).
* This function can be used by first selecting the Simple mode to execute the calculation, and thenperforming a detailed verification of the results in Standard mode.
The operation when Simple mode is selected is described in the following.
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4. Details of Operation
4-2. Input Function of Circuit Operating Conditions (3/3)-> As a modulation mode of a circuit, two types of modes including "PFM & PWM" and "PWM" canbe selected.
When "PFM & PWM" is selected, the efficiency is calculated by automatically switching between
PWM and PFM. See p.36 for the details.
The operation when "PFM & PWM" is selected is described in the following.

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4. Details of Operation
4-3. Part Number Selection Function (1/2)

This is set to "Inductor Selection"
by default.

Can be narrowed down by entering acenter value or the upper/lower limit value

Can be narrow down by check box

Resets thesettings

Clicking displays
the efficiency indescending order

Clicking displays the data
sheet of each part number

Clicking displays the current
which flows into the inductor
in descending order

Selecting the right side of the item rearranges thedisplayed items in ascending/descending order-> The part number of the power inductors can be narrowed down by the specifications of inductance,
size code, thickness, saturation current, maximum DC resistance and application.
Clicking
also displays the data sheet of each part number.
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4. Details of Operation
4-3. Part Number Selection Function (2/2)

Can be changed to "Capacitor
Selection"
Can be narrowed down byentering a center value or theupper/lower limit value

Can be narrow down
by check box

Resetsthesettings

Number of MLCC used
can be entered*

Clicking displays the data
sheet of each part number

Selecting the right side of the item
rearranges the displayed items inascending/descending order* Irrespective of the "Buck" or "Boost" mode, a number of MLCC used can be entered for one part number.
-> The part number of the MLCC can be narrowed by specifications of the capacitance, rated voltage,
temperature characteristics, size code, thickness, capacitance tolerance, and type.
Clicking
also displays the data sheet of each part number.
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4. Details of Operation
4-4. Graph Output Function (1/10)
Check the item(s) to be displayed(a) Voltage VL applied tothe power inductor(b) Current IL whichflows into the power
inductor(c) Output voltage Voutof the DC-DC convertera(e) Power loss of thepower inductor(f) Various parameters(L, Rdc, etc.) of thepower inductor(g) Various parameters(C, Z, etc.) of the MLCC(d) Power conversion
efficiency of the DC-DC
converter-> Clicking the part number of the power inductor displays seven types of graphs including theripple current (IL - Time), output voltage (Vout - Time), and efficiency (Efficiency - Idc).
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4. Details of Operation
4-4. Graph Output Function (2/10)->

are functions common to all graphs. Clicking each button enables the following operations.
: CSV output: Change of graph settings: Saves image (PNG format)* Unchecking the [Graph Option] will close the buttons.

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4. Details of Operation
4-4. Graph Output Function (3/10)(a) Voltage VL applied to the power inductor-> The upper/lower limit voltage of VL is determined by the input voltage Vin and the output voltage Vout.
The Duty ratio is determined by the ratio of Vout to Vin and the ON resistance of the IC, etc.
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4. Details of Operation
4-4. Graph Output Function (4/10)(b) Current IL which flows into the power inductor

DC cut* Setting the Y-Axis from "Normal" to "Ripple" cuts the DC component, andonly displays the current amplitude.
-> The current waveform of IL is displayed as a triangular wave. This is generally called the "ripple current."[Notes]
The amplitude of the ripple current is inverse proportion to the L value of the power inductor. When the
L value drops the amplitude suddenly increases due to the current bias characteristics of the inductor.
This will cause a defect where the DC-DC converter itself does not operate normally, etc.
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4. Details of Operation
4-4. Graph Output Function (5/10)(c) Output voltage Vout

DC cut* Setting the Y-Axis from "Normal" to "Ripple" cuts the DC component, andonly displays the current amplitude.
-> The waveform of the output voltage is one of the main performance indexes of a DC-DC converter.
This is generally called the "ripple voltage."[Notes]
It is necessary to set the ripple voltage low enough according to the IC specification so that an ICwith a load does not malfunction.
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4. Details of Operation
4-4. Graph Output Function (6/10)(d) Power conversion efficiency

Iin

Iin
Power conversion efficiency =𝑉𝑜𝑢𝑡 𝐼𝑑𝑐
× 100[%]
𝑉𝑖𝑛 𝐼𝑖𝑛-> The power conversion efficiency is one of the most important performance indexes of a DC-DC
converter. Although the efficiency is generally calculated by the above equation, it is calculated
from the power loss of the power inductor and the ON resistance of the IC in this software.
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4. Details of Operation
4-4. Graph Output Function (7/10)(e) Power loss of the power inductor-> The power loss for the Idc of a power inductor can be displayed.
Total Loss

Total of the power loss of an inductor (DC Loss + AC Loss)

DC Loss

Power loss when DC current is flowing into the inductor

AC Loss

Power loss when AC current is flowing into the inductor

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4. Details of Operation
4-4. Graph Output Function (8/10)(f) Various parameters of a power inductor-> A total of 24 characteristics graphs Z/R/X/C/L/Q can be displayed for the Idc/Freq/Vin/Voutin a power inductor.
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4. Details of Operation
4-4. Graph Output Function (9/10)(g) Various parameters of MLCC-> A total of 12 characteristics graphs Z/R/X/C/L/Q can be displayed for the Freq/Vout in an MLCC.

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4. Details of Operation
4-4. Graph Output Function (10/10)-> A marker function can be used.

(i)

(i)

(ii)

(i)
(i)

(i)
- Clicking on the characteristics curve displays the marker.
- Entering the horizontal axis allows the marker to be moved to a specified location.
- Multiple markers can be displayed. Clicking a marker or clicking the upper right of a marker
deletes the marker.

box

(ii)
- Placing the mouse pointer on the characteristics curve displays the numerical value of thevertical/horizontal axes in the specified location.
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4. Details of Operation
4-5. [Supplement] PFM Mode and PWM Mode (1/2)
In the Modulation item of the software, the operation mode can be changed between "PFM & PWM"
and "PWM.“

Calculated by automatically switching between PWM and PFM
PFM&PWM

PWM-> For the purpose of optimization of the efficiency, when the output current Idc is too highthe mode is switched to the PWM mode, and when too low, it is switched to the PFM
mode (see p.36 for the details).
Calculated in the PWM mode only in the entire Idc range* Waveform image of the current (IL) which flows into an inductorILIL
PFM mode0

PWM mode0t-> Executes intermittent operation to
suppress the switching losst-> Adjusts the output voltage by the Duty ratio
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4. Details of Operation
4-5. [Supplement] PFM Mode and PWM Mode (2/2)<When "PFM & PWM" is selected>
The efficiency is calculated by automatically switching between PWM and PFM based on thefollowing distinction method.
- PFM mode when the lower limit current of the IL which flows into an inductor becomes 0A state (Figure 1)- PWM mode when the lower limit current of the IL becomes larger than 0A state (Figure 2)

PFM

Figure 1
Inductor current waveformwhen Idc = 0.09A

PWM

Figure 2
Inductor current waveformwhen Idc = 0.13A

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