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LXDC2SCAAB-352
Micro DC-DC converter
1. Features








Buck-Boost DC-DC converter
Low EMI noise and small footprint using inductor-embedded ferrite substrate
High efficiency using synchronous rectifier technology at 2.5MHz operation
Wide Input voltage range : 2.8~5.0V
Output voltage:3.3V
Maximum load current: 1,200mA
Automatic transition between buck mode and boost mode
Fully protected for short-circuit, over-temperature, and under voltage
2. Description
The LXDC2SCAAB-352 is a buck-boost DC-DC converter, which is suitable for a space-limited or a
noise-sensitive portable application. The device utilizes an inductor-embedded ferrite substrate, and the substrate
eliminates radiated EMI noise and conduction noise efficiently.
The LXDC2SCAAB-352 has automatic buck-boost operations to prolong Li-ion battery life and efficiency. By
switching automatically between the buck-mode operation (stepping down the voltage) when the battery is fully
charged and the boost-mode operation (stepping up the voltage) as the battery is discharged, the
LXDC2SCAAB-352 maximizes the overall operating voltage from the lithium battery.
3. Typical Application Circuit
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LXDC2SCAAB-352
Micro DC-DC converter
4.Mechanical details
4-1 Outline
Unit:mm
4-2
Symbol
Dimension
Symbol
Dimension
L
2.8±0.2
d
0.5±0.1
W
2.9±0.2
e
0.54±0.1
T
1.15MAX
f
0.4±0.1
g
0.5±0.1
a
0.26±0.2
h
0.39±0.1
b
0.49±0.1
i
0.36±0.2
c
0.4±0.1
j
0.44±0.1
Pin Function
Pin No,
Symbol
I/O
MODE
Input
2,5,6,9
GND
-
3,4
Vout
Output
7
EN
Input
1
Description
Mode=H: auto PFM mode
Mode=L: Forced PWM mode
Ground pin
Regulated voltage output pin.
ON/OFF control pin
EN=H: Device ON, EN=L: Device OFF
8
Vin
Input
Vin pin supplies current to the LXDC2SC internal regulator.
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Micro DC-DC converter
4-3
Functional Block Diagram
5. Ordering Information
Part number
LXDC2SCAAB-352
Device Specific Feature
MOQ
Standard Type
T/R, 2,500pcs/R
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Micro DC-DC converter
6. Electrical Specification
6-1
Absolute maximum ratings
Parameter
symbol
rating
Unit
Vin
6.3
V
EN, MODE
6.3
Input voltage
Pin voltage
V
Operating Ambient temperature
TOP
-40 to +85
o
Operating IC temperature
TIC
-40 to +125
o
TSTO
-40 to +85
o
Condition
Min.
Storage temperature
6-2
C
C
C
Electrical characteristics (Ta=25℃)
Parameter
Symbol
Input voltage
Vin
UVLO voltage
UVLO
Typ.
2.8
Rising
1.75
Max.
Unit
5.0
V
1.795
V
Falling
1.60
1.71
Input leak current
Iinoff
Vin=3.8V, EN=0V
Output voltage
accuracy
Vout
PWM mode
Load current range
Iout
Vin=3.8V
Ripple voltage
Vrpl
Vin=3.8V, Iout=100mA,
BW=100MHz
20
mVpp
Efficiency
EFF
Vin=3.8V, Iout=100mA
EN=H, MODE=H
95
%
VENH
ON:Enable
VENL
OFF:Disable
3.217
3.3
2
uA
3.383
V
1.2
A
1.4
Vin
0
0.4
V
EN control voltage
MODE control
Voltage
VMODEH
Automatic PFM/PWM mode
VMODEL
Forced PWM mode
SW Frequency
Fosc
1.4
-
Vin
0
-
0.4
V
2.5
MHz
(*1) External capacitors (Cout: 22uF×2) should be placed near the module for proper operation.
(*2) The above characteristics are tested using the test circuit in section 8.
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Micro DC-DC converter
6-3
Thermal and Current De-rating Information
The following figure shows the power dissipation and temperature rise characteristics example. These data are
measured on Murata’s evaluation board of this device at no air-flow condition.
Loss-ΔT Characteristics (Vin=3.8V)
Io - Loss Characteristics (Vin=3.8V)
800
600
500
ΔT[℃]
Power Dissipation[mW]
700
400
300
200
100
0
0
200
400
600
800
Iout[mA]
1000
50
45
40
35
30
25
20
15
10
5
0
0
1200
100
200
300
400
Power Dissipation [mW]
500
600
The output current of the device may need to be de-rated if it is operated in a high ambient temperature or in a
continuous power delivering application. The amount of current de-rating is highly dependent on the
environmental thermal conditions, i.e. PCB design, nearby components or effective air flows. Care should
o
especially be taken in applications where the device temperature exceeds 85 C.
o
The IC temperature of the device must be kept lower than the maximum rating of 125 C. It is generally
recommended to take an appropriate de-rating to IC temperature for a reliable operation. A general de-rating for
the temperature of semiconductor is 80%.
MLCC capacitor’s reliability and lifetime are also depending on temperature and applied voltage stress. Higher
temperature and/or higher voltage cause shorter lifetime of MLCC, and the degradation can be described by the
Arrhenius model. The most critical parameter of the degradation is IR (Insulation Resistance). The below figure
shows MLCC’s B1 life based on a failure rate reaching 1%. It should be noted that wear-out mechanisms in
MLCC capacitor is not reversible but cumulative over time.
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Micro DC-DC converter
Capacitor B1 Life vs Capacitor Case temperature
100000
Capacitor B1 Life (Thousand Hours)
Vin=5V
Vin=3.8V
10000
Vin=2.8V
1000
100
10
1
0.1
20
40
60
80
100
Capacitor Case Temperature (℃ )
120
The following steps should be taken before the design fix of user’s set for a reliable operation.
o
1. The ambient temperature of the device should be kept below 85 C
2. The IC temperature should be measured on the worst condition of each application. The temperature must be
o
kept below 125 C. An appropriate de-rating of temperature and/or output current should be taken.
3. The MLCC temperature should be measured on the worst condition of each application. Considering the
above figure, it should be checked if the expected B1 life of MLCC is acceptable or not.
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Micro DC-DC converter
7. Detailed Description
Automatic buck-boost operations
The LXDC2SCAAB uses 4-switch buck-boost circuit topology. The device compares the input and output voltage,
and chooses the buck converter mode or boost converter mode automatically. Its transition is very smooth and
seamless.
Enable
The device starts operation when EN is set high and starts up with soft start. For proper operation, the EN pin
must be terminated to logic high and must not be left floating. Pulling the EN pin to logic low forces the device into
shutdown mode.
Mode selection
The MODE pin allows selecting the operating mode. If the MODE pin is pulled to logic high voltage (VMODH), the
converter operates automatic PFM and PWM mode. In this mode, the converter operates in PFM mode at light
load current, and when the load current increase, the operating mode will change to PWM mode automatically. In
this mode, the converter can work in high efficiency over wide load current range.
If the MODE pin is pulled to logic low voltage (VMODL), the device operates in PWM forced mode. In this mode,
the converter operates in PWM mode with the full load current range. The advantage of this mode is that the
converter operates with the fixed frequency that allows simple filtering of switching frequency. In this mode, the
efficiency is lower compared to the PFM mode at light load current.
PFM mode at light load
PWM mode at heavy load
Nominal output voltage
UVLO (Under Voltage Lock Out)
The under voltage lockout circuit prevents the device from malfunctioning at low input voltages and the battery
from excessive discharge. It disables the output stage of the converter once the falling V IN trips the under-voltage
lockout threshold VUVLO which is typically 1.65V. The device starts operation once the rising VIN trips VUVLO
threshold plus its hysteresis of 75 mV at typ. 1.725V.
Soft Start
The device has an internal soft-start function that limits the inrush current during start-up. The soft-start system
progressively increases the switching on-time from a minimum pulse-width to that of normal operation. Because
of this function, the output voltage increases gradually from zero to nominal voltage at start-up event. The nominal
soft-start time is 3msec.
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Micro DC-DC converter
Discharge Function
To make sure the device starts up under defined conditions, the output gets discharged with a typical discharge
resistor of 120 Ω whenever the device shuts down. This happens when the device is disabled or any of the
protection function (thermal shutdown, under voltage lockout, over current) is triggered.
Over Current Protection
The converter has a hiccup-mode over current protection function.
When the current in the P-Channel MOSFET is sensed to reach the current limit for 16 consecutive switching cycles,
the internal protection circuit is triggered, and switching is stopped for approximately 40ms. The device then
performs a soft-start cycle.
Thermal Shutdown
o
As soon as the internal IC’s junction temperature exceeds 150 C (typ), the device goes into thermal shutdown.
The device returns to its normal operation when the Internal IC’s junction temperature again falls below
o
120 C(typ).
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Sep, 2015
LXDC2SCAAB-352
Micro DC-DC converter
8. Test Circuit
Cout : 22uF/6.3V GRM155R60J226M / GRM188R60J226M
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Micro DC-DC converter
9. Measurement Data
Micro DC-DC Converter evaluation board
Measurement setup
The enable switch has three positions.
1. When it is toggled “ON”, the device starts operation.
2. When it is toggled “OFF”, the device stops operation and stays in shut down mode.
3. When it is set to the middle of “ON” and “OFF”, the EN pin becomes floating and can be can have an external
voltage applied through the EN terminal pin on the EVB. If you don’t apply an external voltage to the EN pin,
the enable switch should not to be set to the middle position.
The mode switch has three states (PWM, PFM, and Open).
1. When it is shorted to “PWM” side, the device operates in PWM forced mode.
2. When it is shorted to “PFM” side, the device operates in PFM/PWM automatic mode.
3. When it is set to open, the mode pin becomes floating and can have an external voltage applied to it through
the Mode terminal pin on the EVB. If you don’t apply external voltage to the Mode pin, the mode switch should
not to be set to the middle position.
※The 47uF capacitor is for the evaluation kit only, and has been added to compensate for the long test cables.
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Micro DC-DC converter
Typical Measurement Data (reference purpose only)
(Ta=25℃)
Efficency
Vin=3.8V,
PFM/PWM Operation
100
95
EFF[%]
90
85
80
75
1
10
100
1000
Iout[mA]
Output Ripple-Noise
Vin=3.8V,
BW : 100MHz
Vrpl [mV]
PFM/PWM Operation
50
45
40
35
30
25
20
15
10
5
0
0
200
400
600
800
Iout [mA]
1000
1200
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LXDC2SCAAB-352
Micro DC-DC converter
Load Regulation
Vin=3.8V
PFM/PWM Operation
3.383
Vout [V]
3.341
3.300
3.259
3.218
0
200
400
600
800
Iout [mA]
1000
1200
Load Transient Response
Vin=3.8V,
PFM/PWM Operation
152mV
ΔIo=1.2A
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Micro DC-DC converter
10.Reliability Tests
No.
1
2
3
Items
Vibration
Resistance
Result
(NG)
18
G
(0)
Frequency : 10~2000 Hz
2
Acceleration : 196 m/s
Direction
: X,Y,Z 3 axis
Period
: 2 h on each direction
Total 6 h.
Solder specimens on the testing jig
(glass epoxy boards) shown in
appended Fig.2 by a Pb free solder.
The soldering shall be done either by
iron or reflow and be conducted with
care so that the soldering is uniform
and free of defect such as by heat
shock.
Deflection : 1.6mm
Solder specimens onto test jig shown
below. Apply pushing force at 0.5mm/s
until electrode pads are peeled off or
ceramics are broken. Pushing force is
applied to longitudinal direction.
18
G
(0)
Pushing Direction
18
G
(0)
18
G
(0)
18
G
(0)
Test Methods
Appearance :
No severe damages
Solder specimens on the testing jig
(glass fluorine boards) shown in
appended Fig.1 by a Pb free solder.
The soldering shall be done either by
iron or reflow and be conducted with
care so that the soldering is uniform
and free of defect such as by heat
shock.
Deflection
Soldering strength
(Push Strength)
QTY
Specifications
9.8 N Minimum
Specimen
4
5
Solderability of
Termination
Resistance to
Soldering Heat
(Reflow)
75%
of
the
terminations is to be
soldered evenly and
continuously.
Appearance
No severe damages
Electrical
specifications
Satisfy
specifications listed
in paragraph 6-2.
Jig
Immerse specimens first an ethanol
solution of rosin, then in a Pb free
solder solution for 3±0.5 sec. at
245±5 °C.
Preheat
: 150 °C, 60 sec.
Solder Paste : Sn-3.0Ag-0.5Cu
Flux : Solution of ethanol and rosin
(25 % rosin in weight proportion)
Preheat Temperature : 150-180 °C
Preheat Period
: 90+/-30 sec.
High Temperature
: 220 °C
High Temp. Period
: 20sec.
Peak Temperature
: 260+5/-0 °C
Specimens are soldered twice with
the above condition, and then kept in
room condition for 24 h before
measurements.
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Micro DC-DC converter
No.
6
7
8
9
Items
Specifications
Test Methods
High Temp.
Exposure
Temperature:85±2 ℃
Period:1000+48/-0 h
Room Condition:2~24h
Temperature
Cycle
Condition:100 cycles in the following
table
Humidity
(Steady State)
Appearance
No severe damages
Electrical
specifications
Satisfy
specifications listed
in paragraph 6-2.
Step
Temp(°C)
Time(min)
1
Min.
Operating
Temp.+0/-3
30±3
2
Max.
Operating
Temp.+3/-0
30±3
Temperature:85±2 ℃
Humidity:80~90%RH
Period:1000+48/-0 h
Room Condition:2~24h
Temperature:-40±2 ℃
Period:1000+48/-0 h
Room Condition:2~24h
Low Temp.
Exposure
QTY
Result
(NG)
18
G
(0)
18
G
(0)
18
G
(0)
18
G
(0)
10
ESD(Machine
Model)
C:200pF、R:0Ω
TEST Voltage :+/-100V
Number of electric discharges:1
5
G
(0)
ESD(Human
Body Model)
C:100pF、R:1500Ω
TEST Voltage :+/-1000V
Number of electric discharges:1
5
G
(0)
11
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LXDC2SCAAB-352
Micro DC-DC converter
Fig.1
Land Pattern
d
a
e
f
e
d
3
1
2
1
3
48
9
8
4
57
6
7
5
b
c
b
a
g
h
Unit:mm
Symbol
Dimension
Symbol
Dimension
a
0.55
e
0.4
b
0.4
f
0.5
c
0.5
g
0.45
d
0.6
h
0.5
・Reference purpose only.
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LXDC2SCAAB-352
Micro DC-DC converter
Fig.2
Testing board
100
Unit:mm
40
■: Land pattern is same as figure1
Glass-fluorine board t=1.6mm
Copper thickness over 35 m
Mounted situation
Unit:mm
チップ
Device
45
45
Test method
Unit:mm
20
50
R230
deflection
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LXDC2SCAAB-352
Micro DC-DC converter
11. Tape and Reel Packing
1)Dimensions of Tape (Plastic tape)
Φ1.5+0.1
0
Unit:mm
(0.3)
1.75±0.1
(3.5)
8.0±0.2
(3.2)
(1.4)
2.0±0.05
4.0±0.1
(3.2)
4.0±0.1
引き出し方向
Feeding direction
2) Dimensions of Reel
Unit:mm
2±0.5
Φ180
Φ60
Φ13±0.2
(9.0)
13.0±1.4
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Micro DC-DC converter
3)Taping Diagrams
[1] Feeding Hole :
As specified in (1)
[2] Hole for chip
:
As specified in (1)
[3] Cover tape
:
50um in thickness
[4] Base tape
:
As specified in (1)
[3]
[1]
[2]
[3]
[4]
Feeding Hole
引き出し穴
Feeding derection
引き出し方向
Chip
部品
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Micro DC-DC converter
4)Leader and Tail tape
A
B
Components
部品収納部
C
Symbol
Items
Ratings(mm)
A
No components at trailer
min 160
B
No components at leader
min 100
C
Whole leader
min 400
5)The tape for modules is wound clockwise with the feeding holes to the right side as the tape is pulled
towards the user.
6)Packaging unit: :2,500 pcs./ reel
7) Material:
Base Tape
… Plastic
Reel
… Plastic
Antistatic coating for both base tape and reel
8)Peeling of force
0.7 N max.
0.1~1.0N
165 to 180 °
Cover
Tape
カバーテープ
ベーステープ
Base
Tape
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LXDC2SCAAB-352
Micro DC-DC converter
NOTICE
1. Storage Conditions:
To avoid damaging the solderability of the external electrodes, be sure to observe the following points.
- Store products where the ambient temperature is 15 to 35 °C and humidity 45 to 75% RH.
(Packing materials, In particular, may be deformed at the temperature over 40 °C.).
- Store products in non corrosive gas (Cl2, NH3,SO2, Nox, etc.).
- Stored products should be used within 6 months of receipt. Solderability should be verified if this period
is exceeded
This product is applicable to MSL1 (Based on IPC/JEDEC J-STD-020)
2. Handling Conditions:
Be careful in handling or transporting the product. Excessive stress or mechanical shock may damage the
product because of the nature of ceramics structure.
Do not touch the product, especially the terminals, with bare hands. Doing so may result in poor
solderability.
3. Standard PCB Design (Land Pattern and Dimensions):
All the ground terminals should be connected to ground patterns. Furthermore, the ground pattern
should be provided between IN and OUT terminals. Please refer to the specifications for the standard
land dimensions.
The recommended land pattern and dimensions are shown for a reference purpose only.
Electrical, mechanical and thermal characteristics of the product shall depend on the pattern design and
material / thickness of the PCB. Therefore, be sure to check the product performance in the actual set.
When using underfill materials, be sure to check the mechanical characteristics in the actual set.
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Micro DC-DC converter
4. Soldering Conditions:
Soldering is allowed up through 2 times.
Carefully perform preheating :△ T less than 130 °C.
When products are immersed in solvent after mounting, pay special attention to maintain the temperature
difference within 100 °C. Soldering must be carried out by the above mentioned conditions to prevent
products from damage. Contact Murata before use if concerning other soldering conditions.
Reflow soldering standard conditions (example)
Reflow soldering standard conditions (Example)
Use rosin type flux or weakly active flux with a chlorine content of 0.2 wt % or less.
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Micro DC-DC converter
5. Cleaning Conditions:
The product is not designed to be cleaned after soldering.
6. Operational Environment Conditions:
Products are designed to work for electronic products under normal environmental conditions (ambient
temperature, humidity and pressure). Therefore, products have no problems to be used under the similar
conditions to the above-mentioned. However, if products are used under the following circumstances, it
may damage products and leakage of electricity and abnormal temperature may occur.
- In an atmosphere containing corrosive gas ( Cl2, NH3, SOx, NOx etc.).
- In an atmosphere containing combustible and volatile gases.
- In a dusty environment.
- Direct sunlight
- Water splashing place.
- Humid place where water condenses.
- In a freezing environment.
If there are possibilities for products to be used under the preceding clause, consult with Murata before
actual use.
If static electricity is added to this product, degradation and destruction may be produced.
Please use it after consideration enough so that neither static electricity nor excess voltage is added at the
time of an assembly and measurement.
If product malfunctions may result in serious damage, including that to human life, sufficient fail-safe
measures must be taken, including the following:
(1) Installation of protection circuits or other protective device to improve system safety
(2) Installation of redundant circuits in the case of single-circuit failure
7. Input Power Capacity:
Products shall be used in the input power capacity as specified in this specifications.
Inform Murata beforehand, in case that the components are used beyond such input power capacity range .
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Micro DC-DC converter
8. Limitation of Applications:
The products are designed and produced for application in ordinary electronic equipment
(AV equipment, OA equipment, telecommunication, etc). If the products are to be used in devices requiring
extremely high reliability following the application listed below, you should consult with the Murata staff in
advance.
- Aircraft equipment.
- Aerospace equipment
- Undersea equipment.
- Power plant control equipment.
- Medical equipment.
- Transportation equipment (vehicles, trains, ships, etc.).
- Automobile equipment which includes the genuine brand of car manufacture, car factory-installed option
and dealer-installed option.
- Traffic signal equipment.
- Disaster prevention / crime prevention equipment.
- Data-procession equipment.
- Application which malfunction or operational error may endanger human life and property of assets.
- Application which related to occurrence the serious damage
- Application of similar complexity and/ or reliability requirements to the applications listed in the above.
! Note:
Please make sure that your product has been evaluated and confirmed against your specifications when
our product is mounted to your product.
Product specifications are subject to change or our products in it may be discontinued without advance
notice.
This catalog is for reference only and not an official product specification document, therefore, please
review and approve our official product specification before ordering this product.
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Sep, 2015
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