Fabricated on a 0.41 by 0.65 inch (10.4 by 16.5
mm) Single Inline Package (SIP) module, the OKI-
78SR series are non-isolated switching regulator
(SR) DC/DC power converters for embedded ap-
plications. The fi xed single output converters offer
both tight regulation and high effi ciency directly
at the power usage site and are a direct plug-in
replacement for TO-220 package 78xx series linear
regulators. Typically, no extra outside components
are required.
Two nominal output voltages are offered (3.3
and 5 VDC), each with 1.5 Amp maximum output.
Based on fi xed-frequency buck switching topology,
the high effi ciency means very low heat and little
electrical noise, requiring no external components.
The ultra wide input range is 7 to 36 Volts DC.
Protection features include short circuit current
limit protection. The OKI-78SR is designed to meet
all standards approvals. RoHS-6 (no lead) hazard-
ous material compliance is specifi ed as standard.
PRODUCT OVERVIEW
Connection Diagram
Figure 1. OKI-78SR
Note: Murata Power Solutions strongly recommends an external input fuse, F1.
See specifi cations.
External
DC
Power
Source
F1
CommonCommon
+Vin +Vout
Controller
Reference and
Error Amplifier
t4XJUDIJOH
t'JMUFST
t$VSSFOU4FOTF
FEATURES
Ultra wide 7 to 36 VDC input range
Fixed Outputs of 3.3 or 5 VDC up to 1.5 Amps
Vertical or horizontal SIP-mount, small footprint
package
“No heat sink” direct replacement for 3-terminal
78xx-series linear regulators
High effi ciency with no external components
Short circuit protection
Outstanding thermal derating performance
UL/EN/IEC 60950-1, 2nd Edition safety approvals
Typical units
MDC_OKI-78SR-W36.C01 Page 1 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com
www.murata-ps.com/support
For full details go to
www.murata-ps.com/rohs
　
PART NUMBER STRUCTURE
➀ Dimensions are in inches (mm).
➁ All specifications are at nominal line voltage, Vout = nominal and full load, +25 ˚C., with no external capacitor,
unless otherwise noted.
FUNCTIONAL SPECIFICATIONS SUMMARY AND ORDERING GUIDE
Root Model
Output Input
Effi ciency
Package
➀
VOUT
(Volts)
IOUT
(Amps
max)
Power
(Watts)
R/N (mVp-p) Regulation (Max.)
VIN Nom.
(Volts)
Range
(Volts)
IIN,
no load
(mA)
IIN,
full load
(Amps)Max. Line Load Min. Typ.
OKI-78SR-3.3/1.5-W36-C 3.3 1.5 4.95 40 ±0.25% ±0.25% 24 7-36 5 0.48 84% 85.5% 0.41 x 0.65 x 0.3
(10.4 x 16.5 x 7.62)
OKI-78SR-5/1.5-W36-C 51.5 7.5 75 ±0.25% ±0.25% 24 7-36 5 0.69 89% 90.5% 0.41 x 0.65 x 0.3
(10.4 x 16.5 x 7.62)
Product Label
Because of the small size of these products, the product label contains a
character-reduced code to indicate the model number and manufacturing date
code. Not all items on the label are always used. Please note that the label dif-
fers from the product photograph on page 1. Here is the layout of the label:
The label contains three rows of information:
First row – Murata Power Solutions logo
Second row – Model number product code (see table)
Third row – Manufacturing date code and revision level
The manufacturing date code is four characters:
First character – Last digit of manufacturing year, example 2009
Second character – Month code (1 through 9 = Jan-Sep;
O, N, D = Oct, Nov, Dec)
Third character – Day code (1 through 9 = 1 to 9, 10 = 0 and
11 through 31 = A through Z)
Fourth character – Manufacturing information
Figure 2. Label Artwork Layout
XXXXXX Product code
Mfg.
date
code
Revision levelYMDX Rev.
Model Number Product Code
OKI-78SR-3.3/1.5-W36-C I33115
OKI-78SR-5/1.5-W36-C I50115
OKI-78SR-3.3/1.5-W36H-C I33115H
OKI-78SR-5/1.5-W36H-C I50115H
Maximum Rated Output in Volts
-1.5/3.3 -CRoHS-6 Hazardous
Substance Compliance
78SR Series
78SR
Okami Non-Isolated PoL
OKI -
Maximum Rated Output
Current in Amps
Note:
Some model number combinations
may not be available.
Contact Murata Power Solutions.
H
Blank: Vertical Mount
H Suffi x: Horizontal Mount
W36
Input Voltage Range
7-36V
MDC_OKI-78SR-W36.C01 Page 2 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
Performance and Functional Specifi cations
All specifi cations are typical unless noted. See Note 1
Input
Input Voltage Range See Ordering Guide.
Recommended External Fuse 2 Amps fast blow
Reverse Polarity Protection (Note 9) None. Install an external fuse.
Isolation (note 5) Not isolated. The input and output share a
common return.
Start-Up Voltage NA
Undervoltage Shutdown NA
Overvoltage Shutdown None
Internal Input Filter Type Capacitive
Input Current:
Full Load Conditions See Ordering Guide
Inrush Transient 0.16 A2Sec.
Shutdown Mode (Off, UV, OT) 1 mA
Output in Short Circuit 5 mA
No Load 5 mA
Low Line (Vin=Vmin, Vout=nom) 0.8 Amps (OKI-78SR-3.3/1.5-W36)
1.16 Amps (OKI-78SR-5/1.5-W36)
Refl ected (Back) Ripple Current
(Note 2)
10 mA pk-pk (OKI-78SR-3.3/1.5-W36)
49 mA pk-pk (OKI-78SR-5/1.5-W36)
Output
Output Voltage See Ordering Guide
Output Current Range 0 to 1.5 Amps
Minimum Loading (Note 11) No minimum load
Maximum Output Power 5.15 Watts (OKI-78SR-3.3/1.5-W36)
7.8 Watts (OKI-78SR-5/1.5-W36)
Accuracy (50% load) ±4 % of Vnom
Overvoltage Protection (Note 7) None
Temperature Coeffi cient ±0.02% per °C. of Vout range
Ripple/Noise (20 MHz bandwidth) See Ordering Guide and note 11
Line/Load Regulation See Ordering Guide and note 10
Effi ciency See Ordering Guide and performance graphs
Maximum Capacitive Loading
Cap-ESR=0.001 to 0.01 Ohms 300 μF
Cap-ESR >0.01 Ohms 3300 μF
Current Limit Inception (98% of Vout
setting, after warm up) 3.5 Amps
Short Circuit Mode (Notes 6, 11)
Short Circuit Current Output 10 mA
Protection Method Hiccup autorecovery upon overload removal.
(Note 8)
Short Circuit Duration Continuous, no damage (output shorted to
ground)
Prebias Startup The converter will start up if the external output
voltage is less than Vnominal.
Dynamic Characteristics
Dynamic Load Response (50% to 100% load step, no external caps)
di/dt = 1 A/μSec 25 μSec settling time to within ±2% of fi nal value
Peak deviation 100 mV
Switching Frequency 500 KHz
Environmental
Calculated MTBF (Note 4) Ambient Temp. Hours
OKI-78SR-3.3/1.5-W36-C
Telecordia method (4a)
+25°C 78,721,000
+40°C 59,017,000
OKI-78SR-3.3/1.5-W36-C
MIL-HDBK-217N2 method (4b)
+25°C 14,587,000
+40°C 9,814,000
Operating Ambient Temperature Range
Full power, with derating [3] -40 to +85°C. see derating curves.
Storage Temperature Range -55 to +125 °C.
Relative Humidity to 85%/+85 °C.
Physical
Outline Dimensions See Mechanical Specifi cations [11]
Weight 0.07 ounces (2 grams)
Safety
Certifi ed to UL/cUL 60950-1
CSA-C22.2 No. 60950-1
IEC/EN 60950-1, 2nd Edition
Absolute Maximum Ratings
Input Voltage, Continuous or transient 36 Volts max.
Input Reverse Polarity Protection None. Install external fuse.
Output Current Current-limited. Devices can withstand sustained
short circuit without damage.
Storage Temperature -40 to +125 deg. C.
Specifi cation Notes:
(1) All specifi cations are typical unless noted. General conditions for Specifi cations are +25 deg.C ambient
temperature, Vin=nominal, Vout=nominal, full rated load. Adequate airfl ow must be supplied for extended
testing under power. See Derating curves.
All models are tested and specifi ed with no external capacitors. All models are stable and regulate within
spec under no-load conditions.
(2) Input Back Ripple Current is tested and specifi ed over a 5 Hz to 20 MHz bandwidth. Input fi ltering is Cin=2 x
100 μF, Cbus=1000 μF, Lbus=1 μH. All caps are low ESR types.
(3) Note that Maximum Power Derating curves indicate an average current at nominal input voltage. At higher
temperatures and/or lower airfl ow, the DC/DC converter will tolerate brief full current outputs if the total
RMS current over time does not exceed the Derating curve. All Derating curves are presented near sea level
altitude. Be aware of reduced power dissipation with increasing altitude.
(4a) Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332 Method 1, Case 3, ground fi xed
conditions, Tpcboard=+25 ˚C, full output load, natural air convection.
(4b) Mean Time Before Failure is calculated using the MIL-HDBK-217N2 method, ground benign, +25ºC., full
output load, natural convection.
(5) The input and output are not isolated. They share a single COMMON power and signal return.
(6) Short circuit shutdown begins when the output voltage degrades approximately 2% from the selected
setting. Output current limit and short circuit protection are non-latching. When the overcurrent fault is
removed, the converter will immediately recover.
(7) The output is not intended to sink appreciable reverse current.
(8) “Hiccup” overcurrent operation repeatedly attempts to restart the converter with a brief, full-current output.
If the overcurrent condition still exists, the restart current will be removed and then tried again. This short
current pulse prevents overheating and damaging the converter.
(9) Input Fusing: If reverse polarity is accidentally applied to the input, to ensure reverse input protection,
always connect an external input fast-blow fuse in series with the +Vin input. Use approximately twice the
full input current rating with nominal input voltage.
(10) Regulation specifi cations describe the deviation as the line input voltage or output load current is varied
from a nominal midpoint value to either extreme.
(11) Output noise may be further reduced by installing an external fi lter. Do not exceed the maximum output
capacitance. At zero output current and no external capacitor, the output may contain low frequency
components which exceed the ripple specifi cation. The output may be operated indefi nitely with no load.
MDC_OKI-78SR-W36.C01 Page 3 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
MDC_OKI-78SR-W36.C01 Page 4 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
PERFORMANCE DATA – OKI-78SR-3.3/1.5-W36
Effi ciency vs. Line Voltage and Load Current @ +25˚C. (Vout = Vnom.)
Output Ripple and Noise (Vin=7V, Vout=nominal, Iout=1.6A, Cload=0, Ta=+25˚C.,
ScopeBW=100MHz)
Output Ripple and Noise (Vin=36V, Vout=nominal, Iout=1.6A, Cload=0, Ta=+25˚C.,
ScopeBW=100MHz)
Output Ripple and Noise (Vin=12V, Vout=nominal, Iout=1.6A, Cload=0, Ta=+25˚C.,
ScopeBW=100MHz)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
0
10
20
30
40
50
60
70
80
90
100
Load Current (Amps)
Efficiency (%)
VIN = 7V
VIN = 12V
VIN = 36V
Maximum Current Temperature Derating at sea level (Vin=7V. to 36V.)
0.00
1.00
2.00
20 25 30 35 40 45 50 55 60 65 70 75 80 85
Ambient Temperature (ºC)
Output Current (Amps)
0.33 m/s (65 LFM)
MDC_OKI-78SR-W36.C01 Page 5 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
PERFORMANCE DATA – OKI-78SR-3.3/1.5-W36
Step Load Transient Response (Vin=36V, Vout=nominal, Cload=0, Iout=0.75A to 1.5A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=12V, Vout=nominal, Cload=0, Iout=0.75A to 1.5A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=7V, Vout=nominal, Cload=0, Iout=0.75A to 1.5A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div
Step Load Transient Response (Vin=36V, Vout=nominal, Cload=0, Iout=1.5A to 0.75A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=12V, Vout=nominal, Cload=0, Iout=1.5A to 0.75A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=7V, Vout=nominal, Cload=0, Iout=1.5A to 0.75A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
MDC_OKI-78SR-W36.C01 Page 6 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
PERFORMANCE DATA – OKI-78SR-5/1.5-W36
Effi ciency vs. Line Voltage and Load Current @ +25˚C. (Vout = Vnom.)
Output Ripple and Noise (Vin=7V, Vout=nominal, Iout=1.6A, Cload=0, Ta=+25˚C.,
ScopeBW=100MHz)
Output Ripple and Noise (Vin=36V, Vout=nominal, Iout=1.6A, Cload=0, Ta=+25˚C.,
ScopeBW=100MHz)
Output Ripple and Noise (Vin=12V, Vout=nominal, Iout=1.6A, Cload=0, Ta=+25˚C.,
ScopeBW=100MHz)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
0
10
20
30
40
50
60
70
80
90
100
Load Current (Amps)
Efficiency (%)
VIN = 7V
VIN = 12V
VIN = 36V
Maximum Current Temperature Derating at sea level (Vin=7V. to 36V.)
0.00
1.00
2.00
20 25 30 35 40 45 50 55 60 65 70 75 80 85
Ambient Temperature (ºC)
Output Current (Amps)
0.33 m/s (65 LFM)
MDC_OKI-78SR-W36.C01 Page 7 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
PERFORMANCE DATA – OKI-78SR-5/1.5-W36
Step Load Transient Response (Vin=36V, Vout=nominal, Cload=0, Iout=0.75A to 1.5A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=12V, Vout=nominal, Cload=0, Iout=0.75A to 1.5A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=7V, Vout=nominal, Cload=0, Iout=0.75A to 1.5A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=36V, Vout=nominal, Cload=0, Iout=1.5A to 0.75A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=12V, Vout=nominal, Cload=0, Iout=1.5A to 0.75A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
Step Load Transient Response (Vin=7V, Vout=nominal, Cload=0, Iout=1.5A to 0.75A,
Slew=1A/μS, Ta=+25˚C.) Trace 2=Vout, 100 mV/div. Trace 4=Iout, 0.5A/div.
MECHANICAL SPECIFICATIONS, VERTICAL MOUNT
0.05 (1.3)
0.200 (5.1)
0.205
(5.2)
REF
0.100 (2.5)
0.06
(1.5)
0.30 (7.6)
0.16 (4.1)
0.13 (3.3)
REF
0.030±0.002
Pin #1
OVER 75-150 u" NICKEL
PIN FINISH: PURE MATTE TIN 100-300 u"
PIN MATERIAL: COPPER ALLOY
Pin #3
C
L
Pin #1
0.41
(10.4)
0.65
(16.5)
Pin #1
INPUT/OUTPUT CONNECTIONS
OKI-78SR
Pin Function
1 Positive Input
2 Common (Ground)
3 Positive Output
Third Angle Projection
Dimensions are in inches (mm shown for ref. only).
Components are shown for reference only.
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 1˚
MDC_OKI-78SR-W36.C01 Page 8 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
MECHANICAL SPECIFICATIONS, HORIZONTAL MOUNT
.05 (1.3)±.01
C
L
Pin #3
Pin #1
Pin #1
OVER 75-150 u" NICKEL
PIN FINISH: PURE MATTE TIN 100-300 u"
PIN MATERIAL: COPPER ALLOY
Pin #1
.01
.02
+
-
0.17
(4.318)
.025 (0.635)
(3 PLS)
0.200 (5.1)
0.205
(5.2)
REF
0.100 (2.5)
0.06
(1.5)
0.30 (7.6)
0.16 (4.1)
REF
0.41
(10.4)
0.65
(16.5)
INPUT/OUTPUT CONNECTIONS
OKI-78SR
Pin Function
1 Positive Input
2 Common (Ground)
3 Positive Output
Third Angle Projection
Dimensions are in inches (mm shown for ref. only).
Components are shown for reference only.
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 1˚
MDC_OKI-78SR-W36.C01 Page 9 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
STANDARD PACKAGING
Third Angle Projection
Dimensions are in inches (mm shown for ref. only).
Components are shown for reference only.
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚
Carton accommodates four (3) trays of 120 yielding 360 converters per carton.
Each static dissipative polyethylene foam tray
accommodates 120 converters
10.00±.25
(254.0)
10.00 ±.25
(254.0)
2.5±.25 (63.5)
Closed height
0.39 (10.0)
0.63 (16.0)
Notes:
1. Material: Dow 220 antistat ethafoam
(Density: 34-35 kg/m3)
2. Dimensions: 252 x 252 x 16 mm
8 x 15 array (120 per tray)
9.92
(252.0)
9.92
(252.0)
0.94
(24.0)
0.33
(8.5) 0.43
(11.0)
0.2
(5.0)
0.2
(5.0)
45° X
x4
0.49
(12.5)
6.5
MDC_OKI-78SR-W36.C01 Page 10 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
Input Fusing
Certain applications and/or safety agencies may require fuses at the inputs of
power conversion components. Fuses should also be used when there is the
possibility of sustained input voltage reversal which is not current-limited. For
greatest safety, we recommend a fast blow fuse installed in the ungrounded
input supply line.
The installer must observe all relevant safety standards and regulations. For
safety agency approvals, install the converter in compliance with the end-user
safety standard.
Recommended Input Filtering
The user must assure that the input source has low AC impedance to provide
dynamic stability and that the input supply has little or no inductive content,
including long distributed wiring to a remote power supply. The converter will
operate with no additional external capacitance if these conditions are met.
For best performance, we recommend installing a low-ESR capacitor
immediately adjacent to the converter’s input terminals. The capacitor should
be a ceramic type such as the Murata GRM32 series or a polymer type. Initial
suggested capacitor values are 10 to 22 μF, rated at twice the expected maxi-
mum input voltage. Make sure that the input terminals do not go below the
undervoltage shutdown voltage at all times. More input bulk capacitance may
be added in parallel (either electrolytic or tantalum) if needed.
Recommended Output Filtering
The converter will achieve its rated output ripple and noise with no additional
external capacitor. However, the user may install more external output capaci-
tance to reduce the ripple even further or for improved dynamic response.
Again, use low-ESR ceramic (Murata GRM32 series) or polymer capacitors.
Initial values of 10 to 47 μF may be tried, either single or multiple capacitors in
parallel. Mount these close to the converter. Measure the output ripple under
your load conditions.
Use only as much capacitance as required to achieve your ripple and noise
objectives. Excessive capacitance can make step load recovery sluggish or
possibly introduce instability. Do not exceed the maximum rated output capaci-
tance listed in the specifi cations.
Input Ripple Current and Output Noise
All models in this converter series are tested and specifi ed for input refl ected
ripple current and output noise using designated external input/output compo-
nents, circuits and layout as shown in the following fi gures. The Cbus and Lbus
components simulate a typical DC voltage bus. Please note that the values of
Cin, Lbus and Cbus will vary according to the specifi c converter model.
TECHNICAL NOTES
C
IN
V
IN
C
BUS
L
BUS
C
IN
= 2 x 100μF, ESR < 700mΩ @ 100kHz
C
BUS
= 1000μF, ESR < 100mΩ @ 100kHz
L
BUS
= 1μH
+VIN
-VIN
CURRENT
PROBE
TO
OSCILLOSCOPE
+
–
+
–
Figure 3 Measuring Input Ripple Current
C1
C1 = 1μF
C2 = 10μF
LOAD 2-3 INCHES (51-76mm) FROM MODULE
C2 R
LOAD
SCOPE
+VOUT
-VOUT
Figure 4. Measuring Output Ripple and Noise (PARD)
MDC_OKI-78SR-W36.C01 Page 11 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murata-ps.com/support
Minimum Output Loading Requirements
All models regulate within specifi cation and are stable under no load to full
load conditions. Operation under no load might however slightly increase
output ripple and noise.
Temperature Derating Curves
The graphs in this data sheet illustrate typical operation under a variety of
conditions. The Derating curves show the maximum continuous ambient air
temperature and decreasing maximum output current which is acceptable
under increasing forced airfl ow measured in Linear Feet per Minute (“LFM”).
Note that these are AVERAGE measurements. The converter will accept brief
increases in current or reduced airfl ow as long as the average is not exceeded.
Note that the temperatures are of the ambient airfl ow, not the converter
itself which is obviously running at higher temperature than the outside air.
Also note that “natural convection” is defi ned as very fl ow rates which are not
using fan-forced airfl ow. Depending on the application, “natural convection” is
usually about 30-65 LFM but is not equal to still air (0 LFM).
Murata Power Solutions makes Characterization measurements in a closed
cycle wind tunnel with calibrated airfl ow. We use both thermocouples and an
infrared camera system to observe thermal performance. As a practical matter,
it is quite diffi cult to insert an anemometer to precisely measure airfl ow in
most applications. Sometimes it is possible to estimate the effective airfl ow if
you thoroughly understand the enclosure geometry, entry/exit orifi ce areas and
the fan fl owrate specifi cations.
CAUTION: If you routinely or accidentally exceed these Derating guidelines,
the converter may have an unplanned Over Temperature shut down. Also, these
graphs are all collected at near Sea Level altitude. Be sure to reduce the derat-
ing for higher altitude.
Soldering Guidelines
Murata Power Solutions recommends the specifi cations below when installing these converters. These specifi cations vary depending on the solder type. Exceeding these specifi ca-
tions may cause damage to the product. Your production environment may differ; therefore please thoroughly review these guidelines with your process engineers.
Wave Solder Operations for through-hole mounted products (THMT)
For Sn/Ag/Cu based solders: For Sn/Pb based solders:
Maximum Preheat Temperature 115° C. Maximum Preheat Temperature 105° C.
Maximum Pot Temperature 270° C. Maximum Pot Temperature 250° C.
Maximum Solder Dwell Time 7 seconds Maximum Solder Dwell Time 6 seconds
Output Fusing
The converter is extensively protected against current, voltage and temperature
extremes. However your output application circuit may need additional protec-
tion. In the extremely unlikely event of output circuit failure, excessive voltage
could be applied to your circuit. Consider using an appropriate fuse in series
with the output.
Output Current Limiting
Current limiting inception is defi ned as the point at which full power falls below
the rated tolerance. See the Performance/Functional Specifi cations. Note par-
ticularly that the output current may briefl y rise above its rated value in normal
operation as long as the average output power is not exceeded. This enhances
reliability and continued operation of your application. If the output current is
too high, the converter will enter the short circuit condition.
Output Short Circuit Condition
When a converter is in current-limit mode, the output voltage will drop as the
output current demand increases. If the output voltage drops too low (approxi-
mately 98% of nominal output voltage for most models), the bias voltage may
shut down the PWM controller. Following a time-out period, the PWM will
restart, causing the output voltage to begin rising to its appropriate value. If the
short-circuit condition persists, another shutdown cycle will initiate. This rapid
on/off cycling is called “hiccup mode”. The hiccup cycling reduces the average
output current, thereby preventing excessive internal temperatures and/or
component damage.
The “hiccup” system differs from older latching short circuit systems
because you do not have to power down the converter to make it restart. The
system will automatically restore operation as soon as the short circuit condi-
tion is removed.
MDC_OKI-78SR-W36.C01 Page 12 of 12
OKI-78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
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Murata Power Solutions, Inc.
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