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 nonisolated switching regulator
(SR) DC/DC power converters for embedded ap
plications. The fixed single output converters offer
both tight regulation and high efficiency directly
at the power usage site and are a direct plugin
replacement for TO220 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 fixedfrequency buck switching topology,
the high efficiency 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 OKI78SR is designed to meet
all standards approvals. RoHS6 (no lead) hazard
ous material compliance is specified as standard.
PRODUCT OVERVIEW
Connection Diagram
Figure 1. OKI78SR
Note: Murata Power Solutions strongly recommends an external input fuse, F1.
See specifications.
External
DC
Power
Source
F1
Common
Common
+Vin
+Vout
Controller
Reference and
Error Amplifier
t!4XJUDIJOH
t!'JMUFST
t!$VSSFOU!4FOTF
FEATURES
Ultra wide 7 to 36 VDC input range
Outputs of 3.3 or 5 VDC up to 1.5 Amps
Vertical or horizontal SIPmount, small footprint
package
“No heat sink” direct replacement for 3terminal
78xxseries linear regulators
High efficiency with no external components
Short circuit protection
Outstanding thermal derating performance
UL/EN/IEC 609501, 2nd Edition safety approvals
Typical units
MDC_OKI78SRW36.C03
Page 1 of 12
OKI78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murataps.com
www.murataps.com/support
For full details go to
www.murataps.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
Eff
ciency
Package
➀
V
OUT
(Volts)
I
OUT
(Amps
max)
Power
(Watts)
R/N (mVpp)
Regulation (Typ.)
V
IN
Nom.
(Volts)
Range
(Volts)
I
IN
,
no load
(mA)
I
IN
,
full load
(Amps)
Max.
Line
Load
Min.
Typ.
OKI78SR3.3/1.5W36C
3.3
1.5
4.95
40
±0.25%
±0.25%
24
736
5
0.48
84%
85.5%
0.41 x 0.65 x 0.3
(10.4 x 16.5 x 7.62)
OKI78SR5/1.5W36C
5
1.5
7.5
75
±0.25%
±0.25%
24
736
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
characterreduced 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 200
9
Second character – Month code (1 through 9 = JanSep;
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
Model Number
Product Code
OKI78SR3.3/1.5W36C
I33115
OKI78SR5/1.5W36C
I50115
OKI78SR3.3/1.5W36HC
I33115H
OKI78SR5/1.5W36HC
I50115H
Maximum Rated Output in Volts

1.5
/
3.3

C
RoHS6 Hazardous
Substance Compliance
78SR Series
78SR
Okami NonIsolated 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 Suffix: Horizontal Mount
W36
Input Voltage Range
736V
Figure 2.
Label Artwork Layout
XXXXXX
Product code
Mfg.
date
code
Revision level
YMDX
Rev.
MDC_OKI78SRW36.C03
Page 2 of 12
OKI78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murataps.com/support
Performance and Functional Specifi
cations
All specifcations 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.
StartUp 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 A
2
Sec.
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 (OKI78SR3.3/1.5W36)
1.16 Amps (OKI78SR5/1.5W36)
reflected (Back) Ripple Current
(Note 2)
10 mA pkpk (OKI78SR3.3/1.5W36)
49 mA pkpk (OKI78SR5/1.5W36)
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 (OKI78SR3.3/1.5W36)
7.8 Watts (OKI78SR5/1.5W36)
Accuracy (50% load)
±4 % o� Vnom
Overvoltage Protection (Note 7)
None
Temperature Coeffcient
±0.02% per °C. o� Vout range
Ripple/Noise (20 MHz bandwidth)
See Ordering Guide and note 11
Line/Load Regulation
See Ordering Guide and note 10
Efficiency
See Ordering Guide and per�ormance graphs
Maximum Capacitive Loading
CapESR=0.001 to 0.01 Ohms
300
μF
CapESR >0.01 Ohms
3300
μF
Current Limit Inception (98% o� Vout
setting, a�ter 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 i� 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 final value
Peak deviation
100 mV
Switching Frequency
500 KHz
Environmental
Calculated MTBF (Note 4)
Ambient Temp.
Hours
OKI78SR3.3/1.5W36C
Telecordia method (4a)
+25°C
78,721,000
+40°C
59,017,000
OKI78SR3.3/1.5W36C
MILHDBK217N2 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 Specifcations [11]
Weight
0.07 ounces (2 grams)
Sa�ety
Certifed to UL/cUL 609501
CSAC22.2 No. 609501
IEC/EN 609501, 2nd Edition
Absolute Maximum Ratings
Input Voltage, Continuous or transient
36 Volts max.
Input Reverse Polarity Protection
None. Install external �use.
Output Current
Currentlimited. Devices can withstand sustained
short circuit without damage.
Storage Temperature
40 to +125 deg. C.
Specifi
cation Notes:
(1)
All specifcations are typical unless noted. General conditions for Specifcations are +25 deg.C ambient
temperature, Vin=nominal, Vout=nominal, full rated load. Adequate airfow must be supplied �or extended
testing under power. See Derating curves.
All models are tested and specifed with no external capacitors. All models are stable and regulate within
spec under noload conditions.
(2)
Input Back Ripple Current is tested and specifed over a 5 Hz to 20 MHz bandwidth. Input fltering 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 airfow, the DC/DC converter will tolerate brie� �ull current outputs i� the total
RMS current over time does not exceed the Derating curve. All Derating curves are presented near sea level
altitude. Be aware o� reduced power dissipation with increasing altitude.
(4a) Mean Time Be�ore Failure is calculated using the Telcordia (Belcore) SR332 Method 1, Case 3, ground fxed
conditions, Tpcboard=+25 °C, �ull output load, natural air convection.
(4b) Mean Time Be�ore Failure is calculated using the MILHDBK217N2 method, ground benign, +25ºC., �ull
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% �rom the selected
setting. Output current limit and short circuit protection are nonlatching. When the overcurrent �ault 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 brie�, �ullcurrent output.
I� 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: I� reverse polarity is accidentally applied to the input, to ensure reverse input protection,
always connect an external input �astblow �use in series with the +Vin input. Use approximately twice the
�ull input current rating with nominal input voltage.
(10) Regulation specifcations describe the deviation as the line input voltage or output load current is varied
�rom a nominal midpoint value to either extreme.
(11) Output noise may be �urther reduced by installing an external flter. Do not exceed the maximum output
capacitance. At zero output current and no external capacitor, the output may contain low �requency
components which exceed the ripple specifcation. The output may be operated indefnitely with no load.
MDC_OKI78SRW36.C03
Page 3 o� 12
OKI78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murataps.com/support
MDC_OKI78SRW36.C03
Page 4 of 12
OKI78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murataps.com/support
PERFORMANCE DATA – OKI78SR3.3/1.5W36
Efficiency 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 (%)
V
IN
=
7V
V
IN
= 12V
V
IN
= 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_OKI78SRW36.C03
Page 5 of 12
OKI78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murataps.com/support
PERFORMANCE DATA – OKI78SR3.3/1.5W36
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_OKI78SRW36.C03
Page 6 of 12
OKI78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murataps.com/support
PERFORMANCE DATA – OKI78SR5/1.5W36
Efficiency 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 (%)
V
IN
=
7V
V
IN
= 12V
V
IN
= 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 (˚C)
Output Current (Amps)
0.33 m/s (65 LFM)
MDC_OKI78SRW36.C03
Page 7 of 12
OKI78SR Series
Fixed Output 1.5 Amp SIP DC/DC Converters
www.murataps.com/support
PERFORMANCE DATA – OKI78SR5/1.5W36
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.