78SR 2 Amp Series
www.murata-ps.com
2 Amp, 3.3V, 5.0V, & 5.2V Output, High
Efficiency, Synchronous Switching Regulators
2V
New 5.
model
FEATURES
Up to 95% efficiency– no costly heat sinks or fans
required
3.3V/2A & 5V/2A models; pin compatible with 1.5A 78xx
regulators
Wide 8– 32Vdc input voltage range
Two package options:
3-pin vertical mount SIP
Low profile, horizontal mount SIP
No external Input/Output filter capacitors required
–40 to +70°C full load operation at 24Vin with no
derating
Excellent load (±0.25%) and line (±0.35%) regulation
Low-cost upgrade for 78HT2, 78SR1, 78ST1, and
PT5100 switchers
TECHNICAL NOTES
Open frame design minimizes self-heating & pc-board
footprint
Includes output short-circuit protection and thermal
shutdown
Low noise output for powering sensitive instrumentation
Ordering Information
Part No.
Output
Voltage
78SR-3.3/2-C
3.3Vdc
78SR-5/2-C
5.0Vdc
78SR-5.2/2-C
5.25Vdc
78SRH-3.3/2-C 3.3Vdc
78SRH-5/2-C
Output
Current
Input
Voltage
Package
Type
Vertical
2.0A
8.0-32Vdc
5.0Vdc
78SRH-5.2/2-C 5.25Vdc
Murata’s 78SR-3.3/2 (3.3V, 2 Amp output) and 78SR-5/2 (5V, 2 Amp output) step-down,
switching regulators are ultra high-efficiency, modern replacements for LM78xx series
1.5Amp linear regulators. They are pin- and size-compatible, drop-in replacements for
TO-220 style, 3-pin SIP or modular packages which require heat sinks. And, to ensure the
lowest installed cost, no messy thermal grease, no mounting hardware and no external
components are required for full operation.
A 200KHz switching frequency, combined with a synchronous rectifier buck regulator
topology, provides for efficiencies exceeding 95%. 78SR switchers can easily drive 2A loads
from 12V or 24Vsupplies—at ambient temperatures up to +70°C—without heat sinks,
fans, or thermal derating. A thermally efficient 3-pin vertical mount SIP occupies less than
0.09in.2 (58mm2) of pc-board real estate, while a horizontal mount option has an installed
height of less than 0.290in. (7.4mm).
78SR Series 2A switching regulators are lower cost, improved-efficiency upgrades for
many 78HT2, 78SR1, 78ST1, and PT5100 series switchers. Their higher efficiency ensures
significantly lower heat generation and provides increased run time in battery-powered
applications, making these regulators ideal for today’s low power “green” applications.
Horizontal
1. Input/Output (I/O) Filtering: As shown in the accompanying noise and ripple graphs,
78SR Series regulators exhibit excellent low noise performance with no additional I/O
filter components. However, if additional noise reduction is required, be sure to use low
ESR capacitors that are rated for continuous operation (with an additional 20% safety
margin) at the highest input voltage and ambient temperatures. Adding external output
capacitors will improve the unit’s load-transient response.
Applications in which 78SR regulators are located more than 24 inches (61cm) from
the input power supply should include an external 47uF/50V (or greater) aluminum
electrolytic capacitor, connected as close as possible to the regulator’s +Vin and GND
terminals (pins 1 and 2). An external input capacitor is particularly important if the input
voltage is applied to the regulator via a mechanical switch or relay. Contact bounce at
turn-on can produce large inductive current spikes, and these current spikes can generate potentially damaging voltage transients at the regulator’s input terminals.
2. Input Fusing: 78SR switching regulators are not internally fused. If fusing their input
and/or output terminals is required, use the data shown in the Efficiency Curves as a
guide to select an appropriate slow-blow fuse.
For full details go to
www.murata-ps.com/rohs
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MPM_78SR-2A.C01 Page 1 of 6
78SR 2 Amp Series
2 Amp, 3.3V, 5.0V, & 5.2V Output, High
Efficiency, Synchronous Switching Regulators
Performance/Functional Specifications
TECHNICAL NOTES (continued)
Typical at TA = +25°C & VIN = 12V, unless otherwise noted
Input/Output
Models
Output Voltage
Rated Output Current
Output Voltage Accuracy
Input Voltage Range
Line Regulation (100% load)
Load Regulation (0-100% load)
Quiescent Current (mAdc)
Input Current vs. Input Voltage
Efficiency
Transient Response
Input & Output Noise
78SR-3.3/2-C 78SR-5/2-C
78SR-5.2/2-C
3.3Vdc
5.0Vdc
5.25Vdc
2.0A
2.0A
2.0A
±2%
±2%
±2%
8.0-32Vdc
8.0-32Vdc
8.0-32Vdc
±0.35%
±0.35%
±0.35%
±0.2%
±0.2%
±0.2%
25 typ., 30 max 20 typ., 35max 20 typ., 35max
See Efficiency Curves
See Efficiency Curves
See Performance Curves
See Performance Curves
Continuous
Output Short Circuit Protection ➀
Input/Output Isolation
None
Overvoltage Protection
None
Undervoltage Protection
None
Environmental
Models
Operating Temperature
Storage Temperature
78SR-3.3/2-C
Cooling ➂
Humidity (Non-condensing)
Physical
Mechanical
Package
Pins
Weight
Pin Soldering
78SR-5/2-C
78SR-5.2/2-C
–40 to +70°C
–40 to +85°C
Free Air Convection
0 to 85%
3. Input-Output Isolation: 78SR regulators’ internal input and output
circuits share a common connection (GND, pin 2), there is no
electrical isolation between their INPUT (pin 1) and OUTPUT (pin 3)
terminals.
4. Overvoltage Protection: 78SR switching regulators do not provide
input or output overvoltage protection. In the extremely rare situation
where a catastrophic failure occurs, the output voltage may rise to
excessively high levels. If the load circuit must be protected against
all possible overvoltage situations, voltage-limiting circuitry must be
provided externally.
5. Soldering & Handling Precautions: All units are designed to be
hand soldered to pc-boards, using lead-free no-clean solders
(+260°C, 5 seconds max.). See the Mechanical Specifications section for pin 1 orientation and recommended pc-board hole dimensions.
78SR series regulators have limited built-in ESD protection; therefore they should always be treated as ESD susceptible devices.
6. Horizontal-Pin Models (78SRH): 78SRH switching regulators are
pin-compatible replacements for TO-220 style LM78xx linear regulators which are installed with their metal tabs or heat sinks laying flat
on the surface of the pc-board. In replacement applications, 78SRH
units must be soldered to the pc-board such that the insulating body
of diode D1 lies flat and in contact with the pc-board’s surface.
See Mechanical Specifications
Open-frame SIP
0.025" (0.64mm) square, tin-plated bronze
0.15 ounces (4.2g)
+260°C for 5 seconds
Absolute Maximum Ratings ➁
Input Voltage:
Operating Temperature
Output Current
+36Vdc
+85°C
3.0 Amps
➀ 78SR Series regulators can withstand a continuous short-circuit across their output
terminals. However, extended short-circuit operation will decrease the unit’s long-term
reliability.
➁ These are stress ratings only; Exposure of devices to any of these conditions may adversely affect long-term reliability. Proper operation under conditions other than those
listed in the Performance/Functional Specifications Table is not implied.
③ See derating chart for more information.
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MPM_78SR-2A.C01 Page 2 of 6
78SR 2 Amp Series
Typical Performance Curves
2 Amp, 3.3V, 5.0V, & 5.2V Output, High
Efficiency, Synchronous Switching Regulators
TA = +25°C, VIN as indicated
Noise and Ripple - 10% and 100% Load, 20 MHz Bandwidth
78SR-3.3/2 Vin = 12V, ILOAD = 0.2A
78SR-3.3/2 Vin = 12V, ILOAD = 2.0A
78SR-3.3/2 Vin = 24V, ILOAD = 2.0A
78SR-5/2
78SR-5/2
78SR-5/2
Vin = 12V, ILOAD = 0.2A
Vin = 12V, ILOAD = 2.0A
Vin = 24V, ILOAD = 2.0A
Transient Response - 50% Load Step
78SR-3.3/2 25% to 75% Load Step
78SR-3.3/2 25% to 75% Load Step
Vin = 12V
78SR-3.3/2 75% to 25% Load Step
Vin = 24V
Vin = 12V
CH1: Vout, 50mV/div.
CH1: Vout, 50mV/div.
CH1: Vout, 50mV/div.
CH2: Load Current 1A/div.
CH2: Load Current 1A/div.
CH2: Load Current 1A/div.
25%
25%
75%
75%
78SR-5/2
40μsec/div.
25% to 75% Load Step
75%
40μsec/div.
78SR-5/2 25% to 75% Load Step
Vin = 12V
25%
78SR-5/2
40μsec/div.
75% to 25% Load Step
Vin = 24V
Vin = 12V
CH1: Vout, 50mV/div.
CH1: Vout, 50mV/div.
CH1: Vout, 50mV/div.
CH2: Load Current 1A/div.
CH2: Load Current 1A/div.
CH2: Load Current 1A/div.
25%
25%
75%
75%
40μsec/div.
75%
40μsec/div.
25%
40μsec/div.
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MPM_78SR-2A.C01 Page 3 of 6
78SR 2 Amp Series
2 Amp, 3.3V, 5.0V, & 5.2V Output, High
Efficiency, Synchronous Switching Regulators
78SR-3.3/2-C Input Current
78SR-5/2-C Input Current
1.0
1.4
2.0A LOAD
2.0A LOAD
1.2
INPUT CURRENT (AMPS)
INPUT CURRENT (AMPS)
0.8
0.6
1.0A LOAD
0.4
1.0
0.8
0.6
1.0A LOAD
0.4
0.5A LOAD
0.2
0.5A LOAD
0.2
0.0
0.0
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
35
INPUT VOLTAGE
INPUT VOLTAGE
78SR-3.3/2-C Efficiency
78SR-5/2-C Efficiency
95
90
90
85
85
EFFICIENCY (%)
100
95
EFFICIENCY (%)
100
80
Vin = 8V
75
Vin = 12V
70
Vin = 15V
65
Vin = 24V
Vin = 28V
60
80
Vin = 8V
75
Vin = 12V
70
Vin = 15V
65
Vin = 24V
Vin = 28V
60
Vin = 32V
55
0.25
0.50
0.75
1.00
1.25
Vin = 32V
1.50
1.75
2.00
LOAD CURRENT (AMPS)
55
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
LOAD CURRENT (AMPS)
Thermal Derating Curve*
OUTPUT CURRENT (AMPS)
2.00
60ºC
65ºC
1.75
70ºC
1.50
1.25
8
12
15
24
28
INPUT VOLTAGE
32
36
*Solid lines are for 3.3V and 5.0V models;
dashed lines are for 5.2V models.
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MPM_78SR-2A.C01 Page 4 of 6
78SR 2 Amp Series
2 Amp, 3.3V, 5.0V, & 5.2V Output, High
Efficiency, Synchronous Switching Regulators
SHIPPING TRAYS AND BOXES
10.50”
REF
EACH FOAM TRAY CONTAINS 63 UNITS. IN FULL MPQ QUANTITIES,
THREE TRAYS EQUAL TO A TOTAL OF 189 (3x63) UNITS PER BOX.
11.25”
REF
2.75
REF
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MPM_78SR-2A.C01 Page 5 of 6
78SR 2 Amp Series
2 Amp, 3.3V, 5.0V, & 5.2V Output, High
Efficiency, Synchronous Switching Regulators
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES:
2 PL DEC ±0.02 (±0.51)
3 PL DEC ±0.010 (±0.254)
Standard Package
0.16
(4.1)
0.80
(20.3)
D1
L1
L1
Pins: 0.025 (0.64) sq.
0.100 (2.54)
centers
0.85
(21.6)
PC-Board Hole:
0.037 - 0.043
(0.94 - 1.09) Dia.
$!4%,32
#
0.095
(2.4)
1
0.15
(3.8) Min.
3
OUTPUT (+VOUT)
GND
INPUT (+VIN)
0.23
(5.7)
2
Horizontal Package
(H Pin Option)
L1
0.07
(1.8)
L1
L1
1
2
3
0.30 (7.6) min.
0.280
(7.1)
D1
OUTPUT (+VOUT)
ISO 9001 and 14001 REGISTERED
GND
INPUT (+VIN)
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
Pins: 0.025 (0.64) sq.
0.100 (2.54)
centers
PC-Board Hole:
0.037 - 0.043
(0.94 - 1.09) Dia.
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without
notice.
© 2017 Murata Power Solutions, Inc.
www.murata-ps.com/support
MPM_78SR-2A.C01 Page 6 of 6