78SR 2 Amp Series
2 Amp, 3.3V & 5V Output, High Efficiency,
Synchronous Switching Regulators
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
Open frame design minimizes self-heating & pc-board
footprint
Includes output short-circuit protection and thermal
shutdown
Low noise output for powering sensitive instrumentation
Datel’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
(58mm
2
) 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.
TECHNICAL NOTES
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.
Ordering Information
Part No.
78SR-3.3/2-C
78SR-5/2-C
78SRH-3.3/2-C
78SRH-5/2-C
Output
Voltage
3.3Vdc
5.0Vdc
3.3Vdc
5.0Vdc
Output
Current
2.0A
2.0A
2.0A
2.0A
Input
Voltage
8.0-32Vdc
8.0-32Vdc
8.0-32Vdc
8.0-32Vdc
For full details go to
www.murata-ps.com/rohs
www.murata-ps.com
Technical enquiries
email: sales@murata-ps.com, tel:
+1 508 339 3000
MPM_78SR-2A_B01
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MURATA [ MURATA MANUFACTURING CO., LTD. ]
