®
®
78SR Series
3.3V/5V/12V Outputs
High-Efficiency Switching
Regulators with LM78XX Pinouts
DATEL’s 7805SR (5V output), 7812SR (12V output) and
7803SR (3.3V output) step-down switching regulators are
modern drop-in replacements for older, inefficient, LM7805 and
LM7812 linear regulators. The 78XXSR's are pin- and size-
compatible with industry-standard TO-220 SIP packages. A
260kHz switching frequency provides for efficiencies as high as
95%. Full-load (up to 0.5A) operation from 9V, 12V, 24V, or 36V
supplies at ambient temperatures up to +70°C requires no heat
sinks, no temperature derating, no forced-air cooling, and no
external capacitors.
78SR switching regulators provide many significant
improvements over their linear counterparts: lower quiescent
current (3mA vs. 5 mA), higher input voltage (40V vs. 32V),
and better output accuracy (±1.5% vs. ±5%). All these features
combine to make 78SR regulators ideal for new or existing
LM7805 & LM7812 applications requiring full-load operation at
elevated voltages.
Order online at www.datel.com
Features
•
3.3V/0.5A, 5V/0.5A or 12V/0.4A outputs; Pin and size-compatible
with LM7805 & LM7812 regulators
•
Up to 95% efficiency – no heat sinks or thermal derating required!
•
3-pin SIP fits existing TO-220 footprints; <0.1 square inch
pc-board space
•
+7.5-36Vdc operating input range; Low 3mA quiescent current
•
Built-in filter capacitors – no external components required
•
–40 to +70°C operation at full load; Short-circuit protection
•
Excellent load (±0.2%) and line (±0.3%) regulation
•
Ideal for powering instrumentation from 9V/12V/24V/28V
supplies or batteries
•
Can be used with unregulated dc supplies
Technical Notes
1. Input/Output (I/O) Filtering:
As shown in the noise and ripple graphs,
78SR switching regulators exhibit excellent low-noise performance with
no external I/O capacitors. However, if additional noise reduction is
required, be sure to use low-ESR capacitors that are rated for continu-
ous operation (with an additional 20% safety margin) at the highest
system voltages and temperatures. Adding external output capacitors
will also improve the unit’s load-transient response.
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 selecting an appropriate
slow-blow fuse.
3. Input-Output Isolation:
78SR regulators’ internal input and output
circuits share a common connection (GND, pin 2); there is no electrical
isolation between the 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
in which a catastrophic failure occurs, the output voltage may rise
to excessively high levels. If your load must be protected against
all possible overvoltage situations, external voltage-limiting circuitry
must be provided.
5. Operation at 40Vdc:
Operating with inputs up to 40Vdc is permissible
if, for inputs between 36 and 40Vdc, the maximum load current is
reduced to 0.35A for 7805SR and 7803SR, and to 0.3A for 7812SR.
Under no circumstances should the input voltage be allowed to
exceed 45Vdc.
6. Soldering & Handling Precautions:
All units are designed to be
hand soldered to pc-boards using no-clean solders (+260°C, 5 sec-
onds max.). Water-soluble solders can also be used, but the units
must be washed and dried using processes appropriate to the type of
solder employed. See the Mechanical Specifications section for pin 1
orientation and recommended plated-through hole dimensions.
While 78SR regulators easily withstand a 2kV ESD discharge to any
terminal (using human body model), they should always be treated as
ESD sensitive devices.
DATEL, Inc., Mansfield, MA 02048 (USA)
•
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
•
E–mail: sales@datel.com
•
Internet: www.datel.com
78SR Series
H I G H - E F F I C I E N C Y S W I T C H I N G R E G U L ATO R S
Performance/Functional Specifications
Typical at T
A
= +25°C
Input/Output
Models
Output Voltage
Rated Output Current
Output Voltage Accuracy
Input Voltage Range
➀
Line Regulation (100% load)
Load Regulation (0-100% load)
Quiescent Current
Input Current
Efficiency
Transient Response
Input & Output Noise
Short Circuit Protection
➁
Isolation
Overvoltage Protection
Undervoltage Protection
7803SR
+3.3Vdc
0.5A
±2%
+7.5-36Vdc
±0.3%
±0.2%
7805SR
+5.0Vdc
0.5A
±1.5%
+7.5-36Vdc
±0.3%
±0.2%
7812SR
+12.0Vdc
0.4A
±2%
+15-36Vdc
±0.3%
±0.2%
Environmental
Models
Operating Temperature
Storage Temperature
Cooling
Humidity (Non-condensing)
Physical
Mechanical
Package
Pins
Weight
Pin Soldering
➀
See Technical Notes 5 and 6.
➁
While these regulators can withstand a continuous short-circuit across their
output terminals, they will experience a significant temperature rise. Extended
short-circuit operation will adversely affect the unit’s reliability.
See Mechanical Specifications
Open-frame SIP
0.025” (0.64mm) square, tin-lead
plated bronze
0.08 ounces (2.2g)
+260°C for 5 seconds
7803SR
7805SR
–40 to +70°C
–40 to +85°C
Free Air Convection
0 to 85%
7812SR
3mA typ., 5mA max.
See Performance Curves
See Performance Curves
See Performance Curves
See Performance Curves
Continuous
None
None
None
Typical Performance Curves
T
A
= +25°C, V
IN
as indicated
Noise and Ripple - 10% and 100% Load, 20MHz Bandwidth
7803SR
Vin = 12V,
I
LOAD
= 50mA
7805SR
Vin = 12V,
I
LOAD
= 50mA
7812SR
Vin = 24V,
I
LOAD
= 40mA
7803SR
Vin = 12V,
I
LOAD
= 500mA
7805SR
Vin = 12V,
I
LOAD
= 500mA
7812SR
Vin = 24V,
I
LOAD
= 400mA
DATEL, Inc., Mansfield, MA 02048 (USA)
•
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
•
E–mail: sales@datel.com
•
Internet: www.datel.com
2
78SR Series
H I G H - E F F I C I E N C Y S W I T C H I N G R E G U L ATO R S
7812SR Efficiency
100%
95%
90%
EFFICIENCY
85%
80%
75%
70%
65%
14
16
18
20
22
24
26
28
30
INPUT VOLTAGE (Volts DC)
32
34
36
38
40
Mechanical Specifications
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES:
2 PL DEC ±0.02 (±0.51)
3 PL DEC ±0.010 (±0.254)
400mA Load
200mA Load
40mA Load
400
350
INPUT CURRENT (mA)
300
7812SR Input Current
400mA Load
250
200
150
100
50
0
14
16
18
20
22
24
26
28
30
32
34
36
38
40
INPUT VOLTAGE (Volts DC)
200mA Load
40mA Load
Ordering Information
7805SR
DATEL Part No.
7803SR
7805SR
7812SR
Output Voltage
+3.3Vdc
+5.0Vdc
+12.0Vdc
Output Current
0.5A
0.5A
0.4A
Input Voltage
+7.5-36Vdc
+7.5-36Vdc
+15-36Vdc
+7.5 - 36Vdc
1
+V
IN
+V
OUT
3
+5Vdc
@ 500mA
GND
2
GND
Figure 1. Typical Connections
®
®
DATEL (UK) LTD.
Tadley, England Tel: (01256)-880444
Internet: www.datel-europe.com E-mail: datel.ltd@datel.com
DATEL S.A.R.L.
Montigny Le Bretonneux, France Tel: 01-34-60-01-01
Internet: www.datel-europe.com E-mail: datel.sarl@datel.com
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: (508) 339-3000 (800) 233-2765
Fax: (508) 339-6356
Internet: www.datel.com
E-mail: sales@datel.com
ISO 9001:2000 REGISTERED
DS-0540B
5/04
DATEL GmbH
München, Germany Tel: 89-544334-0
Internet: www.datel-europe.com E-mail: datel.gmbh@datel.com
DATEL KK
Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-6354-2025
Internet: www.datel-co.jp E-mail: salestko@datel.co.jp, salesosa@datel.co.jp
DATEL China
Shanghai, China Tel: 011-86-51317131
E-mail: davidx@datel.com
DATEL 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. The DATEL logo is a registered DATEL, Inc. trademark.
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