®
®
A SUBSIDIARY OF C&D TECHNOLOGIES
78SR Series
NEW
low-profile package
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!
•
Two SIP-packages fit existing TO-220 footprints:
Vertical-pin models occupy less than 0.1 square in.
Optional horizontal pins provide 0.350 in. installed height
•
+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
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.
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.
7. Horizontal-Pin Models (78XXSRH):
78XXSRH switching regulators
are pin-compatible replacements for TO-220 style LM78XX linear reg-
ulators that are installed with their metal tabs lying flat on the surface
of the pc-board. However, because the surface of inductor L1 on
78XXSRH models is electrically conductive, it must not be allowed to
come in contact with any exposed pc-board traces, other than power
ground (GND).
While the 2-mil-thick (0.05mm) polyester label attached to L1 provides
some degree of electrical insulation (only if L1 sits perfectly flat on
the pc-board), it is recommended that a 0.020” (0.5mm) clearance be
maintained between L1 and all exposed pc-board traces.
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
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
7805SR
400mA Load
200mA Load
+7.5 - 36Vdc
1
+V
IN
+V
OUT
3
+5Vdc
@ 500mA
40mA Load
GND
2
GND
400
350
INPUT CURRENT (mA)
300
7812SR Input Current
Figure 1. Typical Connections
Ordering Information
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)
DATEL Part No.
Output Voltage
Output Current
0.5A
0.5A
0.4A
0.5A
0.5A
0.4A
Input Voltage
+7.5-36Vdc
+7.5-36Vdc
+15-36Vdc
+7.5-36Vdc
+7.5-36Vdc
+15-36Vdc
200mA Load
40mA Load
Standard Pin Package
7803SR
+3.3Vdc
7805SR
+5.0Vdc
7812SR
+12.0Vdc
Horizontal Pin Package
7803SRH
+3.3Vdc
7805SRH
+5.0Vdc
7812SRH
+12.0Vdc
Standard Package
0.41
(10.4)
0.19
(4.8)
Mechanical Specifications
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES:
2 PL DEC ±0.02 (±0.51)
3 PL DEC ±0.010 (±0.254)
L1
0.75
(19.1)
Horizontal Package
(H Pin Option)
1
0.15
(3.8) Min.
1
2
3
Pins: 0.025 (0.64) sq.
0.100 (2.54)
centers
0.21
(5.3)
PC-Board Hole:
0.037 - 0.043
(0.94 - 1.09) Dia.
OUTPUT (+V
OUT
)
0.35
(8.9) max.
0.15
(3.8) min.
L1
1
2
3
Pins: 0.025 (0.64) sq.
0.100 (2.54)
centers
PC-Board Hole:
0.037 - 0.043
(0.94 - 1.09) Dia.
INPUT (+V
IN
)
GND
INPUT (+V
IN
)
GND
®
®
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 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
OUTPUT (+V
OUT
)
A SUBSIDIARY OF C&D TECHNOLOGIES
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: (508) 339-3000 (800) 233-2765
Fax: (508) 339-6356
ww.datel.com
E-mail: sales@datel.com
www.cdpowerelectronics.com
DS-0540C
9/04
ISO 9001:2000 REGISTERED
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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