DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 Email: sales@datel.com Internet: www.datel.com
78SR Series
3.3V/5V/12V Outputs
High-Effi ciency Switching
Regulators with LM78XX Pinouts
Features
3.3V/0.5A, 5V/0.5A or 12V/0.4A outputs; Pin and size-compatible
with LM7805 & LM7812 regulators
Up to 95% effi ciency no heat sinks or thermal derating required!
Two SIP-packages fi t 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 fi lter capacitorsno external components required
40 to +70C 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
DATEL's 7805SR (5V output), 7812SR (12V output) and
7803SR (3.3V output) step-down switching regulators are
modern drop-in replacements for older, ineffi cient, 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 effi ciencies as high as
95%. Full-load (up to 0.5A) operation from 9V, 12V, 24V, or 36V
supplies at ambient temperatures up to +70C requires no heat
sinks, no temperature derating, no forced-air cooling, and no
external capacitors.
78SR switching regulators provide many signifi cant
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.
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 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 Effi ciency 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 (+260C, 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 Specifi cations 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 fl at on the surface
Order online at www.datel.com
A SUBSIDIARY OF C&D TECHNOLOGIES
NEW
low-profi le package
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 A T O R S
78SR Series
2
DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 Email: sales@datel.com Internet: www.datel.com
Input/Output
Models 7803SR
7805SR
7812SR
Output Voltage
+3.3Vdc +5.0Vdc +12.0Vdc
Rated Output Current 0.5A
0.5A
0.4A
Output Voltage Accuracy
2%
1.5% 2%
Input Voltage Range
+7.5-36Vdc
+7.5-36Vdc
+15-36Vdc
Line Regulation (100% load)
0.3%
0.3% 0.3%
Load Regulation (0-100% load)
0.2%
0.2% 0.2%
Quiescent Current
3mA typ., 5mA max.
Input Current
See Performance Curves
Effi ciency
See Performance Curves
Transient Response
See Performance Curves
Input & Output Noise
See Performance Curves
Short Circuit Protection
Continuous
Isolation
None
Overvoltage Protection
None
Undervoltage Protection
None
Environmental
Models 7803SR
7805SR
7812SR
Operating Temperature
40 to +70C
Storage Temperature
40 to +85C
Cooling
Free Air Convection
Humidity (Non-condensing)
0 to 85%
Physical
Mechanical
See Mechanical Specifi cations
Package
Open-frame SIP
Pins
0.025" (0.64mm) square,
tin-plated
bronze
Weight
0.08 ounces (2.2g)
Pin Soldering
+260C for 5 seconds
See Technical Note 5.
While these regulators can withstand a continuous short-circuit across their
output terminals, they will experience a signifi cant temperature rise. Extended
short-circuit operation will adversely affect the unit's reliability.
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 fl at on
the pc-board), it is recommended that a 0.020" (0.5mm) clearance be
maintained between L1 and all exposed pc-board traces.
8. Dropout Voltage: 78SR series regulators described in this data sheet
specify a minimum input voltage at which full-load accuracy and output
regulation are guaranteed (7.5V for 7803SR and 7805SR, and 15.0V
for 7812SR). However, these devices will stay in regulation at lower
input voltages if they are operated at less than their rated loads.
The following dropout-voltage data, derived from sample testing per-
formed at an ambient temperature of +25C with resistive loads, should
be used for information purposes only. For these tests, a unit was
considered to be out of regulation when its output changed by more
+/-0.005Vdc from its nominal value. All voltages were measured directly
at the regulator's I/O pins.
0% Load
25% Load
50% Load
100% Load
7803SR
6.0V 6.2V 6.2V 6.3V
7805SR
6.3V 6.2V 6.2V 6.8V
7812SR
12.8V 13.0V 12.8V 13.0V
Typical Dropout Voltage
Technical Notes (continued)
DATEL Part No.
Output Voltage
Output Current
Input Voltage
Standard Pin Package
7803SR +3.3Vdc
0.5A
+7.5-36Vdc
7805SR +5.0Vdc
0.5A
+7.5-36Vdc
7812SR +12.0Vdc
0.4A
+15-36Vdc
Horizontal Pin Package
7803SRH +3.3Vdc 0.5A
+7.5-36Vdc
7805SRH +5.0Vdc 0.5A
+7.5-36Vdc
7812SRH +12.0Vdc 0.4A +15-36Vdc
Ordering Information
Performance/Functional Specifi cations
Typical at T
A
= +25C
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 A T O R S
78SR Series
3
DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 Email: sales@datel.com Internet: www.datel.com
7805SR
Vin = 12V, I
LOAD
= 50mA
Typical Performance Curves
T
A
= +25C, V
IN
as indicated
Noise and Ripple - 10% and 100% Load, 20MHz Bandwidth
Transient Response - 90% Load Step
7805SR
Vin = 12V, I
LOAD
= 500mA
7812SR
Vin = 24V, I
LOAD
= 40mA
7812SR
Vin = 24V, I
LOAD
= 400mA
7812SR
100% to 10% Load Step
7805SR
10% to 100% Load Step
7805SR
100% to 10% Load Step
7812SR
10% to 100% Load Step
7803SR
Vin = 12V, I
LOAD
= 50mA
7803SR
Vin = 12V, I
LOAD
= 500mA
7803SR
10% to 100% Load Step
7803SR
100% to 10% Load Step
Vin = 9V
Vin = 9V
Vin = 18V
Vin = 9V
Vin = 9V
Vin = 18V
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 A T O R S
78SR Series
4
DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 Email: sales@datel.com Internet: www.datel.com
7812SR Effi ciency
7812SR Input Current
7805SR Effi ciency
7803SR Effi ciency
7803SR Input Current
7805SR Input Current
50
55
60
65
70
75
80
85
90
8
10 12 14 16 18 20 22 24 26 28 30 32 34 36
INPUT VOLTAGE
E
F
F
I
CI
E
N
CY
0.00
0.05
0.10
0.15
0.20
0.25
8
10 12 14 16 18 20 22 24 26 28 30 32 34 36
INPUT VOLTAGE
I
N
P
U
T
CURRE
NT
(
A
M
P
S
)
25% LOAD
100% LOAD
50% LOAD
25% LOAD
100% LOAD
50% LOAD
60
65
70
75
80
85
90
95
8
10 12 14 16 18 20 22 24 26 28 30 32 34 36
INPUT VOLTAGE
E
F
F
I
CI
E
NCY
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
8
10 12 14 16 18 20 22 24 26 28 30 32 34 36
INPUT VOLTAGE
NP
UT
CURRE
NT
(
A
M
P
S
)
25% LOAD
100% LOAD
50% LOAD
25% LOAD
100% LOAD
50% LOAD
70
75
80
85
90
95
100
14
16
18
20
22
24
26
28
30
32
34
36
INPUT VOLTAGE
EF
F
I
C
I
EN
C
Y
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
14
16
18
20
22
24
26
28
30
32
34
36
INPUT VOLTAGE
I
N
P
U
T
CURRE
NT
(
A
M
P
S
)
25% LOAD
100% LOAD
50% LOAD
25% LOAD
100% LOAD
50% LOAD
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 A T O R S
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
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. Specifi cations are subject to change without notice. The DATEL logo is a registered DATEL, Inc. trademark.
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 Mnchen, 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
ISO 9001:2000 REGISTERED
DS-0540D 11/04
A SUBSIDIARY OF C&D TECHNOLOGIES
Mechanical Specifi cations
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES: 2 PL DEC 0.02 (0.51)
3 PL DEC 0.010 (0.254)
PC-Board Hole:
0.037 - 0.043
(0.94 - 1.09) Dia.
Pins: 0.025 (0.64) sq.
0.100 (2.54)
centers
Horizontal Package
(H Pin Option)
0.15
(3.8) min.
0.35
(8.9) max.
L1
OUTPUT
(+V
OUT
)
GND
INPUT
(+V
IN
)
1
2
3
1
1
0.75
(19.1)
0.41
(10.4)
OUTPUT
(+V
OUT
)
PC-Board Hole:
0.037 - 0.043
(0.94 - 1.09) Dia.
GND
INPUT
(+V
IN
)
0.21
(5.3)
Pins: 0.025 (0.64) sq.
0.100 (2.54)
centers
0.15
(3.8) Min.
0.19
(4.8)
1
2
3
L1
Standard Package
PDF 
ZIP