Updating switching power supplies

UPDATE.NOV–Update switch power supplies–Nov–SC

Updating switching power supplies

Recently introduced power sources continue to shrink and meet more
demanding regulations

BY SPENCER CHIN Associate Editor

While ac-to-dc OEM switching power supplies have not undergone any
breakthrough changes of late, they continue to benefit from many less
obvious but important enhancements. These include the addition of power
factor correction and universal ac input, the development of modular power
supplies, and the incorporation of battery-backup capability. Supplies
that meet the special requirements of the medical market are also
available. From a performance standpoint, the most important trend
continues to be the addition of power factor correction (PFC) either
inside the supply or as a separate front-end module. PFC is needed to
smooth out the high harmonic currents encountered during switching and
eliminate the possibility of wires and transformers overheating. The IEC
555 (now IEC 555-2) standard dictates the allowable amount of harmonic
current generated by the supply. Incorporating power factor correction
into the switcher also has the side benefit of automatically implementing
universal input, whereby the supply automatically operates over an 85 to
264-Vac range without requiring the user to change jumpers or wires.

Power factor correction One new switcher with power factor correction is
the series HV from Shindengen. This supply is available in a 250-W version
outputting 24 V at 10 A or a 500-W version outputting 30 V at 30 A and works
with better than 80% efficiency. Voltage regulation is +/-5%, and ripple
and noise is 1.5 Vp-p. The supply measures 5 x 2.76 or 3.94 x 8 in. ()
Switching Systems International has added a 500-W power factor correction
module to its line. Designated the PF501, the switcher provides a single
375 to 400-Vdc output. Other specifications include a line regulation of
2%, load regulation of 3%, and ripple and noise of 3% peak-to-peak. ()
Higher up on the power scale is the series RCW from Kepco, rated at 750 W.
This single-output supply uses an FET-based forward converter and conducts
continuously rather than in narrow high-current pulses, allowing it to
meet the IEC 555-2 harmonic current limits. Output ratings range from 3.3
V at 150 A to 48 V at 15 A. () The 1,000-W QD16 from Cherokee is
available with up to four outputs. The main output is available in 5, 12,
24, and 28 V; the second output 5 and 12 V; the third output 12 and 15 V;
and the fourth output 5, 12, and 24 V. Line and load regulation is +/-0.
5%, and ripple and noise is 1% peak-to-peak. The supply measures 5 x 8 x
12.25 in. () The NU1000 supply from Farnell Advance Power is rated at 1,
000 W and outputs 5, 12, 15, and 24 V. It has remote sensing, overvoltage
protection, dc OK signal, remote inhibit, and current limiting. The supply
meets UL, CSA, and VDE requirements. It measures 5 x 8 x 11 in. () At 2,
000 W is the model PM2549 from Pioneer. This single-output switcher is
available with nine voltage-current combinations spanning 2 to 48 V. Line
and load regulation is +/-0.25%, and the supply is protected from
overloads, overvoltages, and overtemperatures. Dimensions are 5 x 8 x 15
in. () Deltron has its model PFC-555 switcher, available in both 1,300
and 2,600-W versions. The supply is designed for use as a front end to the
company's series M switcher, or other suppliers' switchers. It exhibits a
line and load regulation of 3% and is 93% efficient. The supply measures
3.80 x 5.05 x 10.06 in. () For use in severe environments, the series PB
from Arnold Magnetics has line isolation and EMI suppression to DO 160B
and MIL-STD-461. Surge/spike protection meets MIL-STD-704D and
MIL-STD-1399, and environmental performance meets MIL-STD-810D. The
operating temperature range is -55 degrees to +85 degreesC without
derating. The supply is available with 24 to 300-V outputs. ()

Universal input almost universal Power factor correction is being
designed into supplies mostly at the a medium to high power
levels–typically above 300 W, where its benefits are most apparent.
Universal input, on the other hand, is being incorporated even into
low-power switchers so they can be used in both domestic and European
equipment. The FLU2-20 from Power General produces 20 W and provides a
5-V main output, and 12-, 15-, or 24-V secondary outputs. Mean-time before
failure is 210,000 hours, and operating temperature range is 0 degrees to
70 degreesC before derating. The supply measures 3 x 5 x 1.2 (H) in. ()
Slightly higher in power than the FLU2-20 is the series 25 single-output RBS
and triple-output RBT switchers from Astec, both rated at 25 W. The
single-output RBS provides 5-, 12-, or 24-V outputs. The triple-output RBT
provides combinations of +/-5, +/-12, and +/-15 V. Line and load
regulation is +/-2% on the main output, +/-5% on auxiliaries. Ripple and
noise is 1% peak-to-peak. Measuring 3 x 4 x 1.3 in., the supplies have EMI
filtering to VDE Level B and full circuit protection. A 110-W version is
also available. ()
At 40 W is the model PSM-403 from Phihong. This switcher, designed for
networks, measures 6.2 (L) x 3.2 (W) x just 1.5 (H) in. It outputs 5 V at
3 or 6 A, +12 V at 0.5 or 0.7 A, and -12 V at 0.2 A. The supply meets UL,
CSA, and VDE specifications. () Zenith Magnetics has introduced new 30
and 45 W universal input switchers designated the ZPS-30 and ZPS-45,
respectively. Both have a 5-V main output and +/-12- or +/-15-V auxiliary
outputs. Line and load regulation is +/-3% on the 5- and +/-12-V outputs
and +/-5% on the +/-15-V outputs. Peak-to-peak ripple and noise is 50 mV
on the 5-V output, 120 mV on the +/-12-V outputs, and 150 mV on the
+/-15-V outputs. Mean-time-before-failure is 500,000 hours per MIL-HDBK
217E. Dimensions are 3 x 5 x 1.35 or 1.85 in. () Available from Globtek
is the 60-W DSP-654X. This supply outputs +/-5, +/-12, +/-15, and 24 V and
switches at 30 kHz. The open-frame supply measures 2.76 x 5.12 in. A 30-W
version is also available. () Rated 80 W, the series NFS 80 from
Computer Products provides four outputs rated 5 V at 8 A, 12 V at 2.5 A, 15
V at 2.5 A, and 24 V at 2 A. The operating temperature is 0 degrees to 50
degreesC, and efficiency 70%. Line regulation is +/-0.1% max. The supply
meets UL, CSA, and VDE requirements. () Further up the power ladder is
the 110-W series PU 110 from International Power Sources. This universal
input supply is available in models with single outputs of 5 V at 22 A, 12
V at 9 A, 15 V at 7.5 A, and 24 V at 4.5 A. Multi-output models are
available with combinations of 5 V at 10 A, 12 V at 5 A, 24 V at 1 A, -5 V
at 1 A, and -12 V at 1 A. Output tolerances range from +/-2% on
single-output units to +/-3 to +/-4% on multi-output units. The open
pc-board version of the supply measures 7 x 4.25 x 1.95 in. () Also
producing 110 W is the UPS110 from Autec Power Systems. This supply,
measuring 7 x 4.25 x 1.87 in., powers small to medium-sized digital
systems. It is available with fixed output voltages of +/-5, +/-12, +/-15,
and +24 V, as well as with adjustable output voltages of 12 to 14, 15 to
18, and 24 to 30 V. Peak currents range from 1.5 to 22 A, depending on
model. () Converter Concepts newest product is its series ST 120, rated
120 W. This supply has four outputs, rated 5, 12, 15, and 24 V. Line
regulation is +/-1%, and efficiency 75%, and switching frequency 100 kHz.
The supply measures 10 x 4.187 x 2.063 in. () Melcher has a 150-W
universal input switcher, the series LK. This supply outputs 5, 12, 15,
24, 30, or 48 V. This supply has inrush current limiting, programmable
output voltage, thermal protection, and overprotection from transients and
under and overvoltages. Line and load regulation is 25 mV, and output
ripple 30 mVp-p. The operating temperature range is -25 degrees to +71
degreesC, un-derated. () Also rated 150 W is the series AF from Power
Solutions. This supply is available with one to four regulated outputs,
available in ratings of 5, +/-12, +/-15, or 24 Vdc. It measures just 3.8 x
6.8 x 1.5 (H) in.–one of the smallest footprints for supplies of this
power rating, says the company. () Xentek offers a new line of
autoranging supplies rated from 175 to 500 W. The AR series supplies each
have four outputs, with the main output rated 5 V at 15 to 70 A, depending
on the wattage. Efficiency is 75%, and switching frequency 100 kHz. Line
and load regulation is 1%. Dimensions range from 11.50 x 4.25 x 2 to 13.50
x 5 x 3.50 in. () Until now, designers wishing to operate from
three-phase voltages worldwide have had to add a transformer to step down
the 380/415-Vac three-phase European voltage to the 208-Vac, or otherwise
rewire the supply to operate on single-phase 240 Vac. But HC Power
recently introduced its ECT 15, a 1,500-W supply that has a built-in
circuit that allows operation on either three-phase ac input. This is
implemented through a front panel switch. On top of this valuable feature,
the ECT 15 adds power factor correction. Outputs are rated 2 Vdc at 340 A
to 48 Vdc at 31 A. A 2,000-W version, the ECT 20, is also available. ()

Modular supplies Modular power supplies, made up of modules which give the
user flexibility in configuring his input and output configuration, are
also gaining popularity with users constrained by standard supply choices.
One of the latest modular supplies is the Unimod series H from Unipower.
This supply is configurable for up to 1,200 W from a choice of 25
different dc modules having output ratings from 2 to 48 Vdc. The supply
has an autoranging 90 to 132/175 to 264 Vac input and is also available
with power factor correction module. () Competing with the series H is
the series 36M from Qualidyne. The supply can incorporate up to nine
outputs totaling 2,000 W. Output ratings range from 2 to 56 Vdc over a 5
to 300-A range. Input voltage range is 180 to 264 Vac. The series 36M
exhibits a line regulation of 0.2%, load regulation of 0.8%, and output
ripple and noise of 1% peak-to-peak. () From LH Research is the series B
modular supply. This supply is configurable from 600 to 2,000 W and can be
ordered with modules for auto-strapping universal input as well as power
factor correction. Output voltages range from 2 to 48 Vdc. Line regulation
is 0.1%, and load regulation 0.4% from no load to full load. Switching
frequency is 140 kHz, and efficiency exceeds 75%. () For medium power
needs, Power-One has its new mid-range Energy series with ac input
sections with for 250, 350, and 450 W outputs. Each chassis is
configurable with one main output and three auxiliary modules. Up to seven
outputs are available when dual-output auxiliary modules are used. Output
voltages are 5, +/-12, +/-15, and 24 V. Options include power factor
correction and an autoranging universal input. Dimensions are 5 (W) x 2.5
(H) x 10 (L) in. () Westcor's latest modular switcher is the MegaPAC,
which can be configured to produce from 400 to 1,600 W with one to eight
slide-in output modules. Outputs are rated 2 to 95 Vdc and have remote
sense, overvoltage protection, and current limiting standard. Efficiency
ranges from 80 to 85%. The fan-cooled supply measures 11.8 (L) x 6 (W) x
3.4 (H) in. () Able to produce up to 5,000 W is the model 10005 from
Power Ten. This switcher, part of the company's 4600 series, outputs 0 to
1,000 V at 0 to 2.5 through 0 to 5 A, depending on the number of modules
hooked up. The field-replaceable modules can operate in series or
parallel. Line and load regulation is 0.1%. The supply measures 19 (W) x
22 (D) x 5 1/4 (H) in. ()

For rack mounting Some users are demanding switching supplies that fit
into their 19-in. racks without overheating the components. For these
applications, the Monovolt PK 60 FKK from BICC-Vero is available. Offering
a switch-selectable 110/220-V input, the supply fits a 19-in. subrack per
DIN 41494 spec. Plug-in depth is 160 mm. The supply operates at 0 degrees
to 70 degreesC without derating. () Elma Electronic also has a new line
of plug-in supplies for VME systems. The supplies fit into 3U and 6U slots
and have DIN connectors. They are available in 150-, 180-, and 270-W
models with 5, and +/-12 V outputs. Input power is 85 to 264, 90 to 132, 180
to 264, 103 to 135, or 211 to 245 V. ()
Also able to mount in a 19-in. rack is the series 05D-9112-XX from
Conversion Equipment Corp. This supply, rated 300 W, has an autoranging 90
to 135/180 to 250 Vac input. Outputs are 5 V and 10 A and 12 V at 10 A.
The supply can power up to four disk combinations of hard disk and tape
drives. ()

Battery backup useful The ability to operate from a dc battery input as
well as ac is becoming useful where users want uninterrupted power. In
effect, this capability gives a switching power supply user valuable
backup power which only uninterruptible power supplies have provided. ()
Battery backup is the key feature of the Mini-Ups supply from Sierra West
Power Systems. The supply normally operates off 110 or 220 Vac, but
automatically switches to 12, 24, or 48 Vdc if the ac input is lost or
falls below 90 Vac. Outputs are 5 Vdc at 1.5 A and +12 Vdc at 2 A. The
30-W supply is housed on an open-frame chassis measuring 5 x 5.5 x 1.5 (H)
in. () Another supply with a dc as well as an ac input is the series GL
from Sola. This 40-W switcher not only has a universal 85 to 264-Vac input
but also accepts 120 to 370 Vdc. It is available with a single output
(model GLS), dual output (model GLD), or triple output (model GLT). Output
voltages are 5, 12, 15, or 24 V, depending on model. Features common to
all include on-board line fuse protection, overload protection, and EMI
filtering. () The TDI-596 from Technology Dynamics produces 500 W and
accepts 48 Vdc as well as 85 to 264 Vac. Power factor correction is also
standard. The single output is rated 24 V at 30 A. Features of the supply
include remote programming, remote sense, and protection from overvoltages
and short circuits. The supply comes in a standard 5 x 8 x 12.5-in. case.
() Jeta Power Systems has a new 1,200-W supply with both battery backup
and power factor correction. Designated the model P1204, the supply
provides 2 to 28 V on the main output and 2 to 24 V on the auxiliary
outputs. A two-stage dc battery charger maintains power in event of ac
power failure. Other features of the supply include current sharing,
remote programming, overload and thermal protection, and remote sense.
() Factors other than power factor correction, universal input, a modular
configuration, or battery backup can also be important to some users. For
applications requiring just high power, Sorensen has introduced the 2-kW
series S. This supply operates from 180 to 264 Vac and can operate in an n
+ 1 configuration with current sharing. Standard features include current
limiting. Outputs are rated 2 to 48 Vdc. ()
While more switching supplies can operate in an n + 1 redundant mode,
most only do so with a third-wire connection. Todd Products has introduced
its MPS series which eliminates a third-wire connection. Instead, the
supply uses a proprietary zero-wire paralleling technique with a
nondissipative droop regulator that automatically shares output power and
ensures glitch-free operation. Any number of supplies can be linked in
parallel. () Rated 350 W, the MPS supplies provide four outputs with the
main output rated 5 V at 50 A. The second output is rated rated 12 V at 8
A, the third output -12 V at 4 A, and the fourth output 24 V at 1.5 A, -5
V at 2 A, or 12 V at 2 A. () For military applications is the AW 100 and
AW 200 from Abbott Electronics. Rated 100 and 200 W respectively, they
accept 115-Vac inputs and output 5 to 28 Vdc. The supplies exhibit 0.1%
line and load regulation and operate over a -55 degrees to +100 degreesC
range without derating. They meet MIL-STD-810C, MIL-STD-901C, and
MIL-STD-461C requirements. () For applications where space and weight
are critical, the model 7070 from James weighs under 1.5 lb and measures
6.65 (L) x 4.35 (W) x 2.02 (H) in. It produces 60 W at 5 and +/-12 V and
operates from 87 to 132 or 174 to 264 Vac, single-phase. The supply is
protected from short circuits and brownouts. () Wide-range adjustable
outputs are the main feature of a new line of 325 to 600-W supplies from
Acopian. These supplies operates on 90 to 132 Vac, single-phase (180 to
264 Vac is optional). Output voltages are 5 to 15, 5 to 30, and 15 to 50
V. Line and load regulation are +/-0.05%, and ripple is 100 or 150 mVp-p.
Protection from overloads, overvoltages, and short circuits is standard.
() For low-power applications requiring only a domestic line voltage, the
series SW from Pico Electronics is available in single- and dual-output
models rated 5, 10, and 15 W. These switchers operate from -25 degrees to
+70 degreesC without derating and need no heat sink. Output voltages are
combinations of +/-5, 12, or +/15 V, depending on the model. Line
regulation is +/-1%, and load regulation +/-2%. ()

For medical needs Medical equipment is a growing area for switching
supplies, and the Mark III Model 3001 from Zytronics meets the UL 544
standards for isolation voltage required by the medical industry. This
switcher produces 125 W over three outputs, the main rated 5 V and the two
auxiliary outputs rated 15 and either 12 or 24 V. Load regulation is
+/-5%, and ripple and noise is 50 mVp-p. Mean-time-before-failure is 200,
000 hours. () Condor has a new 225-W switcher that's also approved to UL
544, and meets IEC 601-1 and VDE 0750 as well. The model GPM-225 is
available with single outputs rated 5, 12, 15, 24, and 28 V. It has
universal input and carries all major agency approvals. ()

The following companies supplied information used in this article. A
complete list of switching power supply manufacturers can be found in
Electronic Engineer's Master, Vol. D.

Abbott Electronics Inc., Los Angeles, CA William Standen
213-202-8820,

Acopian Easton, PA Tom Skopal 215-258-5441

Applied Power Conversion, Technology Dynamics Bergenfield, NJ Mark
Jacobus 201-385-0500

Arnold Magnetics Corp. Camarillo, CA Bob Deininger 805-484-4221

Astec America, Inc. Oceanside, CA Roberta Halliburton 619-439-4245

Autec Power Systems Simi Valley, CA Dan Erb 805-522-0888

BICC-Vero Electronics, Inc. Hamden, CT Christine Lockwood
203-288-8001

Cherokee International, Inc. Tustin, CA Dennis Pouliet 714-544-6665

Computer Products South Boston, MA Janice Williams 617-268-1170

Condor D.C. Power Supplies, Inc. Oxnard, CA Mike Kirkowski
805-486-4565

Conversion Equipment Corp Orange, CA Paul Fejes 714-637-2970

Converter Concepts, Inc. Pardeeville, WI Rick Hartt 608-429-2144

Deltron, Inc. North Wales, PA Jack Phillips 215-699-9261

Elma Electronic, Inc. Fremont, CA Kris Holla 510-656-3400

Farnell Advance Power Supplies, Inc. Solon, OH L. Briggs Dunn
216-349-0755

Globtek, Inc. Northvale, NJ Margaret Sullivan 201-784-1000

HC Power Inc. Irvine, CA Jack Graham 714-261-2114

International Power Sources, Inc. Ashland, MA Rich Sakakeeny
508-881-7434

James Electronics, Inc. Chicago, IL Vince Kennedy 312-463-6500

Jeta Power Systems, Inc. Signal Hill, CA Jagdish Chopra 213-427-0095

Kepco, Inc. Flushing, NY Paul Birman 718-461-7000×742

LH Research, Inc. Tustin, CA Steve Johnson 1-800-547-2537

Melcher, Inc. Chelmsford, MA Marie Harris 508-256-1812

Phihong Milpitas, CA Alan Richards 408-263-2200 95035

Pico Electronics, Inc. Mount Vernon, NY Dennis Kelemen 914-699-5514

Pioneer Magnetics, Inc. Santa Monica, CA Fred Heath 310-829-6751

Power General, Unitrode Corp. Canton, MA Charles Welsch 617-828-6216

Power Solutions Pompano Beach, FL Norm Berkowitz 305-943-4110

Power Ten, Inc. Sunnyvale, CA Vince Mutascio 408-738-5959

Power-One D.C Power Supplies Camarillo, CA Dennis Broundi
805-987-8741

Qualidyne Systems, Inc. San Diego, CA Mel Berman 619-575-1100

Shindengen America Inc. Westlake Village, CA Peter Gajewski
805-373-1130

Sierra West Power Systems Las Cruces, NM John Camilliere 505-522-8828

Sola, A Unit of General Signal Elk Grove Village, IL Wilbert Jones
708-439-2800

Sorensen Co. Paxton, IL Bob Unger 217-379-2171

Switching Systems International Placentia, CA Guy Lacerte
714-996-0909

Technology Dynamics Inc. Bergenfield, NJ Mark Jacobus 201-385-0500

Todd Products Corp. Brentwood, NY Paul Todd 516-231-3366

Unipower Corp. Pompano Beach, FL Ed Schneider 305-974-2442

Westcor Corp. Los Gatos, CA Nancy Pepper 408-395-7050

Xentek, Inc. Vista, CA Chuck Henry 619-727-0940

Zenith Components Glenview, IL Kerry Richards 708-391-8510

Zytronics Bedford, NH Jan St. Pierre 603-623-8888 70 Tirrell Hill Rd
03110