Toroidal Transformers
Standard Toroidal Isolation Transformers Toroidal Transformer ConstructionMedical Grade Isolation TransformersLow Profile PC Mount Toroid TransformersFeatures Of Toroidal TransformersLow Profile Miniature 50/60Hztransformers Toroidal Power Inductors Current TransformersStandard Toroidal Auto TransformersWhy Choose A Toroidal Transformer
About Toroidal Transformers
These are power transformers utilizing a toroidal core. Primary and secondary coils are wound on this core and the toroidal shape allows for a shorter mean length per turn, reducing I^{2}R losses in winding which are the main losses in this type of transformer yielding a smaller design improving overall efficiency.
Line frequency toroidal transformers start with a core made from a continuous strip of thin, typically M4, grainoriented electrical grade silicon steel. Silicon grains in the steel are oriented based on the rolling direction of the steel and is slit parallel to that orientation, creating the preferred path for magnetic flux. Strips are available in numerous widths; for smaller and midsized cores these are typically available in 1mm increments, and larger toroidal cores strips are available in 5mm increments.This steel has a thin inorganic coating for high interlaminar resistance, providing insulation between lamination windings and a good stacking factor.
To create the core, a strip of grainoriented electrical grade silicon steel is tightly wound under controlled conditions and tension on a mandrel, similar to a clock spring with the ends spotwelded in place, assuring a firm and congruous magnetic path. Unfortunately winding of the core creates mechanical and magnetic stresses, which change the molecular structure of the core. To return the material to a fully stress relief condition, the core is placed in an annealing furnace. Using a precise heating and cooling profile ensures that the silicon grains are in the single preferred magnetic direction.
Core insulation consists of four layers of 2mil polyester film (other materials are available) applied to the core using a toroidal tape winding machine. This insulation provides 100% surface coverage, also protecting and cushioning the core from the windings and reducing vibration. Primary windings are applied by a toroidal winder and if needed lead wires are attached. The primary to secondary insulation uses the same process and materials as the core insulation, to meet standard test requirement of 4kV RMS for 1 minute between primary and secondary.
Secondary windings are applied by a toroidal winder and if needed lead wires are attached. The copper wire has a base coat of polyester and heavy topcoat of an amide imide (200°C). The copper wire is wound uniformly over the entire core to provide: better heat dissipation, minimum flux leakage, and to maintain a low voltage between adjacent turns. The outer insulation is then applied using the same process and materials as the other insulation layers, except only two layers of polyester film are used.
Toroidal Transformer Design Options
 Thermal Protection  Usually in primary circuit, normally closedauto reset opens at high temperature UL, CSA, VDE listed components.
 Center Hole Potting  Thermoplastic material for high mounting precision. Threaded insert or press fitted stud is optional. Thermally conductive compound is available.
 Electrostatic Screen  Copper foil (2mil) laminated between polyester film and tape to reduce capacitive coupling between primary and secondary windings, tightly wound over primary insulation.
 Medical / Safety Shield  Polyester laminated (5mil) copper foil creates a physical barrier between primary and secondary windings, terminated at one end with green and yellow earth wire to meet UL2601 and IEC601.
 Magnetic Shield  Several turns of silicon grainoriented silicon steel are tightly wound around the toroidal circumference, fixed in place by outer insulation.
Toroid Mounting Options
Toroid Mounting  Disk  Toroid Mounting  Flange  Toroid Mounting  PCB
Toroid Metal Disk Mounting Exploded View
50/60Hz power toroidal transformers have unmatched flexibility and efficiency providing a higher performance compact transformer. Since there is no air gap, it results in a stacking factor of 97.5% of its weight. Power toroidal transformers can also operate at higher flux densities than EI transformers, thus reducing the number of turns necessary to induce a given voltage across the same cross section of the core. This means a lower series resistance in the winding, reducing the I^{2}R copper losses. Given the same power output requirements, ambient temperature, and temperature rise allowances, a toroidal transformer will use less material to produce an equivalent transformer leading to a smaller and lighter solution than an equivalent EI laminated transformer. With all the above reasons the question should not be “Why choose a toroidal transformer,” it should be why not!
Toroidal Transformer Core Compared to EI Core
SIMPLIFIED MOUNTING
A one bolt mounting scheme easily and quickly mounts the toroid, avoiding costly mechanical design and tooling charges associated with the first piece of custom conventional EI laminated transformers. A power toroid, toroidal auto transformers and toroidal medical grade isolation transformers have a low centerofgravity along with reduced weight, such that a lower gauge sheet metal is required to support a toroidal transformer. This, further reduces your product’s weight and material and labor cost by eliminating three screws per assembly.
LOW NOLOAD LOSSES
Compared to conventional EI transformers, toroidal power transformers have extremely low noload losses. When used in an application where a circuit is in a quiescent or “standby” mode for long periods of time, the potential power reduction can be significant, sometimes 80% to 90% lower.
LOW WEIGHT
Because they are more efficient, toroid isolation transformers and toroidal auto transformers can be up to 50% lighter (depending on power rating) than EI laminated transformers. Low weight simplifies end product design by reducing mounting hardware and supporting enclosure requirements.
LOW ACOUSTICAL NOISE
The core of a toroid transformer is formed from a single strip of grainoriented electrical grade silicon steel, tightly wound in the form of a clock spring with the ends spotwelded in place. The copper wire is wound over polyester film, forming a silent, stable design without the use of environmentally harmful glues or varnishes. It will not clack or buzz anywhere near the level as would many pieces of separate lamination under the same changing magnetic field. The core actually intensifies the field, not contributing to the problem of layertolayer vibration.
HIGHER EFFICIENCY
The combination of very low core losses (1/2 watt per pound), a lower mean length per turn, and fewer turns yield lower I^{2}R losses. This unique construction allows toroid power transformers to be typically between 15% and 30% more efficient than EI laminated transformers. As a rule, the larger the transformer the more efficient a toroidal transformer becomes.
LOWER OPERATING TEMPERATURE
Since most of the losses in a toroid transformer are in the copper wire, the toroid cools off quicker than the conventional EI transformer type with more iron. At half the load, the toroidal transformer's temperature rise is only about 30% of what it is at full load.
FLEXIBLE DIMENSIONS
Power toroids and power chokes are not constrained to specific lamination sizes. Since the height and diameter of toroids may be carefully varied, it allows flexibility to accommodate specific height and width design requirements.
RADIATE LOWER MAGNETIC FIELDS
Toroid transformers, including toroidal medical isolation transformers, are made from one solid piece of material focusing the field within the core. In addition, the primaries and secondaries are wound uniformly around the entire core. This results in very low radiated magnetic fields. The toroidal transformer is perfect for applications with circuitry, which is highly sensitive to stray magnetic fields. In certain cases, the single bolt mounting allows the toroid to be rotated in place, to yield the best possible results without any additional tooling or sheet metal work. This can be specifically important in medical equipment having especially sensitive electronics; a toroidal medical isolation transformer typically can be placed in closer proximity to these electronics without additional shielding.
SMALL SIZE
Toroidal power transformers have lower core loss, operate at a higher flux density, and allow the conductive windings to be in intimate contact with the core. This enhances current flow at all points in the core yielding a transformer, which is smaller than its EI transformer counterpart. Electrical and mechanical designers appreciate a toroid’s compact dimensions especially where low height is a consideration.
These standard toroidal transformers provide general isolation for general purpose applications for most electrical products which require a stepdown or stepup in voltage. They consist of dual 117 V primaries and dual secondaries. Power capacity ranges from 100 to 3,000 VA.
By offering dual primaries these are easily configurated for 120 V or 240 V operation. Dual secondaries range from 2 to 12 V windings to 2 to 120 V windings. This variety offers the option of stepping down/stepping up your linevoltage or simply providing isolation from your voltage source to your equipment.
Toroidal Isolation Transformer Schematic
Standard Power Toroidal Transformers Include:
 Dual 117 V primaries for 120 V or 240 V operation
 Secondary voltage options
 4 kV isolation between primary and secondary windings
 Standard mounting options
 10″stranded leads
Standard Power Toroidal Transformers
Part Number 
VA Rating 
Secondary Voltage 
OD 
Height 
Weight 
Secondary Current 
Competitor P/N Reference 
XF001002012 
100 
2 x 12 
3.8" 
1.8" 
2.4 
2 x 4.16 
AA50952012 
XF001002015 
100 
2 x 15 
3.8" 
1.8" 
2.4 
2 x 3.33 
AA50952015 
XF001002018 
100 
2 x 18 
3.8" 
1.8" 
2.4 
2 x 2.77 
AA50952018 
XF001002024 
100 
2 x 24 
3.8" 
1.8" 
2.4 
2 x 2.08 
AA50952024 
XF001002030 
100 
2 x 30 
3.8" 
1.8" 
2.4 
2 x 1.66 
AA50952030 
XF001602012 
160 
2 x 12 
4.0" 
2.2" 
3.6 
2 x 6.66 
AA51852012 
XF001602015 
160 
2 x 15 
4.0" 
2.2" 
3.6 
2 x 5.33 
AA51852015 
XF001602018 
160 
2 x 18 
4.0" 
2.2" 
3.6 
2 x 4.44 
AA51852018 
XF001602024 
160 
2 x 24 
4.0" 
2.2" 
3.6 
2 x 3.33 
AA51852024 
XF001602030 
160 
2 x 30 
4.0" 
2.2" 
3.6 
2 x 2.66 
AA51852030 
XF001602120 
160 
2 x 120 
4.0" 
2.2" 
3.6 
2 x 0.66 
AA51852117 
XF002252012 
225 
2 x 12 
4.6" 
2.2" 
5.1 
2 x 9.27 
N/A 
XF002252015 
225 
2 x 15 
4.6" 
2.2" 
5.1 
2 x 7.5 
AA52402015 
XF002252018 
225 
2 x 18 
4.6" 
2.2" 
5.1 
2 x 6.25 
AA52402018 
XF002252024 
225 
2 x 24 
4.6" 
2.2" 
5.1 
2 x 4.68 
AA52402024 
XF002252030 
225 
2 x 30 
4.6" 
2.2" 
5.1 
2 x 3.75 
AA52402030 
XF002252120 
225 
2 x 120 
4.6" 
2.2" 
5.1 
2 x 0.93 
AA52402117 
XF003002015 
300 
2 x 15 
4.6" 
2.9" 
6.5 
2 x 10 
AA53002015 
XF003002018 
300 
2 x 18 
4.6" 
2.9" 
6.5 
2 x 8.33 
AA53002018 
XF003002024 
300 
2 x 24 
4.6" 
2.9" 
6.5 
2 x 6.25 
AA53002024 
XF003002030 
300 
2 x 30 
4.6" 
2.9" 
6.5 
2 x 5 
AA53002030 
XF003002042 
300 
2 x 42 
4.6" 
2.9" 
6.5 
2 x 3.65 
N/A 
XF003002120 
300 
2 x 120 
4.6" 
2.9" 
6.5 
2 x 1.25 
AA53002117 
XF004002024 
400 
2 x 24 
5.4" 
2.4" 
7.2 
2 x 8.33 
AA53752024 
XF004002030 
400 
2 x 30 
5.4" 
2.4" 
7.2 
2 x 6.66 
AA53752030 
XF004002042 
400 
2 x 42 
5.4" 
2.4" 
7.2 
2 x 4.76 
N/A 
XF004002055 
400 
2 x 55 
5.4" 
2.4" 
7.2 
2 x 3.63 
N/A 
XF004002120 
400 
2 x 120 
5.4" 
2.4" 
7.2 
2 x 1.66 
AA53752117 
XF005002024 
500 
2 x 24 
5.4" 
2.8" 
8.8 
2 x 10.41 
AA54602024 
XF005002030 
500 
2 x 30 
5.4" 
2.8" 
8.8 
2 x 8.33 
AA54602030 
XF005002042 
500 
2 x 42 
5.4" 
2.8" 
8.8 
2 x 5.95 
N/A 
XF005002055 
500 
2 x 55 
5.4" 
2.8" 
8.8 
2 x 4.54 
N/A 
XF005002120 
500 
2 x 120 
5.4" 
2.8" 
8.8 
2 x 2.08 
AA54602117 
XF006502024 
650 
2 x 24 
6.0" 
2.9" 
11.5 
2 x 13.54 
AA56252024 
XF006502030 
650 
2 x 30 
6.0" 
2.9" 
11.5 
2 x 10.83 
AA56252030 
XF006502042 
650 
2 x 42 
6.0" 
2.9" 
11.5 
2 x 7.73 
N/A 
XF006502055 
650 
2 x 55 
6.0" 
2.9" 
11.5 
2 x 5.9 
N/A 
XF006502120 
650 
2 x 120 
6.0" 
2.9" 
11.5 
2 x 2.7 
AA56252117 
XF008002024 
800 
2 x 24 
6.4" 
2.8" 
13 
2 x 16.66 
AA58002024 
XF008002030 
800 
2 x 30 
6.4" 
2.8" 
13 
2 x 13.33 
AA58002030 
XF008002042 
800 
2 x 42 
6.4" 
2.8" 
13 
2 x 9.52 
N/A 
XF008002055 
800 
2 x 55 
6.4" 
2.8" 
13 
2 x 7.27 
N/A 
XF008002120 
800 
2 x 120 
6.4" 
2.8" 
13 
2 x 3.33 
AA58002117 
XF010002030 
1000 
2 x 30 
6.6" 
3.3" 
15.6 
2 x 16.66 
N/A 
XF010002042 
1000 
2 x 42 
6.6" 
3.3" 
15.6 
2 x 11.9 
N/A 
XF010002055 
1000 
2 x 55 
6.6" 
3.3" 
15.6 
2 x 9.09 
AA59902055 
XF010002120 
1000 
2 x 120 
6.6" 
3.3" 
15.6 
2 x 4.16 
AA59902117 
XF015002042 
1500 
2 x 42 
8.2" 
3.0" 
23.6 
2 x 17.85 

XF015002055 
1500 
2 x 55 
8.2" 
3.0" 
23.6 
2 x 13.63 

XF015002120 
1500 
2 x 120 
8.2" 
3.0" 
23.6 
2 x 6.25 

XF020002042 
2000 
2 x 42 
8.2" 
4.0" 
29 
2 x 23.8 

XF020002055 
2000 
2 x 55 
8.2" 
4.0" 
29 
2 x 18.18 

XF020002120 
2000 
2 x 120 
8.2" 
4.0" 
29 
2 x 8.33 

XF030002055 
3000 
2 x 55 
9.2" 
4.1" 
39 
2 x 27.27 

XF030002120 
3000 
2 x 120 
9.2" 
4.1" 
39 
2 x 12.5 


These standard toroidal auto transformers stepup or stepdown line voltage, to suit your equipment’s input voltage requirement. Auto transformers consist of a single winding with various taps. They provide no isolation since there is no physical separation between the primary and secondary winding.
In circumstances where voltage isolation between the input and output is not needed, auto transformers are ideal. Since the primary and secondary windings of an auto transformer share common turns, you can expect a size and weight reduction of about 3070%, which results in a significant cost reduction.
Toroidal Auto
Transformer Schematic
Our Standard Toroidal Auto Transformers Include:
 115 V or 230 V input and a 115 V or 230 V output
 Power ratings ranging from 100 to 1,000 VA
 Standard mounting options
 10″stranded leads
Standard Toroidal Auto Transformers
Part Number 
Power Rating (VA) 
Primary Voltage 
Secondary Voltage 
Diameter 
Height 
Weight 
XFA0100A 
100 VA 
115 Vac 
230 Vac 
3.2" 
1.8" 
1.5 lbs 
XFA0100B 
100 VA 
230 Vac 
115 Vac 
3.2" 
1.8" 
1.5 lbs 
XFA0200A 
200 VA 
115 Vac 
230 Vac 
3.8" 
1.8" 
2.8 lbs 
XFA0200B 
200 VA 
230 Vac 
115 Vac 
3.8" 
1.8" 
2.8 lbs 
XFA0300A 
300 VA 
115 Vac 
230 Vac 
4.5" 
1.9" 
3.6 lbs 
XFA0300B 
300 VA 
230 Vac 
115 Vac 
4.5" 
1.9" 
2.8 lbs 
XFA0400A 
400 VA 
115 Vac 
230 Vac 
4.9" 
1.9" 
4.5 lbs 
XFA0400B 
400 VA 
230 Vac 
115 Vac 
4.9" 
1.9" 
4.5 lbs 
XFA0500A 
500 VA 
115 Vac 
230 Vac 
5.0" 
2.3" 
5.5 lbs 
XFA0500B 
500 VA 
230 Vac 
115 Vac 
5.0" 
2.3" 
5.5 lbs 
XFA0600A 
600 VA 
115 Vac 
230 Vac 
5.2" 
2.4" 
6 lbs 
XFA0600B 
600 VA 
230 Vac 
115 Vac 
5.2" 
2.4" 
6 lbs 
XFA0700A 
700 VA 
115 Vac 
230 Vac 
5.4" 
2.6" 
7.5 lbs 
XFA0700B 
700 VA 
230 Vac 
115 Vac 
5.4" 
2.6" 
7.5 lbs 
XFA0800A 
800 VA 
115 Vac 
230 Vac 
5.6" 
2.5" 
7.5 lbs 
XFA0800B 
800 Vac 
230 Vac 
115 Vac 
5.6" 
2.5" 
7.5 lbs 
XFA0900A 
900 VA 
115 Vac 
230 Vac 
5.8" 
2.6" 
8.7 lbs 
XFA0900B 
900 VA 
230 Vac 
115 Vac 
5.8" 
2.6" 
8.7 lbs 
XFA1000A 
1000 VA 
115 Vac 
230 Vac 
5.9" 
2.9" 
9 lbs 
XFA1000B 
1000 VA 
230 Vac 
115 Vac 
5.9" 
2.9" 
9 lbs 
These medical grade high isolation toroidal transformers are integrated into medical devices used in hospitals, medical research facilities, and biomedical companies. They assist in bringing these electronic devices into compliance with the UL 60601 medical safety standard for an additional level of safety and protection.
Design, testing, and construction of toroidal medical isolation transformers are strictly monitored under safety regulations, guidelines and governing laws:
 Minimum air clearance
 Maximum patient leakage current
 Minimum creepage distance
 Maximum enclosure leakage current
 The values of test voltage (high potential voltage test between windings)
 Maximum patient auxiliary current
 Limited max. earth leakage current
 Maximum temperature rise at load and at over load
Standard Medical Isolation Transformers
Part Number 
Nominal Power VA 
Secondary Current at 120V 
Secondary Current at 240V 
OD x Hieght Inches Weight lbs 
Competitor P/N Reference 
MED0100 
100 
.83A 
.42A 
4.0 x 2.0
2.8 
MT0100DS 
MED0200 
200 
1.67A 
.83A 
4.6 x 2.5
4.8 
MT0230DS 
MED0300 
300 
2.50A 
1.25A 
5.0 x 3.0
7.2 
N/A 
MED0400 
400 
3.33A 
1.67A 
5.5 x 3.0
8.8 
MT0400DS 
MED0600 
600 
5.00A 
2.50A 
6.6 x 2.6
11.4 
MT0600DS 
MED0800 
800 
6.67A 
3.33A 
6.6 x 3.1
14.2 
N/A 
MED1000 
1000 
8.33A 
4.17A 
6.6 x 4.25
19.3 
MT1000DS 
MED1500 
1500 
12.5A 
6.25A 
8.2 x 3.9
25.6 
MT1500DS 
MED2000 
2000 
16.67A 
8.33A 
9.0 x 4.0
31.8 
MT2000DS 
MED2500 
2500 
20.83A 
10.42A 
9.0 x 4.3
40 
MT2500DS 
MED3000 
3000 
25.0A 
12.5A 
10.2 x 4.3
47 
MT3000DS 
MED4000 
4000 
33.33A 
16.67A 
11.3 x 4.0
56 
N/A 
MED5000 
5000 
41.67A 
20.83A 
12.36 x 4.5
74 
MT5000DS 
Custom Toroidal Medical Transformer Designs
We can also provide custom medical isolations transformer designs to fit your specific needs. The popular configurations have a combination of the following:
 Custom primary and secondary voltage
 Variety of connection and harnessing options
 Custom mounting and enclosures to meet customer requirements
 Low height/easily configured into minimal space
 Custom medical transformer designs can be added to our UL medical file for a nominal charge
Our lowprofile miniature toroid isolation transformers are rated for 50/60Hz operation and have capacities up to 50 VA. Toroidal power transformers are mainly used in 115/230 V (50/60Hz) applications. They are easily mounted by using a single M4 bolt inserted in a through hole provided in the center of the potting. This provides secure and reliable means of mounting.
These toroidal power transformers are built to UL class A insulation system and are UL recognized to UL 50851 and UL 5085.
They’re also CUL recognized to CSA C22.2 no. 66 and construction meets the requirements of UL 1950 VDE 0805 IEC 950 and EN60950.
Toroid Isolation Transformers offer:
 Greater efficiency
 Lower audible vibration
 Easier mounting
 Lower stray losses (leakage flux)
Toroidal Isolation Transformer Schematic
Low Profile Miniature Isolation Transformers
Standard Low Profile Miniature Toroidal Isolation Transformers
Power VA 
Part Number 
Competitor P/N Reference 
Full Load Voltage (U_{0}) 
Current
mA 
No Load Voltage (U_{0}) 
NoLoad Current 
Reg. % 
Δt
˚C 
Eff
% 
Dim. lxWxH mm 
1.6 
XF10200
XF10201
XF10202
XF10203
XF10204
XF10205 
62000
62001
62002
62003
62004
62005 
2x7
2x9
2x12
2x15
2x18
2x22 
114
89
67
53
44
36 
2x8.94
2x11.63
2x15.43
2x19.30
2x23.41
2x28.19 
1.0 (mA) 
29 
10 
77 
37.5x7.0x17.0
71 (grams) 
3.2 
XF10206
XF10207
XF10208
XF10209
XF10210
XF10211 
62010
62011
62012
62013
62014
62015 
2x7
2x9
2x12
2x15
2x18
2x22 
229
178
133
107
89
73 
2x10.2
2x13.0
2x17.3
2x21.4
2x25.7
2x31.3 
1.5 (mA) 
41 
20 
70 
42.0x7.0x17.5
89 (grams) 
5.0 
XF10212
XF10213
XF10214
XF10215
XF10216
XF10217 
62020
62021
62022
62023
62024
62025 
2x7
2x9
2x12
2x15
2x18
2x22 
357
278
208
167
139
114 
2x9.7
2x12.4
2x17.0
2x21.3
2x25.5
2x30.5 
2.0 (mA) 
45 
29 
70 
47.0x6.0x18.0
115 (grams) 
7.0 
XF10218
XF10219
XF10220
XF10221
XF10222
XF10223 
62030
62031
62032
62033
62034
62035 
2x7
2x9
2x12
2x15
2x18
2x22 
500
389
292
233
194
159 
2x9.5
2x12.2
2x16.2
2x20.3
2x24.3
2x29.7 
3.0 (mA) 
34 
25 
74 
47.0x6.0x21.5
145 (grams) 
10.0 
XF10224
XF10225
XF10226
XF10227
XF10228
XF10229 
62040
62041
62042
62043
62044
62045 
2x7
2x9
2x12
2x15
2x18
2x22 
714
556
417
333
278
227 
2x8.3
12x10.8
2x14.4
2x18.0
2x21.7
2x26.3 
3.0 (mA) 
20 
24 
82 
53.5x6.8x23.5
216 (grams) 
15.0 
XF10230
XF10231
XF10232
XF10233
XF10234
XF10235 
62050
62051
62052
62053
62054
62055 
2x7
2x9
2x12
2x15
2x18
2x22 
1071
833
625
500
417
341 
2x8.9
2x11.1
2x14.8
2x18.5
2x22.2
2x27.2 
4.0 (mA) 
23 
27 
81 
57.5x7.0x24.0262 (grams) 
25.0 
XF10236
XF10237
XF10238
XF10239
XF10240
XF10241 
62060
62061
62062
62063
62064
62065 
2x7
2x9
2x12
2x15
2x18
2x22 
1785
1377
1041
832
694
568 
2x8.3
2x10.7
2x14.2
2x17.8
2x21.4
2x26.2 
5.0 (mA) 
19 
28 
84 
58.0x13.8x34.5
388 (grams) 
35.0 
XF10242
XF10243
XF10244
XF10245
XF10246
XF10247 
62070
62071
62072
62073
62074
62075 
2x7
2x9
2x12
2x15
2x18
2x22 
2500
1944
1458
1166
972
795 
2x8.4
2x10.6
2x14.0
2x17.6
2x20.9
2x25.7 
7.0 (mA) 
17.7 
31 
85 
72.0x17.0x33.5
453 (grams) 
50.0 
XF10248
XF10249
XF10250
XF10251
XF10252
XF10253 
62080
62081
62082
62083
62084
62085 
2x7
2x9
2x12
2x15
2x18
2x22 
3571
2777
2083
1666
1388
1136 
2x8.1
2x10.4
2x13.8
2x17.3
2x20.7
2x25.4 
8.0 (mA) 
15.5 
30 
86 
78.0x22.5x35.0
670 (grams) 
Our Low Profile PCB Mount toroidal power transformers come fully encapsulated in a plastic case. These are designed for throughhole PCB mounting, and are provided with a builtin central screw holder that will accommodate M4/M5 machine screws or selftapping screws. This permits you to secure the toroidal Isolation transformer to the PC board prior to soldering.
There is also room inside the case allowing for other components to be included with the transformer to form a homogeneous unit. Typical components that can be added include: PTC thermistors, fuses, resettable thermal switches, rectifiers and voltage regulators.
All low profile PC mount toroidal isolation transformer models are configured for 2x115 V Input voltages at 50/60Hz. They pass high voltage testing at 0.5 KVAC between primary to primary, secondary to secondary and 4 kV primary to secondary. They are specified at an ambient temperature of 70°F and can withstand elevated ambient temperatures of up to 70˚C.
Advantages of Low Profile PC Mount Toroidal Isolation Transformers:
 Low profile
 Low magnetic field radiation
 Acoustic noise virtually eliminated
 Compact size
 High efficiency
 Low leakage losses
 4 kV isolation between primary and secondary windings
 Manufactured in an ISO 9001 approved facility
 Comply to UL 5085 and VDE 61558 (except for all 2 x 22 V models)
 Bear the CE mark
 Designed and built to meet Class F (155?C) insulation system requirements
Low Profile PC Mount Transformer Dimensions 
VA RATING 
L 
W 
H 
A 
B 
C 
D 
E 
1.6 
39.6 
39.6 
18.5 
35.56 
35.56 
25.4 
30.48 
20.32 
3.2 
44.7 
44.7 
19.5 
40.64 
40.64 
30.48 
35.56 
25.4 
5 
49.7 
49.7 
19.5 
45.72 
45.72 
35.56 
40.64 
30.48 
7 
49.7 
49.7 
23.1 
45.72 
45.72 
35.56 
40.64 
30.48 
10 
55 
55 
26 
50.8 
50.8 
40.64 
45.72 
35.56 
15 
60 
60 
26.3 
55.88 
55.88 
45.72 
50.8 
40.64 
25 
60 
60 
37.5 
55.88 
55.88 
45.72 
50.8 
40.64 
35 
72 
72 
37.5 
66.04 
66.04 
55.88 
60.96 
50.8 
50 
82.4 
82.4 
37.5 
76.2 
76.2 
66.04 
71.12 
60.96 
Additional Features of Low Profile PC Mount Toroidal Isolation Transformers:
 115 V or 230 V input and a 115 V or 230 V output
 Primary intended to be used in 115 V or 230 V @ 50/60Hz
 UL recognition for class A insulation
 UL recognized to UL 50851 and UL 50852
 CUL recognized to CSA C22.2 no. 66
 Design construction meets UL 1950, VDE 0805, IEC 950
 Hipot testing between Primary to Secondary 4000 V (VDE0550)
 Maximum ambient temperature of +60°C
Standard Low Profile PC Mount Toroidal Isolation Transformers
1.6 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016300 
70000 
2 x 
7V 114 mA 
2 x 9V 
2 x 8.80Ω 
Weight total = 80 g
Weight Cu = 20 g
Efficiency = 77%
External Fuse 32mA (stb) at 230V
Fixing = M4 threaded screw 
L016301 
70001 
2 x 
9V 89 mA 
2 x 11.6V 
2 x 15.8Ω 
L016302 
70002 
2 x 
12V 67 mA 
2 x 15.4V 
2 x 26.9Ω 
L016303 
70003 
2 x 
15V 53 mA 
2 x 19.3V 
2 x 43.4Ω 
L016304 
70004 
2 x 
18V 44 mA 
2 x 23.4V 
2 x 65.9Ω 
*L016305 
70005 
2 x 
22V 36 mA 
2 x 28.2V 
2 x 88.1Ω 
3.2 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016310 
70010 
2 x 
7V 229 mA 
2 x 10.2V 
2 x 7.0Ω 
Weight total = 110 g
Weight Cu = 26 g
Efficiency = 70%
External Fuse 32mA (stb) at 230V
Fixing = M4 threaded screw 
L016311 
70011 
2 x 
9V 178 mA 
2 x 13.0V 
2 x 11.3Ω 
L016312 
70012 
2 x 
12V 133 mA 
2 x 17.3V 
2 x 20.7Ω 
L016313 
70013 
2 x 
15V 107 mA 
2 x 21.4V 
2 x 28.9Ω 
*L016314 
70014 
2 x 
18V 89 mA 
2 x 25.7V 
2 x 45.4Ω 
*L016315 
70015 
2 x 
22V 73 mA 
2 x 31.3V 
2 x 62.2Ω 
5 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016320 
70020 
2 x 
7V 357 mA 
2 x 9.7V 
2 x 4.0Ω 
Weight total = 144 g
Weight Cu = 33 g
Efficiency = 68%
External Fuse 50mA (stb) at 230V
Fixing = M4 threaded screw 
L016321 
70021 
2 x 
9V 278 mA 
2 x 12.4V 
2 x 6.5Ω 
L016322 
70022 
2 x 
12V 208 mA 
2 x 17.0V 
2 x 12.3Ω 
L016323 
70023 
2 x 
15V 167 mA 
2 x 21.3V 
2 x 19.0Ω 
*L016324 
70024 
2 x 
18V 139 mA 
2 x 25.5V 
2 x 28.8Ω 
*L016325 
70025 
2 x 
22V 114 mA 
2 x 30.5V 
2 x 39.1Ω 
7 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016330 
70030 
2 x 
7V 500 mA 
2 x 9.5V 
2 x 2.5Ω 
Weight total = 174 g
Weight Cu = 36 g
Efficiency = 74%
External Fuse 63mA (stb) at 230V
Fixing = M4 threaded screw 
L016331 
70031 
2 x 
9V 389 mA 
2 x 12.2V 
2 x 4.1Ω 
L016332 
70032 
2 x 
12V 292 mA 
2 x 16.2V 
2 x 7.7Ω 
L016333 
70033 
2 x 
15V 233 mA 
2 x 20.3V 
2 x 12.0Ω 
L016334 
70034 
2 x 
18V 194 mA 
2 x 24.3V 
2 x 17.9Ω 
*L016335 
70035 
2 x 
22V 159 mA 
2 x 29.7V 
2 x 24.4Ω 
10 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016340 
70040 
2 x 
7V 714 mA 
2 x 8.3V 
2 x 1.0Ω 
Weight total = 252 g
Weight Cu = 45 g
Efficiency = 82%
External Fuse 80mA (stb) at 230V
Fixing = M4 threaded screw 
L016341 
70041 
2 x 
9V 556 mA 
2 x 10.8V 
2 x 1.7Ω 
L016342 
70042 
2 x 
12V 417 mA 
2 x 14.4V 
2 x 3.2Ω 
L016343 
70043 
2 x 
15V 333 mA 
2 x 18.0V 
2 x 5.0Ω 
L016344 
70044 
2 x 
18V 278 mA 
2 x 21.7V 
2 x 7.5Ω 
*L016345 
70045 
2 x 
22V 227 mA 
2 x 26.3V 
2 x 10.3Ω 
15 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016350 
70050 
2 x 
7V 1071 mA 
2 x 8.9V 
2 x 0.85Ω 
Weight total = 304 g
Weight Cu = 57 g
Efficiency = 80%
External Fuse 100mA (stb) at 230V
Fixing = M4 threaded screw 
L016351 
70051 
2 x 
9V 833 mA 
2 x 11.1V 
2 x 1.3Ω 
L016352 
70052 
2 x 
12V 625 mA 
2 x 14.8V 
2 x 2.3Ω 
L016353 
70053 
2 x 
15V 500 mA 
2 x 18.5V 
2 x 3.1Ω 
L016354 
70054 
2 x 
18V 417 mA 
2 x 22.2V 
2 x 5.3Ω 
*L016355 
70055 
2 x 
22V 341 mA 
2 x 27.2V 
2 x 7.4Ω 
25 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016360 
70060 
2 x 
7V 1785 mA 
2 x 8.3V 
2 x 0.4Ω 
Weight total = 435 g
Weight Cu = 85 g
Efficiency = 83%
External Fuse 100mA (stb) at 230V
Fixing = M4 threaded screw 
L016361 
70061 
2 x 
9V 1377 mA 
2 x 10.7V 
2 x 0.7Ω 
L016362 
70062 
2 x 
12V 1041 mA 
2 x 14.3V 
2 x 1.3Ω 
L016363 
70063 
2 x 
15V 832 mA 
2 x 17.8V 
2 x 2.0Ω 
L016364 
70064 
2 x 
18V 694 mA 
2 x 21.4V 
2 x 2.7Ω 
*L016365 
70065 
2 x 
22V 568 mA 
2 x 26.2V 
2 x 4.1Ω 
35 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016370 
70070 
2 x 
7V 2500 mA 
2 x 8.2V 
2 x 0.19Ω 
Weight total = 590 g
Weight Cu = 187 g
Efficiency = 82%
External Fuse 200mA (stb) at 230V
Fixing = M5 threaded screw 
L016371 
70071 
2 x 
9V 1944 mA 
2 x 10.6V 
2 x 0.32Ω 
L016372 
70072 
2 x 
12V 1458 mA 
2 x 14.0V 
2 x 0.53Ω 
L016373 
70073 
2 x 
15V 1167 mA 
2 x 17.6V 
2 x 0.84Ω 
L016374 
70074 
2 x 
18V 972 mA 
2 x 20.9V 
2 x 1.10Ω 
*L016375 
70075 
2 x 
22V 795 mA 
2 x 25.7V 
2 x 1.34Ω 
50 VA 
Part Number 
Competitor P/N Reference 

Secondary 
Resistance 20°C 
Design Details 

L016380 
70080 
2 x 
7V 3571 mA 
2 x 8.1V 
2 x 0.13Ω 
Weight total = 800 g
Weight Cu = 209 g
Efficiency = 85%
External Fuse 315mA (stb) at 230V
Fixing = M5 threaded screw 
L016381 
70081 
2 x 
9V 2777 mA 
2 x 10.4V 
2 x 0.20Ω 
L016382 
70082 
2 x 
12V 2083 mA 
2 x 13.9V 
2 x 0.34Ω 
L016383 
70083 
2 x 
15V 1666 mA 
2 x 17.3V 
2 x 0.54Ω 
L016384 
70084 
2 x 
18V 1389 mA 
2 x 20.8V 
2 x 0.82Ω 
*L016385 
70085 
2 x 
22V 1136 mA 
2 x 25.4V 
2 x 1.25Ω 








These standard power chokes come in ratings from 0.2Ws to 25Ws. Toroidal power chokes are most commonly used in line frequency (50/60Hz) AC circuits as part of a DC filter.
By using a toroidal power choke, you can reduce the physical size of the overall filter. This is through the size reduction yielded by the toroidal power inductor design and also the required filter capacitors in your LC circuit. The toroidal power inductor also contains any stray magnetic field, further enhancing your filter design.
Toroid Toroidal Power Inductors 50/60Hz offer:
 Greater efficiency
 Lower audible vibration
 Easier mounting
 Lower stray losses (leakage flux)
Standard Toroidal Power Inductors 50/60Hz
Part Number 
Competitor P/N Reference 
Current
I DC (A) 
Current RMS 
L (mH) 
Power (WS) 
Losses
CoreCopper 
OD x HT (Inches) 
OD x HT (mm) 
WT (Ibs.) 
WT (kg) 
IND0540
IND0560 
L0540
L0560 
5
5 
3.5
3.5 
40
60 
0.5
0.75 
1.5  12.8
3  13.8 
3.8x1.9
4.6x2.0 
97x48
117x51 
2.5
4 
1.1
1.8 
IND1020
IND1040
IND1060 
L1020
L1040
L1060 
10
10
10 
7
7
7 
20
40
60 
1
2
3 
4  16.7
5  23.4
7  28.6 
5.5x2.0
5.5x2.4
5.9x2.8 
140x51
140x61
150x71 
6
8
11.5 
2.7
3.6
5.2 
IND1510
IND1515
IND1520
IND1540 
L1510
L1515
L1520
L1540 
15
15
15
15 
10.6
10.6
10.6
10.6 
10
15
20
40 
1.13
1.69
2.25
4.5 
4  18.7
5  22.7
5  26.3
8  37.8 
5.5x2.0
5.5x2.4
5.9x2.8
6.5x2.8 
140x51
140x61
140x61
165x71 
6
7.5
8
15 
2.7
3.4
3.6
6.8 
IND2010
IND2015
IND2020
IND2040 
L2010
L2015
L2020
L2040 
20
20
20
20 
14.1
14.1
14.1
14.1 
10
15
20
40 
2
3
4
8 
5  23.2
7  28.4
8  32.8
12  42.8 
5.5x2.4
5.9x2.8
6.5x2.8
8.0x3.5 
140x61
150x71
165x71
203x89 
8
11.5
14
27 
3.6
5.2
6.4
12.3 
IND3005
IND3010
IND3015
IND3020 
L3005
L3010
L3015
L3020 
30
30
30
30 
21.2
21.2
21.2
21.2 
5
10
15
20 
2.25
4.5
6.75
9 
5  26.1
8  37.8
11  45.9
13  43.2 
5.5x2.4
6.5x2.8
8.0x3.0
8.0x3.5 
140x61
165x71
203x76
203x89 
8.5
15
22
28 
3.9
6.8
10.0
12.7 
IND4005
IND4010
IND4015 
L4005
L4010
L4015 
40
40
40 
28.3
28.3
28.3 
5
10
15 
4
8
12 
8  32
13  43.2
20  56 
6.5x2.8
8.0x3.5
10x3.4 
165x71
203x89
254x86 
14
27
39 
6.4
12.3
17.7 
IND5005
IND5010 
L5005
L5010 
50
50 
35.3
35.3 
5
10 
6.25
12.5 
11  35
20  57.5 
8.0x3.0
10.0x3.4 
203x76
254x86 
23
39 
10.4
17.7 
IND6005 
L6005 
60 
42.4 
5 
9 
12  43.2 
8.0x3.5 
203x89 
29 
13.2 
