ZXY-B2111 Audio Isolation Transformer, 1:1 600 Ohm Line Audio Transformer, SMD Potted, 4.6 kV Hi-Pot

1. Product Name

ZXY-B2111, 1:1 600 Ω audio isolation transformer: an ED8×11 nickel-steel lamination core with 0.15 mm grade PC laminations interleaved and fully stacked, 520 turns of 2UEW-F Ø0.04 mm enamel wire on each of two windings, a thickened double-section bobbin, and a black high-temperature housing fully potted over the assembly. Six SMD gull-wing pins in two rows of three. Body 13.8 mm max by 10.6 mm max and 8.0 mm max high.

Two faces, one part. One face carries the six terminals and the potted winding; the other is a plain moulded wall. Because the fill is inside the case, the outside of the part is a closed block, and nothing about the winding is exposed to handling, cleaning or reflow.

2. Construction & Materials

The core. ED8×11 nickel-steel laminations, 0.15 mm thick and of grade PC, interleaved and fully stacked. Nickel-steel is chosen because at the bottom of the audio band a laminated nickel-iron core saturates later than a ferrite of the same volume, which is what lets the part hold 1.4 H and stay inside ±0.25 dB down at 200 Hz. The thin foil keeps eddy currents small at these frequencies, and interleaving joins the two halves of the magnetic circuit with many overlapping seams rather than one butt joint.

The two details that decide the ratings. The isolation barrier is the wall between the two winding sections, and it is why the hi-pot is 4,600 VDC: the bobbin is thickened and split into two sections, so the windings are separated by moulded material plus the fill rather than by tape alone. The lead is a formed gull-wing, which is what makes the part a reflow component; the recommended profile peaks at 260 °C and the housing is heat tested to 280 °C.

The seal. The epoxy resin sits over the winding face and stops short of the solderable part of the pins. That boundary is deliberate: the fill has to cover the coil to seal it and hold the core tight, and it must not creep onto the terminals, because a pin with resin on it will not wet properly in the oven.

Both windings are 520 turns of 2UEW-F Ø0.04 mm enamel wire. Equal turns on equal windings is what makes the two sides interchangeable and what holds the ratio to ±1 %. The specification adds a workmanship requirement that the windings are laid flat, because a winding that crosses back over itself adds wire length and pushes the DC resistance out of the ±10 % window.

3. Feature

Matched 1:1 windings. Both windings are 520 turns of the same wire on the same bobbin, and the ratio is held to ±1 % when measured at 15 kHz and 1 V across pins 1-3 and 4-6. Equal turns on equal windings is what makes the part usable as a balanced line isolator rather than only as a step device.

ED8×11 nickel-steel lamination core. The core is built from 0.15 mm nickel-steel laminations of grade PC, interleaved and fully stacked. Interleaving puts alternate laminations in opposite orientation, so the joint between the two halves of the stack never lines up in one plane, and full stacking leaves no gap in the magnetic path.

Thickened double-section bobbin. The bobbin is split into two sections and thickened, which separates the two windings physically and provides the wall thickness the 4,600 VDC hi-pot rating depends on.

Fully potted housing. The body is a black high-temperature-resistant shell filled over the core and the winding. The fill holds the assembly rigid, keeps moisture out of the winding, and lets the part be handled and reflowed without the core moving inside the case.

Six SMD gull-wing terminals. Three pins per row, formed into gull wings, so the part is placed and reflowed with the rest of the board. The recommended profile peaks at 260 °C and the housing is heat endurance tested to 280 °C.

4. Advantage

Flat response across the specified band. Response is held inside ±0.25 dB from 200 Hz to 4 kHz referred to 2 kHz. In a 600 Ω line that is what stops the part colouring the signal it passes, which is the whole point of fitting an isolation transformer in the first place.

Return loss in a 600 Ω system. 24 dB minimum across the same band means the part presents something close to 600 Ω at both ends, so it reflects little energy back down the line and does not produce the ripple a mismatch causes.

Low insertion loss. 2 dB maximum at 2 kHz with the secondary terminated in 412 Ω. A transformer that loses less level needs less make-up gain downstream, and less gain means less noise added to the signal.

Dielectric strength stated as a test. 4,600 VDC at a 1 mA leakage limit for 60 s between secondary and primary, with insulation resistance of 100 MΩ minimum at 200 VDC. Both are acceptance items on every unit rather than a type-test claim.

Small potted body for a dense board. 13.8 mm by 10.6 mm and 8.0 mm high, with the six pins on a 5 mm same-row span and the rows 11.0 mm apart, so the footprint is a rectangle the layout can plan around instead of a wire-ended part that has to be hand placed.

5. Application

Line isolation between audio stages. Where two stages sit at different ground potentials inside one chassis, a 1:1 transformer carries the signal across without joining the two grounds together.

Isolation between pieces of equipment. Between two units on a 600 Ω-referenced line the part breaks the earth loop that would otherwise appear as hum, and holds the level on both sides of the break.

Signal transmission from 200 Hz to 4 kHz. The specified band covers speech and programme material, and the ±0.25 dB window is quoted over that band rather than over the whole audio range.

Positions needing verified galvanic isolation. Where the design has to demonstrate separation between the windings, the 4,600 VDC hi-pot and the 100 MΩ insulation resistance are the two figures a test house will ask for.

In a signal chain the part sits between a source and the next stage and carries the signal across a barrier without joining the two grounds. Level and response should not change.

6. Specifications

The data below is the approved specification for ZXY-B2111, reproduced as declared.

6.1 Summary

6.2 Electrical

6.3 Mechanical and footprint

6.4 Construction

6.5 Quality and testing

7. Ordering

The part is ordered as ZXY-B2111. The core, bobbin and housing are the fixed part of the design; the winding, the turns ratio and the pin-out can be built to a customer drawing where the standard 600 Ω 1:1 build does not fit the equipment. Where a build differs, state the ratio and the impedance with the order so the acceptance table can be issued with it.

Brand / manufacturer: ZXY, Shenzhen Zhixiangyuan Electronics Co., Ltd. http://www.zxycoil.com