ZXY-ED12.6-20H SMD Audio Isolation Transformer, Permalloy Core, 100 Hz - 20 kHz, 1:1 Turns Ratio, 20 H Inductance, 10-Pin SMD, 17.8 x 13.3 x 10.0 mm

1. Product Name

ZXY-ED12.6-20H SMD 10-pin permalloy core audio isolation transformer for signal coupling. Sealed permalloy core, tape-wrapped, primary winding connected to pins 1-5, secondary winding connected to pins 6-10, ten formed SMD pins, 1:1 turns ratio, minimum primary inductance 20H, frequency range 100Hz to 20kHz, dimensions: height 10.0mm × length 17.8mm × width 13.3mm.

Winding arrangement. The schematic shows the two windings as separate coils with polarity dots at pins 1 and 6, so the winding direction is determined by the device itself, not by the assembler. The four terminals shown on the schematic—1, 5, 6, and 10—are exactly the four terminals used in the electrical parameter tests.

There is no shared conductor between the two windings—only the core is shared. This is precisely the function of the device: the signal crosses the isolation barrier as changing magnetic flux, and nothing else can pass through.

2. Features

Isolation protects the upstream circuit. The transformer prevents the output stage of the upstream device from being damaged by a fault on the far side of the isolation barrier—the primary reason for purchasing an isolation device.

Eliminates AC mains interference. Interference traveling along shared conductors is blocked at the isolation barrier, so it does not reach the next stage as hum.

100Hz to 20kHz frequency range. Covers the entire audio band, from the low end of the voice range to the high end of the audible range—exactly the band that coupling stages in mixing consoles or modem lines must pass.

Solves common-ground hum problems. Ground loops form when the same signal is grounded at two points, a common source of persistent hum in racks of independently powered equipment; this transformer breaks the loop.

Reduces interference in both wiring schemes. Both balanced and unbalanced transmission reduce the pickup of external interference, so the same device works regardless of which scheme the circuit board uses.

The two units are identical in construction, shown from the two most critical faces for assembly: the left shows the sealed core and pin comb, the right shows the coil face inside the tape wrap. The 1:1 turns ratio and 20H primary inductance result from the combination of this winding and this core, which is why the device is sold as a complete unit rather than as separate core and coil.

3. Advantages

Small size, high inductance. Achieving 20H inductance in a 10.0mm × 17.8mm × 13.3mm SMD package is exactly the value of the permalloy core: the inductance comes from the core, not from the volume.

Permalloy core with sealed finish. Nickel-iron core with high-gloss tape wrap, windings fully covered, core end faces kept aligned.

Formed SMD pins. Ten pins are formed for surface-mount application, allowing the device to go through reflow soldering without an additional manual soldering step.

Reinforced bobbin with core positioning. The plastic bobbin positions the two core halves rather than relying on tape, ensuring inductance consistency across batches.

Customizable design. When the standard 20H product is not suitable, windings can be customized to customer specifications.

Factory-direct supply. Standard products are available from stock, ensuring lead times do not affect the critical path.

The annotations identify the three key factors that determine whether the device works in a reflow production line: the core is positioned by the bobbin rather than held by tape, the tape wrap continuously covers the entire winding, and the pins are formed to sit flat on the pads. The top view also shows the pin comb—five leads per side, 2.55mm center pitch, with the middle body width slightly less than 13.3mm.

4. Applications

Communication equipment and high-speed modems. Line coupling applications requiring electrical isolation between the modem side and the line side.

Telephone coupling and analog modems. The 100Hz to 20kHz band covers the voice channel and the modulated carriers above it.

Signal isolation output for mixing consoles. An isolated output does not connect the console ground to the ground of the equipment it feeds.

Multi-channel signal isolation output. When multiple isolated outputs are on the same circuit board, one device is used per channel.

In both views, the device sits between the two halves of the circuit rather than at the edge—exactly where an isolation transformer belongs: once installed, there is no shared conductor between the stages on either side. The 10.0 mm height is the critical dimension to check against surrounding components—the housing maintains clearance from small components around it, but nothing may be stacked on top.

5. Application Specifications

The following specifications are the declared data for this model: product data, electrical parameter table at 25 °C, outline and pin dimensions, and pin assignment with winding polarity.

5.1 Product Specifications

5.2 Electrical Specifications, 25 °C

Inductance is measured at 1 kHz, 0.3 V test signal, taken as minimum; DC resistance tolerance is ±15%; turns ratio is measured at 10 kHz, 1 V, held to ±2%; dielectric withstanding voltage is 1250 V, leakage current limited to 1 mA, for 60 s.

5.3 Outline and Pin Dimensions

5.4 Pin Assignment and Winding Polarity

The primary winding is on pins 1-5, the secondary winding is on pins 6-10, with polarity dots at the start of each winding: pin 1 for the primary and pin 6 for the secondary. The dielectric test is applied between the combination of pins 1 and 5 and the combination of pins 6 and 10, i.e., the two groups referred to in the table as 1,5 - 6,10.

6. Quality and Test Assurance

All parameters are measured at an ambient temperature of 25 °C. Test items include inductance, DC resistance of both windings, turns ratio, and dielectric withstanding voltage from primary to secondary, each judged against the limits in the table below.

The dielectric test is applied between primary pins 1 and 5 and secondary pins 6 and 10, holding 1250 V with leakage current limited to 1 mA for 60 s. This test is the core guarantee of the device's isolation performance and the item to re-verify when batch integrity is in question.

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