ADuM4160 USB Isolator Assembly Guide

No matter which kit you are building, dealing with small unmarked parts is inevitable. These parts are also lightweight so sneezing into a pile of parts is not recommended. Some parts are mounted on a tape – it is generally good idea to keep them this way until the moment you are ready to solder them.

The easiest way to get parts out of the bag is to cut the bag along the long edge with scissors. Connectors can stay in the bag for now. For next several steps, a pair of tweezers and magnifier glass will be helpful.

• 1. A pair of 0.1″ headers with 2 pin jumpers. Used to program USB speed on both sides of the isolators. They will be soldered very late in the build, together with connectors – for now it’s best to put them away.
• 2. Analog Devices ADuM4160 IC, the heart of the circuit. Wide 16-pin SOIC package, clearly marked on the top. Usually comes on a tape, but may be packaged differently, for example, in a piece of IC “tube”. This is the largest of small parts, you won’t miss it.
• 3. 1MOhm 1206 resistors. Three on a tape, marked “105” (or “501” if you are holding it upside down) on top. Usually black in color, but may also be blue.
• 4. 24Ohm 1206 resistors. Four on a tape, marked “240”, “24R0”, or similar. Usually black in color, but may also be blue.
• 5. 0.1uF 1206 ceramic capacitors. Four on a tape in “Isolator Only” set, five in “Full” set. Tan in color, no markings. Very hard to distinguish from number 6 in “Full” set, the only way to avoid mix-up is to keep them separated.

The rest of the parts are present only in “Full” kit. Most of them have distinctive shape and therefore easily identifiable, but beware of number 6!

• 6. 3300pF 1206 ceramic capacitor. One on a tape. Tan in color, no markings. Very hard to distinguish from number 5, the only way to avoid mix-up is to keep them separated.
• 7. Linear Technology LT1376-5 buck controller IC. SO-8 package, marked on top. Usually comes in a piece of IC tube.
• 8. 6-10uH inductor, Sumida CDRH5D18 or similar. May be marked differently.
• 9. 1N4148 diode. Stripe on the case marks negative pin.
• 10. MBRS130 diode. Stripe on the case marks negative pin.
• 11. Tantalum low-ESP input capacitor. Marked with 2 numbers, first indicating capacitance, second – rated voltage. On the picture, 22-35 means 22uF, 35V. Stripe on the case marks positive pin. D-size package, usually black but may be tan, like number 12. To distinguish between them, read second number, which indicates voltage. Input capacitor is usually rated to 35V, output – only to 10V. Also, capacitance value of input cap is around 20uF, whereas output cap has 68-100uF.
• 12. Tantalum low-ESP output capacitor. Marked with 2 numbers, first indicating capacitance, second – rated voltage. On the picture, 686 means 68uF, 10 means 10V. Stripe on the case marks positive pin. D-size package, usually tan but may be black, like number 11. To distinguish between them, see description for number 11.

Soldering 1206 resistors is much easier than SO packages ( ADuM4160 and LT1376 ). The part has only 2 pads to solder and at the same time big enough to handle with a pair of decent tweezers. All that is necessary is apply flux to the pads, then add small amount of solder to one pad, apply more flux, place the part, melt the solder while holding part in place, check alignment and then solder other pad. The key to success here is correct amount of solder – this amount shall be small. Also, first pad is somewhat harder to do than second, therefore when deciding which one to start with, pick one which has more empty space around – as you can see on Photo 5a, I picked pads facing away from ADuM4160. Photo 5b shows closeup of two pads with correct amount of solder applied. Photo 5c shows a pair of resistors with one side soldered. Don’t forget second pair on the other side of ADuM4160 and then solder other sides of all 4 resistors. Don’t forget to apply flux from time to time. Photo 5d shows final result.

After finishing this step, builders of “Isolator Only” kit may skip to Step 15, where connector placement is shown.

Picture on the left shows my test setup. For best results, connect them in the following order: power first, then host, then peripheral. If your peripheral is not detected or PC gives detection errors, reconnect it while leaving power and host connected.

“Isolator Only” kit has much more powering options. Please refer to “Tweaking” section for some ideas. Testing procedure is similar.

What to do if circuit doesn’t work? Checking everything with an ohmmeter is a good idea. Also, very common detection error issue, as well as ways to remedy it, are described in this article.