Subject: ADuM6028-5WBRIZ Supplying Three AMC1350 Devices – Startup/Compatibility Question
Dear Analog Devices Support,
I am currently developing a voltage sensing circuit using the ADuM6028-5WBRIZ to generate an isolated 5 V supply for the high-voltage side of three AMC1350 isolated amplifiers.
The isolated supply (5V-ISO) powers only the following loads:
- Three AMC1350 devices (VDD1 side only)
- Local decoupling capacitors (100 nF + 1 µF for each supply rail)
No other active circuitry is connected to the isolated supply.
During hardware testing, we observed that the ADuM6028 appears to enter a high current condition when the isolated rail is connected. As part of the investigation, we disconnected the isolated output using the ferrite beads on the VISO and GNDISO rails. With the isolated load disconnected, the input current of the ADuM6028 is approximately 28 mA, which appears reasonable.
This has led us to wonder whether there are any known startup or interaction issues when the ADuM6028 is used to power multiple AMC1350 devices simultaneously.
Specifically, we would appreciate your advice on the following:
- Is powering three AMC1350 devices from a single ADuM6028-5WBRIZ considered a supported and typical application?
- Are there any known startup issues, inrush current effects, or latch-up conditions associated with this combination?
- Are there any recommendations regarding:
- Output capacitance on the isolated rail,
- Power-up sequencing,
- Ferrite bead usage,
- Decoupling arrangement,
- Or any other design considerations that could result in abnormal startup current?
We have reviewed the datasheets for both devices, but we would like to know whether Analog Devices has encountered similar behavior in customer applications or has any application notes or recommendations specific to this combination.
Thank you in advance for your assistance.
