Hello, I've got problem with ADUM4160 - I have already broken 3 of them and I have no idea why it happend. All three broken ICs have a short between VBUS2, and GND2.
How I broken them:
1. I powered up with external 5V power supply only the downstream side (without anything connected to USB) and measured 3.3V on VDD2.
2. I powered up only the upstream side by connecting it with USB cable to the computer and measured 3.3V on VDD1.
3. Next I tried to do both - first I powered up the upstream side, then the downstream side and in this moment circuit failed and triggered 0.3A constant current from my lab power supply.
My board is configured like this:
- VDD1, PDEN, SPU shorted
- VDD2, PIN, SPD shorted
- VBUS2 and VDD2 are not shorted
- 100nF ceramic capacitors: VBUS1-GND1, VDD1-GND1, VBUS2-GND2, VDD2-GND2
- on each line UD-, UD+, DD-, DD+ there are 2 parallel 47R resistors (I didn't have 24R laying around)
- on the downstream side there is also a connector for 5V power supply (VBUS2-GND2)
- GND1 pins (2 and 8) are shorted with short wire
- same with GND2 pins (9 and 15)
- also my prototype is soldered on universal/prototype board which I realise is far from ideal
Does anyone have a clue what am I doing wrong?