Question
I have a question regarding the product ADN4650 (a Dual-Channel LVDS Isolator).I would like to know if it is possible to supply one side of the IC withV_INN1=3.0V without damaging the performance and the reliability of the system.The other side of the IC will be supplied with V_INN2=3.3V, as it is thought.In the datasheet, it is written that the LDO input range V_INN1 goes from 3.0Vto 3.6V.
Answer
The device performance depends on Vdd1 and Vdd2 rather than Vin1 or Vin2. Sosupplying Vin1 with 3.0V and Vin2 with 3.3V will not have any effect, althoughthe 3V side will use slightly less power (typ 60mA * 3V = 180 mW, vs. 60 mA *3.3V = 198 mW).
We’ve only characterised the LDO across 3V to 3.6V for ADN4650, but inpractice, there’s even a bit of room outside both ends of that range. So 3V and3.6V are certainly OK. The main concern beyond 3.6V is that there is extrapower dissipation within the LDO circuit and the package. The concern below 3V,is that at some point, there won’t be enough headroom to ensure a stable 2.5Von the LDO output (including during changes in load, etc.)