I am looking for an isolator that operates with Vdd1=2.5V and Vdd2=3.3V. (Vdd1 side has 2.5V logic levels)
In the datasheets for ADuM1400 and 3480 I read that the output goes to a default state when no transitions occur on the input within 5us.
I want to feed Reset and SPI chip select signals through one or two channels. On these signals, the time between transitions is much longer.
Question is: does the Adum140 output, when enabled, follow the input level, no matter what time between input transitions?
The datasheet Rev.A, page 20 only states
"If the input side is off or not operating, the low fail-safe output state (ADuM140D0/ADuM140E0/ADuM141D0/ADuM141E0/ ADuM142D0/ADuM142E0) sets the output to low"
In this context, what does "off or not operating" mean: Channel disabled and/or channel not changing state?
I understand that if the device has a disable input pin (like ADum140D) the input can be disabled and that the outut then sets the output to a known state.
When the ADuM14x datasheet says that if the input side is off or not operating, the output will be in the default state, these conditions include the input supply not powered, the inputs set to disable by the DISABLE pin, or a malfunctioning input side. Otherwise the input should follow the output, even if the input is not changing.The ADuM140 should work in your VDD1 = 2.5V and VDD2 = 3.3V with 2.5V logic on side 1 and 3.3V logic on side 2.