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Rise time requirements of ADG3308

Question asked by AndrewC on Jul 9, 2018
Latest reply on Jul 18, 2018 by AndrewC

I am looking at using an ADG3308 for level translation between 5 and 3.3 V on a SPI interface between a microcontroller (5 V) and a MEMS accelerometer (3.3 V).

I notice that in the Theory of Operation, Input Driving Requirements section (top of second column, page 16 in Rev. E datasheet), it states:

To ensure correct operation of the ADG3308/ADG3308-1, the circuit that drives the input of the device should be able to ensure rise/fall times of less than 3 ns when driving a load consisting of a 6 kΩ resistor in parallel with the input capacitance of the ADG3308/ADG3308-1 channel.

I assume the low rise time is required to trigger the one-shot generator correctly.

The microcontroller I am using gives it's I/O port rise time as 10-25 ns, which seems to comparable to other MCUs I have looked at. Does this mean the ADG3308 will not work in my application? If so, is there an alternative part which can handle slower rise times?

 

Thanks in advance,

Andrew

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