In the datasheet for the ISL71840SEH analog mux it says the range the VREF input is 4.5 to 5.5 V. However, if I were to use 3.3V for VREF, would it still work?
On page 23 it says that about 30% of VREF is what sets the logic threshold, so with 5V VREF the threshold would be about 1.5V, and with 3.3V VREF the threshold would be about 1V.
If a 1V logic threshold works for me, then can I use 3.3V for VREF, or are there other consequences of going below 4.5 V?
Hello Charles,
The specification in the SMD for VIH/VIL is done with Vref = 5V. It is saying that when VIH is ≥ 1.6V, on a logic input (A2,A1,A0, ENbar), it will be in the Hi-state. When VIL ≤ 1.2V, on a logic input (A2,A1,A0, ENbar), it will be in the Low-state. Between 1.2V and 1.6V the logic stage is undetermined. As stated in Figure 80 in the Renesas data sheet the switching point at Vref = 5V is around 1.4V.
We only guarantee VIH / VIL with Vref = 5V. All parts are tested across temperature and radiation with Vref = 5V to ensure they meet the VIL and VIH of 1.2V and 1.6V.
If VREF is 5V the logic control inputs will support 3.3 V logic
There is no specification or testing done with Vref at 3.3V.
We apologize but we cannot answer questions on a public forum for our space parts unless the information is already posted on our public website. In this case, the information I provided in on a public SMD.
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