My customer is using an external clock circuit for 32.768KHz.
There is a spec for that in the data sheet.
They are using a circuit meets the spec(VOH/VOL) above, however the voltage at OSC32K_EXTAL is 2.3V which is lower than 0.7*VDD=2.31V.
This drop is considered because the circuit is providing clock not only to i.MX257 but also to a FPGA.
Is 2.3V for OSC32K_EXTAL OK?
What are VIH and VIL specs for OSC32K_EXTAL?