J-Link Base - VTref Voltage range

Hi,

We are using J-Link Base products from variety of generations for JTAG interface.

Until now, we worked with 3.3V logic signals on JTAG.

We would like to work also with 1.8V logic signals on JTAG.

For that, we would like to know:

1. What is the Voltage range for VTRef pin (and J-Link base I/O voltage levels)?
2. Are there various voltage ranges of VTRef in different J-Link Base generations?

Thank you.