The Quartus® II software generates this error when synthesizing VHDL code that assigns a value greater than 153 minutes using the time datatype. In the Quartus II software, the time datatype is represented as a signed 64-bit integer, and therefore numbers greater than 2^63 femtoseconds (fs) cannot be represented.
For example:
constant TIME_B: time := 1 sec;
constant TIME_C: time := 154 min;
constant MY_CONST_failed: natural := (TIME_C/TIME_B);
To work around this limitation in the Quartus® II software, ensure the time datatype is within the 2^63 fs maximum limit.