Description
The maximum HSTL Class I output clock frequency in APEX™ II devices is 125MHz.
The maximum HSTL Class II output clock frequency for APEX II devices is 200MHz. If your drive strength requirements do not preclude you from using HSTL Class II, use this I/O standard as an alternative to HSTL Class I.
If you require HSTL Class I output clock speeds greater then 125MHz, the Stratix® - series device families support higher speeds for HSTL Class I output functions.