DC Characteristics and Timing Specifications
= 1000 / (1000/toggle rate at default load + derating factor * load
value in pF/1000)
For example, the output toggle rate at 0 pF (default) load for SSTL-18
Class II 18mA I/O standard is 270 MHz on a –6 device column I/O pin.
The derating factor is 29 ps/pF. For a 10pF load, the toggle rate is
calculated as:
1000 / (1000/270 + 29 × 10/1000) = 250 (MHz)
Tables 5–44 through 5–46 show the I/O toggle rates for Cyclone II
devices.
Table 5–44. Maximum Input Clock Toggle Rate on Cyclone II Devices (Part 1 of 2)
Maximum Input Clock Toggle Rate on Cyclone II Devices (MHz)
Dedicated Clock
Column I/O Pins
Row I/O Pins
Inputs
I/O Standard
–6 –7
–8
–6
–7
–8
–6
–7
–8
Speed Speed Speed Speed Speed Speed Speed Speed Speed
Grade Grade Grade Grade Grade Grade Grade Grade Grade
LVTTL
2.5V
450
450
450
300
450
500
500
500
500
500
500
500
500
—
405
405
405
270
405
500
500
500
500
500
500
500
500
—
360
360
360
240
360
500
500
500
500
500
500
500
500
—
450
450
450
300
450
500
500
500
500
500
500
500
500
350
350
500
405
405
405
270
405
500
500
500
500
500
500
500
500
315
315
500
360
360
360
240
360
500
500
500
500
500
500
500
500
280
280
500
420
450
450
300
420
500
500
500
500
500
500
500
500
350
350
500
380
405
405
270
380
500
500
500
500
500
500
500
500
315
315
500
340
360
360
240
340
500
500
500
500
500
500
500
500
280
280
500
1.8V
1.5V
LVCMOS
SSTL_2_CLASS_I
SSTL_2_CLASS_II
SSTL_18_CLASS_I
SSTL_18_CLASS_II
1.5V_HSTL_CLASS_I
1.5V_HSTL_CLASS_II
1.8V_HSTL_CLASS_I
1.8V_HSTL_CLASS_II
PCI
PCI-X
—
—
—
DIFFERENTIAL_SSTL_2_
CLASS_I
500
500
500
DIFFERENTIAL_SSTL_2_
CLASS_II
500
500
500
500
500
500
500
500
500
Altera Corporation
February 2008
5–47
Cyclone II Device Handbook, Volume 1
ALTERA [ ALTERA CORPORATION ]
