8©2018 Integrated Device Technology, Inc. May 30, 2018
9FGV1005 Datasheet
1
Measured from single-ended waveform.
2
Measured from differential waveform.
3
Measured from -150mV to +150mV on the differential waveform (derived from REFCLK+ minus REFCLK-). The signal must be monotonic through
the measurement region for rise and fall time. The 300mV measurement window is centered on the differential zero crossing.
4
Measured at crossing point where the instantaneous voltage value of the rising edge of REFCLK+ equals the falling edge of REFCLK-.
5
Refers to the total variation from the lowest crossing point to the highest, regardless of which edge is crossing. Refers to all crossing points for this
measurement.
6
Defined as the absolute minimum or maximum instantaneous period. This includes cycle to cycle jitter, relative ppm tolerance, and spread spectrum
modulation.
7
Defined as the maximum instantaneous voltage including overshoot.
8
Defined as the minimum instantaneous voltage including undershoot.
9
Defined as the total variation of all crossing voltages of rising REFCLK+ and falling REFCLK-. This is the maximum allowed variance in V
CROSS
for
any particular system.
10
Refer to section 4.3.7.1.1 of the PCI Express Base Specification, Revision 3.0 for information regarding ppm considerations.
11
System board compliance measurements must use the test load. REFCLK+ and REFCLK- are to be measured at the load capacitors CL. Single
ended probes must be used for measurements requiring single ended measurements. Either single ended probes with math or differential probe
can be used for differential measurements. Test load C
L
= 2pF.
12
T
STABLE
is the time the differential clock must maintain a minimum ±150mV differential voltage after rising/falling edges before it is allowed to droop
back into the VRB ±100mV differential range.
13
“ppm” refers to parts per million and is a DC absolute period accuracy specification. 1 ppm is 1/1,000,000th of 100.000000MHz exactly or 100Hz.
For 300ppm, then we have an error budget of 100Hz/ppm × 300 ppm = 30kHz. The period is to be measured with a frequency counter with
measurement window set to 100ms or greater. The ±300 ppm applies to systems that do not employ spread spectrum clocking, or that use common
clock source. For systems employing spread spectrum clocking, there is an additional 2,500 ppm nominal shift in maximum period resulting from
the 0.5% down spread resulting in a maximum average period specification of +2,800 ppm.
14
Matching applies to rising edge rate for REFCLK+ and falling edge rate for REFCLK-. It is measured using a ±75mV window centered on the median
cross point where REFCLK+ rising meets REFCLK- falling. The median cross point is used to calculate the voltage thresholds the oscilloscope is
to use for the edge rate calculations. The rise edge rate of REFCLK+ should be compared to the fall edge rate of REFCLK-; the maximum allowed
difference should not exceed 20% of the slowest edge rate.
15
At default amplitude settings.
16
Guaranteed by design and characterization.
Table 9. Low-Power (LP) Push-Pull HCSL Differential Outputs
V
DDO
= 3.3V ±5%, 2.5V ±5%, 1.8V ±5%, T
A
= -40°C to +85°C unless stated otherwise.
Parameter Symbol Conditions Minimum Typical Maximum Units Notes
Slew Rate T
R/F
Scope averaging on. 1 2.5 4 V/ns 2,3,16
Slew Rate Matching ΔT
R/F
9 20 % 1,14,16
Crossing Voltage (abs) V
CROSS
Scope averaging off. 250 424 550 mV 1,4,5,16
Crossing Voltage (var) ΔV
CROSS
Scope averaging off. 16 140 mV 1,4,9,16
Voltage High V
HIGH
660 785 850 mV 1
Voltage Low V
LOW
-150 13 150 mV 1
Absolute Maximum Voltage V
MAX
808 1150 mV 1,7,15
Absolute Minimum Voltage V
MIN
-300 -54 mV 1,8,15
