ECP2 datasheet(93/386 Pages) LATTICE

93 / 386 page

3-41

DC and Switching Characteristics

Lattice Semiconductor

LatticeECP2/M Family Data Sheet

SERDES External Reference Clock (LatticeECP2M Family Only)

The external reference clock selection and its interface are a critical part of system applications for this product.

Table 3-13 speciﬁes reference clock requirements, over the full range of operating conditions.

Figure 3-13. Jitter Transfer

SERDES Power-Down/Power-Up Speciﬁcation

Table 3-14. Power-Down and Power-Up Speciﬁcation

Table 3-13. External Reference Clock Speciﬁcation (refclkp/refclkn)

Symbol

Description

Min.

Typ.

Max.

Units

FREF

Frequency range

—

320

MHz

FREF-PPM

Frequency tolerance

-300

—

300

ppm

VREF-IN-SE

Input swing, single-ended clock

100

—

1200

mV, p-p

VREF-IN

Input levels

—

VCCP + 0.8

VREF-CM-DC

Input common mode range (DC coupled)

0.5

—

1.2

VREF-CM-AC

Input common mode range (AC coupled)

—

1.5

DREF

Duty cycle

—

TREF-R

Rise time (20% to 80%)

500

1000

TREF-F

Fall time (80% to 20%)

500

1000

ZREF-IN-TERM

Input termination

50/2K

Ohms

CREF-IN-CAP

Input capacitance

—

1.5

1. The signal swing for a single-ended input clock must be as large as the p-p differential swing of a differential input clock to get the same

gain at the input receiver. Lower swings for the clock may be possible, but will tend to increase jitter.

2. When AC coupled, the input common mode range is determined by:

(Min input level) + (Peak-to-peak input swing)/2 ≤ (Input common mode voltage) ≤ (Max input level) - (Peak-to-peak input swing)/2

3. Measured at 50% amplitude.

4. Input capacitance of 1.5pF is total capacitance, including both device and package.

Symbol

Description

Max.

Units

tPWRDN

Power-down time after all power down register bits set to ‘0’

tPWRUP

Power-up time after all power down register bits set to ‘1’

Frequency (MHz)

Note: This graph is for a nominal device.

-25.00

-20.00

-15.00

-10.00

-5.00

0.00

5.00

0.1

100

Jitter T.

Gain@25°C,1.20V,

PJ=100ps

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