XRT8020 データシートの表示（PDF） - Exar Corporation
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XRT8020 Datasheet PDF : 12 Pages
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XRT8020
NOVEMBER 2003
650 MHZ CLOCK & CRYSTAL MULTIPLIER WITH LVDS OUTPUTS
REV. 1.0.2
DESCRIPTION
The XRT8020 is a monolithic analog phase locked
loop that provides a high frequency LVDS clock out-
put, using a low frequency crystal or reference clock.
It is designed for SONET/SDH and other low jitter ap-
plications.The high performance of the IC provides a
very low jitter LVDS clock output up to 650 MHz, while
operating at 3.3 volts. The XRT8020 has a selectable
8x, 16x or 32x internal multiplier for an external crys-
tal or signal source. The Output Enable pin provides
a true disconnect for the LVDS output. The very com-
pact (4 x 4 mm) low inductance package is ideal for
high frequency operation.
APPLICATIONS
• Gigabit Ethernet
• SONET/SDH
• SPI - 4 Phase 2
• 8x, 16x or 32x Clock Multiplier for Computer and
Telecommunication Systems
FEATURES
• 575 MHz to 675 MHz operating range
• Low Output Jitter: 9ps rms typical at 622 MHz
• On Chip Crystal Oscillator Circuit
• Optimized for 15 to 40 MHz crystals
• Uses parallel fundamental mode crystal
• Selectable 8x, 16x or 32x multiplier
• Selectable ÷ 1 or ÷ 2 LVDS output
• LVDS output meets TIA/EIA 644A Specification
(2001)
• 3.3V ±10% Low power CMOS: 80 mW typical
• -40°C to +85°C operating temperature
• Extremely small 16-lead QFN package
FIGURE 1. BLOCK DIAGRAM OF THE XRT8020
XTAL1
15-40 MHz
Crystal
XTAL2
AVDD
AVDD
+3.3V
REXT
10kΩ
OVDD
12 - 20 pF
12 - 20 pF
XRT8020
Oscillator
Circuit &
Input Buffer
VCO
Calibration Logic
Phase
Detector
Charge
Pump
Loop
Filter
Feedback Divider
÷ 8, 16 or 32
Voltage Reference
&
Bias Generator
VCO
Selectable
÷ 1 or ÷ 2
Divider
OUTP
LVDS Output
OUTN
AGND
AGND
AGND
FS1
FS0
PD
OE
OGND
(Crystal)
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com
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