AOZ6135HI - ALPHA & OMEGA SEMICONDUCTORS

1www.pericom.com 01/04/13

Product Features

 LVDS compatible outputs

 Supply voltage of 3.3V ±10%

 25MHz input frequency

 HCSL outputs, 0.7V Current mode dierential pair

 Jitter 60ps cycle-to-cycle (typ)

 Spread of ±0.25%, -0.5%, -0.75%, and no spread

 Industrial temperature range

 Packaging: (Pb-free and Green)

 16-pin, 173 mils wide TSSOP

PI6C557-03

PCI Express Clock

Description

e PI6C557-03 is a spread spectrum clock generator

supporting PCI Express and Ethernet requirements. e device

is used for PC or embedded systems to substantially reduce

Electromagnetic Interference (EMI).

e PI6C557-03 provides two dierential (HCSL) spread spectrum

outputs. e PI6C557-03 is congured to select spread and clock

selection. Using Pericom's patented Phase-Locked Loop (PLL)

techniques, the device takes a 25MHz crystal input and produces

two pairs of dierential outputs (HCSL) at 25MHz, 100MHz,

125MHz and 200MHz clock frequencies. It also provides spread

selection of ±0.25%, -0.5%, -0.75%, and no spread.

Block Diagram

VDDX

CLK0

GNDA

VDDA

CLK1

IREF

SS0

X1/CLK

GNDX

SS1

Pin Conguration

Phase Lock Loop

Crystal

Driver

VDD

GND

X1/CLK

25 MHz

crystal or clock

Control

Logic

SS1:SS02

S1:S0

CLK0

CLK1

Pulling

Capacitors

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PI6C557-03

PCI Express Clock

www.pericom.com 01/04/13

Pin Description

Pin # Pin Name I/O Type Description

1S0 Input Select pin 0 (Internal pull-up resistor). See Table 1.

2 S1 Input Select pin 1 (Internal pull-up resistor). See Table 1.

3 SS0 Input Spread Select pin 0 (Internal pull-up resistor). See Table 2.

4 X1/CLK Input Crystal or clock input. Connect to a 25MHz crystal or single ended clock.

5 X2 Output Crystal connection. Leave unconnected for clock input.

6OE Input Output enable. Internal pull-up resistor.

7 GNDX Power Crystal ground pin.

8 SS1 Input Spread Select pin 1 (Internal pull-up resistor). See Table 2.

9 IREF Output Precision resistor attached to this pin is connected to the internal current reference.

10 CLK1 Output HCSL compliment clock output

11 CLK1 Output HCSL clock output

12 VDDA Power Connect to a +3.3V source.

13 GNDA Power Output and analog circuit ground.

14 CLK0 Output HCSL compliment clock output

15 CLK0 Output HCSL clock output

16 VDDX Power Connect to a +3.3V source.

Table 1: Output Select Table

S1 S0 CLK(MHz)

0 0 25

0 1 100

1 0 125

1 1 200

Table 2: Spread Selection Table

SS1 SS0 Spread

0 0 Center ±0.25

0 1 Down -0.5

1 0 Down -0.75

1 1 No Spread

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PI6C557-03

PCI Express Clock

www.pericom.com 01/04/13

Application Information

Decoupling Capacitors

Decoupling capacitors of 0.01μF should be connected between

each VDD pin and the ground plane and placed as close to the

VDD pin as possible.

Crystal

Use a 25MHz fundamental mode parallel resonant crystal with

less than 300PPM of error across temperature.

Crystal Capacitors

CL = Crystals's load capacitance in pF

Crystal Capacitors (pF) = (CL - 8) *2

For example, for a crystal with 16pF load caps, the external ef-

fective crystal cap would be 16 pF. (16-8)*2=16.

Current Source (Iref) Reference Resistor - RR

If board target trace impedance is 50Ω,

then RR = 475Ω providing an IREF of 2.32 mA. e output

current (IOH) is 6*IREF.

Output Termination

e PCI Express dierential clock outputs of the PI6C557-03

are open source drivers and require an external series resistor

and a resistor to ground. ese resistor values and their allow-

able locations are shown in detail in the PCI Express Layout

Guidelines section.

e PI6C557-03 can be congured for LVDS compatible voltage

levels. See the LVDS Compatible Layout Guidelines section.

=475

6*IREF

=2.3mA IREF

See Output Termination

Sections

Ω

Output Structures

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PI6C557-03

PCI Express Clock

www.pericom.com 01/04/13

PCI Express Layout Guidelines

Common Recommendations for Dierential Routing Dimension or Value Unit

L1 length, route as non-coupled 50Ω trace. 0.5 max inch

L2 length, route as non-coupled 50Ω trace. 0.2 max inch

L3 length, route as non-coupled 50Ω trace. 0.2 max inch

33 Ω

49.9 Ω

Dierential Routing on a Single PCB Dimension or Value Unit

L4 length, route as coupled microstrip 100Ω dierential trace. 2 min to 16 max inch

L4 length, route as coupled stripline 100Ω dierential trace. 1.8 min to 14.4 max inch

Dierential Routing to a PCI Express connector Dimension or Value Unit

L4 length, route as coupled microstrip 100Ω dierential trace. 0.25 min to 14 max inch

L4 length, route as coupled stripline 100Ω dierential trace. 0.225 min to 12.6 max inch

T R

PCI-Express

Load or

Connector

L1 L2

L3’

L1’ L2’

L4’

PI6C557-03

Output

Clock

0.175 V

0.52 V

0.175 V

0.52 V

OR t

500 ps 500 ps

700 mV

PCI Express Device Routing

Typical PCI Express (HCSL) Waveform

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PI6C557-03

PCI Express Clock

www.pericom.com 01/04/13

Application Information

LVDS Recommendations for Dierential Routing Dimension or Value Unit

L1 length, route as non-coupled 50Ω trace. 0.5 max inch

L2 length, route as non-coupled 50Ω trace. 0.2 max inch

100 Ω

150 Ω

L3 length, route as 100Ω dierential trace.

LVDS Device Routing

Typical LVDS Waveform

L2’

L1’

L3’

Q R

LVDS

Device

Load

PI6C557-03

Clock

Output

1150 mV

1250 mV

OR t

500 ps 500 ps

1325 mV

1000 mV

1150 mV

1250 mV

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PI6C557-03

PCI Express Clock

www.pericom.com 01/04/13

Supply Voltage to Ground Potential ...........................................................5.5V

All Inputs and Outputs ..................................................... -0.5V to VDD+0.5V

Ambient Operating Temperature .................................................-40 to +85°C

Storage Temperature .....................................................................-65 to +150°C

Junction Temperature .............................................................................. 150°C

Soldering Temperature ............................................................................. 260°C

Electrical Specications

Maximum Ratings

Recommended Operation Conditions

Parameter Min. Typ. Max. Unit

Ambient Operating Temperature -40 +85 °C

Power Supply Voltage (measured in respect to GND) +3.0 +3.6 V

DC Characteristics (VDD = 3.3V ±10%, TA = -40°C to +85°C)

Symbol Parameter Conditions Min. Typ. Max. Unit

VDD Supply Voltage 3.0 3.3 3.60 V

Input High Voltage(1) S0, S1, OE, CLK, SS0, SS1 2.0 VDD +0.3 V

Input Low Voltage(1) S0, S1, OE, CLK, SS0, SS1 GND -0.3 0.8 V

IIL Input Leakage Current 0 < Vin < VDD

With input pull-up

and pull-downs -20 20

µA

Without input pull-up

and pull-downs -5 5

Operating Supply

Current

= 50Ω, C

= 2pF 65 mA

DDOE

OE = LOW 35 mA

CIN Input Capacitance Input pin capacitance 7 pF

COUT Output Capacitance Output pin capacitance 6 pF

Pin Inductance 5 nH

OUT

Output Resistance CLK Outputs 3.0 kΩ

Notes:

1. Single edge is monotonic when transitioning through region.

Note:

Stresses greater than those listed under MAXIMUM RAT-

INGS may cause permanent damage to the device. is is a

stress rating only and functional operation of the device at

these or any other conditions above those indicated in the

operational sections of this specication is not implied. Ex-

posure to absolute maximum rating conditions for extended

periods may aect reliability.

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PI6C557-03

PCI Express Clock

www.pericom.com 01/04/13

AC Characteristics (VDD = 3.3V ±10%, TA = -40°C to +85oC)

Symbol Parameter Conditions Min. Typ. Max. Unit

Input Frequency 25 MHz

VOUT Output Frequency 25 200 MHz

VOH Output High Voltage (1,2) @VDD = 3.3V 660 700 850 mV

Output Low Voltage(1,2) -150 0 mV

CPA

Crossing Point Voltage(1,2) Absolute 250 350 550 mV

VCN Crossing Point Voltage(1,2,4) Variation over all edges 140 mV

JCC Jitter, Cycle-to-Cycle(1,3) 60 100 ps

Modulation Frequency Spread Spectrum 30 31.5 33 kHz

tOR Rise Time(1,2) From 0.175V to 0.525V 175 332 700 ps

tOF Fall Time(1,2) From 0.525V to 0.175V 175 344 700 ps

∆

/∆T Rise/Fall Time Variation(1,2) 125 ps

SKEW

Skew between outputs VDD/2 50 ps

TDU TY-

CYCLE

Duty Cycle(1,3) 45 55 %

Output Enable Time(5) All outputs 0.1 μs

TOT Output Disable Time(5) All outputs 0.1 μs

tSTABLE From power-up to VDD=3.3V 1.6 3.0 ms

SPREAD

Setting period aer spread change 3.0 ms

Ferror Synthesizer Error PLL locked, xtal load is matched and

SSC o 0ppm

Notes:

1. RL = 50Ω with CL = 2 pF and RR = 475Ω

2. Single-ended waveform

3. Dierential waveform

4. Measured at the crossing point

5. CLK pins are tri-stated when OE is LOW

ermal Characteristics

Symbol Parameter Conditions Min. Typ. Max. Unit

θJA ermal Resistance Junction to Ambient Still air 90 °C/W

ermal Resistance Junction to Case 24 °C/W

Recomended Crystal Specication

Pericom recommends:

a) GC2500003 XTAL 49S/SMD(4.0 mm), 25M, CL=18pF, +/-30ppm

http://www.pericom.com/pdf/datasheets/se/GC_GF.pdf

b) FY2500081, SMD 5x3.2(4P), 25M, CL=18pF, +/-30ppm

http://www.pericom.com/pdf/datasheets/se/FY_F9.pdf

c) FL2500047, SMD 3.2x2.5(4P), 25M, CL=18pF, +/-20ppm

http://www.pericom.com/pdf/datasheets/se/FL.pdf

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PI6C557-03

PCI Express Clock

www.pericom.com 01/04/13

Ordering Information(1-3)

Ordering Code Package Code PackageType

PI6C557-03LE L Pb-free & Green, 16-Pin TSSOP

Note:

1. ermal characteristics and package top marking information can be found at http://www.pericom.com/packaging/

2. E = lead-free and green packaging

3. Adding an X sux = tape/reel

Pericom Semiconductor Corporation • 1-800-435-2336 | All Trademarks Property of Respective Owners

Packaging Mechanical: 16-contact TSSOP (L)

Note: For latest package info, please check: http://www.pericom.com/products/packaging/mechanicals.php

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