SY58021UMGTR - Micrel, Inc.

SY58021U

4GHz, 1:4 LVPECL Fanout

Buffer/Translator with Internal Termination

Precision Edge®

Precision Edge is a registered trademark of Micrel, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

General Description

The SY58021U is a 2.5V/3.3V precision, high-speed, fully

differential 1:4 LVPECL fanout buffer. Optimized to provide

four identical output copies with less than 15ps output

skew and only 70 fsRMS phase jitter, the SY58021U can

process clock signals as fast as 4GHz.

The differential input includes Micrel’s unique, 3-pin input

termination architecture interfaces to differential LVPECL,

CML, and LVDS signals (AC- or DC-coupled) as small as

100mV without any level-shifting or termination resistor

networks in the signal path. For AC-coupled input interface

applications, an on-board output reference voltage (VREFAC)

is provided to bias the VT pin. The outputs are 100k

LVPECL compatible, with extremely fast rise/fall times

guaranteed to 70fs.

The SY58021U operates from a 2.5V ±5% supply or 3.3V

±10% supply and is guaranteed over the full industrial

temperature range (–40°C to +85°C). For applications that

require faster rise/fall times, or greater bandwidth, consider

the SY58022U 1:4 fanout buffer with 400mV LVPECL

output swing, or the SY58020U 1:4 CML fanout buffer. The

SY58021U is part of Micrel’s high-speed, Precision Edge®

product line.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Precision Edge®

Features

• Precision 1:4 LVPECL fanout buffer

• Low jitter performance:

− 70fsRMS phase jitter (typical)

• Accepts an input signal as low as 100mV

• Unique input termination and VT pin accepts DC-

coupled and AC-coupled differential inputs: LVPECL,

LVDS, and CML

• 100k LVPECL-compatible 800mV swing output

• Power supply 2.5V ±5% and 3.3V ±10%

• −40°C to +85°C temperature range

• Available in 16-pin (3mm × 3mm) QFN package

Applications

• All SONET and GigE clock distribution

• Fibre Channel clock and data distribution

• Backplane distribution

• High-end, low-skew, multiprocessor, synchronous clock

distribution

Block Diagram

September 2011 M9999-090111-B

hbwhelp@micrel.com or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 2 M9999-090111-B

hbwhelp@micrel.com

\Ordering Information(1)

Part Number Package Type Operating Range Package Marking Lead Finish

SY58021UMI QFN-16 Industrial 021U Sn-Pb

SY58021UMITR(2) QFN-16 Industrial 021U Sn-Pb

SY58021UMG(3) QFN-16 Industrial 021U with Pb-Free bar-line indicator Pb-Free

NiPdAu

SY58021UMGTR(2, 3) QFN-16 Industrial 021U with Pb-Free bar-line indicator Pb-Free

NiPdAu

Notes:

1. Contact factory for die availability. Dice are guaranteed at TA = 25°C, DC electrical only.

2. Tape and Reel.

3. Pb-Free package recommended for new designs.

Pin Configur ation

16-Pin QFN

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 3 M9999-090111-B

hbwhelp@micrel.com or (408) 955-1690

Pin Description

Pin Number Pin Name Pin Function

1, 4 IN, /IN

Differential Input: This input pair receives the signal to be buffered. Each pin of this pair internally

terminates with 50 to the VT pin. Note that this input will default to an indeterminate state if left

open. See “Input Interface Applications” section.

2 VT

Input Termination Center-Tap: Each input terminates to this pin. The VT pin provides a center-tap

for each input (IN, /IN) to the termination network for maximum interface flexibility. See “Input

Interface Applications” section.

3 VREF-AC

Reference Output Voltage: This output biases to VCC –1.2V. It is used when AC-coupling to

differential inputs. Connect VREF-AC directly to the VT pin. Bypass with 0.01µF low ESR capacitor

to VCC. See “Input Interface Applications” section.

8, 13 VCC Positive Power Supply: Bypass with 0.1µF//0.01µF low ESR capacitors as close to the VCC pins

as possible.

5, 16 GND,

Exposed Pad

Ground. Exposed pad must be connected to a ground plane that is the same potential as the

ground pin.

14, 15, 11, 12,

9, 10, 6, 7

/Q0, Q0, /Q1,

Q1, /Q2, Q2,

/Q3, Q3

LVPECL Differential Output Pairs: Differential buffered output copy of the input signal. The output

swing is typically 800mV Proper termination is 50 to VCC–2V at the receiving end. Unused

output pairs may be left floating with no impact on jitter or skew. See “LVPECL Output

Termination” section.

Micrel, Inc. SY58021U

September 2011 4 M9999-090111-B

hbwhelp@micrel.com or (408) 955-1690

Absolute Maximum Ratings(1)

Power Supply Voltage (VCC)......................... −0.5V to +4.0V

Input Voltage (VIN) ............................................ −0.5V to VCC

LVPECL Output Current (IOUT)

Continuous............................................................50mA

Surge ..................................................................100mA

Source or Sink Current on VT Pin

VT Current .........................................................±100mA

Source or Sink Current on IN, /IN

Input Current.......................................................±50mA

Source or Sink Current on VREF-AC

(4)

VREF Current.......................................................±1.5mA

Soldering (20s)........................................................... 260°C

Storage Temperature (Ts) ......................... −65°C to +150°C

Operating Ratings(2)

Power Supply Voltage (VCC) .................. +2.375V to +3.60V

Operating Temperature Range (TA)............–40°C to +85°C

Package Thermal Resistance

QFN (θJA)

Still-Air.......................................................+60°C/W

500 lpfm ....................................................+54°C/W

QFN (ψJB)

Junction-to-Board Resistance(3) ................+33°C/W

Input DC Electrical Characteristics(5)

TA = –40°C to +85°C.

Symbol Parameter Condition Min. Typ. Max. Units

VCC = 2.5V 2.375 2.5 2.625

VCC Power Supply Voltage VCC = 3.3V 3.0 3.3 3.60 V

ICC Power Supply Current No load, VCC = maximum 125 160 mA

VIH Input HIGH Voltage IN, /IN (Note 6) VCC − 1.6 V

CC V

VIL Input LOW Voltage IN, /IN 0 VIH − 0.1 V

VIN Input Voltage Swing IN, /IN (see Figure 1a) 0.1 1.7 V

VDIFF_IN Differential Input Voltage Swing IN, /IN (see Figure 1b) 0.2 V

RIN IN-to-VT Resistance 40 50 60 

VT_IN IN-to-VT Voltage 1.28 V

VREF-AC Output Reference Voltage VCC − 1.30 VCC − 1.2 VCC − 1.1 V

Notes:

1. Permanent device damage may occur if ratings in the “Absolute Maximum Ratings” section are exceeded. This is a stress rating only and functional

operation is not implied for conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum

ratings conditions for extended periods may affect device reliability.

2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.

3. Thermal performance assumes exposed pad is soldered (or equivalent) to the device’s most negative potential on the PCB.

4. Due to the limited drive capability, use for input of the same package only.

5. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established.

6. VIH (minimum) not lower than 1.2V.

Micrel, Inc. SY58021U

September 2011 5 M9999-090111-B

hbwhelp@micrel.com or (408) 955-1690

LVPECL Output DC Electrical Characteristics(5)

VCC = 3.3V ±10% or 2.5 ±5%; RL = 50 to VCC − 2V; TA = –40°C to +85°C, unless otherwise stated.

Symbol Parameter Condition Min. Typ. Max. Units

VOH Output HIGH Voltage VCC − 1.145 VCC − 0.895 V

VOL Output LOW Voltage VCC − 1.945 VCC − 1.695 V

VOUT Output Voltage Differential Swing (see Figure 1a) 550 780 1050 mV

VDIFF_OUT Differential Output Voltage Swing (see Figure 1b) 1100 1560 2100 mV

AC Electrical Characteristics

VCC = 2.5V ±5% or 3.3 ±10%; RL = 50 to VCC − 2V; TA = –40°C to +85°C, unless otherwise stated.

Symbol Parameter Condition Min. Typ. Max. Units

VOUT ≥ 400mV Clock 4 GHz

fMAX Maximum Operating Frequency NRZ Data 5 Gbps

tPD Propagation Delay 150 220 300 ps

tCHAN Channel-to-Channel Skew Note 7 4 15 ps

tSKEW Part-to-Part Skew Note 8 50 ps

tJITTER RMS Phase Jitter

Output: 622MHz

Integration Range:

12kHz − 20MHz

70 fs

tr, tf Output Rise/Fall Time (20% to 80%) At full swing 35 75 110 ps

Notes:

7. Skew is measured between outputs of the same bank under identical transitions.

8. Skew is defined for two parts with identical power supply voltages at the same temperature and with no skew of the edges at the respective inputs.

Micrel, Inc. SY58021U

September 2011 6 M9999-090111-B

hbwhelp@micrel.com

Phase Noise Graph

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 7 M9999-090111-B

hbwhelp@micrel.com

Timing Diagram

Single-Ended and Differential Swings

Figure 1a. Single-Ended Voltage Swing Figure 1b. Differential Voltage Swing

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 8 M9999-090111-B

hbwhelp@micrel.com

Typical Characteristics

VCC = 2.5V, GND = 0, VIN = 100mV, TA = 25°C, unless otherwise stated.

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 9 M9999-090111-B

hbwhelp@micrel.com

Functional Characteristics

VCC = 2.5V, GND = 0, VIN = 100mV, TA = 25°C, unless otherwise stated.

Input Stage

Figure 2. Simplified Differential Input Buffer

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 10 M9999-090111-B

hbwhelp@micrel.com

Input Interface Applications

Figure 3a. LVPECL Input Interface Figure 3b. AC-Coupled LVPECL Input

Interface Figure 3c. LVDS Input Interface

Figure 3d. DC-Coupled CML Input

Interface Figure 3e. AC-Coupled CML Input

Interface

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 11 M9999-090111-B

hbwhelp@micrel.com

LVPECL Output

LVPECL outputs have very-low output impedance (open

emitter), and small signal swing which results in low EMI.

LVPECL is ideal for driving 50- and 100-controlled

impedance transmission lines. There are several

techniques in terminating the LVPECL output (Figures 4

through 6).

Figure 4. Parallel Termination-Thevenin Equivalent

Figure 5. Parallel Termination (3-Resistor)

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 12 M9999-090111-B

hbwhelp@micrel.com

Figure 6. Terminating Unused I/O

Related Micrel Products and Support Documentation

Part Number Function Data Sheet Link

SY58020U 6GHz, 1:4 CML Fanout Buffer/Translator

with Internal I/O Terminations www.micrel.com/product-info/products/sy58020u.shtml

SY58021U 4GHz, 1:4 LVPECL Fanout Buffer/Translator

with Internal Termination www.micrel.com/product-info/products/sy58021u.shmtl

SY58022U

5.5GHz, 1:4 Fanout Buffer/Translator with

400mV LVPECL Outputs and Internal

Terminations

www.micrel.com/product-info/products/sy58022u.shtml

M-0317 HBW Solutions www.micrel.com/product-info/as/solutions.shtml

or (408) 955-1690

Micrel, Inc. SY58021U

September 2011 13 M9999-090111-B

hbwhelp@micrel.com

Package Information

16-Pin QFN

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com

Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This

information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,

fications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellec

property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no

liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or

arranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right

speci tual

w .

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a

roduct can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended fo

urgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury

to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and

Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale.

orated.

or (408) 955-1690