SY89846/7U - Electronic component Microchip - Free user manual and instructions

USER MANUAL SY89846/7U Microchip

Precision 1:5 LVDS and LVPECL Fanout Buffer with 2:1 MUX and Fail-Safe Input with Internal Termination

SY89846/847U Evaluation Board

General Description

The SY89846U and SY89847U evaluation boards are designed for convenient setup and quick evaluation with SMA connectors on each I/O. The board is optimized to interface directly to a 50Ω oscilloscope.

The board is designed in multiple layers for better performance and simple signal evaluation. For best AC performance, the board is configured in AC-coupled In and AC-coupled Out configuration. For applications that require a DC-coupled configuration, step-by-step instructions for modifying the board are included.

All datasheets and support documentation can be found on Micrel's website at: www.micrel.com.

Features

• SY89846U LVPECL outputs
• SY89847U LVDS outputs
- SMA I/O connectors
• +2.5V or +3.3V power supply
• AC-coupled configuration for ease-of-use
• I/O interface includes on-board termination
• Fully assembled and tested
- Can be reconfigured for DC-coupled operation

Related Documentation

• SY89846U, Precision 1:5 LVPECL Fanout with 2:1 MUX and Fail-Safe Input with Internal Termination Datasheet
• SY89847U, Precision 1:5 LVDS Fanout with 2:1 MUX and Fail-Safe Input with Internal Termination Datasheet

Evaluation Board

MICREL SY89846-47 HIGH BANDWIDTH 1-408-955-1690 Q1: 2000 Q2: 2000 VCC: 2000 VCC IN0: 300 300 300 DO: 300 300 300 VIN: 300 300 300 OUT: 300 300 300 IN1: 300 300 300 IN2: 300 300 300 IN3: 300 300 300 IN4: 300 300 300 IN5: 300 300 300 IN6: 300 300 300 IN7: 300 300 300 IN8: 300 300 300 IN9: 300 300 300 IN10: 300 300 300 IN11: 300 300 300 IN12: 300 300 300 IN13: 300 300 300 IN14: 300 300 300 IN15: 300 300 300 IN16: 300 300 300 IN17: 300 300 300 IN18: 300 300 300 IN19: 300 300 300 IN20: 300 300 300 IN21: 300 300 300 IN22: 300 300 300 IN23: 300 300 300 IN24: 300 300 300 IN25: 300 300 300 IN26: 300 300 300 IN27: 300 300 300 IN28: 300 300 300 IN29: 300 300 300 IN30: 355.5V IN31: 25V IN32: -25V IN33: -25V IN34: -25V IN35: -25V IN36: -25V IN37: -25V IN38: -25V IN39: -25V IN40: -25V IN41: -25V IN42: -25V IN43: -25V IN44: -25V IN45: -25V IN46: -25V IN47: -25V IN48: -25V IN49: -25V IN50: -25V IN51: -25V IN52: -25V IN53: -25V IN54: -25V IN55: -25V IN56: -25V IN57: -25V IN58: -25V IN59: -25V IN60: -25V IN61: -25V IN62: -25V IN63: -25V IN64: -25V IN65: -25V IN66: -25V IN67: -25V IN68: -25V IN69: -25V IN70: -25V IN71: -25V IN72: -25V IN73: -25V IN74: -25V IN75: -25V IN76: -25V IN77: -25V IN78: -25V IN79: -25V IN80: -25V

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Evaluation Board Description

The SY89846U and SY89847U share a common evaluation board. The individual evaluation boards are labeled to identify the specific device on that board. The SY89847U is an LVDS-output evaluation board and the SY89846U is an LVPECL-output evaluation board.

The default configuration for the boards is the AC-coupled configuration. The choice between two configurations offers flexibility for different applications.

AC-Coupled Evaluation Board

The AC-coupled configuration is suited for most customer applications and is preferred by the majority of users because of its ease-of-use. It requires only a single power supply and offers the most flexibility when interfacing to a variety of signal sources.

The DC-bias levels and AC-coupling capacitors are supplied on-board for each input. The user only needs to supply a minimum input voltage swing and the bias voltage will automatically adjust the input to the correct level as the power supply voltage varies.

DC-Coupled Evaluation Board

SY89846U

For DC-coupled operation, the boards can be modified to use two power supplies in a "split-supply configuration". The term split-supply simply means the +3.3V supply is split into a +2V and -1.3V, or for a +2.5V supply it is split into a +2V and -0.5V power supply configuration. This effectively offsets the board by +2V. The +2V offset in this two-power supply configuration then provides the correct terminations for the device by setting the ground potential on the board to be exactly 2 volts below the V_CC supply. The V_EE voltage is then set to -1.3V for 3.3V devices or -0.5V for 2.5V devices so the device power pins still see a full 3.3V or 2.5V potential between V_CC and V_EE .

Step-by-step instructions for modifying an AC-coupled evaluation board for DC-coupled operation are supplied in the sub-section, "Modifying your AC-Coupled Board for DC-Coupled Operation."

SY89847U

DC-coupled operation can be accomplished by modifying the board to use two power supplies into a "split-supply configuration". In order to correctly interface LVDS to a 50Ω-(to-ground) scope, V_CC must be V_OCM above the ground level. Therefore, a 2.5V supply will be split into +1.2V and -1.3V to ensure a proper V_CC to V_EE voltage difference.

Evaluation Board

J12 Q0 J11 /Q C13 0.1μF C14 0.1μF VCC R3 100k R4 100k VEE C25 0.1μF VCC C1 0.1μF C2 0.1μF C3 0.1μF VCC C4 0.1μF R1 0Ω R16 10k R17 0.1μF VT0 VEE VEE VCC VCC S /C0 VC0 32 31 30 29 28 27 26 25 VT1 VREF_AC0 VREF_AC1 U1 3Y89040U Q1 24 X /Q1 23 X VCC 22 Q2 21 OCE 20 VCC 19 IN1 IN0 IN0 OUT0 OUT1 OUT2 OUT3 OUT4 OUT5 OUT6 OUT7 OUT8 OUT9 OUT10 OUT11 OUT12 OUT13 OUT14 OUT15 OUT16 OUT17 OUT18 OUT19 OUT20 OUT21 OUT22 OUT23 OUT24 OUT25 OUT26 OUT27 OUT28 OUT29 OUT30 OUT31 OUT32 OUT33 OUT34 OUT35 OUT36 OUT37 OUT38 OUT39 OUT40 OUT41 OUT42 OUT43 OUT44 OUT45 OUT46 OUT47 OUT48 OUT49 OUT50 OUT51 OUT52 OUT53 OUT54 OUT55 OUT56 OUT57 OUT58 OUT59 OUT60 OUT61 OUT62 OUT63 OUT64 OUT65 OUT66 OUT67 OUT68 OUT69 OUT70 OUT71 OUT72 OUT73 OUT74 OUT75 OUT76 OUT77 OUT78 OUT79 OUT80 J16 /IN1 C21 0.1μF R8 50Ω R9 50Ω R2 0Ω VEE C6 0.1μF C7 0.1μF C8 0.1μF R13 0Ω R14 0Ω VCC S1 R15 10k R16 10k VEE J7 /Q4 J8 Q4 C23 0.1μF C24 0.1μF R12 100k VEE J9 /Q2 C18 0.1μF J10 Q2 C19 0.1μF VEE J7 /Q4 J8 Q4

SY89846U AC-Coupled Evaluation Board

I/O Power Supply V		cc GND	V	EE
AC-Coupled Input/AC-Coupled Output 2.5V 2.5V 0V 0V
AC-Coupled Input/AC-Coupled Output 3.3V 3.3V 0V 0V
AC-Coupled Input/DC-Coupled Output 2.5V 2.0V 0V -0.5V
AC-Coupled Input/DC-Coupled Output 3.3V 2.0V 0V -1.3V

Table 1. SY89846U AC/DC-Coupled Evaluation Board Power Supply Connections

Evaluation Board

J12 Q0 J11 /Q C13 0.1μF C14 0.1μF GND VCC C25 0.1μF VCC C1 0.1μF C2 0.1μF R1 0Ω 32 31 30 29 28 27 26 25 VT0 VEE VEE VCC VCC C0 /C0 VCC Q1 24 R17 100k C3 0.1μF VCC2 C4 0.1μF J1 IN0 C16 0.1μF C17 0.1μF J2 IN0 J3 OE J4 SEL J5 IN1 C20 0.1μF C21 0.1μF J6 /IN1 R8 50Ω R9 50Ω R2 0Ω 9 10 11 12 13 14 15 16 VREF_AC1 VREF_AC0 VEE VEE VCC VCC Q4 Q3 /VCC Q1 23 /VCC 22 /VCC 21 /VCC 20 /VCC 19 /VCC 18 /VCC 17 /VCC R18 100k C5 0.1μF VCC C18 0.1μF J10 Q2 C19 0.1μF J9 /Q2 S1 R13 0Ω R14 0Ω R15 10k R16 10k VEE VCC C6 0.1μF C7 0.1μF C8 0.1μF C23 0.1μF C24 0.1μF J7 /Q4 J8 Q4

SY89847U AC-Coupled Evaluation Board

I/O Power Supply V		cc GND V		EE
AC-Coupled Input/AC-Coupled Output 2.5V 2.5V 0V 0V
AC-Coupled Input/DC-Coupled Output 2.5V 1.2V 0V -1.3V

Table 2. SY89847U AC/DC-Coupled Evaluation Board Power Supply Connections

AC-Coupled Evaluation Board Setup

Setting up the SY89846/47U AC-Coupled Evaluation Board

The following steps describe the procedure for setting up the evaluation board:

1. Set the voltage setting for a DC supply to be 2.5V or 3.3V (2.5V for SY89847U) and turn off the supply.
2. On the evaluation board, short the GND terminal to the V_EE terminal and connect them to the negative side of the DC power supply.
3. Connect the V_cc terminal to the positive side of the DC power supply.
4. Turn on the power supply and verify that the power supply current is <420mA.

5. Turn off the power supply.

6. Using a differential signal source, set the amplitude of each side of the differential pair to be 800mV (1600mV measured differentially). Turn off, or disable the outputs of the signal source.

7. Using equal length 50Ω impedance coaxial cables, connect the signal source to the SMA inputs on the evaluation.
8. Using equal length 50Ω impedance coaxial cables, connect the outputs of the evaluation board to the oscilloscope or other measurement device that has an internal 50Ω termination.
9. Turn on the power and verify the current is <500mA.
10. Input to the SEL or OE pin can be provided by the dip-switch or a signal from the SMA connector. If SMA connector is used, add a 50Ω resistor close to the SEL and OE input in order to terminate the transmission line and remove R14 and R13.
11. Enable the signal source and monitor the outputs.

Modifying an AC-Coupled Board for DC-Coupling Operation

When DC-coupling the Output is Necessary

For applications where AC-coupling the output is not appropriate, the board can be reconfigured for DC-coupled output operation. The inputs remain AC-coupled.

The following procedure details the steps for converting an AC-coupled board to a DC-coupled board:

SY89846U

1. Replace capacitors C13, C14, C18, C19, C23, and C24 with 0Ω resistors.
2. Remove R3, R4, R6, R7, R11, and R12.

SY89847U:

1. Replace capacitors C13, C14, C18, C19, C23, and C24 with 0Ω resistors.

DC-Coupled Evaluation Board Setup

The following steps describe the procedure for setting up the DC-coupled evaluation board:

SY89846U

1. Set the voltage for DC supply number 1 to be 2V and connect the positive side to V_cc
2. Set the voltage for DC supply number 2 to be -1.3V (or -0.5V for a 2.5V application) and connect the negative side to V_EE .
3. Connect the negative side of power supply 1 to the positive side of power supply 2. This is the 0V ground potential for the board.

4. Turn off the power supplies and connect the GND terminal on the board to the negative side of DC power supply 1 and the positive side of DC power supply 2.

5. Verify that the power supply current is <420mA.

6. Turn off the power supply.

7. Using a differential signal source, set the amplitude of each side of the differential pair to be 800mV (1600mV measured differentially). The offset is not critical, as the AC-coupled inputs will be automatically biased to the correct offset. Turn off or disable the outputs of the signal source.

8. Using equal length 50Ω impedance coaxial cables, connect the outputs of the evaluation board to the oscilloscope or other measurement device that has an internal 50Ω termination. Any outputs that are not connected to a scope or any other instrument should be terminated with a 50Ω termination-to-ground at the SMA on the board.

9. Turn on the power and verify the current is <500mA.

10. Enable the signal source and monitor the outputs.

SY89847U:

1. Set the voltage for DC supply number 1 to be 1.2V and connect the positive side to V_cc
2. Set the voltage for DC supply number 2 to be -1.3V and connect the negative side to V_EE .
3. Connect the negative side of power supply 1 to the positive side of power supply 2. This is the 0V ground potential for the board.

4. Turn off the power supplies and connect the GND terminal on the board to the negative side of DC power supply 1 and the positive side of DC power supply 2.

5. Verify that the power supply current is <420mA.

6. Turn off the power supply.

7. Using a differential signal source, set the amplitude of each side of the differential pair to be 325mV (650mV measured differentially). The offset is not critical, as the AC-coupled inputs will be automatically biased to the correct offset. Turn off or disable the outputs of the signal source.

8. Using equal length 50Ω impedance coaxial cables, connect the outputs of the evaluation board to the oscilloscope or other measurement device that has an internal 50Ω termination. Any outputs that are not connected to a scope or any other instrument should be terminated with a 50Ω termination-to-ground at the SMA on the board.

9. Turn on the power and verify the current is <500mA.

10. Enable the signal source and monitor the outputs.

Evaluation Board Layout

PC Board Layout

The evaluation boards are constructed with Rogers 4003 material, and are coplanar in design to minimize noise, achieve high bandwidth, and minimize crosstalk. I/O strips signal traces are micro-strip.

Top	Signal
L1	GND
L2	V_CC
L3 V	_EE
L4	GND
Bottom Signal and GND

Table 3. Layer Stack

Bill of Materials

Item	Part	Number	Manufacturer	Description
C1-C9, C11, C13-C25	VJ0402Y104KXXAT		Vishay^(1)	0.1μF, 25V, 10% Ceramic Capacitor, Size 0402, X7R Dielectric	23
C10, C12 293D685	X9025C2T Vishay		(1)	6.8uF, 25 V, 10%, Tantalum Electrolytic Capacitor, Size 293D	2
R15, R16 CRCW04	401002F Vishay		(1)	10kΩ, 1/16W, 5%, Resistor SMD, Size 0402	2
R1, R2, R13, R14	CRCW040200R0F		Vishay^(1)	0Ω, 1/16W, 5% Thick-film Resistor, Size 0402	4
R3, R4, R6, R7, R11, R12, R17, R18	CRCW0402820F		Vishay^(1)	100Ω, 1/16W, 5% Thick-film Resistor, Size 0402	8
J1-J12	142-0701-851		Johnson Components^(2)	Jack Assembly End Launch SMA	12
P1	5005K-ND		Digi-Key.^(3)	Red Test Point	1
P2	5006K-ND		Digi-Key.^(3)	Black Test Point	1
P3	5007K-ND		Digi-Key.^(3)	Yellow Test Point	1
S1	CKN1362-ND		Digi-Key.^(3)	Dip Switch	1
U1	SY89846U		Micrel, Inc.^(4)	Ultra-Precision 1:5 LVPECL Divider/Fanout Buffer	1
U1	SY89847U		Micrel, Inc.^(4)	Ultra-Precision 1:5 LVDS Divider/Fanout Buffer	1

Notes:

1. Vishay: www.vishay.com.

2. Johnson Components: www.johnsoncomponents.com.

3. Digi-Key: www.digikey.com

4. Micrel, Inc.: www.micrel.com.

HBW Support

Hotline: [phone]

Email Support: [e-mail]

Application Hints and Notes

For application notes on high-speed termination on PECL and LVPECL products, clock synthesizer products, SONET jitter measurement, and other Bandwidth products go to Micrel Inc., website at http://www.micrel.com/. Once in Micrel's website, follow the steps below:

1. Click on "Product Info".
2. In the Applications Information Box, choose "Application Hints and Application Notes."

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