SY89467/468U - Electronic component Microchip - Free user manual and instructions

USER MANUAL SY89467/468U Microchip

Precision 1:20 LVDS and LVPECL Fanout Buffer w/2:1 MUX and Internal Termination with Fail Safe Input

SY89467/468U Evaluation Board

General Description

The SY89467U and SY89468U 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

• SY89467U LVPECL outputs
• SY89468U LVDS outputs
- SMA I/O connectors
• 2 input and 3 output accessible board design
• +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

• SY89467U, Precision 1:20 LVPECL Fanout with 2:1 MUX and Internal Termination with Fail-Safe Input Datasheet
• SY89468U, Precision 1:20 LVDS Fanout with 2:1 MUX and Internal Termination with Fail-Safe Input Datasheet

Evaluation Board

SY89467.8 MICREL HIGH BANDWIDTH [phone]

Evaluation Board Description

The SY89467U and SY89468U share a common evaluation board with two inputs (IN0, IN1) and three outputs (Q1, Q12, Q15). The individual evaluation boards are labeled to identify the specific device on that board. The SY89467U is an LVPECL-output evaluation board and the SY89468U is an LVDS-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.

SY89467U DC-Coupled Boards

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-Coupling Operation."

SY89468U DC-Coupled Evaluation Boards

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

GND J12 /C2 0.1μF R28 100Ω GND C5 0.1μF C6 0.1μF VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC U1 SY89467U GND IN0 C7 0.1μF J1 J2 /INO C10 0.1μF GND J3 J4 SEL EO GND IN1 C12 0.1μF J5 J6 /IN1 C15 0.1μF R20 10K R16 0Ω R17 0Ω S1 SW VCC R21 10K VCC VCC GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND

SY89467U 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. SY89467U AC-Coupled Evaluation Board Power Supply Connections

GND J12 /Q2 C1 0.1μF J11 Q2 C2 0.1μF VEE C3 0.1μF GND C4 0.1μF VEE R1 100Ω R2 100Ω R3 100Ω R4 100Ω R5 100Ω R6 100Ω VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC

SY89468U 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. SY89468U AC-Coupled Evaluation Board Power Supply Connections

AC-Coupled Evaluation Board Setup

Setting up the SY89467/468U 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 SY89468U) 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 R16 and R17.
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:

SY89467U

1. Replace capacitors C1, C2, C7, C10, C12, C14, C15, C16, C21, and C22 with 0Ω resistors.
2. Remove R18, R19, R28, R29, R32, and R33.

SY89468U:

1. Replace capacitors C1, C2, C7, C10, C12, C14, C15, C16, C21, and C22 with 0Ω resistors.

DC-Coupled Evaluation Board Setup

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

SY89467U

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.

1. Turn on the power and verify the current is <500mA.
2. Enable the signal source and monitor the outputs.

SY89468U:

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, are coplanar in design, fabricated to minimize noise, achieve high bandwidth and minimize crosstalk.

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

Bill of Materials

Item	Part Number	Manufacturer	Description
C1-C23, C25, C27, C28	VJ0402Y104KXXAT	Vishay^(1)	0.1μF, 25V, 10% Ceramic Capacitor, Size 0402, X7R Dielectric	26
C24, C26 293D6	85X9025C2T Vishay	(1)	6.8μF, 25 V, 10%, Tantalum Electrolytic Capacitor, Size 293D	2
R20, R21 CRCW	0401002F Vishay	(1)	10kΩ, 1/16W, 5%, Resistor SMD, Size 0402 2
R9, R13, R16, R17	CRCW040200R0F	Vishay^(1)	0 Ω, 1/16W, 5% Thick-film Resistor, Size 0402 4
R1-R6, R8, R10, R11, R12, R14, R18, R19, R22-R29, R32, R33	CRCW0402820F	Vishay^(1)	100Ω, 1/16W, 5% Thick-film Resistor, Size 0402	23
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	SY89467U	Micrel, Inc.^(4) Ultra	-Precision 1:20 LVPECL Fanout Buffer	1
U1	SY89468U	Micrel, Inc.^(4) Ultra	-Precision 1:20 LVDS 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

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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 product 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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