SY88347DL - Carte d'évaluation Microchip - Free user manual and instructions

USER MANUAL SY88347DL Microchip

The SY88347DL evaluation board enables fast and thorough evaluation of the SY88347DL. The board is an easy-to-use, single supply design, designed to be driven by a high-speed, pattern generator. The SY88347DL evaluation board is intended to terminate to a 50_ scope and provides for simple user adjustability of the LOS threshold through the adjustment of an on-board potentiometer.

All data sheets and support documentation can be found on Micrel's web site at: www.micrel.com.

Features

• SY88347DL PECL Limiting Post Amplifier with High-Gain TTL Loss-of-Signal
• Single +3.3V power supply
• AC-coupled configuration for direct interface with 50Ω test equipment
• On-board LOS sensitivity adjustment

Related Documentation

- SY88347DL: 3.3V, 3.2Gbps PECL Limiting Post Amplifier with High-Gain TTL Loss-of-Signal

Evaluation Board

SY8B903 SY8B923 SY8B993 VCC GND MICREL VIN 1 BIN 2 BIN 3 VIN 4 E50EVL 5 DIN+ 21 DIN- VCC PHAN REV. A. 09/2004 JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN JPN

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 (408) 474-500 • http://www.micrel.com

Evaluation Board Description

The SY88347DL evaluation board is designed to operate with a single 3.3V ±5% power supply and is configured with AC-coupled inputs and outputs. The high-speed input and output channels are brought out to SMA connectors through matched length AC-coupled differential strip-line traces.

AC-Coupled Input

The AC-Coupled inputs automatically bias the input levels to the correct DC-operating point set by the VT jumper input. Therefore, the inputs can be driven by a differential signal smaller than 100mV (200mV _pp ) without level-shifting or termination resistor network in the signal path.

AC-Coupled Output

The SY88347DL is configured with AC-coupled outputs allowing the board to interface directly with 50Ω equipment. AC-coupling allows the board to use a single power supply. If only one output is being used, the unused complimentary output should be terminated into 50Ω to ground.

SY88347DL AC-Coupled Evaluation Board Setup

This section explains how to connect and setup the SY88347DL evaluation board per Figure 1. Ensure proper ESD precautionary measures are taken before handling sensitive electronic equipment, including the SY88347DL evaluation board.

Measurements

Evaluating DOUT and /DOUT

1. Set a DC power supply to +3.3V and turn it off. Connect the positive lead to V_CC post and the negative lead to GND post.
2. Set the desired frequency on a pattern generator with an amplitude between 5mV_PP and 1800mV_PP . Typical data patterns are 2^7-1 or 2^23-1 PRBS patterns, depending upon the application. Since the inputs to the board are AC-Coupled, the voltage offset of the pattern generator is not significant so it can be set between GND and VCC.
3. Connect the pattern generator with differential outputs as a data source to the DIN and /DIN inputs on the SY88347DL evaluation board. Use matched-length differential cables.
4. Turn the power supply on.
5. Observe the DOUT and /DOUT outputs with a 50Ω scope. The output rise and fall times should be less than 120ps, with an amplitude around 400mV (800mV _PP differential).

LOS Hysteresis Measurements

The SY88347DL evaluation board provides a potentiometer to allow for convenient adjustment of LOS_LVL without the need for an extra power supply. LOS_LVL taps off a potentiometer connected between V_CC and V_REF . V_REF is a reference voltage of approximately V_CC -1.3V . Hence, LOS_LVL can be set to any voltage between V_CC and V_CC-1.3 , as specified in the SY88347DL data sheet. The potentiometer creates a voltage divider. Thus,

$$ L O S _ {L V L} = \left[ V _ {C C} - \frac {1 . 3 \times R (k \Omega)}{(R (k \Omega) + 2 . 8 k \Omega)} \right] $$

Where: R is the resistance of the potentiometer VAR1 from V_cc to the tap at LOSLVL. The steps below show how to measure the LOS hysteresis as a function of the input voltage swing at the DIN and /DIN inputs:

Minimum Input Swing Hysteresis Measurement

The minimum acceptable input swing for the SY88347DL is 5mV_PP

1. Set a DC power supply to +3.3V and turn it off. Connect the positive lead to V_CC post and the negative lead to GND post.
2. Connect a DMM or similar voltage measurement device between the LOS_LVL pin and V_CC .
3. Connect a second DMM or similar voltage measurement device between the LOS output and GND. For the remainder of this document, this DMM will be referred to as the LOS DMM.
4. Connect the pattern generator with differential outputs as a data source to the DIN and /DIN inputs on the SY88347DL evaluation board. Use matched-length differential cables.
5. Turn the power supply on.
6. Adjust the trimpot VAR1 so the voltage at the LOS_LVL pin is around 1.3V below V_CC . This sets the LOS for maximum sensitivity. At this level, the LOS output should go HIGH or LOW (measured with the LOS DMM set up in step 3) as the input voltage swing at DIN and /DIN is varied around 5mV PP. The input voltage at which the LOS output goes HIGH or LOW is the LOS assert voltage or LOS de-assert voltage, respectively.

7. Now adjust the trimpot is to vary the voltage so it is closer to V_CC . Note that as the voltage at the LOS_LVL pin approaches V_CC , a larger input voltage swing is required to trigger assert and de-assert levels. On the contrary, as the LOS_LVL voltage moves away from V_CC , assert and de-assert levels are triggered by input voltage swings as small as 5mV_PP .

8. The hysteresis between assert and de-assert levels can be calculated with the following equation: Hysteresis (dB) = 20log (LOS De-assert voltage/LOS Assert voltage). This hysteresis should be >2dB.

Evaluation 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.

L1	GND and Signal
L2	GND
L3	VCC
L4	GND

Table 1. Layer Stack

Header Pins J1 LOS 3 VCC 4.75kΩ L1 VCC C42 1μF C41 10μF GND J1 C1 0.1μF /EN 2 SY88347DL 1 EN VCC 10 DIN DOUT 9 /DIN /DOUT 8 VREF LOS 7 LOSLVL GND 6 C6 0.1μF VCC VAR1 15kΩ Trimpot 50Ω 50Ω C3 0.1μF J2 J3 J4

Figure 1. Setup for Measurement

Bill of Materials (SOIC)

Item	Part Number	Manufacturer	Description	Qty.
C1, C2, C3, C4, C21, C23, C25	VJ0402Y104KXXAT	Vishay^(1)	0.1μF, 25V, 10% Ceramic Capacitor, Size 0402, X5R, Dielectric	7
C20, C22, C24	VJ0402Y222KXXAT	Vishay^(1)	220pF, 25V, 10% Ceramic Capacitor, Size 0402, X5R, Dielectric	3
C40	VJ0603Y104KXXAT	Vishay^(1)	0.1μF, 25V, 10% Ceramic Capacitor, Size 0603, X5R, Dielectric	1
C41	293D106X0025CT	Vishay^(1)	10μF, Surface Mount Capacitor, Size C	1
C42	293D105X0025CT	Vishay^(1)	1μF, Surface Mount Capacitor, Size C	1
L1	BLM21A102F	Murata^(2)	Ferrite Bead, Size 0603	1
JP1, JP2, JP3	TSW-103-07-S-S	Samtec^(3)	0.1mil Center through hole terminal strip	3
R7	CRCW04025001F	Vishay^(1)	5kΩ, 10%, 1/16W Resistor SMD, Size 0402	1
VAR1	3269W-1-153G	Bourns^(4)	15kΩ Trimpot	1
J1–J4	142-0701-851	Johnson Components^(5)	Jack Assembly End Launch SMA	4
U1	SY88347DL	Micrel, Inc.^(6)	Post Amplifier	1

Notes:

1. Vlshay: www.vishay.com.
2. Murata: www.murata.com.
3. Samtec: www.samtec.com.
4. Bourns: www.bourns.com.
5. Johnson Components: www.johnsoncomponents.com.
6. Micrel, Inc.: www.micrel.com.

HBW Support

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Application Hints and Notes

For application notes on high-speed termination on PECL and LVPECL products, clock synthesizer products, SONET jitter measurement, and other High Bandwidth product, go to Micrel's 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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