ANALOG DEVICES EVAL-ADL5308 Logarithmic Converter User Guide

ANALOG DEVICES EVAL-ADL5308 Logarithmic Converter

Product Information

Specifications

• Range: 10 pA to 25 mA
• Logarithmic slope: 200 mV/dec
• Logarithmic intercept: 10 pA

Features

• Full-featured evaluation board for the ADL5308
• Supports external electrical input or onboard photodiode (PD) for optical input
• On-chip or external PD bias (PDB)
• Comparator reference and output connectors with adjustable hysteresis

Evaluation Kit Contents

• ADL5308-EVALZ evaluation board

Equipment Needed

• 5 V DC power supply (minimum 50 mA output current)
• Precision source measurement unit (for example, Keithley 236)
• Triax cable
• Triax-to-BNC adapter (Triax center to BNC center, Triax shield to BNC shield)

Documents Needed

• ADL5308 datasheet

General Description
The ADL5308-EVALZ evaluation board allows the evaluation of the ADL5308 logarithmic converter IC. The ADL5308 is a monolithic logarithmic trans- impedance amplifier, optimized for measurement of low frequency, and wide dynamic range signal power in fiber optic systems. It produces an output voltage proportional to the logarithm of the ratio between the input current at pin INP, and an internal reference current. The reference current can also be supplied externally through the IREF interface. The logarithmic slope and intercept are both factory-trimmed to a nominal value of 200 mV/dec and 10 pA respectively. Both can be adjusted through the I2C interface.

ADL5308-EVALZ Evaluation Board Photograph

Evaluation Board Test Setup
The Linduino One board is normally shipped with the ADL5308-KITEVALZ board as a kit. For more information, refer to the Ordering Guide section of the ADL5308 data sheet. A 14-conductor ribbon cable provides I2C and regulated +3.3 V connections between the interface board and evaluation board.

Product Usage Instructions

Quick Test Procedure

1. Connect the ADL5308-EVALZ evaluation board to the Linduino One board using the provided 14-conductor ribbon cable.
2. Connect the power supply and precision source measurement unit to the appropriate connectors on the evaluation board.
3. Follow the instructions in the ADL5308 data sheet to set up the desired test configuration.
4. Use the graphical user interface (described in the next section) to monitor and analyze the output of the ADL5308.

Driving the Input Using an Actual Photodiode

1. Disconnect any electrical input from the evaluation board.
2. Connect the photodiode to the appropriate connector on the evaluation board.
3. Adjust the PD bias (PDB) to the desired level using either the on-chip or external bias option.
4. Follow the instructions in the ADL5308 data sheet to set up the desired test configuration.
5. Use the graphical user interface (described in the next section) to monitor and analyze the output of the ADL5308.

Graphical User Interface
Refer to the ADL5308 data sheet for detailed information on using the graphical user interface to control and monitor the ADL5308-EVALZ evaluation board.

Evaluation Board Schematics and Artwork
Refer to the ADL5308 data sheet for the schematics and artwork of the evaluation board.

Ordering Information
For ordering information, refer to the Ordering Information section of the ADL5308 data sheet.

Bill of Materials
Refer to the Bill of Materials section of the ADL5308 data sheet for a list of materials included in the evaluation kit.

FAQ

• Q: Where can I find the ADL5308 data sheet?
  A: The ADL5308 data sheet is available from Analog Devices, Inc. It must be consulted with this user guide when using the ADL5308-EVALZ evaluation board.

• Q: How can I adjust the logarithmic slope and intercept of the ADL5308?
  A: The logarithmic slope and intercept can be adjusted through the I2C interface. Refer to the ADL5308 data sheet for detailed instructions.

FEATURES

• Full-featured evaluation board for the ADL5308
• Supports external electrical input or on-board photodiode (PD) for optical input
• On-chip or external PD bias (PDB)
• Comparator reference and output connectors with adjustable hysteresis

EVALUATION KIT CONTENTS

• ADL5308-EVALZ evaluation board

EQUIPMENT NEEDED

• 5 V DC power supply (minimum 50 mA output current)
• Precision source measurement unit (for example, Keithley 236)
• Triax cable
• Triax-to-BNC adapter (Triax center to BNC center, Triax shield to BNC shield, Triax inner guard may be connected to BNC shield or left floating.)
• BNC-to-SMA adapter
• Two digital multimeters
• Oscilloscope
• DC2026C (Linduino® One) board (Required only for adjusting the ADL5308’s internal registers. Not needed for the evaluation of ADL5308 in factory default settings.)

DOCUMENTS NEEDED

• ADL5308 data sheet

GENERAL DESCRIPTION

The ADL5308-EVALZ evaluation board allows evaluation of the ADL5308 logarithmic converter IC. The ADL5308 is a monolithic logarithmic transimpedance amplifier, optimized for measurement of low frequency, and wide dynamic range signal power in fiber optic systems. It produces an output voltage proportional to the logarithm of the ratio between the input current at pin INP, and an internal reference current. The reference current can also be supplied externally through the IREF interface. The logarithmic slope and intercept are both factory-trimmed to a nominal value of 200 mV/dec and 10 pA respectively. Both can be adjusted through the I2C interface. Full specifications on the ADL5308 are available in the ADL5308 data sheet available from Analog Devices, Inc., and must be consulted with this user guide when using the ADL5308-EVALZ evaluation board.

ADL5308-EVALZ EVALUATION BOARD PHOTOGRAPH

EVALUATION BOARD TEST SETUP

The complete ADL5308 evaluation system includes the ADL5308-EVALZ evaluation board, the DC2026C (Linduino One) board, and the ADL5308 Analysis | Control | Evaluation (ACE) plug-in. Plug-ins are product-specific applications downloaded and run in the ACE software in a Microsoft Windows® environment. For instructions on how to install and use the ACE software, go to www.analog.com/ACE. The ADL5308-EVALZ communicates with ACE through the Lindui-no One board. The Linduino One board is normally shipped with the ADL5308-KIT-EVALZ board as a kit. For more information, refer to the Ordering Guide section of the ADL5308 data sheet. A 14-conductor ribbon cable provides I2C and regulated +3.3 V connections between the interface board and evaluation board.

The ADL5308-EVALZ evaluation board requires a 5 V DC power supply with at least 50 mA of current. The current input pin is connected to an SMU’s current source. The voltage-output pin is connected to a digital multimeter (DMM). The PC is connected to the Linduino One board, which communicates with the ADL5308 IC’s I2C interface. The PC runs the ADL5308 GUI plug-in through the ACE software, which sets the ADL5308 IC’s on-chip registers. These on-chip reg-
sisters adjust the slope and intercept of the VVLOG vs. IINP characteristic, as well as other parameters.

QUICK TEST PROCEDURE

To identify each component and connection, see Figure 2, and to prepare the ADL5308-EVALZ evaluation board for testing, do the following steps (If adjustments to the ADL5308’s internal registers are not required, skip all the steps related to the ACE software and the DC2026C (Linduino One) board.):

1. Verify that the ACE software is installed.

2. In the main ACE window, click Tools > Manage Plug-ins > Available Plug-ins, and then in the search bar, search for Board.ADL5308. Highlight the search result and click Install Selected.

3. With the 5 V DC power supply’s output turned off, connect
   its positive output to the VPOS turret on the ADL5308-EVALZ evaluation board and its negative output to the GND turret.

4. With the SMU’s output turned off, connect its current source output to the evaluation board’s INP input SMA connector (J1) using a Triax cable with a Triax-to-BNC adapter and a BNC-to-SMA adapter. The Triax-to-BNC adapter’s internal connection should be: Triax center to BNC center, Triax shield to BNC shield, Triax inner guard may be connected to BNC shield or floating.

5. Connect the evaluation board’s VLOG and PDB outputs to the digital multimeters.

6. Verify DC2026C (Linuino One) board is set to 3.3 V with a jumper.

7. Connect the Linduino One board to the ADL5308-EVALZ evaluation board via the included 14-pin ribbon cable.

8. Turn on the 5 V DC power supply. Verify that the current consumption is approximately 32 mA.

9. Connect the Linduino One board to the PC using the included USB cable. When LEDs stop blinking, the hardware connections are complete.

10. Launch the ACE software on the PC.

11. The ACE software shows that the ADL5308 plug-in is available on the Attached Hardware. Double-click the plug-in to add to the system. A successfully connected system with a properly loaded plug-in is shown in Figure 3.

12. Click Reset Board, and verify that the Firmware Loaded light indicator turns green.

13. Double-click the ADL5308 icon. The ADL5308 GUI window opens, which shows the register settings that can be changed as shown in Figure 4. For more information, refer to the Register Summary section of the ADL5308 data sheet.

14. Apply input current from the SMU and measure the VLOG and VPDB voltages. For some expected test results for the default register setting, see Table 1.

Table 1. Quick Test Expected Results

IINP

|

VVLOG

|

VPDB

---|---|---
1 nA| 0.406 V ± 0.01 V| 1.5 V ± 0.2 V
1 µA| 1.0 V ± 0.01 V| 1.5 V ± 0.2 V
10 mA| 1.805 V ± 0.01 V| 4.4 V ± 0.2 V

DRIVING THE INPUT USING AN ACTUAL PHOTODIODE
With some minimal modifications to the ADL5308-EVALZ evaluation board, an actual PD may be used to evaluate the performance of the ADL5308.

Do the following procedures for the necessary component changes and for more information, see the Evaluation Board Schematics and Artwork section:

1. Remove resistors R18, R24 and R25, and capacitor C10.
2. Install 0 Ω jumpers at locations R18 and R25.
3. Install PD at location P2.
4. If an external PD cathode voltage is required, EXTPDB can be used with the P3 jumper in the pin 1-2 position.

Input capacitive load negatively affects the bandwidth and noise level of logarithmic TIAs. For best bandwidth and noise performance, do not install a 0 Ω jumper at locations R18 and R25. Instead, solder the PD’s anode directly to the R25 pad close to the ADL5308’s INP pin (pin 2). For more information, refer to the Photodiode Bias (PDB) section of the ADL5308 data sheet.

GRAPHICAL USER INTERFACE

EVALUATION BOARD SCHEMATICS AND ARTWORK

ORDERING INFORMATION

BILL OF MATERIALS

Reference Designator| Description| Manufacturer|

Part Number

---|---|---|---
C1| Ceramic capacitor, 1 µF, 10%, 0402| TDK| C1005X6S1C105K050BC
C9, C10| Ceramic capacitors, 1 nF, 10%, X7R, 0603| AVX| 06031C102KAT2A
C11| Ceramic capacitor, 0.1 µF, 10%, X5R, 0402| Yageo| CC0402KRX5R8BB104
C2, C8| Ceramic capacitors, 4.7 µF, 10%, X6S, 0603| Murata| GRM188C81C475KE11D
C3, C6| Ceramic capacitors, 100 pF, 10%, X7R, 0402| Yageo| CC0402KRX7R7BB102
CMP, CREF, HYST, J1, J2, PDB, VLOG| PCB connectors, coaxial, SMA end launch| Cinch| 142-0701-851
E1| Ferrite bead, 120 Ω, 0603| Wurth Elektronik| 74279262
EXTPDB, GND, GND1, SUM, VPOS| Test points| Mill-max| 2501-2-00-80-00-00-07-0
P1| PCB connector, shrouded, HDR, solder termination,| Molex| 87831-1420
 | male pin, number of positions 14|  |
P3| PCB connector, HDR, solder termination, male pin,| Harwin| M20-9990345
 | number of positions 3|  |
R1, R2, R6, R9, R11, R12, R15, R19| Thick-film resistors, 0 Ω, 5%, SMD, 0402, 1/10 W| Panasonic| ERJ-2GE0R00X
R10| Thick-film resistor, 220 Ω, 5%, SMD, 0603, 1/4 W| Rohm| ESR03EZPJ221
R16| Thick-film resistor, 49.9 Ω, 1%, SMD, 0603, 1/5 W| Panasonic| ERJP03F49R9V
R18, R21, R24, R25| Thick-film resistors, 499 Ω, 1%, SMD, 0402, 1/16 W| Vishay| CRCW0402499RFKED
R20, R22| Thin-film resistors, 1 kΩ, 1%, SMD, 0402, 1/16 W| Yageo| RT0402FRE071KL
R3, R4, R5| Thick-film resistors, 4.99 kΩ, 1%, SMD, 0402, 1/10 W| Panasonic| ERJ-2RKF4991X
R7| Thick-film resistor, 49.9 Ω, 1%, SMD, 0402, 1/10 W| Panasonic| ERJ- 2RKF49R9X
U1| I2C serial EEPROM, clock compatibility 400 kHz| Microchip Technology| 24LC025-I/ST
U2| ADL5308 IC| Analog Device Inc.| ADL5308ACCZ
C4, C51| Ceramic capacitors, 1 µF, 10%, 0402| TDK| C1005X6S1C105K050BC
C71| Ceramic capacitor, 100 pF, 50 V, 1%, COG, 0402| Murata| GCM1555C1H101FA16D
P21| Photodiode| N/A2| N/A2
R13, R171| Thick-film resistors, 4.99 kΩ, 1%, SMD, 0402, 1/10 W| Panasonic| ERJ-2RKF4991X
R14, R231| Thick-film resistors, 0 Ω, 5%, SMD, 0402, 1/10 W| Panasonic| ERJ- 2GE0R00X
R81| Thick-film resistor, 10 kΩ, 1%, SMD, 0402, 1/5 W| Vishay| CRCW040210K0FKEDHP

ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high-energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.

Legal Terms and Conditions

By using the evaluation board discussed herein (together with any tools, components documentation, or support materials, the “Evaluation Board”), you are agreeing to be bound by the terms and conditions set forth below (“Agreement”) unless you have purchased the Evaluation Board, in which case the Analog Devices Standard Terms and Conditions of Sale shall govern. Do not use the Evaluation Board until you have read and agreed to the Agreement. Your use of the Evaluation Board shall signify your acceptance of the Agreement. This Agreement is made by and between you (“Customer”) and Analog Devices, Inc. (“ADI”), with its principal place of business at Subject to the terms and conditions of the Agreement, ADI hereby grants to Customer a free, limited, personal, temporary, non-exclusive, non-sublicensable, non-transferable license to use the Evaluation Board FOR EVALUATION PURPOSES ONLY.

Customer understands and agrees that the Evaluation Board is provided for the sole and exclusive purpose referenced above, and agrees not to use the Evaluation Board for any other purpose. Furthermore, the license granted is expressly made subject to the following additional limitations: Customer shall not (i) rent, lease, display, sell, transfer, assign, sublicense, or distribute the Evaluation Board, and (ii) permit any Third Party to access the Evaluation Board. As used herein, the term “Third Party” includes any entity other than ADI, Customer, their employees, affiliates, and in-house consultants. The Evaluation Board is NOT sold to Customer; all rights not expressly granted herein, including ownership of the Evaluation Board, are reserved by ADI. CONFIDENTIALITY. This Agreement and the Evaluation Board shall all be considered the confidential and proprietary information of ADI. The customer may not disclose or transfer any portion of the Evaluation Board to any other party for any reason. Upon discontinuation of use of the Evaluation Board or termination of this Agreement, Customer agrees to promptly return the Evaluation Board to ADI. ADDITIONAL RESTRICTIONS. Customers may not disassemble, decompile, or reverse engineer chips on the Evaluation Board. The customer shall inform ADI of any occurred damages or any modifications or alterations it makes to the Evaluation Board, including but not limited to soldering or any other activity that affects the material content of the Evaluation Board. Modifications to the Evaluation Board must comply with applicable law, including but not limited to the RoHS Directive.

TERMINATION. ADI may terminate this Agreement at any time upon giving written notice to Customer. The customer agrees to return to ADI the Evaluation Board at that time. LIMITATION OF LIABILITY. THE EVALUATION BOARD PROVIDED HEREUNDER IS PROVIDED “AS IS” AND ADI MAKES NO WARRANTIES OR REPRESENTATIONS OF ANY KIND FOR IT. ADI SPECIFICALLY DISCLAIMS ANY REPRESENTATIONS, ENDORSEMENTS, GUARANTEES, OR WARRANTIES, EXPRESS OR IMPLIED, RELATED TO THE EVALUATION BOARD INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, TITLE, FITNESS FOR A PARTICULAR PURPOSE OR NONINFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS. IN NO EVENT WILL ADI AND ITS LICENSORS BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES RESULTING FROM THE CUSTOMER’S POSSESSION OR USE OF THE EVALUATION BOARD, INCLUDING BUT NOT LIMITED TO LOST PROFITS, DELAY COSTS, LABOR COSTS OR LOSS OF GOODWILL. ADI’S TOTAL LIABILITY FROM ANY AND ALL CAUSES SHALL BE LIMITED TO THE AMOUNT OF ONE HUNDRED US DOLLARS ($100.00). EXPORT. The customer agrees that it will not directly or indirectly export the Evaluation Board to another country and that it will comply with all applicable United States federal laws and regulations relating to exports. GOVERNING LAW. This Agreement shall be governed by and construed per the substantive laws of the Commonwealth of Massachusetts (excluding conflict of law rules). Any legal action regarding this Agreement will be heard in the state or federal courts having jurisdiction in Suffolk County, Massachusetts, and Customer hereby submits to the personal jurisdiction and venue of such courts. The United Nations Convention on Contracts for the International Sale of Goods shall not apply to this Agreement and is expressly disclaimed.

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