Microchip Technology Photodiode PGA PICtail User Manual

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Photodiode PGA

PICtail™ Daughter Board

User’s Guide

 2004 Microchip Technology Inc. DS51514A

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Note the following details of the code protection feature on Microchip devices:

• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrity of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digit al Millennium Copyright Act. If suc h a c t s allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of M icrochip’s prod ucts as critical co mponents in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, dsPIC, K

EELOQ, microID, MPLAB, PIC, PICmicro,

PICSTART, PRO MATE, PowerSmart, rfPIC, and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

AmpLab, FilterLab, MXDEV, MXLAB, PICMASTER, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB, rfPICDEM, Select Mode, Sm art Serial, SmartTel and Total Endurance are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.

All other trademarks mentioned herein are property of their respective companies.

Printed on recycled paper.

Microchip received ISO/TS-16949:2002 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona and Mountain View, California in October 2003. The Company’s quality system processes and procedures are for its PICmicro devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified.

8-bit MCUs, KEELOQ

code hopping

DS51514A-page ii  2004 Microchip Technology Inc.

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PHOTODIODE PGA PICTAIL™

DAUGHTER BOARD USER’S GUIDE

Tabl e of Contents

Preface ...........................................................................................................................1

Introduction............................................................................................................1

About This Guide................................................................................................... 2

Recommended Reading........................... .. .................................... .......................4

The Microchip Web Site............................................ .................................... .. ...... 5

Customer Support............................... ........................... ........................... ............ 5

Chapter 1. Overview.......................................................................................................7

1.1 Introduction ............................................................................................... 7

1.2 Kit Contents .............................................................................................. 7

1.3 Photodiode PGA PICtail™ Daughter Board ............................................. 7

1.4 Associated Tools ......................................................................................8

Chapter 2. Setup and Installation...............................................................................11

2.1 Introduction .............................................................................................11

2.2 Required Tools .......................................................................................11

2.3 Connecting the Photodiode PGA PICtail™ Daughter Board ..................11

Chapter 3. Operation....................................................................................................13

3.1 Introduction .............................................................................................13

3.2 Light Sources .......................................................................................... 13

Appendix A. Schematic and Layouts ........................................................................17

A.1 Introduction ............................................................................................. 17

A.2 Demonstration Board Description ........................................................... 17

A.3 Additional Comments .............................................................................18

A.4 Board Schematic ..................................................................................19

A.5 Board - Top Silk Screen And Metal Layers ...........................................20

A.6 Board - Top Metal Layer .......................................................................21

A.7 Board - Bottom Metal Layer ................................................................. 22

Appendix B. Bill-Of-Materials (BOM) .........................................................................23

Worldwide Sales and Service ....................................................................................24

 2004 Microchip Technology Inc. DS51514A-page iii

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Photodiode PGA PICtail™ Daughter Board User’s Guide

NOTES:

DS51514A-page iv  2004 Microchip Technology Inc.

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PHOTODIODE PGA PICTAIL™

DAUGHTER BOARD USER’S GUIDE

NOTICE TO CUSTOMERS

All documentation becomes dated, and this manual is no exception. Microchip tools and documentation are constantly evolving to meet customer needs, so some actual dialogs and/or tool descriptions may dif fer from those in this document. Please refer to our web site (www.microchip.com) to obt ain the latest documentation available.

Documents are identified with a “DS” number. This number is located on the bottom of each page, in front of the page number. The numbering convention for the DS number is “DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the document.

For the most up-to-date information on development tools, see the MPLAB on-line help. Select the Help menu, and then Topics to open a list of available on-line help files.

IDE

INTRODUCTION

This chapter contains general information that will be useful to know before using the Photodiode PGA PICtail™ Daughter Board. Items discussed in this chapter include:

• Ab out thi s guid e

• Recommended Reading

• The Microchip Web Site

• Customer Support

 2004 Microchip Technology Inc. DS51514A-page 1

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Photodiode PGA PICtail™ Daughter Board User’s Guide

ABOUT THIS GUIDE

This document describes how to use the Photodiode PGA PICtail Daughter Board. It also discusses the other available tools that are designed to work with it. The overall outline is as follows:

• Chapter 1: Overview – An introduction to the Photodiode PGA PICtail Daughter Board covering the kit contents, associated tools and how they work together.

• Chapter 2: Set-Up Overvie w – Covers the initial set-up of the Photodiode PGA PICtail Daughter Board, listing required tools, instructions on how to connect this board and demonstating how to verify the se t-up

• Chapter 3: Using the Photodiode-PGA PICtail Daughter Board – Discusses different light sources, usin g the Signal Analysis PC Application and setti ng up the b oard to st and on its own.

• Appendix A: Photodiode PGA PICtail Daughter Board Hardware – Gives detailed information on the Photodiode PGA PICtail Daughter Board. Includes detailed circuit explanation, schematic, board layouts and Bill-of-Materials (BOM)

DS51514A-page 2  2004 Microchip Technology Inc.

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Conventions Used In This Guide

This manual uses the following documentation conventions.

TABLE 1-1:

Description Represents Examples

Arial Font:

Italic Characters Referenced books MPLAB

Emphasized text ...is the only compiler...

Initial Caps A window the Output window

A dialog the Settings dialog A menu selection select Enable Programmer

Quotes A field name in a window or

dialog

Underlined, italic text with right angle bracket

Bold Characters A dialog button Click OK

‘bnnnn A binary number where n is a

Text in angle brackets < > A key on the keyboard Press <Enter>, <F1>

Courier font:

Plain Courier Sample source code #define START

Italic Courier A variable argument file.o, where file can be

0xnnnn A hexadecimal number whe re

Square brackets [ ] Optional arguments mcc18 [options] file

Curly brackets and pipe character: { | }

Ellipses... Replaces repeated text var_name [,

A menu path File>Save

A tab Click the Power tab

digit

Filenames autoexec.bat File paths c:\mcc18\h Keywords _asm, _endasm, static Command-line options -Opa+, -Opa- Bit values 0, 1

n is a hexadecimal digit

Choice of mut ually exclu s ive arguments; an OR selection

Represents code supplied by user

“Save project before build”

‘b00100, ‘b10

any valid filename

0xFFFF, 0x007A

[options] errorlevel {0|1}

var_name...] void main (void)

{ ... }

IDE User’s Guide

 2004 Microchip Technology Inc. DS51514A-page 3

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Photodiode PGA PICtail™ Daughter Board User’s Guide

1.1 INTRODUCTION

The following name and assembly number are found on the Photodiode PGA PICtail™ Daughter Board’s Printed Circuit Boar d (PCB) :

• MCP6SX2DM-PICTLPD

• 102-00029

This PCB goes by the following titles:

• Photodiode PGA PICtail™ Daughter Board

• MCP6SX2 Photodiode-PGA Demo Board

This board supports the photodiode AN951, “Amplifying High-Impedance Sensors – Photodiode Example” (DS00951). It uses the PNZ334 photodiode as a light detector. Its output is conditioned by the MCP6001U op amp, which is set up as a transimpedance amplifier. The output is then amplified (and buffered) by either the MCP6S22 or the MCP6S92 Programmable Gain Amplifier (PGA).

Items discussed in this chapter include:

• Kit Contents

• Photodiode PGA PICtail™ Daughter Board

• Associated Tools

• Ini tia l Set- up

PHOTODIODE PGA PICTAIL™

DAUGHTER BOARD USER’S GUIDE

Chapter 1. Overview

1.2 KIT CONTENTS

• Photodiode PGA PICtail™ Daughter Board – An assembled and tested Printed Circuit Board (PCB)

• PICkit™ 1 CD-ROM (DS40049) – Contains the files and literature mentioned in this user’s guide

• Additional PGA (MCP6S92) in an anti-static bag

1.3 PHOTODIODE PGA PICTAIL™ DAUGHTER BOARD

The Photodiode PGA PICtail™ Daughter Board contains the analog circuitry represented in Figure 1-1. Light incident to the photodiode is converted to current. The op amp converts current to voltage (transimpedance amplifier). This voltage is sent to the CH0 input of the PGA. The PGA gains and buffers this output, which is sent off-board (V makes it possible to control the PGA; its gain and input channel can be set as desired from the software.

). Board power is applied at the +5V and GND inputs. The SPI™ bus

OUT

 2004 Microchip Technology Inc. DS51514A-page 7

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Photodiode PGA PICtail™ Daughter Board User’s Guide

Photodiode PGA

Incident

Light

Test Point

Test Point CH0 Input

Test Point CH1 Input

Test Point

FIGURE 1-1: Photodiode PGA PICtail™ Daughter Board Block Diagram.

The test points make it easier to test key points in the circuit, change the input signals and to use this board as a stand-alone.

• GND Test Point – Connected to the ground plane and is a convenient ground point for any lab equipment

• +5V Test Point – Allows measurement of the positive supply voltage and provides a means to power this board with a laboratory power supply

• CH0 Test Point – The place to measure the transimpedance amplifier’s output voltage (also the PGA’s CH0 input)

• CH1 Test Point – Makes it possible to send any desired signal to the PGA

More details on the circuit and on its design can be found in Appendix A. “Schematic

and Layouts” and in Application Note 951.

PICtail™ Daughter Board

Photodiode

+5V

GND

Op Amp

MCP6001U

MCP6S22

PGA

+5V

GND

SPI™ Bus

OUT

1.4 ASSOCIATED TOOLS

Figure 1-2 shows the bl ock diagr am of th e hardware and so ftware tools that the Photodiode PGA PICtail™ Daughter Board is design ed to work with . More information on these tools can be found in the “Recommended Reading” section.

FIGURE 1-2: Measurement Set-up Block Diagram.

Hardware Software

USB

PICkit™ 1 Flash Sta rter Kit

Signal Analysis PICtail™ Daughter Board

Photodiode PGA PICtail™l Daughter Board

PICkit™ 1 Signal Analysis

PC Program

PICkit™ 1

Firmware

PICA2Dlab.hex

Firmware

DS51514A-page 8  2004 Microchip Technology Inc.

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Overview

1.4.1 PC Platform

The Personal Computer (PC) shown in Figure 1-2 needs to run on Windows®98 SE or later. It provides a convenient interface for the user, communicates with the other boards and provides power through the USB connection.

1.4.2 PICkit™ 1 Signal Analysis PC Program

The PICkit™ 1 Signal Analysis PC Program configures and programs the PIC16F684 PICmicro USB port on the PICkit 1 Flash Starter Kit. It also imports data through the same connection and displays the data in strip chart, histogram, FFT plot and oscilloscope plot formats. Data can be output in CSV format for importing into a spreadsheet program.

microcontroller on the Signal Analysis PICtail Daughter Board through the

1.4.3 PICkit 1 Flash Starter Kit

The PICkit 1 Flash Starter Kit (DV164101) programs PICmicro® microcontrollers, using the PIC16C745’s USB port to communicate with the PICkit 1 Signal Analysis PC Program. It connects to the Signal Analysis PICtail Daughter Board via a header (see Figure 2-1).

This board provides a single +5V supply voltage for the daughter boards. It can drive up to 5 µF on the supply; a larger capacitance may interfere with program timing.

1.4.4 PICkit 1 Firmware

This software resides on the PICkit 1 Flash Starter Kit’s PIC16C745 microcontroller. Use version 2.0.2 or later.

1.4.5 Signal Analysis PICtail Daughter Board

This board is Microchip Development Tool AC164120. It connects to the PICkit 1 Flash Starter Kit, which it uses for power and a communications link to the PC. The on-board PIC16F684 has a 10-bit ADC that converts the Photodiode PGA PICtail™ Daughter Board’s output voltage. The results are temporarily stored on the board’s 25LC640 serial EEPROM chips.

The +5V single supply voltage from the PICkit 1 Flash Starter Kit board is bypassed with a bulk 1 µF capacitor and local 0.1 µF capacitors for each IC.

1.4.6 Firmware for the Signal Analysis PICtail Daughter Board

PICA2Dlab.hex is the standard file that supports the PICkit™ 1 Signal Analysis PC Program. The PGA and 10-bit ADC configuration are selected in the Signal Analysis PC Program and written to the PIC16F684. The PIC16F684 then sends the command(s) over the SPI bus to the PGA.

1.4.7 Interface Details

A more detailed look at how the Photodiode PGA PICtail™ Daughter Board interfaces with the other boards is shown in Figure 1-3.

 2004 Microchip Technology Inc. DS51514A-page 9

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Photodiode PGA PICtail™ Daughter Board User’s Guide

Photodiode PGA

Incident

Light

+5V

Test Point

GND

Test Point CH0 Input

Test Point CH1 Input

Test Point

PICtail™ Daughter Board

Photodiode

Op Amp

MCP6001U

PGA

MCP6S22

SPI Bus

PICtail™ Daughter Board

+5V

GND

SPI™ Bus

OUT

FIGURE 1-3: Detailed Interface Diagram.

Signal Analysis

Serial

EEPROM

PIC16F684

ADC

+5V

GND

PICkit™ 1

Flash Starter Kit

PIC16F745

USB

to PC

DS51514A-page 10  2004 Microchip Technology Inc.

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Chapter 2. Setup and Installation

2.1 INTRODUCTION

This chapter shows how to set up the Photodiode PGA PICtail™ Daughter Board. Items discussed in this chapter include:

This chapter discusses:

• Required Tools

• Connecting the Photodiode PGA PICtail™ Daughter Board

• Set-up Verification

2.2 REQUIRED TOOLS

The PICkit™ 1 Flash Starter Kit User’s Guide explains how to set up the PC and the PICkit™ 1 Flash Starter Kit. Use firmware version 2.0.2 or later.

The Signal Analysis PICtail™ Daughter Board User’s Guide shows how to install the PICkit 1 Signal Analysis PC Program on the PC and set up the Signal Analysis PICtail Daughter Board. It also covers the features of the PICkit 1 Signal Analysis PC Program.

The PICkit 1 CD-ROM (DS40049) contains many of the necessary files. Use version v2.0 or later.

PHOTODIODE PGA PICTAIL™

DAUGHTER BOARD USER’S GUIDE

2.3 CONNECTING THE PHOTODIODE PGA PICTAIL™ DAUGHTER BOARD

An exploded view of how the different boards connect is shown in Figure 2-1.

Photodiode-PGA

PICtail™ Daughter Board

Signal Analysis

PICtail™ Daughter Board

USB Cable

Expansion Header (J3)

PIC16C745 Firmware

Version 2.0.2 or later

Remove PICmicro® MCU from Evaluation Socket

PICkit 1™ Flash Starter Kit

FIGURE 2-1: Board Connections.

 2004 Microchip Technology Inc. DS51514A-page 11

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Photodiode PGA PICtail™ Daughter Board User’s Guide

2.3.1 PICkit 1 Flash Starter Kit

1. Remove any PICmicro microcontroller that may be in the evaluation socket.

2. Connect the USB cable to the PC and to the PICkit 1 Flash Starter Kit board. The

status LEDs (green POWER and yellow BUSY in the LED array) should light up.

It is easiest to use this board when it lays directly on a bench top.

2.3.2 Signal Analysis PICtail Daughter Board

This board plugs into the PICkit 1 Flash Starter Kit’s expansion header J3 (Figure 2-1), and must not cover the LED array. There should be no change in the status LEDs on the PICkit Flash Starter Kit board once it is plugged in.

2.3.3 Photodiode PGA PICtail™ Daughter Board

If you would rather use the MCP6S92 PGA, take it out of the anti-static bag and replace the already-installed MCP6S22 PGA.

1. Plug this board into, and directly above, the Signal Analysis PICtail Daughter

Board (Figure 2-1). There should be no change in the status LEDs on the PICkit Flash Starter Kit board once it is plugged in.

2.1 Set-up Verification

1. Select the Real Time Mode radio button.

2. Click on the Str ip Ch a r t button.

3. Change the sample speed to 20 sample/secs.

4. Click on the green GO button; the strip-chart will show the measured output of

the Photodiode PGA PICtail™ Daughter Board.

5. Move the photodiode close to a light source, such as a desk lamp, and verify that

the strip-chart changes with light intensity (e.g., Figure 2-2).

FIGURE 2-2: Strip Chart.

DS51514A-page 12  2004 Microchip Technology Inc.

Page 17

3.1 INTRODUCTION

This demonstration board makes it easy to explore the operation of a photodiode application. Items discussed in this chapter include:

• Li ght Sou rces

• Using the Signal Analysis PC Program for this Board

• Stand-Alone Board Set-up

3.2 LIGHT SOURCES

Different types of light sources have different characteristics. DC-powered light sources have a constant output intensity. AC-powered light sources have an output intensity that varies with time around an average value.

A battery power light source will have minimal fluctuations in light intensity. A battery-powered flashlight or LED array are good DC light sources.

Incandescent light bulbs and flourescent lights powered by the mains (e.g., 120 V AC at 60 Hz) are typical AC light sources.

When making light intensity measurements, other light sources in the environment may need to be blocked to achieve better measurement accuracy. Place a box over the light source, the demo board and on top of the bench to keep out ambient light; see Figure 3-1.

PHOTODIODE PGA PICTAIL™

DAUGHTER BOARD USER’S GUIDE

Chapter 3. Operation

Box

Light

Source

Bench

FIGURE 3-1: Bench Set-up.

Demo Board

3.2.1 Using the Signal Analysis PC Application for This Board

See “Chapter 2. Using the PICkit™ Signal Analysis PC Application” of the “Signal Analysis PICtail Daughter Board User’s Guide” (DS51476) for details on displaying

measured results. The possible formats include: oscilloscope, FFT, histogram and strip-chart.

The measured results can then be interpreted as illuminance; see AN951, “Amplifying High Impedance Sensors – Photodiode Example” (DS00951).

 2004 Microchip Technology Inc. DS51514A-page 13

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Photodiode PGA PICtail™ Daughter Board User’s Guide

3.2.2 Configure the PGA

The PICkit 1 Signal Analysis PC Program can configure the PGA; see Figure 3-2. The MCP6S22 PGA defaults to Gain = 1 and to input CH0 when it powers up.

Note: The MCP6S92 PGA powers up to a random state; it must have its gain and

input written to it before it will operate as expected.

1. Open the PGA window by clicking the Exte rnal Devic es button.

2. Select the correct PGA from the indicated pull-down list.

3. Select the desired PGA input. Usually the selection will be CH0 for the photo-

diode output, but it can be CH1 when another input source is provided at the CH1 test point (Figure 1-1).

a. Select Write to Register from the indicated pull-down list. (Figure 3-2, #5) b. Set A0 = 1. (Figure 3-2 , #6) c. Set C2:C0 to all zeros. (Figure 3-2, #7) d. Execute the command by clicking on the Write to PGA button.

(Figure 3-2, #8)

4. Select the desired PGA gain.

a. Select Write to Register from the indicated pull-down list. (Figure 3-5, #5) b. Set A0 = 0. (Figure 3-5, #6) c. Select PGA gain from the pull-down list. (Figure 3-5, #4) d. Execute the command by clicking on the Write to PGA button.

(Figure 3-2, #8)

8. Execute

7. Set Input Channel

1. Open PGA Window2. Select PGA3. Select Channel

4. Select Gain5. Select Operation 6. Set Register Pointer

FIGURE 3-2: PGA Configuration.

DS51514A-page 14  2004 Microchip Technology Inc.

Page 19

Operation

3.2.3 Configure the ADC

The ADC is automatically set up by the PICkit 1 Signal Analysis PC Program. The two possible inputs are shown in Figure 3-3.

1. If in the Real Time mode of operation (strip chart), select the number of samples from the first pull-down list.

2. Select the sample rate from the second pull-down list.

1. Select Number of Samples

2. Select Sample Rate

FIGURE 3-3: Standard ADC Options.

The PICkit 1 Signal Analysis PC Program allows the user to manually configure the ADC.

1. Clicking the ADC button (see Figure 3-4) opens the ADC configuration window. This window starts at the power-on default conditions for the ADC; therefore, it must be configured before use.

See the PIC16F684 data sheet (DS41202) for more information on configuring the registers.

FIGURE 3-4: Manual ADC Configuration.

1. Select ADC window2. ADC Window

 2004 Microchip Technology Inc. DS51514A-page 15

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Photodiode PGA PICtail™ Daughter Board User’s Guide

3.2.4 Measurement Example

The photodiode was placed next to a flourescent desk light. The gain was set to 16 V/V , the speed to 5000 samples/sec and the number of samples to 1024. The results are in Figure 3-5.

FIGURE 3-5: Measurement Results.

3.1 Stand-Alone Board Set-up

Figure 3-6 shows one possible method for using the Photodiode PGA PICtail™ Daughter Board by its elf (without th e accompany ing tools shown in F igure 1-2). Most of th e probes from the lab equipment (on the left) connect to the test points. The oscilloscope (O-Scope) probe to V

FIGURE 3-6: Photodiode PGA PICtail™ Daughter Board Block Diagram.

The PGAs’ power supply range is between 2.5V and 5.5V. The MCP6001U op amp will also operate over this range.

The SPI bus needs to be connected to a microcontroller with the appropriate firmware. The MCP6S22 PGA powers up to input CH0 and 1 V/V gain. The MCP6S92 needs to be initialized after power-up.

connects to header J2’s pin # 10 (labeled RC0).

OUT

Incident

Light

Power

Supply

O-Scope

Function

Generator

+5V

Test Point

GND

Test Point

CH0 Input Test Point

CH1 Input Test Point

Photodiode PGA

PICtail™ Daughter Board

SPI™ Bus

OUT

DS51514A-page 16  2004 Microchip Technology Inc.

Page 21

PHOTODIODE PGA PICTAIL™

DAUGHTER BOARD USER’S GUIDE

Appendix A. Schematic and Layouts

A.1 INTRODUCTION

This appendix contains the schematics and layouts for the Photodiode PGA PICtail™ Daughter Board.

The MCP6SX2-PICTLPD Demonstration Board is constructed using a two-layer Printed Circuit Board (PCB). The top layer is for components and traces. The bottom layer is the ground plane.

Information on this board includes:

• Board Schematic

• Board - Top Silk-Screen And Metal Layers

• Board - Top Metal Layer

• Board - Bottom Metal Layer

A.2 DEMONSTRATION BOARD DESCRIPTION

A simplified schematic is shown in Figure 1.3, with the complete schematic being presented in A.4 “Board Schematic”. D Op amp U ance amplifier. Capacitor C

and C2 filter the transimpedance amplifier’s output to reduce noise. They also act

as an anti-aliasing filter for the ADC. The voltage V The MCP6SX2 Programmable Gain Amplifier (PGA) can be either the MCP6S22 or the

MCP6S92. The PGA gains V provides the capability to send another input to the ADC. It receives commands from the PIC16F684 via the SPI™ serial bus.

The PIC16F684 is on the Signal Analysis PICtail Daughter Board (PIC16F684) and provides an internal 10-bit ADC for measuring V SPI serial interface.

The firmware on the PIC16F684 works with the PICkit 1 Signal Analysis PC program (see Section 1.4.6 “Firmware for the Signal Analysis PICtail Daughter Board”).

This is a two-layer board. It has a solid ground plane on the bottom layer to minimize EMC issues, and routes the traces in the top layer. The complete schematic is in

Sections A.4 “Board Schematic”; the board layer plots in A.5 “Board - Top Silk-Screen And Metal Layers”, A.6 “Board - Top Metal Layer”, A.7 “Board - Bottom Metal Layer” and Appendix B. Bill-Of-Materials (BOM). The Gerber files for this

board are available on the Microchip web site (www.microchip.com) and are contained in the zip file 00951.zip.

and resistor R1 convert the current into a voltage; they form a transimped-

stabilizes the transimpedance amplifier.

OUT

is the photodiode that converts light into current.

up to produce the ADC’s input voltage V

appears at this filter’s output.

OUT

PGA

. It also controls the PGA via the

OUT

. It also

 2004 Microchip Technology Inc. DS51514A-page 17

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Photodiode PGA PICtail™ Daughter Board User’s Guide

A.3 ADDITIONAL COMMENTS

The demonstration board includes test points for convenience on the bench. The “+5V” and “GND” test points connect to the board’s supply voltages. The “CH0” test point connects to the PGA’s CH0 input; it is also connected to the transimpedance amplifier’s output (with filtering). The “CH1” test point allows the user to place any desired signal at the PGA’s CH1 input.

The PIC16F684 (and 10-bit ADC) are not part of the demo board schematic; they are part of the Signal Analysis PICtail Daughter Board. (Figure 1-3).

The PICkit 1 Flash Starter Kit provides a +5V single supply-voltage. It can drive up to 5 µF on the supply; a larger capacitive load causes current loading and timing issues.

The PICkit 1 Flash Starter Kit Signal Analysis PICtail Daughter Board uses the +5V single-supply voltage. It has 0.1 µF local bypass capacitors for each IC, and a 1 µF bulk bypass capacitor for the entire board.

This demonstration board also uses the +5V single supply voltage. It has a 0.1 µF local bypass capacitor for the PGA and a 1 µF bulk bypass capacitor for the entire board. A solid ground plane provides a good ground for the PGA.

High-frequency design practices are used to minimize digital interference:

• Solid ground plane

• Surface-mount devices

• Separate digital and analog lines and sections

• Straight and short lines to the PGA

DS51514A-page 18  2004 Microchip Technology Inc.

Page 23

A.4 BOARD SCHEMATIC

 2004 Microchip Technology Inc. DS51514A-page 19

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Photodiode PGA PICtail™ Daughter Board User’s Guide

A.5 BOARD - TOP SILK-SCREEN AND METAL LAYERS

DS51514A-page 20  2004 Microchip Technology Inc.

Page 25

A.6 BOARD - TOP METAL LAYER

 2004 Microchip Technology Inc. DS51514A-page 21

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Photodiode PGA PICtail™ Daughter Board User’s Guide

A.7 BOARD - BOTTOM METAL LAYER

DS51514A-page 22  2004 Microchip Technology Inc.

Page 27

PHOTODIODE PGA PICTAIL™

DAUGHTER BOARD USER’S GUIDE

Appendix B. Bill-Of-Materials (BOM)

TABLE B-1: BILL-OF-MATERIALS

Qty Reference Description M an ufac tur er Part Number

1 C1 Ceramic Capacitor, 18 pF, 50V, 5%, NP0, 0805 SMD Panasonic 1 C2 Ceramic Capacitor, 33 nF, 50V, 10%, X7R, 0805 SMD Panasonic - ECG ECJ-2VB1H333K 2 C3,C4 Ceramic Capacitor, 0.1 µF, 25V, 10%, X7R, 0805 SMD Panasonic - ECG ECJ-2VB1E104K 1 C5 Ceramic Capacitor, 1.0µF, 16V, 10% X7R, 0805 SMD Kemet 1 D1 PIN Photodiode Panasonic - SSG PNZ334 1 J2 Header, 1X14, 0.100" Pitch, Vertical, Tin Molex

Electronics Corp. 1 R1 Chip R esistor, 64.9 kΩ, 1/10W, 1%, 0805 SMD Panasonic - ECG ERJ-6ENF6492V 1 R2 Chip R esistor, 10.0 kΩ, 1/10W, 1%, 0805 SMD Panasonic - ECG ERJ-6ENF1002V 4 GND,CH0,

CH1,+5V

1 U1 MCP6001U, Op Amp, 1 MHz, SOT23-5 Microchip

1 U2 MCP6S22, PGA, 10 MHz, 2 inputs, PDIP-8 (Note 1) Microchip

1 U2 MCP6S92, PGA, 10 MHz, 2 inputs, PDIP-8 (Note 1) Microchip

1 — IC Socket, 8-pin, Gold Plated, 0.300" (for U2) Mill-Max

1 PCB Bare Printed Circuit Board — —

Note 1: Either PGA will work in this appli catio n. The bo ard comes with a MC P6S22 ins tal led. A MC P6S92 c omes in

the anti-static parts bag.

PC Test Point, Compact, SMT Keystone

Electronics

Technology Inc.

Manufacturing

Corp.

- ECG ECJ-2VC1H180J

/Waldom®

C0805C105K4RACTU

22-28-4140

5016

MCP6001U-I/OT

MCP6S22-I/P

MCP6S92-E/P

110-93-308-41-001

 2004 Microchip Technology Inc. DS51514A-page 23

Page 28

WORLDWIDE SALES AND SERVICE

AMERICAS

Corporate Office

2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http:\\support.microchip.com Web Address: www.microchip.com

Atlanta

Alpharetta, GA Tel: 770-640-0034 Fax: 770-640-0307

Boston

Westford, MA Tel: 978-692-3848 Fax: 978-692-3821

Chicago

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Dallas

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Detroit

Farmington Hills, MI Tel: 248-538-2250 Fax: 248-538-2260

Kokomo

Kokomo, IN Tel: 765-864-8360 Fax: 765-864-8387

Los Angeles

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San Jose

Mountain View, CA Tel: 650-215-1444 Fax: 650-961-0286

Toronto

Mississauga, Ontario, Canada Tel: 905-673-0699 Fax: 905-673-6509

ASIA/PACIFIC

Australia - Sydney

Tel: 61-2-9868-6733 Fax: 61-2-9868-6755

China - Beijing

Tel: 86-10-8528-2100 Fax: 86-10-8528-2104

China - Chengdu

Tel: 86-28-8676-6200 Fax: 86-28-8676-6599

China - Fuzhou

Tel: 86-591-750-3506 Fax: 86-591-750-3521

China - Hong Kong SAR

Tel: 852-2401-1200 Fax: 852-2401-3431

China - Shanghai

Tel: 86-21-5407-5533 Fax: 86-21-5407-5066

China - Shenyang

Tel: 86-24-2334-2829 Fax: 86-24-2334-2393

China - Shenzhen

Tel: 86-755-8203-2660 Fax: 86-755-8203-1760

China - Shunde

Tel: 86-757-2839-5507 Fax: 86-757-2839-5571

China - Qingdao

Tel: 86-532-502-7355 Fax: 86-532-502-7205

ASIA/PACIFIC

India - Bangalore

Tel: 91-80-2229-0061 Fax: 91-80-2229-0062

India - New Delhi

Tel: 91-11-5160-8632 Fax: 91-11-5160-8632

Japan - Kanagawa

Tel: 81-45-471- 6166 Fax: 81-45-471-6122

Korea - Seoul

Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934

Singapore

Tel: 65-6334-8870 Fax: 65-6334-8850

Taiwan - Kaohsiung

Tel: 886-7-536-4818 Fax: 886-7-536-4803

Taiwan - Taipei

Tel: 886-2-2500-6610 Fax: 886-2-2508-0102

Taiwan - Hsinchu

Tel: 886-3-572-9526 Fax: 886-3-572-6459

EUROPE

Austria - Weis

Tel: 43-7242-2244-399 Fax: 43-7242-2244-393

Denmark - Ballerup

Tel: 45-4420-9895 Fax: 45-4420-9910

France - Massy

Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79

Germany - Ismaning

Tel: 49-89-627-144-0 Fax: 49-89-627-144-44

Italy - Milan

Tel: 39-0331-742611 Fax: 39-0331-466781

Netherlands - Drunen

Tel: 31-416-690399 Fax: 31-416-690340

England - Berkshire

Tel: 44-118-921-5869 Fax: 44-118-921-5820

09/27/04

DS51514A-page 24  2004 Microchip Technology Inc.