Microchip Technology MCP6S2 Series, MCP6S21 User Manual

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  
MCP6S2X Evaluation Board (Rev. 4)
User’s Guide
 2004 Microchip Technology Inc.
DS51327B
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 Digital Millennium Copyright Act. If such acts
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 intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, 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, Smart 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.
© 2004, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
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® 8-bit MCUs, KEELOQ® code hopping
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.
DS51327B-page ii
 2004 Microchip Technology Inc.
MCP6S2X Evaluation
Board (Rev.4) User’s Guide
Table of Contents
Preface ........................................................................................................1
Introduction................................................................................................ 1
About This Guide....................................................................................... 2
Recommended Reading............................................................................ 4
The Microchip Internet Web Site ............................................................... 4
Customer Support ..................................................................................... 5
Chapter 1. MCP6S2X Evaluation Board (Rev. 4)....................................7
1.1
Introduction ..................................................................................... 7
1.2
Evaluation Board Description ......................................................... 8
1.3
How it is used ................................................................................. 9
1.4
How it works ................................................................................. 10
Appendix A. Schematic and Board Layouts ....................................... 15
A.1
Introduction ................................................................................... 12
A.2
Schematic ................................................................................... 16
A.3
Top Silk Screen ........................................................................... 17
A.4
Top Metal Layer .......................................................................... 18
A.5
Ground Plane Layer .................................................................... 19
A.6
Power Plane Layer ...................................................................... 20
A.7
Bottom Metal Layer ..................................................................... 21
A.8
Bottom Silk Screen Layer (Top View) ......................................... 22
Appendix B. Bill of Materials (BOM) .................................................... 23
B.1
Introduction ................................................................................... 23
Appendix C. Evaluation Board Firmware ............................................ 25
 2004 Microchip Technology Inc.
DS51327A-page iii
MCP6S2X Evaluation Board (Rev.4) User’s Guide
Appendix D. Setup Conditions............................................................. 29
D.1
DIP Switch Configurations (Stand-Alone Mode) ...........................29
D.2
Momentary Push Button Switch ....................................................30
D.3
SMA Connectors ...........................................................................30
D.4
Test Points ....................................................................................31
D.5
Reference Voltage Jumper positions ............................................31
Worldwide Sales and Service ................................................................. 32
DS51327A-page iv
 2004 Microchip Technology Inc.
MCP6S2X Evaluation Board
(Rev. 4) User’s Guide
Preface
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 differ from those in this document. Please refer
to our web site (www.microchip.com) to obtain 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 IDE
on-line help. Select the Help menu, and then Topics to open a list of available on-line
help files.
INTRODUCTION
This chapter contains general information that will be useful to know before using the
MCP6S2X Evaluation Board (Rev. 4). Items discussed in this chapter include:
•
•
•
•
•
•
•
About This Guide
Warranty Registration
Recommended Reading
Troubleshooting
The Microchip Web Site
Development Systems Customer Change Notification Service
Customer Support
 2004 Microchip Technology Inc.
DS51327B-page 1
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
ABOUT THIS GUIDE
Document Layout
This document describes how to use MCP6S2X Evaluation Board (Rev. 4) as a development tool to emulate and debug firmware on a target board. The manual layout is as
follows:
• Chapter 1: MCP6S2X Evaluation Board (Rev. 4) - this section describes how to
use the various features of the MCP6S2X Evaluation Board (Rev. 4).
• Appendix A: Schematic – shows the schematic and printed circuit board (PCB)
layout diagrams for the MCP6S2X Evaluation Board (Rev. 4).
• Appendix B: Bill of Materials (BOM) – shows the parts used to build the
MCP6S2X Evaluation Board (Rev. 4).
• Appendix C: Evaluation Board Firmware – shows the firmware for the
PIC16C505 source code used on the MCP6S2X Evaluation Board (Rev. 4).
• Appendix D: Setup Conditions – shows configuration tables for the DIP switch
settings and connections used for the MCP6S2X Evaluation Board (Rev. 4).
DS51327B-page 2
 2004 Microchip Technology Inc.
Preface
Conventions Used in this Guide
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
Description
Arial font:
Italic characters
Initial caps
Quotes
Underlined, italic text with
right angle bracket
Bold characters
‘bnnnn
Text in angle brackets < >
Courier font:
Plain Courier
Italic Courier
0xnnnn
Square brackets [ ]
Curly brackets and pipe
character: { | }
Ellipses...
 2004 Microchip Technology Inc.
Represents
Examples
Referenced books
Emphasized text
A window
A dialog
A menu selection
A field name in a window or
dialog
A menu path
MPLAB IDE User’s Guide
...is the only compiler...
the Output window
the Settings dialog
select Enable Programmer
“Save project before build”
A dialog button
A tab
A binary number where n is a
digit
A key on the keyboard
Click OK
Click the Power tab
‘b00100, ‘b10
File>Save
Press <Enter>, <F1>
#define START
autoexec.bat
c:\mcc18\h
_asm, _endasm, static
-Opa+, -Opa0, 1
file.o, where file can be
any valid filename
A hexadecimal number where 0xFFFF, 0x007A
n is a hexadecimal digit
Optional arguments
mcc18 [options] file
[options]
Choice of mutually exclusive errorlevel {0|1}
arguments; an OR selection
Replaces repeated text
var_name [,
var_name...]
Represents code supplied by void main (void)
user
{ ...
}
Sample source code
Filenames
File paths
Keywords
Command-line options
Bit values
A variable argument
DS51327B-page 3
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
RECOMMENDED READING
This user's guide describes how to use MCP6S2X Evaluation Board (Rev. 4). Other
useful documents are listed below. The following Microchip documents are available
and recommended as supplemental reference resources.
MCP6S2X PGA Data Sheet (DS21117)
This data sheet provides detailed information regarding the MCP6S21/2/6/8 family of
PGAs.
THE MICROCHIP WEB SITE
Microchip provides online support via our WWW site at www.microchip.com. This web
site is used as a means to make files and information easily available to customers.
Accessible by using your favorite Internet browser, the web site contains the following
information:
• Product Support – Data sheets and errata, application notes and sample
programs, design resources, user’s guides and hardware support documents,
latest software releases and archived software
• General Technical Support – Frequently Asked Questions (FAQ), technical
support requests, online discussion groups, Microchip consultant program
member listing
• Business of Microchip – Product selector and ordering guides, latest Microchip
press releases, listing of seminars and events, listings of Microchip sales offices,
distributors and factory representatives
DEVELOPMENT SYSTEMS CUSTOMER CHANGE NOTIFICATION SERVICE
Microchip’s customer notification service helps keep customers current on Microchip
products. Subscribers will receive e-mail notification whenever there are changes,
updates, revisions or errata related to a specified product family or development tool of
interest.
To register, access the Microchip web site at www.microchip.com, click on Customer
Change Notification and follow the registration instructions.
The Development Systems product group categories are:
• Compilers – The latest information on Microchip C compilers and other language
tools. These include the MPLAB C17, MPLAB C18 and MPLAB C30 C compilers;
MPASM™ and MPLAB ASM30 assemblers; MPLINK™ and MPLAB LINK30
object linkers; and MPLIB™ and MPLAB LIB30 object librarians.
• Emulators – The latest information on Microchip in-circuit emulators.This
includes the MPLAB ICE 2000 and MPLAB ICE 4000.
• In-Circuit Debuggers – The latest information on the Microchip in-circuit
debugger, MPLAB ICD 2.
• MPLAB IDE – The latest information on Microchip MPLAB IDE, the Windows®
Integrated Development Environment for development systems tools. This list is
focused on the MPLAB IDE, MPLAB SIM and MPLAB SIM30 simulators, MPLAB
IDE Project Manager and general editing and debugging features.
• Programmers – The latest information on Microchip programmers. These include
the MPLAB PM3 and PRO MATE® II device programmers and the PICSTART®
Plus development programmer.
DS51327B-page 4
 2004 Microchip Technology Inc.
Preface
CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
•
•
•
•
•
Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Development Systems Information Line
Customers should contact their distributor, representative or field application engineer
(FAE) for support. Local sales offices are also available to help customers. A listing of
sales offices and locations is included in the back of this document.
Technical support is available through the web site at: http://support.microchip.com
In addition, there is a Development Systems Information Line which lists the latest
versions of Microchip's development systems software products. This line also
provides information on how customers can receive currently available upgrade kits.
The Development Systems Information Line numbers are:
1-800-755-2345 – United States and most of Canada
1-480-792-7302 – Other International Locations
 2004 Microchip Technology Inc.
DS51327B-page 5
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
NOTES:
DS51327B-page 6
 2004 Microchip Technology Inc.
MCP6S2X Evaluation Board
(Rev. 4) User’s Guide
Chapter 1. MCP6S2X Evaluation Board (Rev. 4)
1.1
INTRODUCTION
The MCP6S21/2/6/8 family of Programmable Gain Amplifiers (PGA) is available with
one, two, six or eight signal input channels, respectively. The user can digitally select
a specific input channel and set the gain. This family of PGAs can be evaluated using
the MCP6S2X Evaluation Board (Rev. 4). The evaluation board schematic is shown in
Figure 1-1. This board uses the MCP6S21 and MCP6S26 to allow the user to connect
two signal sources to evaluate the PGAs. The 10 kΩ pull-up resistors provide noise
immunity for the PGA digital input pins.
VDD
Connector
ICSP™
VDD Select
JP2
VPP
VDD
GND
PGD
PGC
LVP
VDD
GND
J1
VDD
J6
VDD
MCP6S21
VDD
10 kΩ
470Ω
VOUT SCK
SI
CH0
VREF CS
VOUT_2
READ
Switch
0.1 µF
MCLR
Switch
VDD
MCP6S26
VDD
20 kΩ
PIC16F676
VDD
VOUT_1
VOUT
VIN_0
CH0
CH1
CH2 SCK
SO
CH3
SI
CH4
CH5
CS
VREF
VIN_1
2.5V
ADJ. VREF
RA3
RA0
RA1
RC5
RC3
RC4
DIP Switch
RA5
RA2
RC0
RC1
RC2
10 kΩ
VREF
JP1
FIGURE 1-1:
MCP6S2X Evaluation Board (Rev. 4) simplified schematic.
 2004 Microchip Technology Inc.
DS51327B-page 7
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
1.2
EVALUATION BOARD DESCRIPTION
The single-channel MCP6S21 and six-channel MCP6S26 have been selected for this
evaluation board. The PIC16F676 microcontroller is used to program the PGAs according to the user inputs. User inputs are selected using the on-board DIP switch settings
that are configured according to the table printed on the evaluation board. This allows
the user to program the channel, gain and shutdown of each PGA. Either PGA or both
PGAs can be shut down. The six channels of the MCP6S26 and the PGA gains of 1, 2,
4, 5, 8, 10, 16 and 32 V/V can be configured. Refer to Appendix D.”Setup Conditions”,
for additional information.
When the momentary READ push button switch is pressed, the microcontroller reads
the DIP switch configuration through the I/O ports. The controller determines the proper
command and data bytes to be transmitted to the PGAs and the transmits a 16 or 32-bit
word through the Serial Peripheral Interface (SPI™) port.
When the momentary MCLR push button switch is pressed, the microcontroller Master
Clear is activated. This resets the microcontroller to a known initial state.
The ICSP connector provides the capability of programming the PIC16F676 from a PC.
This requires additional hardware, such as MPLAB® ICD 2.
The two PGAs are cascaded, while the signal output of the MCP6S26 is directly
connected to the analog input of the MCP6S21. This configuration outputs a maximum
signal gain of 1024 V/V.
The digital lines of the PGA are daisy chained. The MCP6S26 has a Serial-Out (SO)
line that can be used to serially program another device. Therefore, the SO line is connected to the Serial-In (SI) line of the MCP6S21. If the MCP6S26 is removed from the
socket, the MCP6S21 cannot be programmed.
The MCP6S2X family of PGAs has a reference voltage input pin to offset the output
signal. There are three reference voltage options on the board: 2.5V, adjustable reference voltage (0V to 5V) and ground. These options can be selected using the on-board
jumper (JP1).
A prototype area is available for user circuit interface. The inputs, outputs and reference voltage traces of the PGAs conveniently pass near the prototype area for ease
of connection. Test point connectors are available to interface with external circuits.
The signals VIN_0, VIN_1, VOUT_1 and VOUT_2 can use SMA connectors that slide horizontally onto the board. 50Ω termination resistors can be added to VIN_O and VIN_1.
Refer to Appendix A.”Schematic and Board Layouts” and Appendix D.”Setup
Conditions”, for additional information.
DS51327B-page 8
 2004 Microchip Technology Inc.
1.3
HOW IT IS USED
1.3.1
Application Procedure - Stand-Alone Mode
1. Apply a 2.5V to 5.5V supply voltage to the VDD and ground (GND) terminals of
J1. Place the VDD SELECT jumper (JP2) at the bottom (nearest J1).
Note:
If jumper JP2 is incorrectly placed, there may be a conflict between power
supplies.
For additional information on powering-up the MCP6S2X Evaluation Board (Rev.
4), refer to Section 1.4.2 “Applying Power”. During power-up, the MCP6S2X
PGA's default settings are Channel 0 (CH0) and gain = 1 V/V.
Note:
Do NOT use the ICSP connector while in this mode (disconnect the cable).
The results may be unpredictable and damage might occur due to
conflicting voltage sources.
2. Connect a voltage-measuring device (such as an oscilloscope) to VOUT_1 for the
MCP6S26 and/or VOUT_2 for the MCP6S21.
3. Select the desired reference voltage using JP1. If the adjustable reference
voltage is selected, adjust this voltage using the potentiometer (ADJ_VREF). A
test point is available to measure the reference voltage.
Refer to Section 1.4.5 “Reference Voltage” for additional information.
Note:
There are soldering pads available across each input terminal for termination resistors (R4 and R5). If these resistors (e.g., 50Ω) are needed for your
application, solder them across the pads.
4. Apply the input signal source at VIN_0 and/or VIN_1. VIN_0 is connected to
Channel 0 and VIN_1 is connected to Channel 1 of the MCP6S26 (refer to
Section 1.4.4 “Analog Interface”). Make sure that the input signal range is at
the proper level to avoid railing the amplifier output when the signal is gained.
Refer to Section 1.4.5 “Reference Voltage” for additional information.
5. Refer to the Table 1-1 and select the desired gain, channel or shutdown using the
on-board DIP switch. Press and release the READ push button switch to program the PGA and notice the change in the output voltage. Refer to
Section 1.4.6 “Programming The PGA” for further explanation.
TABLE 1-1:
 2004 Microchip Technology Inc.
DIP SWITCH CONFIGURATION TABLE
Register
MCP6S26
MSB → LSB
MCP6S21
MSB → LSB
Gain 1
Gain 2
Gain 4
Gain 5
Gain 8
Gain 10
Gain 16
Gain 32
Channel 0
Channel 1
Channel 2
Channel 3
Channel 4
Channel 5
SHDN
SHDN
SHDN
00000
00001
00010
00011
00100
00101
00110
00111
10000
10001
10010
10011
10100
10101
11000
—
11010
01000
01001
01010
01011
01100
01101
01110
01111
—
—
—
—
—
—
—
11001
11010
DS51327B-page 9
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
1.3.2
Application Procedure - Program Mode
1. Place the VDD SELECT jumper (JP2) at the top (away from J1). The MPLAB
ICD 2 will provide 5V to the PGAs and to the microcontroller. Disconnect any
external power supply from J1.
Note:
The ICSP™ connector can only be used to program the PIC16F676. In
order to debug the firmware, use the MPLAB ICD 2 header. Refer to the
MPLAB ICD 2 Header Installation Information (DS51292) for more
information.
2. Configure the MPLAB ICD 2 to provide power to the evaluation board through
the ICSP connector. This is accomplished by changing the MPLAB ICD 2
configuration in MPLAB IDE. The MPLAB ICD 2 needs to be powered by an
external power source.
3. Connect the MPLAB ICD 2 to the ICSP connector and update the PIC16F676
firmware from a PC using MPLAB ICD 2.
Note:
Do not change either of the manual push button switches (MCLR and
READ) while debugging the firmware. The results of this action would be
unpredictable, and may cause damage due to conflicting voltage sources.
4. Follow steps 3 thru 5 in 1.3.1 “Application Procedure - Stand-Alone Mode”.
1.4
HOW IT WORKS
1.4.1
PGA Functions
The PGA has an internal precision operational amplifier in a non-inverting configuration. The gain of this operational amplifier is set using resistive ladders in the feedback
loop. The resistor ratio is set using analog switches that are configured according to the
instructions stored in the memory registers.
The MCP6S21/2/6/8 family of PGAs provide various input channel options: one, two,
six or eight channel inputs, respectively. The non-inverting input of the internal precision operational amplifier is directly connected to the input channels through a multiplexer. The multiplexer is also configured according to the command stored in the
memory registers. Figure 1-2 shows a block diagram of the MCP6S26 with six input
channels. For the single-channel MCP6S21, the non-inverting input is directly connected to the input pin without a multiplexer.
VDD
VOUT
MUX
RF
Gain
Switches
CS
SI
SO
SCK
8
RG
SPI™
Logic
Resistor Ladder (RLAD)
CH0
CH1
CH2
CH3
CH4
CH5
MCP6S26
POR
VSS
VREF
FIGURE 1-2:
The six-channel MCP6S26 PGA Block Diagram. The
single-channel MCP6S21 does not have an input multiplexer.
DS51327B-page 10
 2004 Microchip Technology Inc.
1.4.2
Applying Power
The VDD SELECT jumper (JP2) connects the power plane (VDD) to either an external
power supply (through J1) or to MPLAB ICD 2 (via the ICSP connector (J6)). It selects
between two modes of operation:
1. Stand-Alone Mode - The MCP6S2X Evaluation Board (Rev. 4) is configured
using the on-board switches. Power is brought in to connector J1 from an external supply and the VDD SELECT jumper selects J1. The external supply can be
between 2.5V and 5.5V. When the PIC16F676 is in a valid operating voltage, the
device will run the program stored in the device’s program memory (the
firmware).
2. Program Mode - The MCP6S2X Evaluation Board (Rev. 4) is connected to the
MPLAB ICD 2, which is connected to a PC. Power is brought in via the ICSP
connector and the VDD SELECT jumper selects the ICSP source. VDD is 5.0V.
The PIC16F676 firmware is reprogrammed by MPLAB IDE (application on PC).
1.4.3
Digital Interface
The memory registers are programmed using the SPI™ interface from a PIC16F676
microcontroller. The digital interface uses a standard 3-wire SPI protocol with Chip
Select (CS), Serial Clock (SCK) and Serial In (SI) lines. These lines are directly
connected to the MCP6S26 and have pull-up resistors. These pull-up resistors provide
noise immunity for the PGA from the PICmicro® microcontroller’s I/O pins. The two
PGAs are daisy chained with the SO pin from the MCP6S26 and connected to the SI
pin of the MCP6S21. The SCK and CS lines are also connected to the MCP6S21.
In order to program the MCP6S21 through the daisy chain, the microcontroller pulls CS
low and sends the 32-bit word through the SPI line. The first 16-bit word contains the
command and data bytes for the MCP6S21, while the next 16-bit word contains the
command and data bytes for the MCP6S26. The second 16-bit word can be zeros or a
NOP command. At the end of the 32nd clock cycle, the first 16-bit word is pushed out of
the MCP6S26 (through the SO line) and into the MCP6S21 (through the SI line). When
CS toggles high, the bytes are latched in the registers. Instructions in the registers are
then executed.
1.4.4
Analog Interface
The input channel 0 of the MCP6S26 is connected to VIN_0. The input channels 1, 2 and
3 are connected to VIN_1. Input channel 4 is connected to ground and input channel 5
is connected to the reference voltage. The user can connect two signal sources to
channel 0 and channel 1 at VIN_0 and VIN_1. .
Note:
There are soldering pads available across each input terminal for termination resistors (R4 and R5). If these resistors (e.g., 50Ω) are needed for your
application, solder them across the pads.
The output pin of the MCP6S26 is connected to VOUT_1. This pin is also connected to
Channel 0 of the MCP6S21. The MCP6S21 can be used to gain the signal from the
MCP6S26 by gains of 1, 2, 4, 5, 8, 10, 16 and 32 V/V. If both PGAs are configured for
a gain of 32 V/V, the total signal gain is 1024 V/V. This illustrates the fact that the user
can cascade several PGAs to get higher gains. The output pin of the MCP6S21 is
connected to VOUT_2. The outputs of both PGAs are loaded with 10 kΩ resistors and
56 pF capacitors in parallel. These loads can be changed by the user.
Note:
 2004 Microchip Technology Inc.
The signals VIN_0, VIN_1, VOUT_1 and VOUT_2 can be setup for test points
(surface-mount on top) or for SMA connectors (slide onto board
horizontally). Refer to Appendix D, D.3 “SMA Connectors” for more
information.
DS51327B-page 11
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
1.4.5
Reference Voltage
The MCP6S2X Evaluation Board (Rev. 4) has three reference-voltage settings, as
shown in Figure 1-3. The MCP1525, a precision reference voltage device, is used to
provide a 2.5V reference. The minimum supply voltage for this device is 2.7V.
Therefore, this device will not operate when the evaluation board supply voltage (VDD)
is below 2.7V. An adjustable reference voltage (0V to 5V) is also available using a
mechanical potentiometer. Since the reference voltage input of the PGA requires a
low-impedance source, these reference voltages are buffered using the MCP6022, a
10 MHz operational amplifier. The PGA reference voltage input can also be connected
to ground. All of these options can be selected using the on-board jumper connector
JP1 (refer to Appendix D.”Setup Conditions” and D.5 “Reference Voltage Jumper
Positions” for more information).
VDD
1/2 MCP6022
VDD
+
-
MCP1525
JP1
VDD
10 kΩ
Pot.
FIGURE 1-3:
VREF
1/2 MCP6022
VDD
+
-
Simplified Reference Voltage Schematic.
The input and output of this PGA can swing rail-to-rail (VDD and GND supply voltages).
However, in order to keep linearity, the output voltage should not exceed the Maximum
Output Voltage Swing, referred to in the electrical specifications of the MCP6S21/2/6/8
Data Sheet (DS21117). The reference voltage must be adjusted so that the maximum
output would not exceed the specified limit.
The PGA output voltage, with respect to the input and reference voltages, can be
determined using the following equation:
EQUATION 1-1:
V OUT_1 = G MCP6S26 ( VIN_X – V REF ) + VREF
VOUT_2 = G MCP6S26 × G MCP6S21 ( V IN_X – VREF ) + VREF
Where:
DS51327B-page 12
GMCP6S26 = gain of 1, 2, 4, 5, 8, 10, 16 or 32 V/V
GMCP6S21 = gain of 1, 2, 4, 5, 8, 10, 16 or 32 V/V
VIN_X = signal at the MCP6S26’s selected channel
VREF = Reference Voltage at VREF pin.
 2004 Microchip Technology Inc.
1.4.6
Programming The PGA
The DIP switch lines are connected to the five microcontroller I/O lines (RA5, RA2,
RC0, RC1 and RC2) with pull-down resistors (Refer to Figure 1-1 and Appendix
A. “Schematic and Board Layouts”). The extreme top switch is the Most Significant
Bit (MSB) and the extreme bottom switch is the Least Significant Bit (LSB). Pushing the
switches right corresponds to the ‘1’, as shown on Table 1-1. Once the DIP switch is
configured to the desired setting, the READ push-button switch must be pressed and
released. When the button is released, the microcontroller reads the DIP switch
settings and transmits the corresponding command and data bytes to the PGAs. The
microcontroller remains in a loop to continuously monitor the READ push button switch.
Refer to Table 1-1 for the settings.
 2004 Microchip Technology Inc.
DS51327B-page 13
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
NOTES:
DS51327B-page 14
 2004 Microchip Technology Inc.
MCP6S2X Evaluation
Board (Rev. 4) User’s Guide
Appendix A. Schematic and Board Layouts
A.1
INTRODUCTION
This appendix contains the schematic and printed circuit board (PCB) layout diagrams
for the MCP6S2X Evaluation Board (Rev. 4).
A.1.1
Highlights
The MCP6S2X Evaluation Board (Rev. 4) is constructed using a four-layer PCB. The
top and bottom layers are for components and traces. The second layer is the ground
plane and the third layer is (VDD) the power plane.
Diagrams included in this appendix include:
•
•
•
•
•
•
•
Schematic
Top Silk Screen Layer
Top Metal Layer
Ground Plane Layer
Power Plane Layer
Bottom Metal Layer
Bottom Silk Screen Layer
Note:
 2004 Microchip Technology Inc.
The bottom metal layer (A.7) is missing a connection between pin 8 of the
PIC16F676 (U2 in A.2) and pin 6 of the DIP switch (DSW1 in A.2) and with
the pull-down resistor (R11). These traces have been corrected prior to
shipping by making a solder bridge between these pins.
DS51327B-page 15
3
4
5
6
J6
ICSP CONNECTOR
VPP
VDD
GND
PGD
PGC
LV P
JP2
VDD SELECT
J1
GND
VDD
10k
R10
10K
VDD
MSB
SW1
READ
VDD
1
3
C5
0.1uF
56pF
2
4
LSB
R3
10K
C16
5
R6
20K
4
FB1
10µF/16V
Bypass Cap
C1
D
VDD
3
PROTOAREA SMA 6X6
Proto Area
R19
VDD
C3
2
C7
0.1uF
1
PROTOAREA1
PROTOAREA2
PROTOAREA3
PROTOAREA4
D
1
2
3
4
5
6
VDD
1
VDD
CH0
SCK
Vref
SI
Vss
CS
10K
10K
10K
TP12
CS
R20
4
470
5
5
6
7
MCP6S21
R2
TP15
10K
VOUT 1
TP16
VIN 0
VIN 1
1
49.9
2
R5
4
49.9
RA3
RA2
RC5
RC0
RC4
RC1
RC3
RC2
9
RA1
12
0
6
7
13
11
10
C
9
8
PIC16F676
R15 R14 R13 R12 R11
10K 10K 10K 10K 10K
SW2
TP19
SI_1
C18
0.1uF 1
3
MCLR
2
4
16F676
6
7
Vout
Vdd
CH0
SCK
CH1
SO
CH2
SI
CH3
CS
CH4
Vss
CH5
Vref
TP20
VREF
14
13
12
11
10
B
9
8
MCP6S26
U4
VDD
3
Vout
1
R9
2
100K
C8
1.0 µF
C6
0.1uF
3
out A
Vdd
-INA
out B
+INA
- INB
Vss
+INB
8
7
6
C12
0.1uF
2
 2004 Microchip Technology Inc.
C9
0.1 uF
Vss
U3
MCP1525
Vi n
5
2.5V
Adj _Vr ef
Gnd
JP1
1
RA0
RA4
0.1uF
DSW1
U5
R4
B
VDD
TP18
SI_2
C13
0.1uF
3
TP17
VDD
RA5
8
R18
3
7
6
R17
9
R16
TP11
SCK
10
8
14
OFFON
4
56pF
Vdd
Vss
OFFON
3
Vout
VDD
OFFON
2
C2
2
U1
1
C
1
OFFON
10K
VOUT 2
OFFON
TP14
U2
C14
0.1uF
R1
4
5
Extra Test Points
VDD
MCP6022
VDD
TP5
TP7
VR1
A
R7
C4
0.1uF
TP6
R8
100K
100K
C10
2.2uF
10K POT
A
Title
C11
2.2uF
Size
MCP6S2X Demo Bd.
Number
Revision
103-00018R4
B
Date:
File:
1
2
3
4
MICROCHIP LOGO
5
A
14-Jul-2004
Sheet of
C:\Protel Projects\Kumen Work\MCP6S2X Drawn
Demo Bd\MCP682X
By:
Demo Db.ddb
6
SCHEMATIC
2
Breadboard Area
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
A.2
DS51327B-page 16
1
A.3
TOP SILK SCREEN
 2004 Microchip Technology Inc.
DS51327B-page 17
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
A.4
TOP METAL LAYER
DS51327B-page 18
 2004 Microchip Technology Inc.
A.5
GROUND PLANE LAYER
 2004 Microchip Technology Inc.
DS51327B-page 19
MCP6S2X Evaluation Board (Rev. 4) User’s Guide
A.6
POWER PLANE LAYER
DS51327B-page 20
 2004 Microchip Technology Inc.
A.7
BOTTOM METAL LAYER
 2004 Microchip Technology Inc.
DS51327B-page 21

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Key Features

  • Digitally selectable input channels
  • Programmable gain settings
  • Daisy-chain capability
  • SPI interface for programming
  • Adjustable reference voltage
  • Evaluation Board
  • ICSP connector for programming

Related manuals

Frequently Answers and Questions

How many input channels does the MCP6S21 PGA have?
The MCP6S21 PGA has one input channel.
What is the maximum gain of the MCP6S26 PGA?
The maximum gain of the MCP6S26 PGA is 32 V/V.
How can I program the gain and channel selection of the PGAs?
You can program the gain and channel selection using the DIP switches on the evaluation board. Pressing the READ button sends the configuration to the PGAs.
What is the purpose of the reference voltage on the evaluation board?
The reference voltage can be used to offset the output signal. You can select between 2.5V, adjustable reference voltage (0V to 5V) and ground using the JP1 jumper.
Can I use the evaluation board to program the PIC16F676 microcontroller?
Yes, you can use the ICSP connector on the evaluation board to program the PIC16F676 using the MPLAB ICD 2.
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