PGA2500EVM

      User’s Guide December 2003 SBOU023 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. 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Following are URLs where you can obtain information on other Texas Instruments products & application solutions: Products Applications Amplifiers amplifier.ti.com Audio www.ti.com/audio Data Converters dataconverter.ti.com Automotive www.ti.com/automotive DSP dsp.ti.com Broadband www.ti.com/broadband Interface interface.ti.com Digital Control www.ti.com/digitalcontrol Logic logic.ti.com Military www.ti.com/military Power Mgmt power.ti.com Optical Networking www.ti.com/opticalnetwork Microcontrollers microcontroller.ti.com Security www.ti.com/security Telephony www.ti.com/telephony Video & Imaging www.ti.com/video Wireless www.ti.com/wireless Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright  2003, Texas Instruments Incorporated EVM IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being provided may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety measures typically found in the end product incorporating the goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may not meet the technical requirements of the directive. Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products received may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not exclusive. TI assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or services described herein. Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM User’s Guide prior to handling the product. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact the TI application engineer. Persons handling the product must have electronics training and observe good laboratory practice standards. No license is granted under any patent right or other intellectual property right of TI covering or relating to any machine, process, or combination in which such TI products or services might be or are used. Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright  2003, Texas Instruments Incorporated EVM WARNINGS AND RESTRICTIONS It is important to operate this EVM within the specified input and output ranges described in the EVM User’s Guide. Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions concerning the input range, please contact a TI field representative prior to connecting the input power. Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM. Please consult the EVM User’s Guide prior to connecting any load to the EVM output. If there is uncertainty as to the load specification, please contact a TI field representative. During normal operation, some circuit components may have case temperatures greater than 60°C. The EVM is designed to operate properly with certain components above 60°C as long as the input and output ranges are maintained. These components include but are not limited to linear regulators, switching transistors, pass transistors, and current sense resistors. These types of devices can be identified using the EVM schematic located in the EVM User’s Guide. When placing measurement probes near these devices during operation, please be aware that these devices may be very warm to the touch. Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright  2003, Texas Instruments Incorporated Contents Preface
    About This Manual This document provides the information needed to set up and operate the PGA2500EVM evaluation module (EVM) and accompanying software. For a detailed description of the PGA2500 product, please refer to the product data sheet available from the Texas Instruments web site at http://www.ti.com. Additional support documents are listed in the section of this guide entitled Related Documentation from Texas Instruments. How to Use This Manual Throughout this document, the abbreviation EVM and the term evaluation module are synonymous with the PGA2500EVM. Chapter 1 provides an overview for the PGA2500 digitally-controlled microphone preamplifier. The PGA2500EVM block diagram and primary features are also discussed. Chapter 2 provides general information regarding EVM handling and unpacking, as well as the absolute operating conditions for the EVM. Chapter 3 provides descriptions of the primary hardware functions, as well as hardware configuration details for the EVM. Chapter 4 includes the EVM electrical schematic, PCB layout, and the Bill of Materials. Chapter 5 provides the information required to install and operate the PGA2500EVM applications software using a personal computer running the Microsoft Windows 9x, 2000, or XP operating systems. Contents iii Contents Information About Cautions and Warnings This book contains cautions and warnings. This is an example of a caution statement. A caution statement describes a situation that could potentially damage your software or equipment. This is an example of a warning statement. A warning statement describes a situation that could potentially cause harm to you. The information in a caution or a warning is provided for your protection. Please read each caution and warning carefully. Related Documentation From Texas Instruments The following documents provide information regarding Texas Instruments integrated circuits used in the assembly of the PGA2500EVM. These documents are available from the TI web site. The last character of the literature number corresponds to the document revision, which is current at the time of the writing of this User’s Guide. Newer revisions may be available from the TI web site at http://www.ti.com/ or call the Texas Instruments Literature Response Center at (800) 477−8924 or the Product Information Center at (972) 644−5580. When ordering, identify the document(s) by both title and literature number. Document Literature number PGA2500 Data Sheet SN74AHCT541 Data Sheet SBOS289A SCLS269O If You Need Assistance If you have questions regarding either the use of this evaluation module or the information contained in the accompanying documentation, please contact the Texas Instruments Product Information Center at (972) 644−5580 or visit the TI Semiconductor Online Technical Support pages at www.ti.com. iv Contents FCC Warning This equipment is intended for use in a laboratory test environment only. It may generate, use, or radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to subpart J of part 15 of the FCC regulations, which are designed to provide reasonable protection against radio frequency interference. Operation of this equipment in other environments may cause interference with radio communications, in which case the user at his own expense will be required to take whatever measures may be required to correct this interference. Trademarks All trademarks are the property of their respective owners. Contents v Contents  1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 PGA2500 Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 PGA2500EVM Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 PGA2500EVM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1-2 1-5 1-5 2 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Electrostatic Discharge Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Unpacking the EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Absolute Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2-2 2-2 2-2 3 Hardware Description and Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Analog and Digital Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Microphone Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Phantom Power Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 DC Blocking Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 Protection Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 Configurable Input Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7 Configurable Output Circuitry and Preamp Output Connector . . . . . . . . . . . . . . . . . . . . . . . 3.8 Host Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 Switch and Jumper Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3-2 3-3 3-3 3-3 3-4 3-4 3-4 3-5 3-5 4 Schematic, PCB Layout, and Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4-2 4-3 4-5 5 Software Installation and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Applications Software Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Software Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 Using the Applications Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5-2 5-2 5-3 Contents vii Contents  Figure 1−1. PGA2500 Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 1−2. PGA2500 Serial Port Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 1−3. Functional Block Diagram for the PGA2500EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 3−1. Recommended Power-Supply Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 3−2. Microphone Input Connector Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 3−3. Preamp Output Connector Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 4−1. PGA2500EVM Electrical Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 4−2. PGA2500EVM PCB Silkscreen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 4−3. PGA2500EVM PCB Top Layer (Component Side) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 4−4. PGA2500EVM PCB Bottom Layer (Solder Side) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 5−1. Applications Software Main Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 5−2. Applications Software Device Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1-3 1-5 3-2 3-3 3-4 4-2 4-3 4-3 4-4 5-3 5-3  Table 2−1. Absolute Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3−1. Switch Configuration Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3−2. Jumper Configuration Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 4−1. PGA2500EVM Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 3-5 3-5 4-5     Electrostatic Discharge Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Absolute Operating Conditions Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 viii Chapter 1  This chapter provides a brief technical overview for the PGA2500 digitally-controlled microphone preamplifier, as well as a general description and feature list for the PGA2500EVM. Topic Page 1.1 PGA2500 Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.2 PGA2500EVM Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 1.3 PGA2500EVM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 Introduction 1-1 PGA2500 Product Overview 1.1 PGA2500 Product Overview The PGA2500 is a digitally-controlled, microphone preamplifier integrated circuit designed for amplifying the output of dynamic and condenser microphones and driving high-performance audio analog-to-digital (A/D) converters. A functional block diagram of the PGA2500 is shown in Figure 1−1. Figure 1−1. PGA2500 Functional Block Diagram 0dB CS SCLK ZCEN SERIAL PORT and LOGIC CONTROL GPO1 GPO2 SDI SDO GPO3 GPO4 OVR VCOMIN VOUT+ VIN+ VIN− PGA VOUT− Gain Range AGND VA+ VA+ VA− 0dB or CS1 +10dB to +65dB 1dB per step DC Servo VD− DGND VA− CS2 DCEN CS1 and CS2 are external DC servo integrator capacitors, and are connected across the CS11/CS12 and CS21/CS22 pins, respectively. The analog input to the preamplifier is provided differentially at the VIN+ and VIN− inputs (pins 27 and 26, respectively). The programmable gain amplifier can be programmed to either pass through the signal at unity gain, or apply 10dB to 65dB of gain to the input signal. The gain of the amplifier is adjustable over the full 10dB to 65dB range in 1dB steps. The differential output of the PGA2500 is made available at VOUT+ and VOUT− (pins 17 and 16, respectively). Gain is controlled using a serial port interface. The 4-wire serial port interface is used to program the PGA2500 gain and support functions. A 16-bit control word is utilized to program these functions; see Figure 1−2. A serial data output pin provides support for daisy-chaining multiple PGA2500 devices on a single serial interface bus. 1-2 PGA2500 Product Overview Figure 1−2. PGA2500 Serial Port Protocol CS SCLK SDI Data Ignored DC CM 0 OL D4 D3 D2 D1 0 0 G5 G4 G3 G2 G1 G0 Data Ignored SDO High Impedance DC CM 0 OL D4 D3 D2 D1 0 0 G5 G4 G3 G2 G1 G0 High Impedance DC Servo Enable (active low) CM Servo Enable (active high) Overload Indicator Bit (0 = 5.1Vrms, 1 = 4.0Vrms) Data for GPO4 Data for GPO3 Data for GPO2 Preamplifier Gain where N = G[5:0]DEC For N = 0 Gain = 0dB For N = 1 to 56 Gain (dB) = 9 + N For N = 57 to 63 Gain (dB) = 65 Data for GPO1 The differential analog output of the PGA2500 is constantly monitored by a DC servo amplifier loop. The purpose of the servo loop is to minimize the DC offset voltage present at the analog outputs by feeding back an error signal to the input stage of the programmable gain amplifier. The error signal is then used to correct the offset. The DC servo may be disabled by driving the DCEN input (pin 7) high or setting the DC bit in the serial control word to 1. Normally, the DCEN pin is connected to DGND and the DC bit is set to 0 to enable the DC servo. Two external capacitors are required for the DC servo function, with one capacitor connected between CS11 and CS12 (pins 24 and 23), and the second capacitor connected between CS21 and CS22 (pins 22 and 21). Capacitor values up to 4.7µF may be utilized. However, larger valued capacitors will result in longer settling times for the DC servo loop. A value of 1µF is recommended for use in most microphone preamplifier applications. The PGA2500 includes a common-mode servo function. This function is enabled and disabled using the CM bit in the serial control word, as shown in Figure 1−2. When enabled, the servo provides common-mode negative feedback at the input differential pair, resulting in very low common-mode input impedance. The differential input impedance is not affected by this feedback. This function is useful when the source is floating, or has a high common-mode output impedance. In this case, the only connection between the source and the ground will be through the PGA2500 preamplifier input resistance. In this case, input common-mode parasitic current is determined by high output impedance of the source, not by input impedance of the amplifier. Therefore, input common-mode interference can be reduced by lowering the common-mode input impedance while not increasing the input common-mode current. Increasing common-mode current degrades common-mode rejection. Using the common-mode servo, overall common-mode rejection can be improved by suppressing low and medium frequency common-mode interference. Introduction 1-3 PGA2500 Product Overview The common-mode servo function is designed to operate with a total commonmode input capacitance (including the microphone cable capacitance) of up to 10nF. Beyond this limit, stable servo operation is not ensured. The common-mode voltage control input, named VCOMIN (pin 25), allows the PGA2500 output and input to be DC biased to a common-mode voltage between 0V and +2.5V. This allows for a DC-coupled interface between the PGA2500 preamplifier output and the inputs of common single-supply audio A/D converters. A dedicated 0dB input (pin 8) is provided so that the gain of the PGA2500 may be forced to unity without using the serial port interface. The 0dB input overrides gain settings made through the serial port. While the 0dB input is active (forced high), the serial port register may be updated or data may be passed through the serial interface to other PGA2500 devices in daisy-chain configuration. However, any changes in gain will not take effect until the 0dB input is driven low. The zero-crossing control input, named ZCEN (pin 9), is provided for enabling and disabling the internal zero-crossing detector function. Forcing the ZCEN input high enables the function. Zero-crossing detection is used to force gain changes on zero crossings of the analog input signal. This limits the glitch energy associated with the switched gain network, thereby minimizing audible artifacts at the preamplifier output. Since zero-crossing detection can add some delay when performing gain changes (up to 16ms maximum for a detector timeout event), there may be cases where the user may wish to disable the function. Forcing the ZCEN input low disables zero-crossing detection, with gain changes occurring immediately when programmed. An overflow indicator output, OVR, is provided at pin 5. The OVR pin is an active high, CMOS-logic-level output. The overflow output is forced high when the preamplifier output voltage exceeds one of two preset thresholds. The threshold is programmed through the serial port interface using the OL bit. If OL = 0, then the threshold is set to 5.1Vrms differential, which is approximately −1dB below the specified output voltage range. If OL = 1, then the threshold is set to 4.0Vrms differential, which is approximately −3dB below the specified output voltage range. The PGA2500 includes four general-purpose programmable digital outputs, named GPO1 through GPO4 (pins 1 through 4, respectively), which are controlled via the serial port interface. All four pins are CMOS-logic-level outputs. These pins may be used to control relay drivers or switches used for external preamplifier functions, including input pads, filtering, polarity reversal, or phantom power. 1-4 PGA2500 Product Overview 1.2 PGA2500EVM Features The PGA2500EVM provides a convenient platform for evaluating the performance and features of the PGA2500 product. Key EVM features include the following: - Accepts either XLR or TRS balanced input connections - Configurable front-end circuit options for prototyping pads and filters - XLR balanced output with flexible output loading options - Buffered PC parallel and DATA_IN ports provide host interface connections - DATA_OUT port allows daisy-chaining of multiple PGA2500EVM boards - Register readback function supports host interface diagnostic capability - LED indicators for GPOs and the over range output - Common-mode voltage input (VCOMIN) terminal - Includes applications software which is compatible with most personal com- puters that have a built-in parallel port and run the Microsoft Windows 9x, 2000, or XP operating systems - Requires +5V and −5V analog supplies, as well as a +5V digital supply 1.3 PGA2500EVM Block Diagram The main functions of the PGA2500EVM are shown in Figure 1−3. Configurable input and output circuitry provide convenient prototype options, while the buffered host interface supports the supplied applications software and alternate host configurations. Figure 1−3. Functional Block Diagram for the PGA2500EVM +48V Phantom Power + Microphone Input Preamplifier Output Protection Diodes and Configurable Input Circuitry PGA2500 Configurable Output Circuitry + PC Parallel Port DB25 DATA_IN Port HDR DATA_OUT Port HDR Buffer SN74AHCT541 To GPO and Over Range Indicators and Test Points Dip Switch Static Controls Introduction 1-5 Chapter 2   This chapter provides information regarding PGA2500EVM handling and unpacking, as well as the absolute operating conditions. Topic Page 2.1 Electrostatic Discharge Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2 Unpacking the EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.3 Absolute Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Getting Started 2-1 Unpacking the EVM 2.1 Electrostatic Discharge Warning Many of the components on the PGA2500EVM are susceptible to damage by electrostatic discharge (ESD). Customers are advised to observe proper ESD handling precautions when unpacking and handling the EVM. Failure to observe ESD handling procedures may result in damage to the EVM components. Caution: Failure to observe ESD handling procedures may result in damage to the EVM. 2.2 Unpacking the EVM Upon opening the PGA2500EVM package, please check to verify that the following items are included: - One PGA2500EVM evaluation module - One CD-ROM, containing the applications software and support docu- ments - One straight-through cable, DB25 male to DB25 female, for PC parallel port interface - One printed PGA2500EVM Evaluation Module User’s Guide (TI litera- ture number SBOU023) - One printed PGA2500 data sheet (TI literature number SBOS289A) If any of these items are missing, please contact the Texas Instruments Product Information Center at (972) 644−5580 to inquire about replacements 2.3 Absolute Operating Conditions Warning Caution: Exceeding the absolute operating conditions may result in damage to the EVM and/or the equipment attached to it. The user should be aware of the absolute maximum operating conditions for the evaluation module. Table 2−1 summarizes the critical data points. 2-2 Absolute Operating Conditions Warning Table 2−1. Absolute Operating Conditions Parameter Maximum Condition Power-Supply Voltages(1) VA+ VA− VCOM VCC Phantom Power +5.5V DC Maximum −5.5V DC Maximum −0.3V DC Minimum to (VA+) + 0.3V DC Maximum +5.5V DC Maximum +50V DC Maximum Microphone Input (J1), XLR, or TRS(2) Maximum Input Voltage, Differential 20.0VPP (or 7.0Vrms) Maximum Preamplifier Output (J3)(2) Maximum Output Voltage, Differential 17.5VPP (or 6.2Vrms) Maximum Digital Input Voltage(2) Parallel Port (J5), DATA_IN (J6), and DATA_OUT (J7) −0.3V Minimum to +5.5V Maximum Digital Output Voltage(2) Parallel Port (J5), DATA_IN (J6), and DATA_OUT (J7) +5.5V Maximum 1) 2) Referenced to the GND terminal of connector J4. Assumes VA+ = +5.0V DC and VA− = −5.0V DC. Getting Started 2-3 Chapter 3   This chapter provides descriptions of the hardware components that make up the PGA2500EVM. In addition, configuration information for power supplies, analog input and output connections, switches, and jumpers are provided. Topic Page 3.1 Analog and Digital Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.2 Microphone Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.3 Phantom Power Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.4 DC Blocking Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.5 Protection Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3.6 Configurable Input Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3.7 Configurable Output Circuitry and Preamp Output Connector . . . . 3-4 3.8 Host Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3.9 Switch and Jumper Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Setup Guide 3-1 Analog and Digital Power Supplies 3.1 Analog and Digital Power Supplies All analog and digital power supplies are connected through terminal block J4. Recommended power-supply connections are shown in Figure 3−1. Figure 3−1. Recommended Power-Supply Connections VCOMIN Power Supply Common Ground 0V to +2.5V +5V Digital Chassis (Earth) Ground Common Ground +5V Analog −5V Analog Phantom Power Source, +48V J2 Primary Power Supply J4 VCC EGND GND VCOM VA+ VA− The PGA2500EVM requires two analog supplies and one digital power supply. The analog supplies are VA+ and VA−, respectively. VA+ is typically set to +5.0V DC, while VA− is typically set to −5.0V DC. The analog supplies power the PGA2500 microphone preamplifier integrated circuit. The digital power supply, VCC, is typically set to +5.0V DC. The VCC supply powers the SN74AHCT541 buffer IC (U2) and the associated pull-up resistors for the digital section of the board. An optional third analog power supply may be utilized for the PGA2500 common-mode DC voltage input, VCOMIN (pin 25). The common-mode input can be connected to analog ground by shorting pins 3 and 4 of Jumper JMP3. Alternatively, the common-mode input can be connected to the VCOM supply terminal of connector J4 by shorting pins 1 and 2 of Jumper JMP3. The VCOM supply will typically be set to a DC voltage within the 0V to +2.5V DC range (with respect to GND). The common-mode voltage biases both the output and input terminals of the PGA2500, with the output pins being biased to the VCOMIN voltage level and the input pins being biased to approximately VCOMIN − 0.65V. The GND terminal of connector J4 serves as the common ground connection for both the analog and digital sections of the PGA2500EVM. The EGND (earth ground) terminal should be connected to the earth or chassis ground of the power supply. The common ground (GND) and earth ground (EGND) are connected to one another using a 0.1µF capacitor (C3). 3-2 Microphone Input 3.2 Microphone Input Dynamic and condenser microphones or audio test equipment are connected to the PGA2500EVM input through combo connector J1. The combo connector combines both a 3-pin female XLR and a 1/4-inch TRS jack for connecting to microphones and test signal sources. Both the XLR and TRS jacks are wired for a balanced input. Figure 3−2 illustrates the combo connector pin configuration for the PGA2500EVM. Figure 3−2. Microphone Input Connector Configuration 1 2 3 Hot (+), to VIN+ Cold (−), to VIN− Shield, to EGND R T S Hot (+), to VIN+ Cold (−), to VIN− Shield, to EGND The microphone input includes 1000pF capacitors configured as an EMI filter to help suppress electromagnetic interference present at the preamplifier input. Additional filtering may be required in the customer’s end application circuit, depending on the operating environment. 3.3 Phantom Power Connections The PGA2500EVM supports connection of a phantom power source across the inputs of the preamplifier using terminal block J2. The voltage source is connected to the hot (+) and cold (−) sides of the preamplifier input through 6.81kΩ resistors. Phantom power may be operated at voltages up to +50V DC. Phantom power is required for condenser microphones, but should not be applied when using dynamic microphones, as they may be subject to damage if phantom voltage is applied. When using a dynamic microphone, terminals 3 and 4 of jumper JMP1 should be shorted, while terminals 1 and 2 remain open. When using a condenser microphone requiring a phantom power source, terminals 1 and 2 of jumper JMP1 should be shorted, while terminals 3 and 4 remain open. 3.4 DC Blocking Capacitors Capacitors C19 and C20 are utilized as DC blocking capacitors. They provide AC-coupling to the microphone input, as well as blocking the phantom voltage from reaching the PGA2500 input terminals when using a condenser microphone. The blocking capacitors are selected in order to not degrade the dynamic performance of the PGA2500. The surface-mount aluminum electrolytic capacitors shown in the Bill of Materials (see Table 4−1) are installed by default at the factory. The PGA2500EVM also supports the use of through-hole capacitors for C19 and C20. If using an alternative capacitor, use components rated for 50WV minimum, with 63WV or higher recommended for long-term reliability. Setup Guide 3-3 Protection Network 3.5 Protection Network Resistors R7 and R8, along with Schottky diodes D6 through D9, provide input protection for the PGA2500 preamplifier when using phantom power, or when the input voltage exceeds the VA+ or VA− power supplies by more than 350mV (the approximate turn-on voltage of the Schottky diodes). A common fault condition is for either the hot (+) or cold (−) input of the preamplifier to be shorted to ground. With phantom voltage applied, this will cause the blocking capacitors to discharge, with a large surge current presented at the PGA2500 input pins. Without the protection network, the PGA2500 would be permanently damaged by the surge current, which can reach several amperes in peak magnitude. The Schottky diodes are forced into conduction during this fault condition, steering most of the charge away from the PGA2500 device and towards the power supplies. The series resistors can be set to a value that will help limit the input current, although care must taken to avoid adding too much resistance, since the added noise can degrade the overall performance of the preamplifier. The Schottky diodes add a nonlinear capacitance to the input circuit, which can result in additional distortion. However, with the relatively small input voltage swing present when the preamplifier is set to gains between 10dB and 65dB, the effect on the THD+N of the PGA2500 is small or negligible. For unity-gain applications, where the voltage swing may become large enough in magnitude to transition over a greater portion of the diodes nonlinear capacitance, the THD+N ratio may degrade by as much as 3dB from the published typical performance specifications. 3.6 Configurable Input Circuitry The configurable portion of the input circuit includes R5, R6, R10, R11, R14, R15, CC1, CC2, and jumper JMP2. These components support prototyping of additional circuitry, such as pads and filters. During assembly at the factory, resistors R5 and R6 are not installed, while R10, R11, R14, R15, CC1, and CC2 are replaced by wire shunts. 3.7 Configurable Output Circuitry and Preamp Output Connector The configurable portion of the output circuit includes R1, R2, R3, R12, R13, C23, C24, and C25. These components support prototyping of additional circuitry, such as pads and filters, as well as emulation of various loading conditions. During assembly at the factory, resistors R12 and R13 are replaced by wire shunts. Resistors R1 through R3, as well as capacitors C23 through C25, are not installed. The differential preamplifier output is provided at connector J3, which is a 3-pin male XLR connector. Figure 3−3 illustrates the pin connections for connector J3. Figure 3−3. Preamp Output Connector Configuration 1 2 3 Hot (+), to VOUT+ Cold (−), to VOUT− Shield, to GND 3-4 Host Interface 3.8 Host Interface The PGA2500EVM supports an external host interface to the PGA2500 serial port utilizing connectors J5 through J7. A PC parallel port may be connected to connector J5, using the straight through cable supplied with the EVM package. The PC parallel port is used as the communications interface for the applications software provided with the EVM. Chapter 5 provides details for installing and using the applications software. The DATA_IN header (J6) may be used as an alternative host interface connection, and is designed primarily for interfacing to microprocessors, digital signal processors, or other host devices in either end equipment or hardware development platforms. The DATA_OUT header (J7) is designed primarily for cascading multiple PGA2500EVM boards in a daisy-chain fashion. Daisy-chaining is described in more detail in the PGA2500 datasheet. 3.9 Switch and Jumper Quick Reference Table 3−1 and Table 3−2 provide a quick configuration reference of the switch and jumper settings for the PGA2500EVM. Factory default settings are also indicated. Table 3−1. Switch Configuration Quick Reference Switch Setting Function DCEN LO (default) HI DC Servo Enabled(1)(2) DC Servo Disabled 0dB LO (default) HI Unity (odB) Gain Disabled, Gain Programmed Through Serial Port(2) Unity (0dB) Gain Enabled, Overrides Gain Set Through Serial Port ZCEN LO HI (default) Zero-Crossing Detection Disabled(2) Zero-Crossing Detection Enabled 1) 2) When DCEN = LO, the DC bit in the serial control word may be used to disable and enable the DC servo under software control. A switch is set to LO when in the ON position (labeled ON C & K TDA04 on the switch itself). A switch is set to HI when in the numbered position (labeled 1, 2, 3, or 4 on the switch itself). Table 3−2. Jumper Configuration Quick Reference Jumper Configuration Jumper JMP1: Phantom Power Phantom Power Disabled, Connected to GND (default) Phantom Power Enabled, Connected to J2 Terminal Block Pins 1 to 2 Open Short Pins 3 to 4 Short Open Jumper JMP3: VCOMIN Input Connection VCOMIN (pin 25) Connected to GND (default) VCOMIN (pin 25) Connected to the VCOM Terminal of J4 Pins 1 to 2 Open Short Pins 3 to 4 Short Open Jumper J9: Register Read Back Register Read Back Function Disabled Register Read Back Function Enabled (default) Pins 1 to 2 Open Short Jumpers JMP4 through JMP8, as well as JMP10, are shorted on the PCB layout. They may be cut and replaced by jumpers if desired. Jumper JMP2 is provided in order to add flexibility for the configurable input circuitry. This jumper is left open by default. Setup Guide 3-5 Chapter 4    !   " # This chapter provides the electrical schematic and physical PCB layout information for the PGA2500EVM. The Bill of Materials is included for component reference. Topic Page 4.1 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4.2 PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4.3 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 Schematic, PCB Layout and Bill of Materials 4-1 T S R 3 G 1 2 MICROPHONE INPUT J1 2 OFF 1 R1 * R3 * 1000pF C28 R2 * C22 1000pF C25 * C23 * C21 1000pF R4 * C19 C24 * 0 R13 R12 0 47uF C20 R16 47uF 6.81K R17 6.81K 2 4.7uF 6 10 R7 TP3 VCC 10 −VA +VA −VA D9 D8 VCOM TP5 +VA D7 D6 TP2 EGND TP1 0.1uF AGND 0 0 R15 VA− TP6 4.7uF * Cc2 * Cc1 0.1uF C17 C5 4.7uF 0.1uF C16 C4 PARALLEL PORT J5 1 14 2 15 3 16 4 17 5 18 6 19 7 20 8 21 9 22 10 23 11 24 12 25 13 Normally, Cc1 and Cc2 are replaced by wire jumpers. R11 R6 * JMP2 1 2 0 0 R5 * R14 R10 TP4 VA+ +VA −VA EGND 5 VCC GND 4 C3 VCOM 3 R8 0.1uF C15 JMP10 1 J4 C2 VA− VA+ 2 NOTE: An asterisk (*) symbol indicates that a component is not normally installed during assembly. 3 J3 PREAMP OUT ON JMP1 0.1uF C1 3 1 1 VCC TP10 AGND VCC TP8 VIN− TP7 VIN+ C8 0.1uF J6 DATA_IN RN2 47K C10 0.1uF +VA 10K RN3 0.1uF C9 JMP3 1 2 3 4 −VA VCC Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 10 20 18 17 16 15 14 13 12 11 0.1uF A1 A2 A3 A4 A5 A6 A7 A8 OE1 OE2 GND SN74AHCT541PW J7 DATA_OUT 2 3 4 5 6 7 8 9 1 19 U2 R9 10 C27 4.7uF JMP4 JMP5 D3 R19 475 D2 R18 475 C13 0.1uF JMP9 1 2 SDO_RB SDI CS SCLK SDO C18 4.7uF 1 2 3 4 5 6 7 8 9 10 11 12 13 14 C14 VCC GPO1 GPO2 GPO3 GPO4 OVR DGND DCEN 0DB ZCEN SDI CS SCLK SDO VD− PGA2500DB AGND VIN+ VIN− VCOMIN CS11 CS12 CS21 CS22 VA− VA+ VA+ VOUT+ VOUT− VA− U1 C11 C12 C26 4.7uF 0.1uF 0.1uF C6 0.1uF C7 0.1uF 28 27 26 25 24 23 22 21 20 19 18 17 16 15 D1 GPO2 GPO1 JMP6 D4 R20 475 GPO3 JMP7 D5 R21 475 GPO4 2 1 POWER 2 1 J2 2 1 2 1 4 2 4 2 1 − + 1 3 5 7 9 2 4 6 8 10 1 3 5 7 9 2 4 6 8 10 2 4-2 1 PHANTOM POWER DCEN 0dB ZCEN JMP8 R22 475 OVR TP9 SPARE VCC 1 2 3 4 SW1 RN1 10K 8 7 6 5 Schematic 4.1 Schematic The complete electrical schematic for the PGA2500EVM is shown in Figure 4−1. Refer to the Bill of Materials in Table 4−1 for descriptions of components shown in the schematic. Figure 4−1. Schematic PCB Layout 4.2 PCB Layout The PGA2500EVM is a two-layer printed circuit board using both through-hole and surface-mount components. The silkscreen, top, and bottom layer plots are shown in Figure 4−2 through Figure 4−4, respectively. Figure 4−2. PGA2500EVM PCB Silkscreen Figure 4−3. PGA2500EVM PCB Top Layer (Component Side) Schematic, PCB Layout and Bill of Materials 4-3 PCB Layout Figure 4−4. PGA2500EVM PCB Bottom Layer (Solder Side) 4-4 OPA2500EVM J5 J6, J7 JMP2, JMP9 12 13 14 (continued on next page) J4 J3 10 11 J2 9 C19, C20 J1 47µF 5 C15-C18, C26, C27 8 4.7µF 4 C6, C7 D6-D9 1µF 3 C1-C5, C8-C14 7 0.1µF 2 C21, C22, C28 D1-D5 1000pF 1 Reference Designator 6 Value Item Table 4−1. Bill of Materials 2 2 1 1 1 1 1 4 5 2 6 2 12 3 Qty Per Bd Samtec Samtec AMP Weidmuller Switchcraft or ITT Cannon Weidmuller Neutrik ON Semiconductor Lumex Panasonic Kemet Kemet Kemet Kemet Manufacturer TSW-102-07-G-S TSW-105-07-G-D 747842-6 9967720000 XLB-3-32PCV-M01 PQG3MRA112 1699670000 NCJ6FI-H MBRA120LT3 SML-LX1206IC-TR EEV-FK1J470P T494A475K016AS C0805C105K4RACTU C0805C104K5RACTU C0805C102J5GACTU Mfg Part Number Terminal Strip, 2-Pin (2x1) Terminal Strip, 10-Pin (5x2) DB-25 Connector, Male, Tin-Plated Shell, 0.318in (8.08mm) Mount, Rt Angle PCB w/ Boardlocks, Female Screwlocks 3.5mm PCB Terminal Block, 6 Poles XLR Connector, Male, 3-Pin Vert PC Mount with PCB Retainers XLR Connector, Male, 3-Pin Vert PC Mount with Ground Lug 3.5mm PCB Terminal Block, 2 Poles Combo Connector, Female XLR + TRS Vert PC Mount Surface-Mount Schottky Power Rectifier, Size = SMA Red LED, SMT, Size = 1206 Capacitor, Alum Electrolytic, SMT, 47µF ±20%, 63WV Capacitor, Low ESR Tantalum, SMT, 4.7µF ±10%, 16WV, Size = A Capacitor, Ceramic X7R, SMT, 1µF ±10%, 16WV, Size = 0805 Capacitor, Ceramic X7R, SMT, 1µF ±10%, 50WV, Size = 0805 Capacitor, Ceramic C0G/NPO, SMT, 1000pF ± 5%, 50WV, Size = 0805 Description The complete bill of materials for the PGA2500EVM is shown in Table 4−1. Data for each component is available from the corresponding manufacturer’s web site. 4.3 Bill of Materials Bill of Materials 4-5 4-6 475 6.81K 10K 47K 17 18 OPA2500EVM 19 20 1 4 U2 24 1 26 U1 23 3 4 TP7, TP8, TP10 22 1 1 2 2 5 3 2 Qty Per Bd 25 SW1 21 RN2 RN1, RN3 R16, R17 R18-R22 R7-R9 10 16 Reference Designator JMP1, JMP3 Value 15 Item Table 4−1. Bill of Materials (continued) Samtec 3M Bumpon Texas Instruments Texas Instruments Keystone Electronics ITT Industries/C&K CTS CTS Vishay Dale or Equivalent Panasonic or equivalent Vishay Dale or Equivalent Samtec Manufacturer SNT-100-BK-G-H SJ-5003 SN74AHCT541PW PGA2500IDB 5006 TDA04H0SK1 742C083473J 742C083103J CMF-55 6811BT-9 ERJ-6ENF4750V CMF-55 10R0BT-9 TSW-102-07-G-D Mfg Part Number Shorting Blocks Rubber Feet, Adhesive Backed Octal Buffer/Driver Digitally-Controlled Microphone Preamplifier PCB Test Point, Compact Style, Black DIP Switch, 4 Element, Half Pitch Surface-Mount, Tape Sealed Thick Film Chip Resistor Array, 47kΩ, 8 Terminal, 4 Resistors, Isolated Thick Film Chip Resistor Array, 10kΩ, 8 Terminal, 4 Resistors, Isolated Resistor, Metal Film, Axial Lead, 6.81kΩ ± 0.1%, 1/4W Resistor, Thick Film SMT, 475Ω, ± 1%, 1/10W, Size = 0805 Resistor, Metal Film, Axial Lead, 10Ω, ± 0.1%, 1/4W Terminal Strip, 4-Pin (2x2) Description Bill of Materials Chapter 5 "$    % This chapter provides instructions for installing the PGA2500EVM application software and using the software to control the PGA2500 gain and support functions. Topic Page 5.1 Applications Software Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.2 Software Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.3 Using the Applications Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 Software Installation and Operation 5-1 Applications Software Overview 5.1 Applications Software Overview The applications software supplied with the PGA2500EVM allows the user to control the board via a PC equipped with a parallel printer port running the Microsoft Windows 9x, 2000, or XP operating systems. The software is supplied on the accompanying CD-ROM, while a straight-through cable (DB25 male to DB25 female) is provided for interfacing between the EVM and the PC parallel port. The applications software provides a simple graphical user interface with which the user can program the PGA2500 16-bit control word. All programmable functions are supported. 5.2 Software Installation The applications software is provided on the accompanying CD-ROM. The following steps are required to install the applications software: 1) Insert the accompanying CD-ROM disc into the PC CD-ROM drive. 2) Locate the directory named Apps Software on the CD-ROM disc. 3) Copy the Apps Software folder to your hard disk. 4) Once copied, open the Apps Software folder on your hard disk. There will be two files in the folder: a) PGA2500EVM.exe, the executable program file. b) inpout32.dll, the driver file required for parallel port operation on Windows 9x, 2000, and XP. 5) Using your pointing device, click on and hold the PGA2500EVM.exe file icon and drag it to the desktop to create a shortcut to the program file. Once the shortcut has been made, you can rename the shortcut if desired, but it is recommended to include PGA2500 in the shortcut name. This completes the installation of the PGA2500EVM applications software. 5-2 Using the Applications Software 5.3 Using the Applications Software The program is executed by double-clicking on the desktop shortcut created during the installation process. The Main panel, shown in Figure 5−1, will appear on the screen. The Main panel allows the user to select the parallel port address to be used for communications with the PGA2500EVM. The Main panel also includes a Reset button, which is utilized to set the PGA2500 16-bit control word to the reset default conditions. The default conditions are: - DC Servo Enabled (DC bit set to 0). - Common-Mode Servo Disabled (CM bit set to 0). - Overload level set to 5.1Vrms (OL bit set to 0) - General-purpose digital output bits GPO1 through GPO4 are all set to 0. - Gain set to 0dB (gain bits G0 through G5 are all set to 0). Figure 5−1. Applications Software Main Panel Clicking on the PGA2500 Panel button within the Main panel brings up a second window, which is referred to as the Device panel. The Device panel includes groups of objects, which are utilized to control various bits within the PGA2500 control word. Figure 5−2 shows the PGA2500 Device Panel. Figure 5−2. Applications Software Device Panel Software Installation and Operation 5-3 Using the Applications Software The Soft Mode Control group includes checkboxes for toggling the state of the DC servo (DC), common-mode servo (CM), overload (OL), and GPO1 through GPO4 control bits. An empty checkbox sets the state of the corresponding bit to 0. Clicking on the checkbox will set the corresponding control bit to 1. Clicking on the checkbox again will clear the control bit, setting it to 0. The Hard Mode Control group is not utilized for the PGA2500EVM. Instead, these controls are configured using switch SW1 on the PGA2500EVM. The Gain group includes a slider for setting the gain of the PGA2500. Simple text displays are provided for the programmed gain in dB, as well as the gain and bus data shown in hexadecimal data format. A Readback button is provided with a corresponding text display, and may be used to read and display the control word value in hexadecimal data format. The Readback function is provided mainly as a software and hardware diagnostic function, because it allows the user to determine if the PGA2500 control word is being programmed correctly. This function can be used to debug hardware and cable connection problems, or to help identify possible software compatibility issues. Finally, a Clear button is provided, which sets all of the data bits in the PGA2500 control word to 0. 5-4