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.
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.
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.
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.
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.
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.
Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 PGA2500 Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 PGA2500EVM Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 PGA2500EVM Block Diagram . . . . . . . . . . . . . . . . . . . . . .
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 . . . . . . . . . . . . . . . . . . . . . . . .
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 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.
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.
PGA2500 Product Overview 1.2 PGA2500EVM Features The PGA2500EVM provides a convenient platform for evaluating the performance and features of the PGA2500 product.
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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.
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.
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 .
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.
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.
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.
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.
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 . . . . . . . .
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.
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.
PCB Layout Figure 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.
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.
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 . . . . . . . . . . . . . . . . . .
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.
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.
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.
