LMV1090TLEVAL

User's Guide SNAA066B – May 2009 – Revised May 2013 AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit 1 Overview The LMV1090TL evaluation kit contains the following: • LMV1090TL Demonstration Board, 551600317–001 • Mini USB Board, 551600192–002 • Control Software • Microphone board • Microphone cable • I2C cable MIC 1 MIC CABLE LMV1090TL Demo Board MIC 2 Connect via 6 pin connector MICROPHONE BOARD Mini-USB Board GUI (Control Software) PC Mini USB 2.0 to USB cable Figure 1. Basic Evaluation System 2 Introduction The LMV1090 demo board (Figure 2) offers the means for easy evaluation of the LMV1090 Dual input, Far Field Noise Suppression (FFNS) Microphone Amplifier with Differential Outputs. This board has the LMV1090TL mounted on the PCB together with surrounding components ready for evaluation. This board offers interfaces for connecting two microphones and an I2C interface for controlling the settings of the LMV1090. All trademarks are the property of their respective owners. SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 1 General Description www.ti.com Figure 2. LMV1090TL Demo Board 3 General Description The LMV1090 is a fully analog dual input, differential output, microphone array amplifier designed to reduce background acoustic noise, while delivering superb speech clarity in voice communications applications. The LMV1090 has two differential input microphone amplifier channels plus far-field noise suppression (FFNS) circuitry. The LMV1090 preserves near-field wire signals within 4cm of the microphones. While rejecting far-field acoustic noise greater than 50cm from the microphones. Up to 20dB of far-field rejection is possible in a properly configured and using ±0.5dB matched microphones. 4 Operating Conditions • • • 5 Temperature Range -40°C ≤ TA ≤ 85°C Power Supply Voltage 2.7V ≤ VDD ≤ 5.5V I2C supply voltage 1.7V ≤ I2CVDD ≤ 5.5V LMV1090 Demo Board The LMV1090TL Demonstration Board takes analog inputs from two microphones and performs the Far Field noise cancellation process. It outputs an analog differential signal. This output can be connected to a recording device, such as a personal computer sound card through its LINE IN/MIC IN input or mobile phone through its MIC IN input, for evaluation purposes. The LMV1090TL contains programmable pre and post gain amplifiers, which can be adjusted through I2C commands and the software GUI. See Section 8. The LMV1090TL has four operating modes: • Noise cancellation • Mic1 enabled • Mic2 enabled • Mic1 + Mic2 The operating modes can all be controlled through I2C commands and the software GUI. See Section 8. 2 AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback Power Supply of the LMV1090 Demo Board www.ti.com 6 Power Supply of the LMV1090 Demo Board The LMV1090 demo board provides three possible sources for the power supply: • Using the external supply via header J12 for VDD and GND. I2CVDD pin can get its supply from the VDD pin by placing a jumper across J21 and J22. See Figure 3. • Using a small battery placed in battery holder mounted on the PCB. See Figure 4. For a limited time, the demo board can be operated from the board battery (CR1220 placed in the battery holder BT1). To operate the board using a battery, the following jumpers: J26, J21, and J22 must be configured as shown in Figure 4. • Via the I2C interface header J20. See Figure 5. This is the default configuration of the LMV1090TL demonstration board when received by customer. Using this configuration and a mini USB board eliminates the need for a separate power supply for evaluation. Supplying the demo board is possible by generating jumpers on headers J21 and J22. 6.1 Enable Pin The enable pin must be logic high for operating the on board LMV1090. This is done by placing a jumper on header J25 (see Figure 5). Apply Vdd and GND on header J12 remove current jumpers on J21 and J22. Put jumper across these pins shorting J21 and J22, Figure 3. Power Supply Connectors and Headers SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 3 Power Supply of the LMV1090 Demo Board www.ti.com Take current jumper off and connect to BAT and middle pin remove current jumpers on J21 and J22. Put jumper across these pins shorting J21 and J22 Figure 4. Battery Power Supply EN, Enable pin VDD I2C VDD Figure 5. I2C Power Supply 4 AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback The On Board I2C Compatible Interface www.ti.com 7 The On Board I2C Compatible Interface The I2C Compatible Interface that is available on the LMV1090 demo board is located at the header J20 (see Figure 6). The signals on this header are described in Table 1. SCL I2CVDD SDA GND GND Figure 6. Demo Board I2C Mic Inputs Table 1. I2C Connector PIN Function 1 SCL 2 I2CVDD 3 NC 4 GND 5 SDA 6 NC The SCL pin and the SDA pin both have a 10kΩ pull-up resistor to I2CVDDmounted on the PCB. Figure 6 shows how the mini USB board should be connected to the LMV1090TL demo board. Note the USB cable should be connected away from the board. The supply voltage for the I2C interface of the LMV1090 can be selected with the jumper J22. To avoid possible damages to the LMV1090 part, the I2CVDD voltage should not exceed the VDD voltage. SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 5 LMV1090 Control Demo Software 8 www.ti.com LMV1090 Control Demo Software Together with the LMV1090 demo board, there is a software package available that can assist in evaluation, programming, and testing of the LMV1090 chip via the I2C Interface. This software is operated via the graphical user interface as shown in Figure 7. This software provides two groups of functions. There are four buttons in the top of the screen that allows the following: • Enable and Disable the microphone amplifiers • Muting the microphone input amplifier • Default button for resetting part on the left side of the screen is the mode The 4 buttons on the side select the 4 modes: Noise Cancellation Mode, Only MIC 1 On, Only MIC 2 On, and MIC 1 + MIC 2. On the right side of the screen are 2 slide bars that control the preamplifier and postamplifier gains. Figure 7. Control Demo Software GUI 6 AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback Connecting Microphones to the LMV1090 Demo Board www.ti.com 9 Connecting Microphones to the LMV1090 Demo Board The demo board can be used to connect a set of two microphones to the LMV1090 to evaluate the performance of the LMV1090 in a customer application. To enable these microphone input connectors, the jumpers on header J11 and J16 (see Figure 9) must be placed between pin 3–5 and pin 4–6 of both headers. Microphones can also be connected to 3.5mm connectors J9 and J15 (see Figure 6). For a optimal performance of the Far Field Noise Reduction system it is important to find the correct placement of the microphones. In many applications the microphones are placed next to each other with a distance of 1.5cm to 2.5cm between the microphones. The best noise cancelling performance will occur in systems where the far field signals comes from a source orthogonal to the plane of the microphones and where the desired signal is close to the microphones and is located in line with the microphones as shown in Figure 8. FAR NOISE LMV1090 OPTIMIZED SPEECH NEAR SPEECH Figure 8. Orientation of Microphones and Sound Sources SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 7 Microphone Placement in the Application 10 www.ti.com Microphone Placement in the Application Because the LMV1090 is a microphone array Far Field Noise Reduction solution, proper microphone placement is critical for optimum performance. Two things need to be considered: The spacing between the two microphones and the position of the two microphones relative to near field source. If the spacing between the two microphones is too small, near field speech will be canceled along with the far field noise. Conversely, if the spacing between the two microphones is large, the far field noise reduction performance will be degraded. The optimum spacing between Mic 1 and Mic 2 is 1.5-2.5cm. This range provides a balance of minimal near field speech loss and maximum far field noise reduction. The microphones should be in line with the desired sound source 'near speech' and configured in an endfire array orientation from the sound source (see Figure 9). If the 'near speech' (desired sound source) is equidistant to the source like a broadside array (see Figure 10) the result will be a great deal of near field speech loss. LMV1090 1.5~2.5 cm OPTIMIZED SPEECH NEAR SPEECH CORRECT Figure 9. Endfire Array (Correct) NEAR SPEECH LMV1090 OPTIMIZED SPEECH WRONG Figure 10. Broadside Array (Incorrect) 8 AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback PCB Layout Guidelines www.ti.com 11 PCB Layout Guidelines This section provides general practical guidelines for PCB layouts that use various power and ground traces. Designers should note that these are only "rule-of-thumb" recommendations and the actual results are predicated on the final layout. 11.1 Differential Signals Keep both signals coupled by routing them closely together and keeping them of equal length. Keep all impedances in both traces of the signal equal. 11.2 Power and Ground Connect all ground pins together under the part forming a star point. Keep the current for the de-coupling capacitor of the REF pin B4and the accompanying ground pin B1separated from the other currents. Keep the location of the supply de-coupling capacitor close to VDD pin C1 and ground. 12 Description of Headers and Connectors of the LMV1090 Demo Board The LMV1090 demo board provides many headers and connectors for connecting test equipment and controlling the settings of the part, see Table 2. The function that is controlled by the jumpers on the LMV1090 demo board is also indicated on the PCB in silk screen as shown in Figure 11 (The name in parenthesis is as shown in the silk screen). Table 2. Connector and Header Functions Designator Function or Use J12 Power supply connector for external supply J26 Supply select pin external (VDD) or battery (BAT) J11, J16 Connection for input of electrical test signals at pin 4+5 J8, J10 Low pass filter selection (LPF+, LPF-) J25 Enable pin J21 I2CVDD connect to I2C interface J22 VDD connect to I2C interface J25 Enable pin J26 Supply select pin external (VDD) or battery (BAT) J27 Connects Supply to VDD pin SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback Comment Pin 3+4 differential input with ground at Pin 5+6 Pin 1+2 to connect to an external LPF capacitor. Pin 2+3 select the on board LPF capacitor C5, C14 (a minimum of 1nF is always mounted on the board) AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 9 Schematic www.ti.com 13 Schematic 10 AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback Layout www.ti.com 14 Layout EN Figure 11. Layout, Silk Screen Figure 12. Layout, Top Layer SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 11 Layout www.ti.com Figure 13. Layout, Top Inner Layer Figure 14. Layout, Bottom Inner Layer 12 AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback Layout www.ti.com Figure 15. Layout, Bottom Layer SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 13 Bill of Materials 15 www.ti.com Bill of Materials Designator Component Value Tolerance Rating Package Type Capacitor Ceramic 1.0μF 10% 16V 0603 Capacitor Ceramic 10000pF 10% 50V 0603 C3, C4, C7, C8, C9 Capacitor Ceramic 0.47pF 10% 16V 0603 C5, C14 No Load C5A, C14A Capacitor Ceramic 1nF 10% 100V 0603 C10, C13 Capacitor Ceramic 1μF 10% 16V 0603 C11 No Load C12 Capacitor Tantalum 100μF 10% 10V Case C R1, R2, R4, R5 Resistor 1.1k 1% 1/10W 0603 R3 Resistor 100k 1% 1/10W 0603 R9, R10 Resistor 10k 1% 1/10W 0603 J12, J13, J14, J20, J21, J22, J23, J24, J25, J27 Connector Header Brkway .100 02POS STR U1 LMV1090 C15, C16 C2 No Load No Load J8, J10, J20, J26 Connector Header Brkway .100 06POS STR J11, J16 Connector Header Brkway .100 06POS VERT J9, J15, J28 5 Pole Headphone conn jack stereo 3.5mm horizontal GND Ground hook jumper 5mm high mount BT1 Battery holder CR1220, 1 cell 12mm J8_SH, J10_SH, Jumper Shunt 0.100” 30μin AU (no J11_SH1, J11_SH2, handle) J16_SH2, J21_SH, J22_SH, J25_SH, J26_SH, J27_SH 16 14 Revision History Rev Date 1.0 05/21/09 Initial release. Description 1.01 06/30/09 Corrected graphic 30092061. AN-1948 LMV1090 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated SNAA066B – May 2009 – Revised May 2013 Submit Documentation Feedback IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. 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