LMV1091TMEVAL

User's Guide SNAA069A – November 2009 – Revised May 2013 AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit 1 Overview The LMV1091TL evaluation kit contains the following: • LMV1091TL Demonstration Board, 551600341–001 • Microphone board • Microphone cable MIC 1 MIC CABLE LMV1091TM Demo Board MIC 2 MICROPHONE BOARD Figure 1. Basic Evaluation System 2 Introduction The LMV1091 demo board (Figure 2) offers the means for easy evaluation of the LMV1091 Dual input, Far Field Noise Suppression (FFNS) Microphone Amplifier with Differential Outputs. 3 General Description The LMV1091 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 LMV1091 has two differential input microphone amplifier channels plus far-field noise suppression (FFNS) circuitry. The LMV1091 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 • • • Temperature Range -40°C ≤ TA ≤ 85°C Power Supply Voltage 2.7V ≤ VDD ≤ 5.5V I2C supply voltage 1.7V ≤ I2CVDD ≤ 5.5V All trademarks are the property of their respective owners. SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 1 LMV1091 Demo Board www.ti.com Figure 2. LMV1091TL Demo Board 5 LMV1091 Demo Board The LMV1091TL demo 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. 6 Power Supply of the LMV1091 Demo Board The LMV1091 demo board provides two possible sources for the power supply: • Using the external supply via header J12 for VDD and GND. Header J26 needs to be in the position shown in 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, J26 must be configured as shown in Figure 4. 2 AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated Power Supply of the LMV1091 Demo Board www.ti.com Figure 3. Power Supply Connectors and Headers SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 3 Connecting Microphones to the LMV1091 Demo Board www.ti.com Figure 4. Battery Power Supply 7 Connecting Microphones to the LMV1091 Demo Board The demo board can be used to connect a set of two microphones to the LMV1091 to evaluate the performance of the LMV1091 in a customer application. To enable these microphone input connectors, the jumpers on header J11 and J16 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 5). 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 canceling 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 6. 4 AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated Connecting Microphones to the LMV1091 Demo Board www.ti.com Figure 5. Orientation of Microphones and Sound Sources FAR NOISE LMV1091 OPTIMIZED SPEECH NEAR SPEECH Figure 6. Orientation of Microphones and Sound Sources SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 5 Microphone Placement in the Application 8 www.ti.com Microphone Placement in the Application Because the LMV1091 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 7). If the 'near speech' (desired sound source) is equidistant to the source like a broadside array (see Figure 8) the result will be a great deal of near field speech loss. OPTIMIZED SPEECH LMV1091 1.5~2.5 cm NEAR SPEECH CORRECT Figure 7. Endfire Array (Correct) NEAR SPEECH OPTIMIZED SPEECH LMV1091 WRONG Figure 8. Broadside Array (Incorrect) 6 AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated Pre Amp and Post Amp Gain www.ti.com 9 Pre Amp and Post Amp Gain The Pre-amplifier gain of the LMV1091TM can be controlled using the GA0-GA3 pins. See Table 1 for Pre-amplifier gain control. The Post-Amp gain can be controlled using the GB0-GB2 pins. See Table 2 for Post-amplifier gain control. Table 1. Mic Pre-Amp Gain Settings GA3 GA2 GA1 GA0 Pre-Amplifier Gain 0 0 0 0 6dB 0 0 0 1 8dB 0 0 1 0 10dB 0 0 1 1 12dB 0 1 0 0 14dB 0 1 0 1 16dB 0 1 1 0 18dB 0 1 1 1 20dB 1 0 0 0 22dB 1 0 0 1 24dB 1 0 1 0 26dB 1 0 1 1 28dB 1 1 0 0 30dB 1 1 0 1 32dB 1 1 1 0 34dB 1 1 1 1 36dB Table 2. Post-Amp Gain Settings NOTE: GB2 GB1 GB0 Pre-Amplifier Gain 0 0 0 6dB 0 0 1 9dB 0 1 0 12dB 0 1 1 15dB 1 0 0 18dB 1 0 1 18dB 1 1 0 18dB 1 1 1 18dB The silkscreen on the LMV1091TM demo board has a '1' on the header for GA0–GA3, GB0–GB2, MUTE1, MUTE2, MODE0, and MODE1. The '1' indicates GND pin. SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 7 Noise Reduction Mode Settings 10 www.ti.com Noise Reduction Mode Settings The LMV1091TM has four mode settings: Noise Cancellation Mode, MIC 1 On with MIC 2 off, MIC 2 On with MIC 1 off, and MIC1 and MIC2. See Table 3 for control settings. Mic 1 and Mic 2 can be muted independently, using the Mute 1 and Mute 2 pins. See Table 4 for control settings. Table 3. Noise Reduction Mode Settings Mode 1 Mode 0 Noise Reduction Mode Selection 0 0 Noise Cancellation mode 0 1 Mic 1 On 1 0 Mic 2 On 1 1 Mic 1 + Mic 2 Table 4. Noise Reduction Mute Settings 11 Mute2 Mute1 Noise Reduction Mode Selection 0 0 Mic 1 and Mic 2 on 0 1 Mic 1 mute 1 0 Mic 2 mute 1 1 Mic 1 and Mic 2 mute 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 C4 and the accompanying ground pin B5 separated from the other currents. Keep the location of the supply de-coupling capacitor close to VDD pin D5 and ground. 8 AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated Headers and Connectors of the LMV1091 Demo Board www.ti.com 12 Headers and Connectors of the LMV1091 Demo Board The LMV1091 demo board provides many headers and connectors for connecting test equipment and controlling the settings of the part, see Table 5. The function that is controlled by the jumpers on the LMV1091 demo board is also indicated on the PCB in silk screen as shown in Figure 9 (The name in parenthesis is as shown in the silk screen). Table 5. 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 J8, J10 Connection for input of electrical test signals at pin 4+5 Low pass filter selection (LPF+, LPF-) J26 Supply select pin external (VDD) or battery (BAT) J27 Connects Supply to VDD pin J1 Select for MUTE1 J2 Select for MUTE2 J3 Select for GA0 J4 Select for GA1 J5 Select for GA2 J6 Select for GA3 J7 Select for SD J17 Select for MODE0 J18 Select for MODE1 J19 Select for GB0 J20 Select for GB1 J21 Select for GB2 J13, J14 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). GND outputs (option to test for various parameters SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 9 Schematic www.ti.com 13 Schematic 10 AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated Layout www.ti.com 14 Layout Figure 9. Layout, Silk Screen Figure 10. Layout, Top Layer SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 11 Layout www.ti.com Figure 11. Layout, Top Inner Layer Figure 12. Layout, Bottom Inner Layer 12 AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated Layout www.ti.com Figure 13. Layout, Bottom Layer SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit Copyright © 2009–2013, Texas Instruments Incorporated 13 Bill of Materials 15 www.ti.com Bill of Materials Designator 16 14 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 C5A, C14A Capacitor Ceramic 4.7nF 10% 100V 0603 C13 Capacitor Ceramic 0.1μF 10% 16V 0603 C11 No Load C12 Capacitor Tantalum R1, R2, R4, R5 Resistor J12, J13, J14, J27 Connector Header Brkway .100 02POS 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 J1_SH, J2_SH, J3_SH, J4_SH, J5_SH, J6_SH, J7_SH, J11a_SH, J11b_SH, J16a_SH, J16b_SH, J17_SH, J18_SH, J19_SH, J20_SH, J21_SH, J26_SH Jumper Shunt 0.100” 30μin Au (no handle) J1, J2, J3, J4, J5, J6, J7, J18, J19, J20, J21, J26 Connector Header Brkway .100 03POS STR U1 LMV1091 C15, C16 C2 No Load 100μF 10% 10V Case C 1.1k 1% 1/10W 0603 Revision History Rev Date 1.0 11/12/09 Description Initial release. AN-1989 LMV1091 Noise Suppression Microphone Amplifier Evaluation Kit SNAA069A – November 2009 – Revised May 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated 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. TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms and conditions of sale of semiconductor products. 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