User's Guide SNOA487C - May 2007 - Revised May 2013 AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) 1 Overview The 551012875 and 551012922 Universal Evaluation Boards are designed to aid in the evaluation and testing of Texas Instruments low voltage/low power and some precision operational amplifiers. These boards will accommodate op amps that are assembled in a 6-Pin or 5-Pin SOT-23 and SC-70 package, regardless of the pin orientation. This board is designed to use one or two amplifiers. Many different circuits can be made such as inverting, non-inverting, and differential-IN-differential-OUT amplifiers and low-pass, high-pass, band-pass, bandreject, or notch second-order filters. The amplifiers can be powered with single or dual supplies. These circuits can be configured without any modifications to the board; all that is necessary is to select the correct resistors and capacitors. The other optional components can be left open or shorted depending on the configuration desired. These universal evaluation boards are designed as two-layer boards; the top side of each is designed for op amps with a pinout as shown in Figure 1. The bottom side of each board is designed for op amps with the pinout shown in Figure 2. The board has been manufactured with vias connecting the equivalent pins of the top and bottom amplifiers. For example, Pin 1 of IC1A is connected to Pin 3 of IC2A. Similarly all other equivalent pins of the top and bottom amplifiers are connected. This allows for an efficient use of one board to test two amplifiers of different package types while keeping the same components on the board; just make sure that only one amplifier is soldered to the same pads. Circuit performance of this evaluation board will be comparable to final production designs. Use this evaluation board as a guide for general layout and a tool to aid in device testing and characterization. SOT-23/SC-70 +IN 1 SOT-23/SC-70 6 + V OUT + V 5 - 2 V SD - 1 6 2 5 + V SD + -IN 3 4 OUT Figure 1. Connection Diagram for IC1A and IC1B +IN 3 4 -IN Figure 2. Connection Diagram for IC2A and IC2B WEBENCH is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated 1 Hardware Setup 2 Hardware Setup 2.1 Component Notation www.ti.com The pins of the footprint for IC1A are connected to the equivalent pins for the footprint of IC2A and the same is true for IC1B and IC2B Therefore, this application report will refer to the amplifier in IC1A or IC2A as Amp A and the amplifier in IC1B or IC2B as Amp B. The subscript of the PCB component refers to the specific amplifier; for example, R4A is used for Amp A and R4B for Amp B. In this document, components will be referred to, as an example, C3. If using Amp A this refers to component C3A, if using Amp B this refers to component C3B. In some circuits, a resistor will be installed where the PCB is labeled for a capacitor or a capacitor will be installed where a resistor is labeled. For example, CR6 indicates that a capacitor should be in the R6 position. RC5 means that a resistor will be installed in the C5 position. 2.2 Power Power is applied to the points labeled V-, GND, and V+. If a single supply is used, then V- should be connected to GND. A virtual ground, halfway between the positive supply voltage and ground, is the reference point for the input and output voltages. The output voltage swings above and below this virtual ground. Single-supply operation requires the generation of this virtual ground, usually at a voltage equal to V+/2. The circuit in Figure 3 can be used to generate V+/2; R1 and R2 should be of equal values. This junction along with capacitor C1 will form a low-pass filter used to eliminate conducted noise or transients on the positive supply rail. + V VIN + AMP VOUT - + V R1 C1 R2 Figure 3. Single Supply Virtual Ground 2.3 Op Amp Solder an op amp to either the IC1A or IC2A position. If building a circuit requiring two op amps, solder an additional op amp to either IC1B or IC2B. The corresponding pinout is shown on each side of the PCB. 2.4 Bypassing Install the following capacitors: C6A, C9A, C6B, C9B: 0.1 F C7A, C8A, C7B, C8B: 1 F 2.5 Shutdown To use the shutdown feature of the amplifier in either the SOT-23 or the SC-70 package, install a resistor at R15 and an optional capacitor at C11. The shutdown voltage is applied at S/D-A or S/D-B depending on the package of the amplifier being used. 2 AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback Circuit Configurations www.ti.com 2.6 Input and Output SMA connectors are used for the input and output of signals. They are located on the edges of the PCB. 3 Circuit Configurations 3.1 Non-Inverting Amplifier VIN + VOUT - R8 R12 R7 R14 C3, R4, R5 = 0 (SHORT) C3 Short R4 Short R5 Short R8 Input Termination R7 Output series resistance (used for matching transmission lines or isolation) R14 Gain Resistor R12 Gain Resistor Figure 4. Non-Inverting Amplifier Where: VOUT VIN =1+ R14 R12 SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback (1) AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated 3 Circuit Configurations 3.2 www.ti.com Inverting Amplifier R6 R7 + VOUT VIN R8 R11 R14 C3, R9, R13 = 0 (SHORT) C3 Short R9 Short R13 Short R8 Input Termination R7 Output series resistance (used for matching transmission lines or isolation) R14 Gain Resistor R11 Gain Resistor Figure 5. Inverting Amplifier Where: VOUT VIN 3.3 =- R14 R11 (2) Register Calculations Input Impedance: Set RT to the desired input impedance. Calculate R8 where: R8 = R11 x RT R11 - RT (3) To cancel the input bias current set R6 to the value calculated with the following formula: R6 = 3.4 R11 x R14 R11 - R14 (4) Active Filter Applications Both Sallen-Key and Multiple Feedback filters can be built on this PCB. To design a filter, use the WEBENCHTM tool at www.ti.com. Performance at high frequencies is limited to the gain bandwidth product of the amplifier, but within this frequency range, these active filters can achieve very good accuracy, if lowtolerance resistors and capacitor are used. 4 AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback Circuit Configurations www.ti.com 3.5 Sallen-Key Low-Pass Filter C3 Short R13 Short R7 Output series resistance (used for matching transmission lines or isolation) R8 Input Termination Set the following as determined using WEBENCH: R4, R5, CR6, R14, R12 C5 R4 R5 VIN R7 + CR6 R8 VOUT - R12 R14 C3, R13 = 0 (SHORT) Figure 6. Sallen-Key Low-Pass Filter 3.6 Multiple Feedback Low-Pass Filter Note: If needed, an input termination resistor will need to be soldered on to the SMA connector between the signal pin and the ground pin. R6 Short R13 Short R9 Short C5 Short R7 Output series resistance (used for matching transmission lines or isolation) Set the following as determined using WEBENCH: RC3, CR8, R4, R11, C10 R4 C10 RC3 R11 - VIN RIN R7 VOUT CR8 + R6, R13, R9, C5 = 0 (SHORT) Figure 7. Multiple Feedback Low-Pass Filter SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated 5 Circuit Configurations 3.7 www.ti.com Sallen-Key High-Pass Filter C3 Short R13 Short R14 Short R7 Output series resistance (used for matching transmission lines or isolation) R8 Input Termination Set as determined using WEBENCH: CR4, CR5, RC5, R6 RC5 CR4 CR5 VIN R7 + R6 R8 VOUT - R14 = 0 C3, R13, R14 = 0 (SHORT) Figure 8. Sallen-Key High-Pass Filter 3.8 Multiple Feedback High-Pass Filter Note: If needed, an input termination resistor will need to be soldered on to the SMA connector between the signal pin and the ground pin. R9 Short R4 Short R7 Output series resistance (used for matching transmission lines or isolation) Set the following as determined using WEBENCH: C3, R8, C5, CR11, R14 C5 R14 C3 CR11 - VIN R7 VOUT RIN R8 + R9, R4 = 0 (SHORT) Figure 9. Multiple Feedback High-Pass Filter 6 AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback Circuit Configurations www.ti.com 3.9 Sallen-Key Band-Pass Filter C3 Short R13 Short R7 Output series resistance (used for matching transmission lines or isolation) R8 Input Termination Set as determined using WEBENCH: R4, C4, CR5, R6, RC5, R14, R12 RC5 R4 CR5 VIN R8 R7 + C4 R6 VOUT - R12 R14 C3, R13 = 0 (SHORT) Figure 10. Sallen-Key Band-Pass Filter 3.10 Multiple Feedback Band-Pass Filter Note: If needed, an input termination resistor will need to be soldered on to the SMA connector between the signal pin and the ground pin. R6 Short R13 Short R9 Short R4 Short R7 Output series resistance (used for matching transmission lines or isolation) Set the following as determined using WEBENCH: RC3, R8, C5, CR11, R14 C5 R14 RC3 CR11 - VIN R7 VOUT RIN R8 + R6, R13, R9, R4 = 0 (SHORT) Figure 11. Multiple Feedback Band-Pass Filter SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated 7 Applications Using Two Amplifiers www.ti.com 4 Applications Using Two Amplifiers 4.1 Two-Amplifier Filters Filters using two amplifiers can be built by connecting the output of Amp A to the input of Amp B. 4.2 Single-Ended to Differential Conversion The circuit in Figure 12 will convert a single-ended signal to a differential signal. This is done by using the combination of an inverting amplifier and a non-inverting amplifier. Each amplifier generates output signals of equal magnitude but of opposite polarity. This topology is useful in applications where the signal source is single-ended, but the ADC requires a differential input. The board will need to be modified by connecting Input A to Input B with a jumper wire. R5A +VIN + R8A V +VOUT AMP R12A + - R7A R6A + R1 R14A R6B C1 VDIFF R2 RC4 + -VOUT AMP -VIN - R7B R11B R14B C3A, R4A, R5B, R9B, C3B = 0 (SHORT) Figure 12. Single-Ended to Differential Conversion 8 AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback Applications Using Two Amplifiers www.ti.com 4.3 Differential Input, Differential Output, Non-Inverting Combining two non-inverting amplifiers with a common feedback network, as shown in Figure 13, forms a non-inverting amplifier with a differential input and a differential output. Through the inherent cancellation of the two op amp common-mode error signals this configuration fully exploits the noise reduction benefits of CMRR. In addition the output voltage swing is doubled and depending on the op amp used, the bandwidth and slew rate may also be increased, while maintaining the original gain bandwidth specification. + V CR4A +VIN R7A + +VOUT AMP A R8A V - + R6A R1 R14A C1 R3 R2 R14B R6B + V CR4B -VIN - R7B -VOUT AMP B + R8B C3A, R5A, R5B, C3B = 0 (SHORT) A = 1+ R14A + R14B R3 Figure 13. Differential Input, Differential Output, Non-Inverting SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated 9 551012875-001 Schematic 5 www.ti.com 551012875-001 Schematic Figure 14. 551012875-001 Schematic 10 AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback 551012875-001 Layouts www.ti.com 6 551012875-001 Layouts Figure 15. 551012875-001 Top Layout Figure 16. 551012875-001 Bottom Layout SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated 11 551012922-001 Schematic 7 www.ti.com 551012922-001 Schematic Figure 17. 551012922-001 Schematic 12 AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback 551012922-001 Layouts www.ti.com 8 551012922-001 Layouts Figure 18. 551012922-001 Top Layout Figure 19. 551012922-001 Bottom Layout SNOA487C - May 2007 - Revised May 2013 Submit Documentation Feedback AN-1606 551012875, 551012922 Universal Op Amp Evaluation Boards (SOT-23 and SC-70) Copyright (c) 2007-2013, Texas Instruments Incorporated 13 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. 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