THS4502EVM User’s Guide June 2002 HPL SLOU129
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 input voltage range of 5 V and the output voltage range of +5 V and –5 V. 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.
Information About Cautions and Warnings Preface About This Manual This manual provides information about using the THS4502 fully differential amplifier on evaluation module PCB marked with Edge # 6439396. Additionally, this document provides a good example of PCB design for high-speed applications. The user should keep in mind the following points. - The design of the high-speed amplifier PCB is a sensitive process. - The user must approach the PCB design with care and awareness.
Related Documentation From Texas Instruments 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. FCC Warning This equipment is intended for use in a laboratory test environment only.
Trademarks - Application report (literature number SLMA002), Power Pad Thermally Enhanced Package, http://www−s.ti.com/sc/psheets/slma004/slma002.pdf - Application report (literature number SLMA004), PowerPAD Made Easy, http://www−s.ti.com/sc/psheets/slma004/slma004.pdf - Application report (literature number SSYA008), Electrostatic Discharge (ESD), http://www−s.ti.com/sc/psheets/ssya008/ssya008.pdf Trademarks PowerPAD is a trademark of Texas Instruments.
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Contents 1 Introduction and Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Evaluation Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 THS4502EVM Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . .
Contents 1−1. 2−1. 2−2. 3−1. 3−2. 3−3. 5−1. 5−2. 5−3. Schematic of the Populated Circuit on the EVM (Default Configuration) . . . . . . . . . . . . . . Power Supply Connection for ±5 Vdc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Signal Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Single-Ended In/Single-Ended Out, Utilizing Transformer . . . . . . . . . . . . . . . . .
Chapter 1 The Texas Instruments THS4502 evaluation module (EVM) helps designers evaluate the performance of the THS4502 fully differential operational amplifier (FDA). Also, this EVM is a good example of high-speed PCB design. This document details the THS4502EVM.
Description 1.1 Description The THS4502EVM provides a platform for developing high-speed FDA application circuits. It contains the THS4502 high-speed FDA, a number of passive components, and various features and footprints that enable the user to experiment, test, and verify various operational amplifier circuit implementations. The PC board measures 3.08 by 2.42 inches. 1.
EVM Default Configuration 1.4 EVM Default Configuration As delivered, the EVM has a fully functional example circuit; just add power supplies, a signal source, and monitoring instrument. See Figure 1−1 for the default schematic diagram. The user can change the gain by changing the ratios of the feedback and gain resistors (see the device data sheet for recommended resistor values). The complete EVM schematic in Chapter 5 shows component locations.
1-4
Chapter 2 !" This section describes how to connect the THS4502EVM to test equipment. It is recommended that the user connect the EVM as described in this section to avoid damage to the EVM or the THS4502 installed on the board. Topic Page 2.1 Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2 Power Supply Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.3 Function Generator Setup .
Required Equipment 2.1 Required Equipment - One dual-output dc power supply (±5 V, 1 A output minimum) - One single-output dc power supply (5 V, 1 A output minimum). This power supply is used to activate the power-down function of the EVM, and will be referred to in the text of this document as the power-down supply. - Two dc current meters with resolution to 1 mA and capable of the maximum current the dc power supply can supply.
Power Supply Connection Figure 2−1.
Function Generator Setup 2.3 Function Generator Setup Note: The oscilloscope channels (CH1 and CH2) must be set to 50-Ω input impedance for proper results. 1) Connect the function generator to oscilloscope channel 1. 2) Set vertical channels 1 and 2 of the oscilloscope to 0.2 V/division and the time base to 0.1 µs/division. 3) Set the function generator to generate a 1-MHz, ±0.5 V (1 VPP) sine wave with no dc offset. 4) Verify that the output is 1 MHz, ±0.5 V (1 VPP).
Chapter 3 !" # Example applications are presented in this chapter. These applications are meant to demonstrate the most popular circuits to the user, but many other circuits can be constructed. The user is encouraged to experiment with different circuits, exploring new and creative design techniques. After all, that is the function of an evaluation board. Topic Page 3.1 Single-Ended In/Single-Ended Out, Utilizing Transformer . . . . . . . . . 3-2 3.
Single-Ended In/Single-Ended Out, Utilizing Transformer 3.1 Single-Ended In/Single-Ended Out, Utilizing Transformer The fully differential amp output can be monitored by a single-ended instrument at J4. The THS4502EVM utilizes Mini-Circuits CD542 footprint transformers to make the fully differential-to-single-ended conversion. An ADP4−1WT transformer is installed on the board.
Single-Ended to Fully Differential Application Figure 3−2. Single Supply Operation TP1 Vocm R4 C13 1m F J1 Vin− C1 R1 56.2 W C2 R17 0W R2 374 W R3 402 W 392 W +VS R6 0 W 3 U1 1 − 2 Vocm 8 + 6 4 5 R7 0 W THS4502 J2 Vout+ J3 Vout− R5 392 W Note: For this and some of the following circuits, it is necessary to install capacitors into locations designated for resistors, and vice versa. Because the capacitors and resistors come in the same case size, this should be easily accomplished.
Single-Ended to Fully Differential Application This application circuit has interaction between Rsource, Rtermination, and Rg. Texas Instruments has provided an engineer design utility to facilitate the design of these circuits. Engineer design utilities are available on the Amplifiers and Comparators section of the Analog and Mixed Signal portion of the TI web page. The designer should be aware that each individual feedback path is an inverting path.
Chapter 4 $ #% & ' ( ) * The THS4502EVM layout has been designed for use with high-speed signals and can be used as an example when designing PCBs incorporating the THS4502. Careful attention has been given to component selection, grounding, power supply bypassing, and signal path layout. Disregarding these basic design considerations could result in less than optimum performance of the THS4502 high-speed operational amplifier.
Circuit pathways should be made as symmetrical as possible for both feedback pathways to minimize second and other even harmonic content. The printed-circuit board that is used with PowerPAD packages must have features included in the design to remove the heat from the package efficiently. As a minimum, there must be an area of solder-tinned-copper underneath the PowerPAD package. This area is called the thermal land.
Chapter 5 !" + This chapter describes the EVM hardware. It includes the EVM parts list, and printed circuit board layout. Table 5−1. THS4502EVM Bill of Materials Item Description SMD Size Reference Designator PCB Qty. Manufacturer’s Part Number Distributor’s Part Number 1 CAP, 6.8 µF, tanatalum, 35 V, 10% D C8, C11 2 (AVX) TAJD685K035R (Garrett) TAJD685K035R 2 CAP, 0.1 µF, ceramic, X7R, 16 V 0508 C9, C12 2 (AVX) 0508YC104KAT2A (Garrett) 0508YC104KAT2A 3 CAP, 1.
Item Description SMD Size Reference Designator PCB Qty. Manufacturer’s Part Number Distributor’s Part Number 17 Test points (red) TP1, TP2 2 (Keystone) 5000 (Allied) 839−3600 18 Jack, banana receptacle, 0.25” diameter hole J5, J7, J8 3 (HH Smith) 101 (Newark) 35F865 19 Connector, SMA PCB Jack J1, J2, J3, J4, J6 5 (Amphenol) 901−144−8RFX (Newark) 01F2208 20 Standoff, 4−40 Hex, 0.625” Length 4 (Keystone) 1804 (Allied) 839−2089 21 Screw, Phillips, 4−40, 0.
Figure 5−2.
Figure 5−3. Schematic Diagram VCC+ TP2 PD− TP1 Vocm * J1 Vin− J6 Vin+ C4 R14 * * 392 W +VS 1 − 4 PD 2 Vocm 8 + 5 U1 6 THS4502 R1 56.2 W C2 0W R3 402 W C14 * * J2 Vout+ R6 0W 3 7 374W * R16 R4 C1 0W R2 R17 0W J7 GND R15 R13 C13 1m F TP3 TP4 TP5 VCC+ − VS R5 R8 C5 * R7 0W C6 * 4 T1 3 340 W C7 R10 5 R11 280 W R9 6 1 340 W ADP4 −1WT * * J3 Vout− 392 W C3 J8 +VS Note: 5-4 + C8 6.8mF C9 0.1mF C10 * * +VS J4 Vout J5 −VS + C11 6.8mF C12 R12 0.
