LMH5485-SP-EVM

www.ti.com Table of Contents User’s Guide LMH5485-SP-EVM Evaluation Module ABSTRACT The LMH5485-SP-EVM is a generic, unpopulated printed circuit board (PCB) designed to provide an optimized layout when evaluating the LMH5485-SP in a HKX (CFP-8) package. Only a few components are needed to begin evaluation, Figure 8-1 displays a recommended default schematic. To avoid parasitic component inductance, the board only accepts surface mount resistors and capacitors. The EVM is designed for use with 50-Ω laboratory equipment at the input and output, along with balun footprints at the input and ouput for simple conversion between single-ended and differential signals. For further information on this device and good PCB layout techniques, see LMH5485-SP Radiation Hardened Assured (RHA) Negative Rail Input, Rail-to-Rail Output, Precision, 850-MHz Fully Differential Amplifier. Table of Contents 1 LMH5485-SP-EVM................................................................................................................................................................... 2 2 Features...................................................................................................................................................................................2 3 EVM Specifications.................................................................................................................................................................2 4 Power Connections................................................................................................................................................................ 2 5 Split-Supply Operation...........................................................................................................................................................2 6 Single-Supply Operation........................................................................................................................................................2 7 Input and Output Connections.............................................................................................................................................. 3 7.1 VOCM Input Connections.................................................................................................................................................. 3 7.2 PD Input Connections........................................................................................................................................................ 3 7.3 Using the Optional Differential Outputs (J6 and J7)........................................................................................................... 3 8 LMH5485-SP Schematic and Layout.....................................................................................................................................4 8.1 LMH5485-SP-EVM Layout.................................................................................................................................................5 9 Related Documentation..........................................................................................................................................................7 List of Figures Figure 1-1. LMH5485-SP-EVM Board (Top Side)........................................................................................................................2 Figure 8-1. LMH5485-SP Recommended Default Schematic..................................................................................................... 4 Figure 8-2. LMH5485-SP-EVM Top Layer, Signal....................................................................................................................... 5 Figure 8-3. LMH5485-SP-EVM Layer 2.......................................................................................................................................5 Figure 8-4. LMH5485-SP-EVM Layer 3.......................................................................................................................................6 Figure 8-5. LMH5485-SP-EVM Bottom Layer............................................................................................................................. 6 List of Tables Table 3-1. EVM Specifications..................................................................................................................................................... 2 Trademarks All trademarks are the property of their respective owners. SBOU262 – SEPTEMBER 2021 Submit Document Feedback LMH5485-SP-EVM Evaluation Module Copyright © 2021 Texas Instruments Incorporated 1 LMH5485-SP-EVM www.ti.com 1 LMH5485-SP-EVM Figure 1-1. LMH5485-SP-EVM Board (Top Side) 2 Features This EVM supports the following features: • • • Can be configured for either split-supply or single-supply operation Easily configurable for various gain options Designed for easy connection to standard 50-Ω input and output impedance test equipment 3 EVM Specifications Table 3-1 lists the EVM specifications when used in the recommended configuration: Table 3-1. EVM Specifications Value Single-supply voltage range (V– = GND) 2.7-V to 5.1-V V± Split-supply voltage range ±1.35-V to ±2.55-V IS± Supply current (no load) 10.1-mA IOUT Output drive ±100-mA 4 Power Connections The LMH5485-SP-EVM has test point footprints for easy connection of power. The positive supply input is labeled V+. The negative supply input is labeled V-. The ground input is labeled GND. 5 Split-Supply Operation To operate at split supply, apply the positive supply voltage to V+, negative supply voltage to V– , and the ground reference from supply to GND. 6 Single-Supply Operation To operate as single supply, connect the V– connector and GND connector to ground and apply the positive supply voltage to V+. Inputs and outputs must be biased per data sheet specifications for proper operation. The LMH5485-SP output common-mode voltage defaults to mid-supply if the Vcm connector is left floating. 2 LMH5485-SP-EVM Evaluation Module SBOU262 – SEPTEMBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated www.ti.com Input and Output Connections 7 Input and Output Connections The LMH5485-SP-EVM is equipped with SMA connector footprints for easy connection of signal generators and analysis equipment. The EVM can either be for single-ended or differential input or output with 50-Ω termination. For best results, signals must be routed to and from the EVM with cables having 50-Ω characteristic impedance. Either IN+ (J2) or IN– (J1) can be used for single-ended input. The unused connector should be terminated with a 50-Ω resistive SMA load. If no SMA load is available, then the spaces marked C1 or C2 can be loaded with a 0-Ω resistor, and the spaces marked R1 or R4 can be loaded with a 50-Ω to terminate the unused input. Use both IN+ (J2) and IN– (J1) for differential input. OUT+ (J9) is the output connector for single-ended output signals. The amplifier converts the single-ended or differential input to a differential signal at its output pins. A resistor network (R8, R9, and R10) and transformer on the output of the amplifier (T2) convert the differential output signal to single-ended and provides a 500-Ω load to the amplifier when terminated in 50-Ω. A 50-Ω line-impedance match at OUT+ should be preserved. This results in an output measurement loss, and the overall gain is approximately –20-dB. For more details, see the Applications and Layout Guidelines in the LMH5485-SP Radiation Hardened Assured (RHA) Negative Rail Input, Rail-to-Rail Output, Precision, 850-MHz Fully Differential Amplifier data sheet. 7.1 VOCM Input Connections The Vcm input (J3) is optional and sets the common mode of the output pins. The LMH5485-SP will automatically self-bias the output common-mode voltage to the mid-supply voltage if the Vocm pin is not connected. This is the optimal voltage for maximum output swing and best linearity. The valid range of the Vocm is 0.94-V above the negative supply to 1.2-V below the positive supply. For example, on a ±2.5-V split supply, the Vocm pin can be set anywhere from −1.56-V to 1.3-V. With a single 5-V supply the valid range would be 0.94-V to 3.8-V. Remember, the outputs of the LMH5485-SP can swing from rail to rail; the maximum output swing available, however, is reduced when the Vocm pin is set to a voltage other than mid-supply. If providing 50-Ω termination for the Vcm input signal source is desired, C6 can be populated with a 0-Ω resistor and R5 populated with a 50-Ω resistor. 7.2 PD Input Connections Adding a header and jumper at J5 allows for simple disabling of the LMH5485-SP. An SMA connector can also be loaded at J4 to allow for a power-down signal to be applied for high-speed testing. Normally the J5 jumper is used to enable or disable (power-down) the amplifier. When jumper J5 is open, the amplifier is not powered down, so it is enabled. When the shorting block is connected and J5 is closed, the amplifier is powered down. For high-speed testing, a 0-Ω resistor can be placed at C4 and a 50-Ω resistor at R6 to terminate the PD SMA input. The shorting block should be removed from J5 during high-speed testing. This is because 0-Ω at C4 terminates to the ground and not to the supplies. The state of the amplifier will be undefined when the signal source is disconnected. For this reason, 0-Ω at C4 should only be used when driving the SMA connector with a high speed, controlled impedance source. 7.3 Using the Optional Differential Outputs (J6 and J7) Figure 8-1 shows a recommended schematic configuration where balun T2 is used to convert the output to single-ended. To reconfigure the LMH5485-SP-EVM for fully-differential outputs, remove resistors R19 and R20 to disconnect the balun from the amplifier output. If 50-Ω resistors are loaded in the R26 and R27 resistor positions, and SMA connectors are loaded in the J6 and J7 connector positions, then J6 and J7 can be used for fully-differential output signals. If 50-Ω test equipment is connected to J6 and J7, then the total load to the amplifier is 200-Ω. The data sheet specifications were produced with a 500-Ω load. To match a 500-Ω load, load R26 and R27 with 221-Ω resistors and then load R25 and R28 with 60.4-Ω resistors. SBOU262 – SEPTEMBER 2021 Submit Document Feedback LMH5485-SP-EVM Evaluation Module Copyright © 2021 Texas Instruments Incorporated 3 LMH5485-SP Schematic and Layout www.ti.com 8 LMH5485-SP Schematic and Layout Figure 8-1 illustrates a recommended default schematic configuration. The LMH5485-SP-EVM is an unpopulated board and does not come with pre-installed components. 1 2 3 4 5 6 Refer To Device (U1) Datasheet and EVM User's Guide for recommended operating conditions & default configuration V+ V+ TP3 GND VTP2 TP4 V- V+ C15 DNP C3 0.01uF A C5 0.1uF C8 10uF C10 10uF GND C11 0.1uF C12 0.01uF C13 0.01uF C14 A DNP C16 DNP GND GND GND GND TP5 GND J3 GND GND GND TP6 GND 1 V- 2 3 4 5 DNP Vcm GND GND GND TP1 C6 R5 49.9 CM R18 DNP 0.22uF GND V+ GND R17 DNP J6 R25 DNP Rt+ 60.4 1 +OUT R11 DNP0 5 4 3 2 V- R29 100 GND B B GND J1 C1 1 IN- DNP DNP 49.9 R1 R26 Ro+ DNP221 C21 2 3 4 5 R23 GND 402 J9 R13 GND C17 DNP R21 T1 3 2 1 4 5 6 DNP 191 C18 MNC_ADTL1-4-75 GND GND 6 191 3 R31 60.4 0 C2 0.22uF + 1 DNP R20 Vocm PD Vs- 5962R1920401VXC 0 C19 DNP GND 237 6 5 4 T2 1 2 3 DNP GND J10 R14 R27 RoDNP221 1 OUT- GND J7 C24 1 -OUT 5 4 3 2 GND 0 C 402 49.9 OUT+ GND C20 MNC_ADTL1-4-75 R35 DNP 0 V- DNP 2 3 4 5 R9 56.0 R10 2 R24 GND R4 237 C9 DNP 1000pF C7 DNP 1pF 0402 1 J2 IN+ R8 0 8 - 4 R22 R19 Vs+ 5 DNP C22 DNP R3 C 7 1 5 4 3 2 0 0 R34 DNP 0 U1 V+ 5 4 3 2 R30 60.4 GND R2 GND R15 49.9k V+ C4 0.22uF R6 R28 RtDNP60.4 R12 DNP0 GND 49.9 GND GND J5 PD J4 GND 1 PD 2 1 2 3 4 5 DNP R16 49.9 SH-J5_1-OPEN GND V- D D Texas Instruments and/or its licensors do not warrant the accuracy or completeness of this specification or any information contained therein. Texas Instruments and/or its licensors do not warrant that this design will meet the specifications, will be suitable for your application or fit for any particular purpose, or will operate in an implementation. Texas Instruments and/or its licensors do not warrant that the design is production worthy. You should completely validate and test your design implementation to confirm the system functionality for your application. 1 2 3 Orderable: LMH5485-SP-EVM TID #: N/A Number: AMPS139 Rev: A SVN Rev: Not in version control Drawn By: Engineer: Hasan Babiker 4 5 Mod. Date: 8/13/2021 Designed for: Public Release Project Title: LMH5485-SP-EVM Sheet Title: Assembly Variant: Recommended Default Configuration Sheet: 1 of 3 File: LMH5485-SP-EVM.SchDoc Size: B Contact: http://www.ti.com/support http://www.ti.com © Texas Instruments 2021 6 Figure 8-1. LMH5485-SP Recommended Default Schematic 4 LMH5485-SP-EVM Evaluation Module SBOU262 – SEPTEMBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated www.ti.com LMH5485-SP Schematic and Layout 8.1 LMH5485-SP-EVM Layout Figure 8-2 through Figure 8-5 show the LMH5485-SP-EVM layers. Figure 8-2. LMH5485-SP-EVM Top Layer, Signal Figure 8-3. LMH5485-SP-EVM Layer 2 SBOU262 – SEPTEMBER 2021 Submit Document Feedback LMH5485-SP-EVM Evaluation Module Copyright © 2021 Texas Instruments Incorporated 5 LMH5485-SP Schematic and Layout www.ti.com Figure 8-4. LMH5485-SP-EVM Layer 3 Figure 8-5. LMH5485-SP-EVM Bottom Layer 6 LMH5485-SP-EVM Evaluation Module SBOU262 – SEPTEMBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated www.ti.com Related Documentation 9 Related Documentation For related documenation, see the following: • Texas Instruments, LMH5485-SP Radiation Hardened Assured (RHA) Negative Rail Input, Rail-to-Rail Output, Precision, 850-MHz Fully Differential Amplifier data sheet SBOU262 – SEPTEMBER 2021 Submit Document Feedback LMH5485-SP-EVM Evaluation Module Copyright © 2021 Texas Instruments Incorporated 7 IMPORTANT NOTICE AND DISCLAIMER TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS. 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