ISL28474EVAL1Z Evaluation Board User’s Guide ® Application Note August 23, 2007 AN1353.0 The ISL28474EVAL1Z evaluation board is a design platform containing all the circuitry needed to characterize critical performance parameters of the ISL28474 instrumentation and precision operational amplifiers, using a variety of user defined test circuits. External power connections are made through the VSP (+V), VSM (-V) and Ground connections on the evaluation board. For single supply operation, the VSM and Ground pins are tied together to the power supply negative terminal. For split supplies VSP and VSM connect to their respective power supply terminals. Resistors R3 and R34 are 0Ω but can be changed by the user to provide power supply filtering, or to reduce the voltage rate-of-rise to less than ±1V/µs. Anti-reverse diodes D1, D2 and D3 protect the circuit in the case of accidental polarity reversal. C1 + 0 D1 4.7µF D3 0 R4 CLOSE TO PART Reference Documents A C NC MMBZ52XXB C4 • ISL28274, ISL28474 Data Sheet 0.1µF C14 Evaluation Board Key Features 0.01µF 0 • ISL28474EVAL1Z V+ R1 R2 C2 + 4.7µF D2 0 R3 V- Ordering Information J2 The ISL28474 is the combination of two micropower instrumentation amplifiers (Amp A) and two low power precision amplifiers (Amp B) in a single package. This device is optimized for 2.4V to 5V single supplies, and can be operated from one lithium cell or two Ni-Cd batteries. J1 Power Supplies (Refer to Figure 1) J3 Introduction C5 + DNP VM C3 CLOSE TO PART 0.1µF C18 0.01µF VP The ISL28474EVAL1Z is designed to be operated from a single supply (+2.4VDC to +5VDC), or from split supplies (±1.2VDC to ±2.5V). Amp A is compensated for a gain of 100, and Amp B is compensated for a gain of 10. Each precision amplifier contains it’s own VREF input to establish an input common mode reference. An ENABLE select switch is provided for each amplifier to be used to save power by powering the device down. FIGURE 1. POWER SUPPLY CIRCUIT Amplifier Configuration (Figures 2 and 3) The schematic of instrumentation amplifiers (Amp A) is shown with components supplied in Figure 2, and the schematic of precision amplifiers (Amp B), is shown with components supplied in Figure 3. . VP IN+(X) IN+ IN- ININ+ IN-(X) 100kΩ VCM FB+ FB- 100kΩ ENABLE 1/2 AMP A + V+ - 0Ω VOUT(x) V- + - 10kΩ VREF (X) GND VREF Rg RF 1kΩ 100kΩ VM FIGURE 2. BASIC INSTRUMENTATION AMPLIFIER CIRCUIT 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2007. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1353 . RF 1/2 AMP B 100kΩ IN-(X) RIN- VP IN- IN- IN+ V+ RIN+ V- IN+ IN+(X) VREF (X) 0Ω VOUT(x) VM 10kΩ RREF = (X) 100kΩ 0Ω 10kΩ GND 0Ω + 10kΩ VCM VREF - 10kΩ TO OTHER CHANNEL FIGURE 3. BASIC PRECISION AMPLIFIER CIRCUIT User-selectable Options (Figures 4 and 5) FB+A J6 DNP R27 DNP R9 R28 0 1K DNP R23 DNP R24 IN+A 100K 0 IA FB+ 1 IA FB- 1 IA IN- 1 IA IN+ 1 R14 J8 R19 100K 0 AMP A IN+ 1 IN+B OPEN R16 J9 IN- 1 100K R29 C7 OUT 1 10K DNP R21 C13 OPEN R34 C8 100K OPEN R17 J10 DNP R22 R11 10K DNP IN-B DNP R30 0 OPEN 10k OPEN DNP OUT 0 IA OUT-1 OPEN R31 R13 J7 100K C12 R18 IN-A DNP R36 DNP A voltage divider and filter option (Figure 5) can be added to establish a power supply tracking common mode reference at the VREF input. The differential inputs have additional resistor placements for adding input attenuation, or to establish input DC offsets through the VREF pin (AMP B). For Amp A (Figure 5, Top), a coaxial connection to the amplifier FB+ pin can be made at the FB+ BNC connector. For Amp B (Figure 5, Bottom), the additional unpopulated components allow the user to configure the board for a variety of other applications such as cascaded gain stages, active feedback loops, etc. VREF R8 R10 Component pads are included to enable a variety of user-selectable circuits to be added to the amplifier differential inputs, the VREF input, outputs and the amplifier feedback loop. The outputs (Figure 4) have additional resistor and capacitor placements for loading. AMP B FIGURE 4. OUTPUT STAGE 2 FIGURE 5. 1/2 AMPLIFIER INPUT CIRCUIT AN1353.0 August 23, 2007 Application Note 1353 ISL28474EVAL1Z Components Parts List DEVICE NUMBER DESCRIPTION COMMENTS C1, C2, C6 CAP, SMD, 1206, 4.7µF, 25V, 10%, X7R, ROHS Power Supply Decoupling C3, C4, C23 CAP, SMD, 0805, 0.1µF, 25V, 10%, X7R, ROHS Power Supply Decoupling C14, C18 CAP, SMD, 0805, 0.01µF, 25V, 10%, X7R, ROHS Power Supply Decoupling C7 -C13, C15 -C17, C19 -C22 CAP, SMD, 0805, DNP-PLACE HOLDER, ROHS Optional Caps Not Populated C5 CAP-TANTALUM, SMD, D, 10µF, 35V, 10%, LOW ESR, ROHS Optional Filter Not Populated D1, D2, D3 DIODE-RECTIFIER, SMD, ROHS U1 Reverse Power Protection ISL28474FAZ INSTRUMENTATION AMP/PRECISION AMP COMBINATION ,24P, QSOP, ROHS R8, R10, R11, R18, R20- R23, R27, R30, R32, RES, SMD, 0805, DNP-PLACE HOLDER, ROHS R35- R37, R39- R42, R47, R48, R51, R54- R56, R58, R66, R68, R69 User Selectable Resistors Not Populated R1- R5,R7, R9, R13, R14, R25, R26, R53, R57, RES, SMD, 0805, 0W, 1/8W, TF, ROHS R64, R65, R67, R70 0W User Selectable Resistors R28, R49 RES, SMD, 0805, 1k, 1/8W, 1%,TF, ROHS User Selectable Resistors R6, R12, R15- R17, R33, R38, R44, R45, R60, R63 RES, SMD, 0805, 10k, 1/8W, 1%,TF, ROHS User Selectable Resistors R19, R24, R29, R31, R34, R43, R46, R50, R52, RES, SMD, 0805, 100k, 1/10W, 1%, TF, ROHS R59 S1-S4 User Selectable Resistors SWITCH-SEALED MINI TOGGLE, TH, 3P, SP, ON/NONE/ON, Enable/Disable Select Switches GOLD 3 AN1353.0 August 23, 2007 Application Note 1353 ISL28474EVAL1Z Top View Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 4 AN1353.0 August 23, 2007 ISL28474EVAL1Z Schematic Diagram OUT A FB+A IN-A J5 J6 J7 J8 J9 R8 DNP R9 0 R13 0 R14 0 R18 C7 OPEN R16 10K C8 10K OPEN R17 REF1 0 R28 1K RREF ENABLE A C13 8 C2 U1 4.7UF VM IA OUT-1 D2 0 R2 IA OUT-2 M24.15 13 14 15 16 17 18 A NC 0 R1 D3 C MMBZ52XXB OUT 2 NC IN- 2 IN+ 2 EN 2 19 IA EN 2 20 IA IN+ 2 21 IA IN- 2 22 IA FB- 2 23 IA FB+ 2 24 S3 D1 Application Note 1353 V- EN 1 9 OUT 1 12 NC 11 IN- 1 10 IN+ 1 7 IA EN 1 6 IA IN+ 1 5 IA IN- 1 4 IA FB- 1 3 IA FB+ 1 2 1 0.01UF C14 0.1UF C4 CLOSE TO PART R36 DNP VP OPEN R34 S1 100K J12 H 2 J2 2 2 VM 3 S4 VM J14 H C1 4.7UF C5 DNP R42 DNP C16 V+ C3 C18 0.1UF 0.01UF ENABLE D VP ENABLE D 10K R45 VP J15 OPEN R43 1 3 100K H L VP ENABLE C 10K R44 1K R49 VREF CLOSE TO PART R47 VREF 0 R26 VREF R25 3 L 2 0 R53 0 R57 10K OPEN R61 C22 10K OPEN R60 C21 DNP 0.1UF R33 1 VM S2 100K R3 C17 R5 J1 0 OPEN R46 ENABLE C R58 OPEN 1 DNP C15 DNP L R66 0 R67 0 R64 0 R65 0 R70 DNP 100K OPEN 10K L DNP R51 C23 DNP ENABLE A 3 ENABLE B R38 H J13 R37 1 R68 R52 C11 VP 10K DNP R41 DNP 10K R69 IN+A IN+B R7 R31 VP OPEN ENABLE B VM DNP 4.7UF DNP 0 DNP R63 10K J22 J21 J20 J19 J18 J17 3 4 J16 3 4 5 5 5 OUT D FB+D IN-D IN+D IN+C IN-C OUT C AN1353.0 August 23, 2007 3 4 J10 J11 0 C6 J4 R6 10K R30 J3 VM R39 R4 R35 R32 100K C12 DNP 100K OPEN DNP R48 R50 C19 100K DNP DNP DNP R62 IN-B OUT B 0 5 R40 R59 OPEN R54 R55 R56 C20 DNP 100K DNP DNP 100K OPEN R23 R27 R29 C10 R24 DNP DNP R20 DNP DNP 100K R21 R22 C9 OPEN 10K R10 DNP R19 10K R12 R11 R15