ISL2827xINEVAL1Z Evaluation Board User’s Guide Application Note June 15, 2009 Introduction GND 1 2 2 C3 R32 D2 1 2 D1 1 D3 0 1 A 2 NC 1 0.1µF The ISL2827x series of amplifiers are dual channel instrumentation amplifiers optimized for 2.4V to 5V single supplies. These devices feature an Input Range Enhancement Circuit (IREC) which enables the inputs to swing to the rails. The ISL28270 and ISL28273 maintain CMRR performance from the positive rail down to within 50mV of the negative rail. The ISL28271 and ISL28272 can swing 100mV beyond the rails. The output operation of all devices is rail-to-rail. The ISL28270 and ISL28272 are compensated for a minimum gain of 100 and the ISL28271 and ISL28273 are compensated for a minimum gain of 10. VSP 1 VSM The ISL2827xINEVAL1Z evaluation board is a design platform containing all the circuitry needed to characterize critical performance parameters of the ISL28270, ISL28271, ISL28272 or ISL28273 Dual Instrumentation Amplifiers using a variety of user defined test circuits. AN1290.2 1 ® R33 C 3 2 VM 0 2 C4 1 0.1µF 1 10µF C5 VP FIGURE 1. POWER SUPPLY CIRCUIT Power Supplies (Refer to Figure 1) • ISL28271, ISL28272 Data Sheet, FN6390 External power connections are made through the VSP (+V), VSM (-V) and GND connections on the evaluation board. For single supply operation, the VSM (-V) and GND pins are tied together to the power supply negative terminal. For split supplies, VSP (+V) and VSM (-V) terminals connect to their respective power supply terminals. Resistors R32 and R33 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 and D2 protect the circuit in the case of accidental polarity reversal. Evaluation Board Key Features Amplifier Configuration (Refer to Figure 2) The ISL2827xINEVAL1Z is designed to be operated from a single supply (+2.4VDC to +5VDC), or from split supplies (±1.2VDC to ±2/5V). The board is configured for 2 independent instrumentation amplifiers connected for a closed loop gain of 101 (ISL28270, ISL28272) or a gain of 10 (ISL28271, ISL28273) with inverting and non-inverting high impedance terminated with 100k resistors to ground. Each 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. The schematic of each of the two op amps with the components supplied is shown in Figure 2. The circuit implements a differential input instrumentation amp with a closed loop gain of 101 for the ISL28270 and ISL28272, and 10 for the ISL28271, ISL28273. The circuit can operate from a single 2.4VDC to +5VDC supply, or from dual supplies from ±1.2VDC to ±2.5VDC.The output common mode reference is applied to the VREF pin, and has a range from ground (VM) to VP. Reference Documents • ISL28270, ISL28273 Data Sheet, FN6260 VP ENABLE IN+(x) IN+ IN+ 1/2 ISL28270, ISL28271, ISL28272, ISL28273 + IN- IN- 0Ω VOUT(x) 100kΩ IN-(x) FB+ + -V VCM FB- 10kΩ 100kΩ VREF(x) RG 1kΩ VREF GND RF VM 100kΩ (ISL28270, ISL28272) 9.09kΩ (ISL28271, ISL28273) FIGURE 2. BASIC AMPLIFIER CONFIGURATION 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, 2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1290 User-selectable Options (Refer to Figure 3) VREFA Component pads are included to enable a variety of user selectable circuits to be added to the amplifier differential inputs, the VREF input, and the amplifier feedback loop. A voltage divider and filter option can be added to establish a power supply tracking common mode reference at the VREF input, or a coaxial connection to the amplifier FB+ pin can be made at the FB+ BNC connector. The differential inputs have additional resistor placements for adding input attenuation, or to establish input DC offsets through the VREF pin. V- 1 J4 R6 DNP R5 V+ DNP VREFA C3 J8 FB+A J9 R18 J10 0 R19 DNP R21 +INA R15 R13 DNP -INA OPEN 0 R22 DNP R14 0 VREFA DNP R17 R16 DNP 1k R20 100k R23 100k FIGURE 3. COMPONENT-SELECTABLE OPTIONS ISL2827xINEVAL1Z Components Parts List DEVICE # DESCRIPTION COMMENTS C3, C5 CAP, SMD, 0805, 0.1µF, 25V, 10%, X7R, ROHS Power Supply Decoupling CFA, CFB, CLA, CLB CAP, SMD, 0805, DNP-PLACE HOLDER, ROHS Optional Amplifier Feedback Caps Not Populated C1, C2 CAP, SMD, 1206, 1µF, 25V, 10%, X7R, ROHS Power Supply Decoupling C4 CAP-TANTALUM, SMD, D, 10µF, 35V, 10%, LOW ESR, ROHS Optional VREF Filter Not Populated D1, D2 DIODE-RECTIFIER, SMD, MELF, 2 Ld, 50V, 1A, GPP, ROHS Reverse Power Protection U1 ISL28270FAZ or ISL28271FAZ or ISL28272FAZ or ISL28273FAZ INSTRUMENTATION AMP,16P, QSOP, ROHS R32, R33, RIN+A, RIN+B, RIN-A, RIN-B, RSA, RSB RES, SMD, 0805, 0Ω, 1/8W, TF, ROHS 0Ω User Selectable Resistors RIA, RIB. RES, SMD, 0805, 1k, 1/8W, 1%,TF, ROHS RI Gain Resistors R1, R2 RES, SMD, 0805, 10k, 1/8W, 1%,TF, ROHS ENABLE Pull-up Resistors R15 to R18 RES, SMD, 0805, 100k, 1/10W, 1%, TF, ROHS R9, R12, R20, R22, R27, R29 CAP, SMD, 0805, DNP-PLACE HOLDER, ROHS User Selectable Resistors Not Populated RFA, RFB (ISL28271, ISL28273) RES, SMD, 0805, 9.09k, 1/8W, 1%, TF, ROHS RF Gain Resistors - ISL28271, ISL28272 RFA, RFB (ISL28270, ISL28272) RES, SMD, 0805, 100k, 1/8W, 1%, TF, ROHS RF Gain Resistors - ISL28270 R3, R6, R10, R11, R13, R14, R19, R21, R23, R25, RES, SMD, 0805, DNP-PLACE HOLDER, ROHS R28, R30, RLA, RLB, RX. User Selectable Resistors Not Populated S1, S2 Enable/Disable Select Switches SWITCH-SEALED MINI TOGGLE, TH, 3P, SP, ON/NONE/ON, GOLD 2 AN1290.2 June 15, 2009 Application Note 1290 ISL2827xINEVAL1Z 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 3 AN1290.2 June 15, 2009 R20 R27 4.7K 4.7K 2 D2 VSP 1 GND 1 VP 1 2 D1 1 0 0 2 2 C5 1 CLOSE TO PART 0.1UF C4 1 10UF VP R21 RSA 0 VP 2 CLA 1 OPEN 1 1 16 16 2 2 15 15 3 14 5 U1 QSOP16 14 Generic 4 13 Pack. 5 12 6 6 11 11 7 7 10 10 1 10K S2 3 2 2 DISABLE VM 8 3 8 9 VM 12 1 100K CFB 2 RSB OPEN CLB 1 1 2 VP 4.7K 1UF C2 1 DNP RIN-B 0 R23 R30 0 100K RIB R18 DNP 2 RIN+B R13 5 4 3 1 100 DNP 0 +INB 5 2 2 100K 1 5 R17 -INB 4 3 R29 VOUTB 1 2 0 9 DNP DNP 2 R22 4.7K R12 5 R6 R14 1 4 3 FB+B 3 4 RFB 13 VREFB R19 5 4 3 1 ENABLE VP 1 10K ENB 4 DISABLE DNP R2 ENABLE 3 4 3 2 R25 2 DNP R1 4 3 5 S1 DNP 1 2 ENA RLB 1 OPEN 100K CFA 5 OPEN RFA 100 RLA DNP RIA VOUTA 1 2 0 RX DRAWN BY: ALAN ERZINGER RELEASED BY: DATE: 07/25/06 DATE: UPDATED DATE: BY: ENGINEER: ROBERT POSPISIL TITLE: ISL2827XINEVAL1Z DATE: DNP TESTER MASK# AN1290.2 June 15, 2009 FILENAME: HRDWR ID SHEET 1 Application Note 1290 R16 2 100K 0 R10 4 3 5 R28 RIN+A 1 DNP +INA DNP R15 100K 0 DNP 2 A C 3 NC MMBZ52XXB RIN-A R11 5 4 3 1 1 2 VM 4 -INA 1 D3 R33 C1 1UF C3 0.1UF DNP 2 R9 4 3 2 2 1 5 CLOSE TO PART R3 DNP FB+A R32 1 VM 1 1 VREFA VSM ISL2827xINEVAL1Z Schematic Diagram