ISL281x6EVAL1Z Evaluation Board User’s Guide Application Note August 17, 2007 Introduction • ISL28136 Data Sheet, FN6153 C4 • ISL28146 Data Sheet, FN6321 R20 Reference Documents • ISL28166 Data Sheet, FN6155 J1 C3 0.1µF VM VP FIGURE 1. POWER SUPPLY CIRCUIT Evaluation Board Key Features The ISL281x6EVAL1Z is designed to enable the IC to operate from a single supply, +2.4VDC to +5.5VDC or from split supplies, ±1.2VDC to ±2.75V. The board is configured for a single op amp connected for differential input with a closed loop gain of 10. It also contains a single external reference voltage (VREF) pin and provisions for a user-selectable voltage divider (filter are included). Amplifier Configuration (Figure 2) The schematic of the op amp with the components supplied is shown in Figure 2. The circuit implements a differential input amp with a closed loop gain of 10. The circuit can operate from a single supply or from dual supplies. The VREF pin can be connected to ground to establish a ground referenced input for split supply operation, or can be externally set to any reference level for single supply operation. Power Supplies (Figure 1) External power connections are made through the V+, Vand Ground connections on the evaluation board. For single supply operation, the V- and Ground pins are tied together to the power supply negative terminal. For split supplies V+ RF ISL281x6 100kΩ IN - VP RIN- IN- IN- V+ 10kΩ RIN+ IN+ IN+ VCM 0Ω 0Ω VOUT V- + VM 10kΩ IN+ GND 0 C1 + D1 4.7µF 0.1µF • ISL28156 Data Sheet, FN6154 VREF R1 R24 R21 C2 + 4.7µF D2 0 V+ 0 V- J2 The ISL28136 and ISL28146 high-speed operational amplifiers feature low power consumption, while ISL28156 and ISL28166 operational amplifiers feature ultra-low power consumption. All op amps have rail-to-rail output drive capability and are designed to operate with a single lithium cell or two Ni_Cd batteries. J3 and V- terminals connect to their respective power supply terminals. De-coupling capacitors C1 and C2 connect to ground through R1 and R21 0Ω resistors. Resistors R20 and R24 are 0Ω but can be changed by the user to provide additional power supply filtering, or to reduce the voltage rate-of-rise to less than ±1V/µs. Two additional capacitors, C3 and C4 are connected close to the part to filter out high frequency noise. Anti-reverse diodes D1and D2 protect the circuit in the case of accidental polarity reversal. The ISL281x6EVAL1Z evaluation board is a design platform containing all the circuitry needed to characterize critical performance parameters of the ISL281x6 operational amplifiers, using a variety of user defined test circuits. VREF AN1351.0 0 ® RREF+ RL 100kΩ 10kΩ 10kΩ 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. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1351 User-selectable Options (Figures 3 and 4) The output (Figure 4) has a 10kΩ load resistor to ground, and has additional resistor and capacitor placements for loading. Component pads are included to enable a variety of user-selectable circuits to be added to the amplifier inputs, the VREF input, outputs and the amplifier feedback loops. NOTE: Operational amplifiers are sensitive to output capacitance and may oscillate. In the event of oscillation, reduce output capacitance by using shorter cables, or add a resistor in series with the output. J4 A voltage divider and filter option (Figure 3) can be added to establish a power supply-tracking common mode reference at the VREF input. The inverting and non-inverting inputs have additional resistor placements for adding input attenuation, or to establish input DC offsets through the VREF pin. DNP RINA2+ TO INC10 TO IN+ OPEN J5 OUT DNP R25 10k R23 DNP C9 OPEN 100k R27 R26 0 0 C8 C5 + 4.7µF 0 R22 TO OUT OPEN 0 R6 R9 R3 DNP IN2+ J8 DNP OPEN RINA+ R11 DNP 10k C7 RREF RREFA+ R14 R13 R2 DNP RINA1+ R7 IN1+ J7 R17 DNP DNP OPEN R12 10k RINA2- IN- J6 R8 RREFAR15 DNP R5 0 C6 10k RINAR10 R18 REF1 RGA+ FIGURE 4. 1/2 OUTPUT STAGE FIGURE 3. 1/2 INPUT STAGE ISL281x6EVAL1Z Components Parts List DEVICE NUMBER C1, C2, C5 DESCRIPTION COMMENTS CAP-TANTALUM, SMD, D, 4.7µF, 50V, 10%, LOW ESR, ROHS Power Supply Decoupling C3,C4 CAP, SMD, 0603, 0.1µF, 25V, 10%, X7R, ROHS Power Supply Decoupling C6-C10 CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS User-selectable capacitors - not populated D1, D2 DIODE-RECTIFIER, SMD, SOD-123, 2P, 40V, 0.5A, ROHS Reverse Power Protection U1 (ISL28136EVAL1Z) ISL28136FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23,ROHS U1 (ISL28146EVAL1Z) ISL28146FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS U1 (ISL28156EVAL1Z) ISL28156FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS U1 (ISL28166EVAL1Z) ISL28166FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS R2, R3, R6, R8, R9, R12, R13, RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER R15, R16, R23, R25, R27 User-selectable resistors - not populated R1, R10, R11, R17, R20, R21, RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS R24, R26, R22 0Ω user-selectable resistors R4, R5, R7, R18 RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS Gain and other user selectable resistors R14, R19 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS Gain resistors 2 AN1351.0 August 17, 2007 Application Note 1351 ISL281x6EVAL1Z Top View 3 AN1351.0 August 17, 2007 Application Note 1351 TO J5 PART OUT ISL281x6EVAL1Z Schematic Diagram CLOSE DNP 0 VP V+ 10k R25 C3 0.1µF R26 R27 0 J1 4.7µF 0 0 4.7µF J2 R22 0 D1 C1 R1 R23 C9 R21 DNP OPEN C2 R24 D2 OPEN VM C8 0 J3 4 SOT23_6 4 GENERIC PACK 5 3 2 2 3 6 1 1 U1 100k CLOSE R19 6 5 VP 0.1µF C4 TO PART V- R20 4.7µF 0 10k R17 R18 VP DISABLE S1 10k 2 EN DNP J8 IN2+ J9 R4 DNP RINA2+ OPEN R6 10K C7 RINA1+ R7 J7 IN1+ 3 ENABLE 0 RINA+ R11 OPEN R2 R3 R5 10K RINA2DNP DNP J6 R8 R9 IN- DNP DNP C6 R12 0 R16 DNP RGA+ C10 DNP RINAR10 OPEN 100k RREFA+ R14 DNP R13 RREFAR15 DNP 1 J4 REF1 VM RREF C5 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 AN1351.0 August 17, 2007