Application Note 1565 ISL281X7MSOPEVAL1Z Evaluation Board User’s Guide Introduction tied together to the power supply negative terminal. For split supplies, +V and -V terminals connect to their respective power supply terminals. De-coupling capacitors C2 and C4 connect close to their respective supplies, while two additional capacitors, C1 and C5, are connected close to the part to filter out high frequency noise. Anti-reverse diodes D1 and D2 protect the circuit in the case of accidental polarity reversal. The ISL281X7MSOPEVAL1Z evaluation board is a design platform containing all the circuitry needed to characterize critical performance parameters of the ISL281X7 operational amplifiers in MSOP-8 package, using a variety of user defined test circuits. VREF J11 J10 V+ J9 V- J13 Reference Documents J8 J7 The ISL281X7 operational amplifiers feature low bias current, low noise, and low offset and temperature drift. Evaluation Board Key Features DNP R4 • ISL28127 Data Sheet, FN6633 C2 C4 4.7µF D1 4.7µF D2 S1AB The ISL281X7MSOPEVAL1Z is designed to enable the IC to operate from a single supply, +4.5VDC to +40VDC or from split supplies, ±2.25VDC to ±20V. The board is configured for a single op amp connected for differential input with a closed loop gain of 10. A single external reference voltage (VREF) pin and provisions for a user-selectable voltage divider-filter are included. DNP • ISL28117 Data Sheet, FN6632 R16 • ISL28107 Data Sheet, FN6631 S1AB FIGURE 1. POWER SUPPLY CIRCUIT Amplifier Configuration (Figure 2) The schematic of 1/2 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 must be connected to ground to establish a ground referenced input for dual supply operation, or can be externally set to any reference level for single supply operation. VREF should not be left floating. Power Supplies (Figure 1) External power connections are made through the +V, -V, VREF and Ground connections on the evaluation board. For single supply operation, the -V and Ground pins are RF ISL281X7 100kΩ IN RININ- VP IN- V+ 10kΩ RIN+ IN+ IN + VCM VREF VREF IN+ 10kΩ 0Ω VOUT V+ VM RREF+ RL 100kΩ DNP GND FIGURE 2. BASIC AMPLIFIER CONFIGURATION May 25, 2010 AN1565.0 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. 2010. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1565 User-selectable Options (Figures 3 and 4) The outputs (Figure 4) have additional resistor and capacitor placements for filtering and loading. Component pads are included to enable a variety of userselectable circuits to be added to the amplifier VREF, inputs, outputs, and the amplifier feedback loops. The Inputs (Figure 3) have additional resistor and capacitor, and jumper placements for loading and/or measurement of frequency sensitive parameters. R9 R11 10k 100k C3 R2 OPEN R14 VREF R13 R15 DNP 100k To Output To INTo IN+ FIGURE 3. INPUT STAGE R18 J12 0 DNP DNP DNP R10 DNP R14 R6 R8 R12 10k DNP OUT C6 J2 NODE OPEN R17 R3 DNP DNP 0 R7 R5 R1 DNP J1 IN+ DNP IN- 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. FIGURE 4. OUTPUT STAGE TABLE 1. ISL281X7MSOPEVAL1Z COMPONENTS PARTS LIST DEVICE # DESCRIPTION COMMENTS C2, C4 CAP, SMD, 0805, 4.7µF, 50V, 10%, X7R, ROHS Power Supply Decoupling C1, C5 CAP, SMD, 0603, 0.01µF, 50V, 10%, X7R, ROHS Power Supply Decoupling C3, C6 CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS User selectable capacitors - not populated D1, D2 DIODE-RECTIFIER, 40V, 0.5A, ROHS Reverse Power Protection U1 (ISL28107FUZ) OP AMP, MSOP, ROHS U1 (ISL28117FUZ) OP AMP, MSOP, ROHS U1 (ISL28127FUZ) OP AMP, MSOP, ROHS R1-R4, R6-R8, R10, R13, R14, R16, R17, R19, R20 RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER User selectable resistors - not populated R5, R18 RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS Zero ohm user selectable resistors R9, R12 RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS Gain resistors R11, R15 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS Gain resistors 2 AN1565.0 May 25, 2010 Application Note 1565 FIGURE 5. ISL281X7MSOPEVAL1Z 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 AN1565.0 May 25, 2010 J8 2 4.7UF D1 1 2 S1AB 4.7UF D2 1 1 1 1 C4 1 1 C2 DNP R4 DNP 1 2 VREF J11 3 2 J10 3 J9 J13 V+ R16 J7 V- S1AB 4 NODE 4 3 0 2 1 R9 2 1 10K 2 R5 1 R1 J6 2 2 5 0 C5 0.01UF C1 DNP 5 R18 VREF 1 R13 DNP 2 1 R15 2 100K FIGURE 6. ISL281X7MSOPEVAL1Z SCHEMATIC DIAGRAM 1 2 J12 5 3 4 4 6 2 4 7 6 DNP 3 8 7 1 3 8 1 10K 2 U1 MSOP8 Generic Pack. OPEN R17 R2 R12 1 2 C6 1 1 1 2 2 DNP 0.01UF DNP R20 1 R7 2 DNP DNP R3 + 1 R19 4 3 IN 1 2 OPEN R11 100K DNP J25 C3 1 2 DNP 2 1 R6 1 2 J15 2 DNP DNP J4 J3 DNP R10 OUTPUT Application Note 1565 - 2 1 2 2 2 2 IN 1 1 1 1 R8 1 OUT R14 IN+ J5 IN- AN1565.0 May 25, 2010