ISL281X7SOICEVAL1Z

Application Note 1508 ISL281X7SOICEVAL1Z Evaluation Board User’s Guide Introduction The ISL281X7SOICEVAL1Z evaluation board is a design platform containing all the circuitry needed to characterize critical performance parameters of the ISL281X7 operational amplifiers in SOIC-8 package, using a variety of user defined test circuits. The ISL281X7 operational amplifiers feature low bias current, low noise, and low offset and temperature drift. 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. J7 J8 VV+ VREF Reference Documents • ISL28107 Data Sheet, FN6631 • ISL28117 Data Sheet, FN6632 • ISL28127 Data Sheet, FN6633 DNP C2 R4 4.7µF D1 S1AB Evaluation Board Key Features The ISL281X7SOICEVAL1Z 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. 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 100kΩ IN RINININV+ IN+ V+ VM RREF+ VP ISL281X7 10kΩ RIN+ IN + 0Ω DNP R16 J13 C4 J10 J11 J9 4.7µF D2 VOUT IN+ 10kΩ 100kΩ VCM RL DNP VREF VREF GND FIGURE 2. BASIC AMPLIFIER CONFIGURATION November 9, 2009 AN1508.0 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. 2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1508 User-selectable Options (Figures 3 and 4) Component pads are included to enable a variety of user-selectable 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. ININ+ NODE OUT The outputs (Figure 4) have additional resistor and capacitor placements for filtering and loading. 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. R8 DNP R6 DNP R9 10k R10 DNP R14 DNP R11 J1 R1 R3 DNP J2 R2 DNP DNP R5 0 DNP R7 100k C3 OPEN R14 VREF R15 100k OPEN R17 10k R13 DNP FIGURE 3. INPUT STAGE FIGURE 4. OUTPUT STAGE TABLE 1. ISL281X7SOICEVAL1Z COMPONENTS PARTS LIST DEVICE # C2, C4 C1, C5 C3, C6 D1, D2 U1 (ISL28107FBZ) U1 (ISL28117FBZ) U1 (ISL28127FBZ) R1-R4, R6-R8, R10, R13, R14, R16, R17, R19, R20 R5, R18 R9, R12 R11, R15 DESCRIPTION CAP, SMD, 0805, 4.7µF, 50V, 10%, X7R, ROHS CAP, SMD, 0603, 0.01µF, 50V, 10%, X7R, ROHS CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS DIODE-RECTIFIER, 40V, 0.5A, ROHS OP AMP, SOIC, ROHS OP AMP, SOIC, ROHS OP AMP, SOIC, ROHS RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER User selectable resistors - not populated RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS Zero ohm user selectable resistors Gain resistors Gain resistors COMMENTS Power Supply Decoupling Power Supply Decoupling User selectable capacitors - not populated Reverse Power Protection 2 DNP C6 R12 To Output To INTo IN+ R18 J12 0 AN1508.0 November 9, 2009 Application Note 1508 FIGURE 5. ISL281X7SOICEVAL1Z 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 AN1508.0 November 9, 2009 1 J7 VC2 DNP 4.7µF D1 S1AB J13 C4 DNP 4.7µF D2 S1AB IN- IN+ NODE OUT J3 J4 J5 J6 R16 J8 V+ VREF J10 J11 J9 R4 DNP C3 OPEN R11 100k R19 DNP R20 1 DNP R12 10k R5 IN J1 R1 DNP DNP R7 0 R9 10k DNP R14 R6 DNP R3 OPEN R17 DNP 0.01µF C1 R13 DNP R15 100k C5 VREF 0.01µF FIGURE 6. ISL281X7SOICEVAL1Z SCHEMATIC DIAGRAM DNP C6 4 R8 IN + J2 R2 AN1508.0 November 9, 2009 Application Note 1508 R10 DNP DNP U1 8 R18 J12 0 OUTPUT 2 SOIC8 7 Generic 3 Pack. 6 4 5