J1 1 J1 0 J9 J8 J1 3 J7 USERS MANUAL ISL281X7SOICEVAL1Z AN1508 Rev 0.00 Evaluation Board November 9, 2009 supply negative terminal. For split supplies, +V and - Introduction V terminals connect to their respective power supply The ISL281X7SOICEVAL1Z evaluation board is a terminals. De-coupling capacitors C2 and C4 connect design platform containing all the circuitry needed to close to their respective supplies, while two characterize critical performance parameters of the additional capacitors, C1 and C5, are connected ISL281X7 operational amplifiers in SOIC-8 package, close to the part to filter out high frequency noise. using a variety of user defined test circuits. Anti-reverse diodes D1 and D2 protect the circuit in the case of accidental polarity reversal. The ISL281X7 operational amplifiers feature low bias current, low noise, and low offset and temperature drift. V- V+ VREF Reference Documents ISL28107 Data Sheet, FN6631 C2 C4 ISL28117 Data Sheet, FN6632 4. 7 F 4. 7 F ISL28127 Data Sheet, FN6633 D1 D2 S1 A B S1AB Evaluation Board Key Features The ISL281X7SOICEVAL1Z is designed to enable the FIGURE 1. POWER SUPPLY CIRCUIT IC to operate from a single supply, +4.5VDC to Amplifier Configuration +40VDC or from split supplies, 2.25VDC to 20V. The board is configured for a single op amp (Figure 2) connected for differential input with a closed loop The schematic of 1/2 of the op-amp with the gain of 10. A single external reference voltage components supplied is shown in Figure 2. The (VREF) pin and provisions for a user-selectable circuit implements a differential input amp with a voltage divider-filter are included. closed loop gain of 10. The circuit can operate from a single supply or from dual supplies. The VREF pin Power Supplies (Figure 1) must be connected to ground to establish a ground External power connections are made through the referenced input for dual supply operation, or can be +V, -V, VREF and Ground connections on the externally set to any reference level for single supply evaluation board. For single supply operation, the -V operation. VREF should not be left floating. and Ground pins are tied together to the power RF ISL281X7 100k IN - VP RIN- IN- - IN- 0 V+ 10k VOUT V- RIN+ IN+ + IN+ 10k VM IN + RL VCM RREF+ VREF DNP 100k GND VREF FIGURE 2. BASIC AMPLIFIER CONFIGURATION AN1508 Rev 0.00 Page 1 of 5 November 9, 2009 R4 DNP R16 DNPISL281X7SOICEVAL1Z The outputs (Figure 4) have additional resistor and User-selectable Options capacitor placements for filtering and loading. (Figures 3 and 4) NOTE: Operational amplifiers are sensitive to output Component pads are included to enable a variety of capacitance and may oscillate. In the event of user-selectable circuits to be added to the amplifier oscillation, reduce output capacitance by using shorter VREF, inputs, outputs, and the amplifier feedback cables, or add a resistor in series with the output. loops. The Inputs (Figure 3) have additional resistor and capacitor, and jumper placements for loading and/or measurement of frequency sensitive parameters. IN- IN+ NODE OUT R8 R10 DNP DNP J1 R5 R9 R11 R1 0 10k 100k C3 R18 DNP To Output J12 OPEN To IN- 0 J2 R14 R12 To IN+ R2 10k VREF DNP R15 R13 DNP 100k FIGURE 3. INPUT STAGE FIGURE 4. OUTPUT STAGE TABLE 1. ISL281X7SOICEVAL1Z COMPONENTS PARTS LIST DEVICE DESCRIPTION COMMENTS C2, C4 CAP, SMD, 0805, 4.7F, 50V, 10%, X7R, ROHS Power Supply Decoupling C1, C5 CAP, SMD, 0603, 0.01F, 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 (ISL28107FBZ) OP AMP, SOIC, ROHS U1 (ISL28117FBZ) OP AMP, SOIC, ROHS U1 (ISL28127FBZ) OP AMP, SOIC, ROHS R1-R4, R6-R8, R10, R13, RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER User selectable resistors - not populated R14, R16, R17, R19, R20 R5, R18 RES, SMD, 0603, 0 , 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 AN1508 Rev 0.00 Page 2 of 5 November 9, 2009 R3 DNP R7 R6 DNP DNP R14 DNP C6 OPEN R17 DNP