USERS MANUAL ISL281x8EVAL1Z AN1350 Rev 0.00 Evaluation Board Aug 14, 2007 and V- terminals connect to their respective power supply Introduction terminals. De-coupling capacitors C andC connect to 1 2 The ISL281x8EVAL1Z evaluation board is a design platform ground through R and R 0 resistors. Resistors R and 1 21 20 containing all the circuitry needed to characterize critical R are 0 but can be changed by the user to provide 24 performance parameters of the ISL281x8 operational additional power supply filtering, or to reduce the voltage amplifiers, using a variety of user defined test circuits. rate-of-rise to less than 1V/s. Two additional capacitors, The ISL28138 and ISL28148 high-speed operational C and C are connected close to the part to filter out high 3 4 amplifiers feature low power consumption, while the frequency noise. Anti-reverse diodes D and D protect the 1 2 ISL28158 and ISL28168 operational amplifiers feature circuit in the case of accidental polarity reversal. ultra-low power consumption. All op amps have rail-to-rail output drive capability and are designed to operate with a V- V+ single lithium cell or two Ni Cd batteries. C2 R21 R1 C1 ++ 0 0 4.7F 4.7F Reference Documents D2 D1 ISL28138 Data Sheet, FN6336 ISL28148 Data Sheet, FN6337 C4 C3 0.1F 0.1F ISL28158 Data Sheet, FN6377 ISL28168 Data Sheet, FN6378 VM VP Evaluation Board Key Features FIGURE 1. POWER SUPPLY CIRCUIT The ISL281x8EVAL1Z is designed to enable the IC to operate from a single supply, +2.4VDC to +5.5VDC or from Amplifier Configuration (Figure 2) split supplies, 1.2VDC to 2.75V. The board is configured The schematic of the op amp with the components supplied for a single op amp connected for differential input with a is shown in Figure 2. The circuit implements a differential closed loop gain of 10. It also contains a single external input amp with a closed loop gain of 10. The circuit can reference voltage (VREF) pin and provisions for a operate from a single supply or from dual supplies. The user-selectable voltage divider (filter are included). VREF pin can be connected to ground to establish a ground referenced input for split supply operation, or can be Power Supplies (Figure 1) externally set to any reference level for single supply External power connections are made through the V+, V- operation. and 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 ISL281x8 100k IN - VP RIN- IN- - IN- 0 V+ 10k VOUT V- RIN+ IN+ IN+ + VM 10k IN+ RL VCM RREF+ VREF 10k 100k 0 10k GND VREF FIGURE 2. BASIC AMPLIFIER CONFIGURATION AN1350 Rev 0.00 Page 1 of 5 Aug 14, 2007 R20 J3 0 J2 R24 J1 0ISL281x8EVAL1Z The output (Figure 4) has a 10k load resistor to ground, User-selectable Options (Figures 3 and 4) and has additional resistor and capacitor placements for Component pads are included to enable a variety of loading. user-selectable circuits to be added to the amplifier inputs, the VREF input, outputs and the amplifier feedback loops. NOTE: Operational amplfiers are sensitive to output capacitance and may oscilate. In the event of oscilation, A voltage divider and filter option (Figure 3) can be added to reduce output capacitance by using shorter cables, or add a establish a power supply-tracking common mode reference resistor in series with the output. 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. REF1 RINA- R10 RREF RREFA- 0 R5 C6 R15 J6 IN- R22 R26 TO OUT J5 DNP OUT 10k OPEN RINA2- 0 0 RINA1+ RREFA+ R7 R14 J7 IN1+ 10k RINA+ 100k C7 R11 TO IN- OPEN 0 R6 C10 J8 TO IN+ IN2+ DNP OPEN RINA2+ RGA+ FIGURE 3. 1/2 INPUT STAGE FIGURE 4. 1/2 OUTPUT STAGE ISL281x8EVAL1Z Components Parts List DEVICE NUMBER DESCRIPTION COMMENTS C1, C2, C5 CAP-TANTALUM,S MD, D, 4.7F, 50V, 10%, LOW ESR, ROHS Power Supply Decoupling C3, C4 CAP, SMD, 0603, 0.1F, 25V, 10%, X7R, ROHS Power Supply Decoupling C6 to 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 (ISL28138EVAL1Z) ISL28138FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS U1 (ISL28148EVAL1Z) ISL28148FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS U1 (ISL28158EVAL1Z) ISL28158FHZ-T7, IC-RAIL-TO-RAIL OP AMP, SOT-23, ROHS U1 (ISL28168EVAL1Z) ISL28168FHZ-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 User-selectable resistors - not R15, R16, R23, R25, R27 populated R1, R10, R11, R17, R20, R21, RES, SMD, 0603, 0 , 1/10W, TF, ROHS 0 user selectable resistors R24, R26, R22 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 AN1350 Rev 0.00 Page 2 of 5 Aug 14, 2007 R3 R2 DNP DNP R9 R8 DNP DNP R12 DNP R13 DNP R18 R17 J4 0 10k C5 + 4.7F C8 OPEN R23 C9 OPEN DNP R25 10k R27 DNP