J14 J13 J12 J11 2 3 1 J8 J6 USERS MANUAL ISL28218SOICEVAL1Z AN1595 Rev 0.00 Evaluation Board Users Guide Oct 27, 2010 Introduction Power Supplies (Figure 1) The ISL28218SOICEVAL1Z evaluation board is designed to External power connections are made through the V+, evaluate the performance of the ISL28218 40V Precision V-, VREF, and GND connections on the evaluation board. Low Power Operational Amplifier. The ISL28218 is a single The circuit can operate from a single supply or from dual supply rail-to-rail output, dual amplifier with ground sensing supplies. For single supply operation, the V- and GND inputs that allow the common mode input voltage to swing pins are tied together to the negative or ground 0.5V below the V- rail. The ISL28218 can operate from a reference of the power supply. For split supplies, V+ and single or dual supply with a 3V to 40V supply range. The V- terminals connect to their respective supply terminals. ISL28218 features very low power, low offset voltage and De-coupling capacitors C2 and C4 provide low-frequency low temperature drift making them ideal for applications for power-supply filtering, while additional capacitors, C3 precision medical and instrumentation, current sensing and and C5, which are connected close to the part, filter out power supply and industrial process controls. high frequency noise. Anti-reverse diode D1 (optional) protects the circuit in the momentary case of accidentally Reference Documents reversing the power supplies to the evaluation board. The VREF pin can be connected to ground to establish a ISL28218 Datasheet, FN7532 ground referenced input for split supply operation, or can be externally set to any reference level for single supply Evaluation Board Key Features operation. Single Supply Operation: +3V to +40V Dual Supply Operation: 1.5V to 20V V- V+ VREF Singled-Ended or Differential Input Operation 3 3 External VREF input 2 2 Banana Jack Connectors for Power Supply and VREF Inputs C2 C4 BNC Connectors for Op Amp Input and Output 1F 1F Terminals Convenient PCB pads for Op Amp Input/Output impedance loading. D1 CLOSE TO DUT C3 C5 0.01F 0.01F FIGURE 1. POWER SUPPLY CIRCUIT R13/R23 100k LOAD INA- 2 +3V TO 40V 8 R11/R24 INB- 6 - V+ 1/7 10k ISL28218 V R OUT SENSE 3 INA+ V- R14/R21 INB+ 5 + 4 10k GAIN = 10V/V R18/R19 100k V REF FIGURE 2. CURRENT SENSE AMPLIFIER AN1595 Rev 0.00 Page 1 of 5 Oct 27, 2010 R16 1 2 1 0 1 1 R31 1 2 1 0 1 1ISL28218SOICEVAL1Z Amplifier Configuration User-selectable Options (Figure 3) (Figures 3 and 4) The schematic of the op amp input stage with the Component pads are included to enable a variety of components supplied is shown in Figure 3, with a closed user-selectable circuits to be added to the amplifier loop gain of 10V/V. The differential amplifier gain is inputs, the VREF input, outputs and the amplifier expressed in Equation 1: feedback loops. A voltage divider (Figure 3, R18 and R15) can be added (EQ. 1) V = V V R R + V OUT IN+ IN- F IN REF to establish a power supply-tracking common mode reference using the VREF input. The inverting and For single-ended input with an inverting gain G = -10V/V, non-inverting inputs have additional resistor placements the IN+ input is grounded and the signal is supplied to the for adding input attenuation, or to establish input DC IN- input. VREF can be connected to a reference voltage offsets through the VREF pin. between the V+ and V- supply rails. For non-inverting The output (Figure 4) also has additional resistor and operation with G = 11V/V, the IN- input is grounded and capacitor placements for filtering and loading. the signal is supplied to the IN+ input. The non-inverting gain is strongly dependent on any resistance from IN- to NOTE: Operational amplifiers are sensitive to output GND. For good gain accuracy, a 0 resistor should be capacitance and may oscillate. In the event of oscillation, installed on the empty R5 pad. reduce output capacitance by using shorter cables, or C1 add a resistor in series with the output. OPEN R26 OUT A R4 R11 R13 J15 FROM V OUTA V J1 IN-A OUT A 0 R1 0 10k 100k C6 DNP OPEN TO INA - R14 FIGURE 4. OUTPUT STAGE TO INA + J2 IN+A R2 10k DNP VREF R15 R18 DNP 100k FIGURE 3. INPUT STAGE TABLE 1. ISL28218SOICEVAL1Z COMPONENTS PARTS LIST DEVICE DESCRIPTION COMMENTS C2, C4 CAP, SMD, 1206, 1F, 50V, 10%, X7R, ROHS Power Supply Decoupling C3, C5 CAP, SMD, 0603, 0.01F, 50V, 10%, X7R, ROHS Power Supply Decoupling C1, C6, C7, C8, C9, C10 CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS User selectable capacitors - not populated R11, R14, R21, R24 RESISTOR, SMD, 0603, 10k, 1%, 1/16W, ROHS Gain Setting Resistor R13, R23 RESISTOR, SMD, 0603, 100k, 1%, 1/16W, ROHS Gain Setting Feedback Resistor R1-R3, R5-R8, R10, R12, RESISTOR, SMD, 0603, DNP-PLACE HOLDER, ROHS User selectable resistors - not populated R15, R17, R20, R22, R28- R30, R32, R34-R36 D1 40V DUAL SERIES SCHOTTKY BARRIER DIODE Reverse Power Protection U1 (ISL28218FBZ) ISL28218FBZ, IC 40V RAIL-TO-RAIL OP AMP, SOIC, ROHS AN1595 Rev 0.00 Page 2 of 5 Oct 27, 2010 R5 DNP C8 OPEN R28 DNP