J14 J13 J12 J11 2 3 1 J8 J6 USERS MANUAL ISL28210SOICEVAL1Z AN1594 Rev 0.00 Evaluation Board Users Guide Oct 1, 2010 Introduction Power Supplies (Figure 1) The ISL28210SOICEVAL1Z evaluation board is designed External power connections are made through the V+, to evaluate the performance of the ISL28210 Precision V-, VREF, and GND connections on the evaluation board. Low Noise JFET Operational Amplifier. The ISL28210 is a The circuit can operate from a single supply or from dual dual JFET amplifier that features low noise, high slew supplies. For single supply operation, the V- and GND rate, low input bias current and low offset voltage. With a pins are tied together to the negative or ground wide operating range from 9V to 40V, in combination with reference of the power supply. For split supplies, V+ and its high precision, low noise and high speed operation, V- terminals connect to their respective supply terminals. the ISL28210 is ideal for precision medical and De-coupling capacitors C2 and C4 provide low-frequency instrumentation, sensor conditioning, power supply power-supply filtering, while additional capacitors, C3 control and photodiode amplifiers. and C5, which are connected close to the part, filter out high frequency noise. Anti-reverse diode D1 (optional) Reference Documents protects the circuit in the momentary case of accidentally reversing the power supplies to the evaluation board. ISL28210 Data Sheet, FN6639 The VREF pin can be connected to ground to establish a ground referenced input for split supply operation, or can Evaluation Board Key Features be externally set to any reference level for single supply Single Supply Operation: +9V to +40V operation. Dual Supply Operation: 4.5V to 20V Singled-Ended or Differential Input Operation VREF V- V+ External VREF input 3 3 2 2 Banana Jack Connectors for Power Supply and VREF Inputs BNC Connectors for Op Amp Input and Output C2 C4 Terminals 1F 1F 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 INA- 2 +4.5V R11/R24 8 INB- 6 TO +20V - V+ 1/7 10k ISL28210 V OUT INA+ 3 V- R14/R21 INB+ 5 + PRECISION 10k SENSOR GAIN = -10V/V 4 R18/R19 -4.5V TO -20V 100k V REF FIGURE 2. PRECISION AMPLIFIER WITH G = -10V/V AN1594 Rev 0.00 Page 1 of 5 Oct 1, 2010 1 2 1 R16 0 1 1 R31 2 1 1 0 1 1ISL28210SOICEVAL1Z The output (Figure 4) also has additional resistor and Amplifier Configuration (Figure 3) capacitor placements for filtering and loading. The schematic of the op amp input stage with the components supplied is shown in Figure 3, with a closed NOTE: Operational amplifiers are sensitive to output loop gain of 10V/V. The differential amplifier gain is capacitance and may oscillate. In the event of oscillation, expressed in Equation 1: reduce output capacitance by using shorter cables, or (EQ. 1) V = V V R R + V add a resistor in series with the output. OUT IN+ IN- F IN REF For single-ended input with an inverting gain G = -10V/V, C1 the IN+ input is grounded and the signal is supplied to the OPEN IN- input. VREF can be connected to a reference voltage R4 R11 R13 FROM V OUTA IN-A J1 between the V+ and V- supply rails. For non-inverting R1 0 10k 100k operation with G = 11V/V, the IN- input is grounded and DNP the signal is supplied to the IN+ input. The non-inverting TO INA - gain is strongly dependent on any resistance from IN- to GND. For good gain accuracy, a 0 resistor should be R14 TO INA + IN+A J2 installed on the empty R5 pad. R2 10k DNP VREF User-selectable Options R15 R18 DNP 100k (Figures 3 and 4) FIGURE 3. INPUT STAGE Component pads are included to enable a variety of user-selectable circuits to be added to the amplifier inputs, the VREF input, outputs and the amplifier feedback loops. R26 V J15 OUT A OUT A A voltage divider (Figure 3, R18 and R15) can be added 0 to establish a power supply-tracking common mode C6 reference using the VREF input. The inverting and non- OPEN inverting inputs have additional resistor placements for adding input attenuation, or to establish input DC offsets FIGURE 4. OUTPUT STAGE through the VREF pin. TABLE 1. ISL28210SOICEVAL1Z 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 D1 40V DUAL SERIES SCHOTTKY BARRIER DIODE Reverse Power Protection 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 U1 (ISL28210FBZ) ISL28210FBZ, IC PRECISION LOW NOSIE JFET OP AMP, SOIC, ROHS AN1594 Rev 0.00 Page 2 of 5 Oct 1, 2010 C8 OPEN R5 R28 DNP DNP