USERS MANUAL ISL28233SOICEVAL1Z AN1596 Rev 0.00 Evaluation Board Users Guide Oct 5, 2010 Banana Jack Connectors for Power Supply and VREF Introduction Inputs The ISL28233SOICEVAL1Z Evaluation Board is designed to evaluate the performance of the ISL28233 Chopper BNC Connectors for Op Amp Input and Output Stabilized op amp. The evaluation board contains the Terminals circuitry needed to evaluate the high performance of the Convenient PCB pads for Op Amp Input/Output ISL28233 amplifier. The ISL28233 chopper stabilized impedance loading. rail-to-rail dual op amp features a low 8V maximum V over-temperature and a 0.1Hz 1/f noise corner OS Power Supplies (Figure 2) frequency enabling very high gain single-stage DC External power connections are made through the V+, amplifiers that can operate from single cell batteries V-, VREF, and GND connections on the evaluation board. while consuming only 20A of current. The The circuit can operate from a single supply or from dual ISL28233SOICEVAL1Z evaluation board can be supplies. For single supply operation, the V- and GND configured as a precision high-gain (G = 10,000V/V) pins are tied together to the negative or ground differential amplifier and demonstrates the level of reference of the power supply. For split supplies, V+ and performance possible with this type of amplifier while V- terminals connect to their respective supply terminals. operating from battery voltages as low as 1.65V. De-coupling capacitors C2 and C4 provide low-frequency power-supply filtering, while additional capacitors, C3 Reference Documents and C5, which are connected close to the part, filter out ISL28233 Data Sheet high frequency noise. Anti-reverse diode D1 (optional) protects the circuit in the momentary case of accidentally Evaluation Board Key Features reversing the power supplies to the evaluation board. Single Supply Operation: +1.65V to +5.5V The VREF pin can be connected to ground to establish a ground referenced input for split supply operation, or can Dual Supply Operation: 0.825V to 2.75V be externally set to any reference level for single supply Singled-Ended or Differential Input Operation with operation. High Gain (G = 10,000V/V) External VREF input R13/R23 1M 8 INA- 2 V+ IN - R11/R24 INB- 6 - IN- 0 100 1/7 ISL28233 OUT 3 INA+ R14/R21 R26/R27 INB+ 5 + IN+ 100 IN + V- 4 VCM R18/R19 R28/R29 100k VREF OPEN R15/R22 VREF OPEN GND FIGURE 1. BASIC DIFFERENTIAL AMPLIFIER CONFIGURATION AN1596 Rev 0.00 Page 1 of 5 Oct 5, 2010J14 J13 J12 J11 2 3 1 J8 J6 ISL28233SOICEVAL1Z V- V+ VREF User-Selectable Options 3 3 (Figures 3 and 4) 2 2 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. C2 C4 1F 1F A voltage divider (Figure 3, R18 and R15) can be added to establish a power supply-tracking common mode reference using the VREF input. The inverting and D1 non-inverting inputs have additional resistor placements CLOSE TO DUT for adding input attenuation, or to establish input DC C3 C5 offsets through the VREF pin. 0.01F 0.01F The output (Figure 4) also has additional resistor and FIGURE 2. POWER SUPPLY CIRCUIT capacitor placements for filtering and loading. NOTE: Operational amplifiers are sensitive to output Amplifier Configuration (Figure 3) capacitance and may oscillate. In the event of oscillation, reduce output capacitance by using shorter cables, or The schematic of the op amp input stage with the add a resistor in series with the output. components supplied is shown in Figure 3, with a closed loop gain of 10,000. The circuit implements a Hi-Z C6 differential input with unbalanced common mode OPEN impedance. The differential amplifier gain is expressed in R4 R11 R13 FROM OUTA J1 Equation 1: IN-A R1 0 100 1M DNP (EQ. 1) V = V V R R + V OUT IN+ IN- F IN REF TO INA - For single-ended input with an inverting gain R14 G = -10,000V/V, the IN+ input is grounded and the TO INA + J2 IN+A R2 signal is supplied to the IN- input. VREF must be 100 DNP connected to a reference voltage between the V+ and VREF R15 R18 V- supply rails. For non-inverting operation with DNP 100k G = 10,001V/V, the IN- input is grounded and the signal is supplied to the IN+ input. The non-inverting FIGURE 3. INPUT STAGE gain is strongly dependent on any resistance from IN- to GND. For good gain accuracy, a 0 resistor should be installed on the empty R5 pad. R26 J12 OUT A 0 OUT A C6 FIGURE 4. OUTPUT STAGE TABLE 1. ISL28233SOICEVAL1Z 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, 100, 1%, 1/16W, ROHS Gain Setting Resistor R13, R23 RESISTOR, SMD, 0603, 10M, 1%, 1/16W, ROHS Gain Setting Feedback Resistor R1-R3, R5-R8, R10, R12, R15, RESISTOR, SMD, 0603, DNP-PLACE HOLDER, ROHS User selectable resistors - not populated R17, R20, R22, R28, R29, R30, R32, R34, R35, R36 D1 40V SERIES SCHOTTKY BARRIER DIODE Reverse Power Protection U1 (ISL28233FBZ) ISL28233FBZ, IC-RAIL-TO-RAIL OP AMP, SOIC, ROHS AN1596 Rev 0.00 Page 2 of 5 Oct 5, 2010 R16 1 2 1 0 1 1 R31 1 2 1 0 1 1 C8 OPEN R28 R5 DNP DNP