ISL28196EVAL1Z, ISL28197EVAL1Z Evaluation Board User’s Guide ® Application Note September 25, 2008 Introduction AN1426.0 power supply terminals. De-coupling capacitors C1 and C2 connect to ground through R1 and R21 0Ω resistors. Resistors R20 and R24 are 0Ω but can be changed by the user to provide additional power supply filtering, or to reduce the voltage rate-of-rise to less than ±1V/µs. Two additional capacitors, C3 and C4 are connected close to the part to filter out high frequency noise. Anti-reverse diodes D1 and D2 protect the circuit in the case of accidental polarity reversal. The ISL2819xEVAL1Z evaluation board is a design platform containing all the circuitry needed to characterize critical performance parameters of the ISL28196 and ISL28197 comparators, using a variety of user defined test circuits. The ISL28196 and ISL28197 are CMOS comparators featuring low supply currents (2.5uA and 0.8uA respectively), low input bias currents (15pA), rail-to-rail input and output drive capability, and are designed to operate with two 1.5V Alkaline batteries. Comparator Configuration (Figure 2) C4 J1 V- The ISL2819xEVAL1Z is designed to enable the IC to operate from a single supply, +1.8VDC to +5.5VDC or from split supplies, ±0.9VDC to ±2.75V. The board is configured for a single comparator. An external reference voltage (VREF) pin provides the capability to adjust comparator threshold level. C2 R21 R1 C1 4.7µF 0 0 4.7µF D2 D1 V+ 0 Evaluation Board Key Features R24 • ISL28196, ISL28197 Data Sheet, FN6152 J3 Reference Documents 0 • ISL28197EVAL1Z R20 • ISL28196EVAL1Z J2 The schematic of the comparator with the components supplied is shown in Figure 2. Resistors R12 and R15 form a high resistance voltage divider with a current draw of only 250nA at VREF = 5V. At this level, the low bias current (15pA) adds only 75µV of error to the comparator threshold level of 2.5V. Resistors R5 and R6 form high impedance inputs to prevent loading of the input signal. Ordering Information C3 0.1µF 0.1µF Power Supplies (Figure 1) VM External power connections are made through the +V, -V, VREF 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 and -V terminals connect to their respective VP FIGURE 1. POWER SUPPLY CIRCUIT V+ VREF R15 10M R5 10M - R22 + IN- 0 ISL28196 or ISL28197 R7 1M IN+1 R6 10M IN+2 R12 10M V- FIGURE 2. EQUIVALENT CIRCUIT SCHEMATIC 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2008. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1426 User-selectable Options (Figures 3, 4) Comparator with Hysteresis (Figure 5) Component pads are included to enable a variety of user-selectable circuits to be added to the comparator inputs, the VREF input, and comparator output. A positive feedback hysteresis loop can be created by a connection between the output and one of the non-inverting inputs (IN1+ or IN2+). The other non-inverting input can be used to set the comparator’s threshold level. The ratio of R6 and R7 can be used to select the desired hysteresis level. Since IN-, in this case, becomes the comparator’s signal input, R12 and R15 will have to be removed. A voltage divider and filter option (Figure 4) can be added to establish a power supply-tracking common mode reference 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. J4 The output (Figure 5) has additional resistor and capacitor placements for loading. RREF FIGURE 3. INPUT STAGE J5 R27 OUT DNP DNP R25 DNP 0 TO IN + OPEN FIGURE 4. OUTPUT STAGE V+ VREF DNP = DO NOT POPULATE VIN (COMPARATOR INPUT) 0 OPEN TO IN C10 R13 10M 0 R26 R23 R6 R9 R3 DNP J8 DNP R11 DNP OPEN C8 1M C7 IN2+ R14 R7 DNP J7 R22 IN- R5 10M IN1+ R7 1M IN2+ R6 10M R15 DNP - IN1+ OPEN TO OUT C9 C5 4.7µF 0 DNP 10M R17 R15 OPEN 10M 0 C6 R12 R5 10M R8 R2 J6 DNP IN- DNP R10 R18 REF1 R22 VOUT 0 + VTH (COMPARATOR THRESHOLD LEVEL) ISL28196 OR ISL28197 R12 DNP EXTERNAL CONNECTION V- FIGURE 5. COMPARATOR WITH HYSTERESIS 2 AN1426.0 September 25, 2008 Application Note 1426 ISL2819xEVAL1Z Components Parts List DEVICE # DESCRIPTION COMMENTS C1,C2, C5 CAP-TANTALUM, SMD, D, 4.7µF, 50V,10%.LOW ESR, ROHS Power Supply Decoupling C3, C4 CAP, SMD, 0603, 0.1µF, 25V,10%, X7R, ROHS Power Supply Decoupling C6-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 (ISL28196EVAL1Z) ISL28196FHZ-T7, IC-RAIL-TO-RAIL COMPARATOR, SOT-23, ROHS U1 (ISL28197EVAL1Z) ISL28197FHZ-T7, IC-RAIL-TO-RAIL COMPARATOR, SOT-23, ROHS R2, R3, R8, R9, R13, R14, RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER R16, R18, R19, R23, R25, R27 User-selectable resistors - not populated R1, R10, R11, R17, R20, R21, RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS R22, R24, R26 0Ω user-selectable resistors R4 RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS Gain and other user-selectable resistors R7 RES, SMD, 0603, 1M, 1/10W, 1%, TF, ROHS Input resistors R5, R6, R12, R15 RES, SMD, 0603, 10M, 1/10W, 1%, TF, ROHS Input resistors 3 AN1426.0 September 25, 2008 Application Note 1426 FIGURE 6. ISL2819xEVAL1Z TOP VIEW Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 4 AN1426.0 September 25, 2008 J4 4.7µF 0 0 C1 0 R20 4.7µF 4.7µF D1 D2 DNP C5 10M OPEN C4 C3 0.1µF R19 OPEN DNP 10k 2 S1 3 ENABLE VP 1 VM DNP 4 ISL28196/7 DISABLE FIGURE 7. ISL2819xEVAL1Z SCHEMATIC DIAGRAM J5 DNP R27 5 +- DNP 2 3 VP 6 R25 1 DNP R4 0 R23 R16 DNP 0 C9 U1 J9 R26 OUT VM EN R22 RGA+ OPEN R9 C10 DNP R3 10M RINA2+ 0 VP C8 OPEN R6 J8 VM DNP RINA+ R11 DNP 1M R13 C7 RREFA+ R14 Application Note 1426 IN2+ RINA1+ R7 J7 DNP IN1+ DNP 0.1µF OPEN R8 RINA2- DNP R2 5 DNP 10M R18 C6 10M J6 R1 RREFAR15 R12 IN- R5 R21 RREF R24 0 C2 V+ 0 R17 0 RINAR10 J1 V- J2 J3 REF1 AN1426.0 September 25, 2008