ISL2827xEVAL1Z Evaluation Board User’s Guide Application Note August 2, 2007 Introduction AN1345.0 C12 R46 R46 C12 + 00 4.7UF 4.7μF D2 D2 C10 C10 • ISL28276 Data Sheet, FN6301 0.1μF • ISL28278 Data Sheet, FN6145 1 MMBZ52xxB RF + IN (A, B) RIN- IN- IN- C16 C16 + DNP VP RIN+ IN+ 1/2 ISL2827x 100kΩ VP 0Ω V+ 10kΩ IN+ VOUT(x) V- + VM 10kΩ 10kΩ RREF (A, B)+ 0Ω C18 C18 0.1μF The schematic of each of the 2 op amps with the components supplied is shown in Figure 2. The circuit implements a differential input amp with a closed loop gain of 10. The circuit can operate from a single 2.4VDC to +5VDC supply, or from dual supplies from ±1.2VDC to ±2.5VDC. The VREF pin can be connected to ground to establish a ground referenced input for split supply operation, or can be externally set to any reference level for single supply operation. External power connections are made through the V+, Vand 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 power supply terminals. De-coupling capacitors C12, C17, connect to ground through R1, R46, 0Ω resistors. Resistors R40 and R49 are 0Ω but can be changed by the user to provide VREF R49 0 Amplifier Configuration (Figure 2) Power Supplies (Figure 1) VCM C17 C17 1 + 4.7UF 4.7μF D1 D1 2 V+ V+ FIGURE 1. POWER SUPPLY CIRCUIT The ISL2827xEVAL1Z is designed to enable the IC to operate from a single supply (+2.4VDC to +5VDC), or from split supplies (±1.2VDC to ±2.5V). The board is configured for 2 independent op amps connected for differential input with a closed loop gain of 10. A single external reference voltage (VREF) pin and provisions for a user-selectable voltage divider (filter is included). IN(A, B) + 1 0 VM Evaluation Board Key Features R1 R1 D3 D3 1 A A CC 33 2 NC NC R40 0 Reference Documents J1 1 1 R40 J2 R49 J3 V- The ISL2827x amplifiers feature low noise, low distortion, and rail-to-rail output drive capability. They are designed to operate with single and dual supplies from +5VDC (±2.5VDC) down to +2.4VDC (±1.2VDC). 1 The ISL2827xEVAL1Z evaluation board is a design platform containing all the circuitry needed to characterize critical performance parameters of the ISL28276 and ISL28278 dual operational amplifiers, using a variety of user defined test circuits. J3 additional power supply filtering, or to reduce the voltage rate-of-rise to less than ±1V/µs. Two additional capacitors, C10 and C18, are connected close to the part to filter out high frequency noise. Anti-reverse diodes D1, D2 and zener diode D3 protect the circuit in the case of accidental polarity reversal. 0 ® 100kΩ 0Ω TO OTHER CHANNEL VREF GND 10kΩ FIGURE 2. BASIC AMPLIFIER CONFIGURATION 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. 2007. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1345 User-Selectable Options (Figures 3 to 5) 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. The outputs (Figure 3) have additional resistor and capacitor placements for loading. 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. ROUTA R55 R55 R39 IN+ A DNP ENA 6 4 3 RFA, R45, 100k R36 DNP INA+ 5 V- 7 DNP R53 10K R57 DNP R51 1 DNP R44 ENB 11 IN+ B 2 C19 OPEN IN- A J15 J15 1 OUTA 2 34 5 0 R51 DNP R57 DNP 1 R53 10k C19 OPEN 2 OUT In the standard configuration (Figure5), R41 and R45 are RF feedback resistors for the two independent amplifiers, set for AV = 10. Resistors R47 and R48 connect the DUT output to the output circuit (Figure 3). The additional unpopulated components, R34 to R39, R42 to R44, C10, C11, C13 to C15 and C18 allow the user to configure the board for a variety of other applications such as cascaded gain stages, active feedback loops, etc. INB+ 12 R38 DNP R37 DNP + C13 CFA, DNP 4 INA3 OUTA R42 RGDIFF 15 V+ DNP + - 14 OUTB 13 INB- R47, 0 RSA C14 CLA DNP C15 CLB DNP OUT A OUT B RSB R48, 0 R43, DNP IN- B FIGURE 3. 1/2 OUTPUT STAGE 2 0 C9 C9 1 + 4.7μF R32 R32 R33 R33 10k R25 R25 2 100k 1 10K 10k C7 C7 1 R22 R22 OPEN OPEN ININ+ 2 R26 R26 R9 R9 RINA2+ RREFAR31 R31 100k RGA+ 1 DNP RINA+ RINA+ 0 DNP DNP RINA2+ 2 R3R3 3 4 1 2 2 RREF RREFA+ R30 R30 R18 R18 3 C3 C3 2 OPEN J8 1 RINA1+ R14 R14 2 2 DNP DNP RINA2RINA2- 1 RINAR21 R21 10k C6 C6 OPEN 1 1 INA2+ R8 R8 DNP DNP 1 4 INA1+ J7 J7 DNP 2 R2 R2 3 1 FIGURE 5. OPTICAL COMPONENTS 2 OPEN OPEN J6 J6 4 INA2- 1 100K 100k 1 R17 R17 2 DNP DNP 1 3 5 DNP DNP J5 4 INA1- R41, 100k C11 CFB, DNP VREF J4 J4 REF1 RE RINA1R13 R13 C2 2 0 C2 RFB1 FIGURE 4. 1/2 INPUT STAGE ISL2827xEVAL1Z Components Parts List DEVICE NUMBER C9, C12, C17 DESCRIPTION COMMENTS CAP-TANTALUM, SMD, D, 4.7µF, 50V, 10%, LOW ESR, ROHS Power supply decoupling C10, C18 CAP, SMD, 0603, 0.1µF, 25V, 10%, X7R, ROHS Power supply decoupling C6-C25 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 DIODE-ZENER, SMD, OD-123, 2P, 5.1V, 350mV, ROHS Reverse power protection D3 U1 (ISL28276EVAL1Z) ISL28276FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS U1 (ISL28278EVAL1Z) ISL28278FAZ, IC-RAIL-TO-RAIL PRECISION OP AMP, 16P, QSOP, ROHS R2-R5, R8-R10, R12, R16-R19, RESISTOR, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER R24-R27, R29, R31, R34-R39, R42-R44, R50-R52, R57, R58 User selectable resistors - not populated R1, R11, R13-R15, R24,R25, RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS R32, R40, R46-R49, R55, R56 0Ω user selectable resistors R6, R7, R20-R23, R33, R53, R54 RES, SMD, 0603, 10k, 1/10W, 1%, TF, ROHS RG gain resistors R28, R30, R41, R45 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS RF gain resistors 2 AN1345.0 August 2, 2007 Application Note 1345 ISL2827xEVAL1Z Top View 3 AN1345.0 August 2, 2007 4 INB2- INB1- INB2+ INB1+ ENB ENA INA2+ INA1+ INA2- INA1- (C6) DNP (C4) DNP (R10) DNP (R5) DNP (R12) RINB2- DNP (C1) (C8) DNP (C5) (10 k) (R20) RINB- (R24) DNP RGB- RREFB-(R29) DNP RGB+ (R27) DNP RINB+ (R23) (10 k) (R16) DNP RINB1- (R11) (0) (R4) DNP V+ RGA+ (R26) DNP RREFB+ (R28) (100 k) (R19) DNP RINB1+ (R15) (0) RINB2+ DNP (C7) (R18) DNP (R7) (10 k) (R6) (10 k) (R3) DNP DNP RINA+ (R22) (10 k) RINA2+ DNP (R9) RREFA+(R30) (100 k) (C3) DNP RGA(R25) DNP RREFA- (R31) DNP RINA- (R21) (10 k) (R17) DNP RINA1+ (R14) (0) (R2) DNP (R8) RINA2- DNP (C2) DNP RINA1- (R13) (0) (C10) V- (R32) RREF (R37) DNP 11 7 6 (0) 4.7uF (C9) (10 k) (R33) (R38) DNP INB+ 12 ENB V- ENA INA+ 5 (R36) DNP VREF (R35) DNP (R34) DNP (R39) DNP - - (0) 4.7uF (R43) DNP (C18) V- (0) (R40) (D2) GND 5.1V (C16) (D3) DNP + CFB DNP (C11) V+ 4.7uF (C17) (C15) CLB DNP DNP (C14) CLA V+ (0) (R49) (D1) (R42) RGDIFF DNP RFB1 (R41) (100 k) V- OUTB V+ OUTA INA- 13 INB- 14 15 3 4 (R46) (C12) + + CFA DNP (C13) RFA1 (R45) (100 k) (R44) DNP DNP (0) (R1) RSB (R48) (0) ROUTAB (R47) (0) RSA (C20) DNP (R52) DNP (R50) DNP (C19) DNP (R51) DNP (R54) (10 k) (R56) (0) ROUTB (R53) (10 k) (R55) (0) ROUTA (R58) DNP (R57) DNP OUTB OUTA Application Note 1345 ISL2827xEVAL1Z Schematic Diagram 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 AN1345.0 August 2, 2007