MAX44267EVKIT#

Evaluates: MAX44267 MAX44267 Evaluation Kit General Description The MAX44267 evaluation kit (EV kit) provides a proven design to evaluate the MAX44267 Beyond-the-Rails™ precision, low-noise, low-drift, dual operational amplifier (op-amp) in a 14-pin TSSOP package. The EV kit circuit is preconfigured as noninverting amplifiers, but can be adapted to other topologies by changing a few components. The EV kit comes with a MAX44267AUD+ installed. Features and Benefits ●● Accommodate Multiple Op-Amp Configuration ●● Up to ±12.5V with a Single Supply (+2.25V to +15V) ●● True Zero Output from a Single Supply ●● Proven PCB Layout ●● Fully Assembled and Tested Ordering Information appears at end of data sheet. Quick Start Required Equipment ●● MAX44267 EV kit ●● 12V DC power supply ●● Two precision voltage sources ●● Two digital multimeters (DMMs) Procedure The EV kit is fully assembled and tested. Follow the steps below to verify board operation: 1) Verify that all jumpers (JU1–JU5) are in their default positions, as shown in Table 1. 2) Connect the positive terminal of the +12V supply to the VDD test point and the negative terminal to the GND test point. 3) Connect the positive terminal of the precision voltage source to INAP test point. Connect the negative terminal of the precision voltage source to the GND test point. INAM is already connected to GND via JU1. 4) Connect the positive terminal of the second precision voltage source to the INBP test point. Connect the negative terminal of the precision voltage source to the GND test point. INBM is already connected to GND via JU3. 5) Connect the DMMs to monitor the voltages on OUTA and OUTB test points. With the 10kΩ feedback resistors and 1kΩ series resistors, the gain of the noninverting amplifier is +11V/V. 6) Turn on the power supply. 7) Set the precision voltage sources to 100mV and enable. Observe the output at OUTA and OUTB on the DMMs. Both should read approximately +1.1V. 8) Disable the precision voltage sources and supply. 9) Remove shunts from JU1 and JU3, and install shunts on jumper JU2 and JU4. The gain of the inverting amplifier is -10V/V. 10) Apply each precision voltage source to INAM and INBM test points. Beyond-the-Rails is a trademark of Maxim Integrated Products, Inc. 19-7520; Rev 0; 2/15 11) Enable the precision voltage sources. Observe the output at OUTA and OUTB on the DMMs. Both should read approximately -1.0V. Evaluates: MAX44267 MAX44267 Evaluation Kit Detailed Description of Hardware The MAX44267 precision, low-noise, low-drift dual operational amplifier offers true-zero output that allows the output to cross zero and maximize the dynamic range of an ADC and increase resolution. Op Amp Configurations The MAX44267 is a single-supply, dual op amp that is ideal for differential sensing, noninverting amplification, buffering, and filtering. A few common configurations are shown in the next few sections. The following sections explain how to configure one of the device’s op amps (op amp A). To configure the device’s second op amp (op amp B), the same equations can be used after modifying the component reference designators. filter and buffer operations. The MAX44267 EV kit can be configured in a Sallen-Key topology by replacing and populating a few components. The Sallen-Key topology can be configured as a unity-gain buffer by replacing R5 with a 0Ω resistor and removing resistor R1. The signal is noninverting and applied to INAP. The filter component pads are R2–R4 and R8, where some have to be populated with resistors and others with capacitors. Lowpass Filter: To configure the Sallen-Key as a lowpass filter, remove jumper JU1, populate the R2 and R8 pads with resistors and populate the R3 and R4 pads with capacitors. The corner frequency and Q are then given by: fC = Noninverting Configuration The MAX44267 EV kit comes preconfigured as a noninverting amplifier. The gain is set by the ratio of R5 and R1. The MAX44267 EV kit comes preconfigured for a gain of +11V/V. The output voltage for the noninverting configuration is given by the equation below: R5 VOUTA = (1 + ) VINAP ± VOS  R1  Inverting Configuration To configure the EV kit as an inverting amplifier, remove the shunt on JU1 and install a shunt on jumper JU2 and feed an input signal on the INAM pad. = VOUTA A V (VINAP − VINAM ) Q= www.maximintegrated.com C R3 ( R R2 + R R8 ) R R3 R R4 C R2 C R8 R R4 ( C R2 + C R8 ) Bandpass Filter: To configure the Sallen-Key as a bandpass filter, remove jumper JU1, replace R8, populate R3 and R4 pads with resistors and populate C8 and R2 pads with capacitors. The corner frequency and Q are then given by: fC = R5 R3 A= = V R1 R2 The Sallen-Key topology is ideal for filtering sensor signals with a second-order filter and acting as a buffer. Schematic complexity is reduced by combining the R R2 R R8 C R3 C R 4 Highpass Filter: To configure the Sallen-Key as a highpass filter, remove jumper JU1, populate the R3 and R4 pads with resistors and populate the R2 and R8 pads with capacitors. The corner frequency and Q are then given by: 1 fC = 2 π R R3 R R4 C R2 C R8 where the gain is: Sallen-Key Configuration 2 π R R2 R R8 C R3 C R4 Q= Differential Amplifier To configure the MAX44267 EV kit as a differential amplifier, replace R1, R2, R3, and R5 with appropriate resistors. When R1 = R2 and R3 = R5, the CMRR of the differential amplifier is determined by the matching of the resistor ratios R1/R2 and R3/R5. 1 Q= R R4 + R R8 1 2 π C C8 C R2 R R8 R R3 R R4 (R R4 + R R8 )C C8 C R2 R R8 R R3 R R4 R R5 R R4 R R8 C C8 + C R2 + R R3 C R2 ( R R4 − R ) R R1 R8 ( ) Maxim Integrated │  2 Evaluates: MAX44267 MAX44267 Evaluation Kit Transimpedance Amplifier To configure the MAX44267 EV kit as a transimpedance amplifier (TIA), place a shunt on jumper JU2, replace R1 and R2 with a 0Ω resistor. The output voltage of the TIA is the input current multiplied by the feedback resistor: VOUTA = −(IINAP + IBIAS ) × R R5 ± VOS where: IINAP is the input current source applied at the INAP test point IBIAS is the input bias current Use a capacitor at location R16 or R17 (and C8, if applicable) to stabilize the op amp by rolling off high-frequency gain due to a large cable capacitance. Capacitive Loads Some applications require driving large capacitive loads. The EV kit provides C8 and R6 pads for optional capacitive-load driving circuit. C8 simulates the capacitive load while R6 acts as isolation resistor to improve the op amp’s stability at higher capacitive loads. To improve the stability of the amplifier in such cases, replace R6 with a suitable resistor value to improve amplifier phase margin. VOS is the input offset voltage of the op amp Table 1. MAX44267 EV Kit Jumper Description JUMPER JU1 JU2 JU3 JU4 JU5 SHUNT POSITION Not Installed Installed* Not Installed* Installed Not Installed Installed* Not Installed* Installed Not Installed Installed* DESCRIPTION Disconnects INAM from GND Connects INA- to GND through R1 for noninverting configuration Disconnects INAP from GND Connects INA+ to GND through R2 Disconnects INBM from GND Connects INB- to GND through R9 for noninverting configuration Disconnects INBP from GND Connects INB+ to GND through R10 Disconnects CPVDD from VDD Connects CPVDD to VDD *Default position. www.maximintegrated.com Maxim Integrated │  3 5 4 3 2 INBM GND 1 5 4 3 2 INAM INBM 1 INAM GND 1 2 1 2 JU3 JU1 5 4 3 2 INBP GND 5 4 3 2 INAP 1 1 INBP GND INAP JU4 JU2 C12 SHORT (PC TRACE) C11 SHORT (PC TRACE) C5 SHORT (PC TRACE) C4 SHORT (PC TRACE) 0 0 C10 OPEN R10 R24 1K 1% R9 0 0 C3 OPEN R2 R8 1K 1% R1 R11 OPEN R3 OPEN C13 OPEN TP2 C6 OPEN TP1 CPGND CN CPVDD CPVSS INB+ INB- CP R12 OPEN C14 0.1UF 12 C20 10UF 0 R23 R21 OPEN U1-B MAX44267AUD+ OUTB C7 0.01UF CPVDD R22 OPEN C2 10UF 0 R19 R17 OPEN U1-A MAX44267AUD+ 1 C1 0.01UF OUTA GND C18 0.1UF R4 OPEN 10K 1% C17 0.022UF R13 R20 OPEN VDD VSS VSS INA+ INA- CPVSS 10 11 3 2 R18 OPEN 10K 1% VDD R5 R16 OPEN 7 1 2 1 2 14 6 8 4 13 5 www.maximintegrated.com 9 C15 OPEN R14 0 VSS CPVSS (PC CPVSS FB1 R7 OPEN 1 R15 OPEN VSS SHORT TRACE) CPVDD CPVDD C8 OPEN 0 R6 VDD 2 OUTA OUTB C21 10UF C16 SHORT (PC TRACE) JU5 C9 SHORT (PC TRACE) 2 3 4 5 OUTA 1 2 3 4 5 OUTB GND C19 0.01UF VDD 1 GND GND MAX44267 Evaluation Kit Evaluates: MAX44267 Figure 1. MAX44267 EV Kit Schematic Maxim Integrated │  4 Evaluates: MAX44267 MAX44267 Evaluation Kit 1.0’’ Figure 2. MAX44267 EV Kit Component Placement Guide— Component Side 1.0’’ Figure 3. MAX44267 EV Kit PCB Layout—Component Side www.maximintegrated.com Figure 4. MAX44267 EV Kit PCB Layout—Solder Side 1.0’’ Figure 5. MAX44267 EV Kit Component Placement Guide— Solder Side Maxim Integrated │  5 Evaluates: MAX44267 MAX44267 Evaluation Kit Component List Refer to the file “evkit_bom_max44267_evkit_a.csv” attached to this data sheet for component information. Ordering Information PART TYPE MAX44267EVKIT# EV Kit #Denotes RoHS compliant. www.maximintegrated.com Maxim Integrated │  6 Evaluates: MAX44267 MAX44267 Evaluation Kit Revision History REVISION NUMBER REVISION DATE 0 2/15 DESCRIPTION Initial release PAGES CHANGED — For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2015 Maxim Integrated Products, Inc. │  7