Evaluates: MAX44292/MAX44294 MAX44292 Evaluation Kit Procedure General Description The EV kit is fully assembled and tested. Follow the steps The MAX44292 evaluation kit (EV kit) provides a proven below to verify board operation: design to evaluate the MAX44292 ultra-precision, low- noise, low-drift dual-operational amplifier (op amp) in an 1) Verify that all jumpers (JU1JU4) are in their default 8-pin SO package. The EV kit circuit is preconfigured positions, as shown in Table 1. as noninverting amplifiers, but can be adapted to other 2) Connect the positive terminal of the +36V supply to topologies by changing a few components. VCC and the negative terminal to GND and VSS. 3) Connect the positive terminal of the precision voltage The EV kit comes with a MAX44292ASA+ installed. source to INAP. Connect the negative terminal of the The performance on this EV kit matches the single and precision voltage source to GND. INAM is already quad channels op amps within the same family. The connected to GND through jumper JU1. MAX44291AUA+ is the single version and is available in 4) Connect the positive terminal of the second precision the 8-pin MAX package. The MAX44294ASD+ is the voltage source to the INBP PCB pad. Connect the quad version and is available in the 14-pin SO package. negative terminal of the precision voltage source to GND. INBM is already connected to GND through Features and Benefits jumper JU3. Accommodates Multiple Op-Amp Configurations 5) Connect the DMMs to monitor the voltages on OUTA Component Pads Allow for Sallen-Key Filter and OUTB. With the 10k feedback resistors and Accommodates Easy-to-Use Components 1k series resistors, the gain of each noninverting amplifier is +11. Proven PCB Layout 6) Turn on the +36V power supply. Fully Assembled and Tested 7) Apply 100mV from the precision voltage sources. Observe the output at OUTA and OUTB on the DMMs. Both should read approximately +1.1V. 8) Apply 400mV from the precision voltage sources. Both Quick Start OUTA and OUTB should read approximately +4.4V. Required Equipment Note: For dual-supply operation, a 2.25V to 18V can be applied to VDD and VSS, respectively. MAX44292 EV kit +36V, 10mA DC power supply (PS1) Two precision voltage sources Two digital multimeters (DMMs) Ordering Information appears at end of data sheet. MAX is a registered trademark of Maxim Integrated Products, Inc. 19-7649 Rev 0 6/15Evaluates: MAX44292/MAX44294 MAX44292 Evaluation Kit V = GAIN(V V ) OUTA INAP INAM Detailed Description of Hardware The MAX44292 EV kit provides a proven layout for the where: MAX44292 ultra-precision, low-noise, low-drift, dual op R5 R3 GAIN amp. The device is a single/dual-supply, dual op amp (op R1 R2 amp A and op amp B) that is ideal for sensor interfaces, loop-powered systems, and various types of medical and Sallen-Key Configuration data-acquisition instruments. The Sallen-Key topology is ideal for filtering sensor sig- nals with a second-order filter and acting as a buffer. The default configuration for the device in the EV kit is single-supply operation in noninverting configuration. Schematic complexity is reduced by combining the filter and buffer operations. The EV kit can be configured in a However, the device can operate with a dual supply as long as the voltage across the V and GND pins of the IC do Sallen-Key topology by replacing and populating a few DD components. The Sallen-Key topology can be configured not exceed the absolute maximum ratings. When operating with a single supply, short V to GND. as a unity-gain buffer by replacing R5 with a 0 resistor SS and removing resistor R1. The signal is noninverting and Op-Amp Configurations applied to INAP. The filter component pads are R2R4 The device is a single/dual-supply dual op amp that is ideal and R8, where some have to be populated with resistors for differential sensing, noninverting amplification, buffer- and others with capacitors. ing, and filtering. A few common configurations are shown Lowpass Sallen-Key Filter: To configure the Sallen-Key in the next few sections. as a lowpass filter, remove the shunt from jumper JU1, The following sections explain how to configure one of the populate the R2 and R8 pads with resistors, and populate devices op amps (op amp A). To configure the devices the R3 and R4 pads with capacitors. The corner frequen- second op amp (op amp B), the same equations can be cy and Q are then given by: used after modifying the component reference designators. 1 f = Noninverting Configuration C 2R R C C R2 R8 R3 R4 The EV kit comes preconfigured as a noninverting ampli- fier. The gain is set by the ratio of R5 and R1. The EV kit comes preconfigured for a gain of +11. The output voltage RR C C R2 R8 R3 R4 Q = for the noninverting configuration is given by the equation C (R + R ) R3 R2 R8 below: Highpass Sallen-Key Filter: To configure the Sallen- R5 V (1 ) V V =+ Key as a highpass filter, remove the shunt from jumper OUTA INAP OS R1 JU1, populate the R3 and R4 pads with resistors, and populate the R2 and R8 pads with capacitors. The corner Inverting Configuration frequency and Q are then given by: To configure the EV kit as an inverting amplifier, remove the shunt on jumper JU1 and install a shunt on jumper 1 f = C JU2 and feed an input signal on the INAM PCB pad. 2R R C C R3 R4 R2 R8 Differential Amplifier To configure the EV kit as a differential amplifier, replace RR C C R3 R4 R2 R8 R1R3 and R5 with appropriate resistors. When R1 = R2 Q = R (C + C ) and R3 = R5, the CMRR of the differential amplifier is R4 R2 R8 determined by the matching of the resistor ratios R1/R2 and R3/R5. 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