The Microchip’s MCP6491 operational amplifiers (op amps) has low input bias current (150 pA, typical at 125°C) and rail-to-rail input and output operation
link to page 5 link to page 5 MCP6491/2/41.3Test Circuits C The circuit used for most DC and AC tests is shown in F 6.8 pF Figure 1-1. This circuit can independently set VCM and VOUT (refer to Equation 1-1). Note that VCM is not the circuit’s common mode voltage ((V R P + VM)/2), and that G RF V 100 k 100 k OST includes VOS plus the effects (on the input offset error, V V V OST) of temperature, CMRR, PSRR and AOL. P DD/2 VDD V EQUATION 1-1: IN+ C C B1 B2 G = R R DM F G MCP649X 100 nF 1 µF V = V + V 2 2 CM P DD V = V – V V OST IN + IN– IN– V = V 2 + V – V + V 1 + G OUT DD P M OST DM V V M OUT Where: R R C G RF L L 100 k 100 k 10 k 20 pF GDM = Differential Mode Gain (V/V) VCM = Op Amp’s Common Mode (V) Input Voltage CF 6.8 pF VL VOST = Op Amp’s Total Input Offset (mV) Voltage FIGURE 1-1: AC and DC Test Circuit for Most Specifications. 2012-2013 Microchip Technology Inc. DS20002321C-page 5 Document Outline Package Types Typical Application 1.0 Electrical Characteristics 1.1 Absolute Maximum Ratings 1.2 Specifications 1.3 Test Circuits 2.0 Typical Performance Curves Figure 2-1: Input Offset Voltage Figure 2-2: Input Offset Voltage Drift Figure 2-3: Input Offset Voltage vs. Common Mode Input Voltage Figure 2-4: Input Offset Voltage vs. Common Mode Input Voltage Figure 2-5: Input Offset Voltage vs. Output Voltage Figure 2-6: Input Offset Voltage vs. Power Supply Voltage FIGURE 2-7: Input Noise Voltage Density vs. Frequency. FIGURE 2-8: Input Noise Voltage Density vs. Common Mode Input Voltage. FIGURE 2-9: CMRR, PSRR vs. Frequency. FIGURE 2-10: CMRR, PSRR vs. Ambient Temperature. FIGURE 2-11: Input Bias, Offset Currents vs. Ambient Temperature. FIGURE 2-12: Input Bias Current vs. Common Mode Input Voltage. FIGURE 2-13: Quiescent Current vs. Ambient Temperature. FIGURE 2-14: Quiescent Current vs. Common Mode Input Voltage. FIGURE 2-15: Quiescent Current vs. Common Mode Input Voltage. FIGURE 2-16: Quiescent Current vs. Power Supply Voltage. FIGURE 2-17: Open-Loop Gain, Phase vs. Frequency. FIGURE 2-18: DC Open-Loop Gain vs. Ambient Temperature. FIGURE 2-19: Gain Bandwidth Product, Phase Margin vs. Ambient Temperature. FIGURE 2-20: Gain Bandwidth Product, Phase Margin vs. Ambient Temperature. FIGURE 2-21: Output Short Circuit Current vs. Power Supply Voltage. FIGURE 2-22: Output Voltage Swing vs. Frequency. FIGURE 2-23: Output Voltage Headroom vs. Output Current. FIGURE 2-24: Output Voltage Headroom vs. Output Current. FIGURE 2-25: Output Voltage Headroom vs. Ambient Temperature. FIGURE 2-26: Output Voltage Headroom vs. Ambient Temperature. FIGURE 2-27: Slew Rate vs. Ambient Temperature. FIGURE 2-28: Small Signal Non-Inverting Pulse Response. FIGURE 2-29: Small Signal Inverting Pulse Response. FIGURE 2-30: Large Signal Non-Inverting Pulse Response. FIGURE 2-31: Large Signal Inverting Pulse Response. FIGURE 2-32: The MCP6491/2/4 Shows No Phase Reversal. FIGURE 2-33: Closed Loop Output Impedance vs. Frequency. FIGURE 2-34: Measured Input Current vs. Input Voltage (below VSS). FIGURE 2-35: Channel-to-Channel Separation vs. Frequency (MCP6492/4 only). 3.0 Pin Descriptions TABLE 3-1: Pin Function Table 3.1 Analog Outputs 3.2 Analog Inputs 3.3 Power Supply Pins 3.4 Exposed Thermal Pad (EP) 4.0 Application Information 4.1 Inputs FIGURE 4-1: Simplified Analog Input ESD Structures. FIGURE 4-2: Protecting the Analog Inputs. Figure 4-3: Protecting the Analog Inputs 4.2 Rail-to-Rail Output 4.3 Capacitive Loads FIGURE 4-4: Output Resistor, RISO Stabilizes Large Capacitive Loads. FIGURE 4-5: Recommended RISO Values for Capacitive Loads. 4.4 Supply Bypass 4.5 Unused Op Amps Figure 4-6: Unused Op Amps. Figure 4-7: Example Guard Ring Layout for Inverting Gain 4.6 PCB Surface Leakage 4.7 Application Circuits FIGURE 4-8: Photovoltaic Mode Detector. FIGURE 4-9: Photoconductive Mode Detector. FIGURE 4-10: Second-Order, Low-Pass Butterworth Filter with Sallen-Key Topology. FIGURE 4-11: Second-Order, Low-Pass Butterworth Filter with Multiple-Feedback Topology. FIGURE 4-12: pH Electrode Amplifier. 5.0 Design Aids 5.1 SPICE Macro Model 5.2 FilterLab Software 5.3 MAPS (Microchip Advanced Part Selector) 5.4 Analog Demonstration and Evaluation Boards 5.5 Application Notes 6.0 Packaging Information 6.1 Package Marking Information Appendix A: Revision History Product Identification System Trademarks Worldwide Sales and Service
