MCP6286 Low Noise, Low Power Op Amp Features Description • • • • • • • • • The Microchip Technology Inc. MCP6286 operational amplifier (op amp) has low noise (5.4 nV/√Hz, typical), low power (520 µA, typical) and rail-to-rail output operation. It is unity gain stable and has a gain bandwidth product of 3.5 MHz (typical). This device operates with a single supply voltage as low as 2.2V, while drawing low quiescent current. These features make the product well suited for single-supply, low noise, battery-powered applications. Low Noise: 5.4 nV/√Hz (typical) Low Quiescent Current: 520 µA (typical) Rail-to-Rail Output Wide Supply Voltage Range: 2.2V to 5.5V Gain Bandwidth Product: 3.5 MHz (typical) Unity Gain Stable Extended Temperature Range: -40°C to +125°C No Phase Reversal Small Package Applications • • • • • • • Noise Cancellation Headphones Cellular Phones Analog Filters Sensor Conditioning Portable Instrumentation Medical Instrumentation Battery Powered Systems Package Types MCP6286 SOT-23-5 VOUT 1 VSS 2 VIN+ 3 Design Aids • • • • • • The MCP6286 op amp is offered in a space saving SOT-23-5 package. It is designed with Microchip’s advanced CMOS process and available in the extended temperature range, with a power supply range of 2.2V to 5.5V. 5 VDD 4 VIN– SPICE Macro Models FilterLab® Software Mindi™ Circuit Designer & Simulator MAPS (Microchip Advanced Part Selector) Analog Demonstration and Evaluation Boards Application Notes Typical Application C1 47 nF R2 R1 382 kΩ 641 kΩ + VIN C2 22 nF fP = 10 Hz MCP6286 VOUT – G = +1 V/V Second-Order, Low-Pass Butterworth Filter © 2009 Microchip Technology Inc. DS22196A-page 1 MCP6286 NOTES: DS22196A-page 2 © 2009 Microchip Technology Inc. MCP6286 1.0 ELECTRICAL CHARACTERISTICS 1.1 Absolute Maximum Ratings † VDD – VSS ........................................................................7.0V Current at Input Pins .....................................................±2 mA Analog Inputs (VIN+, VIN-)†† .......... VSS – 1.0V to VDD + 1.0V All Other Inputs and Outputs ......... VSS – 0.3V to VDD + 0.3V Difference Input Voltage ...................................... |VDD – VSS| Output Short-Circuit Current .................................continuous Current at Output and Supply Pins ............................±30 mA † Notice: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. †† See 4.1.2 “Input Voltage And Current Limits” Storage Temperature ....................................-65°C to +150°C Maximum Junction Temperature (TJ).......................... +150°C ESD protection on all pins (HBM; MM) ................ ≥ 4 kV; 400V DC ELECTRICAL SPECIFICATIONS Electrical Characteristics: Unless otherwise indicated, VDD = +2.2V to +5.5V, VSS= GND, TA= +25°C, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2 and RL = 10 kΩ to VL. (Refer to Figure 1-1). Parameters Sym Min Typ Max Units Conditions Input Offset Input Offset Voltage Input Offset Drift with Temperature Power Supply Rejection Ratio VOS -1.5 — +1.5 ΔVOS/ΔTA — ±1 — PSRR 80 100 — IB — ±1 — pA — 50 150 pA TA = +85°C TA = +125°C mV µV/°C TA= -40°C to +125°C dB Input Bias Current and Impedance Input Bias Current — 1500 3000 pA Input Offset Current IOS — ±1 — pA Common Mode Input Impedance ZCM — 1013||20 — Ω||pF Differential Input Impedance ZDIFF — 1013||20 — Ω||pF Common Mode Input Voltage Range VCMR VSS−0.3 — VDD-1.2 V Note 1 Common Mode Rejection Ratio CMRR 76 95 — dB VCM = -0.3V to 1.0V, VDD = 2.2V 80 100 — dB VCM = -0.3V to 4.3V, VDD = 5.5V AOL 100 120 — dB 0.2V < VOUT <(VDD-0.2V) VOL, VOH VSS+15 — VDD–15 mV 0.5V Input overdrive VSS+75 — VDD–75 mV 0.5V Input overdrive RL = 2 kΩ — ±20 — mA Common Mode Open-Loop Gain DC Open-Loop Gain (Large Signal) Output Maximum Output Voltage Swing Output Short-Circuit Current Note 1: ISC Figure 2-12 shows how VCMR changes across temperature. © 2009 Microchip Technology Inc. DS22196A-page 3 MCP6286 DC ELECTRICAL SPECIFICATIONS (CONTINUED) Electrical Characteristics: Unless otherwise indicated, VDD = +2.2V to +5.5V, VSS= GND, TA= +25°C, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2 and RL = 10 kΩ to VL. (Refer to Figure 1-1). Parameters Sym Min Typ Max Units Conditions VDD 2.2 — 5.5 V IQ 300 520 700 µA IO = 0, VDD = 2.2V 320 540 720 µA IO = 0, VDD = 5.5V Power Supply Supply Voltage Quiescent Current per Amplifier Note 1: Figure 2-12 shows how VCMR changes across temperature. AC ELECTRICAL SPECIFICATIONS Electrical Characteristics: Unless otherwise indicated, TA = +25°C, VDD = +2.2 to +5.5V, VSS = GND, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2, RL = 10 kΩ to VL and CL = 60 pF. (Refer to Figure 1-1). Parameters Sym Min Typ Max Units Conditions GBWP — 3.5 — MHz Phase Margin PM — 60 — ° Slew Rate SR — 2 — V/µs Input Noise Voltage Eni — 1.0 — µVP-P Input Noise Voltage Density eni — 22 — nV/√Hz f = 10 Hz — 5.4 — nV/√Hz f = 10 kHz — 0.6 — fA/√Hz f = 1 kHz AC Response Gain Bandwidth Product G = +1 V/V Noise Input Noise Current Density ini f = 0.1 Hz to 10 Hz TEMPERATURE SPECIFICATIONS Electrical Characteristics: Unless otherwise indicated, VDD = +2.2V to +5.5V and VSS = GND. Parameters Sym Min Typ Max Units Operating Temperature Range TA -40 — +125 °C Storage Temperature Range TA -65 — +150 °C θJA — 256 — °C/W Conditions Temperature Ranges Note 1 Thermal Package Resistances Thermal Resistance, 5L-SOT-23 Note 1: The internal junction temperature (TJ) must not exceed the absolute maximum specification of +150°C. DS22196A-page 4 © 2009 Microchip Technology Inc. MCP6286 1.2 Test Circuits The circuit used for most DC and AC tests is shown in Figure 1-1. It independently sets VCM and VOUT; see Equation 1-1. The circuit’s common mode voltage is (VP + VM)/2, not VCM. VOST includes VOS plus the effects of temperature, CMRR, PSRR and AOL. EQUATION 1-1: G DM = R F ⁄ R G CF 6.8 pF RG 100 kΩ V OST = V IN– – V IN+ VOST = Op Amp’s Total Input Offset Voltage © 2009 Microchip Technology Inc. CB1 100 nF MCP6286 V OUT = V REF + ( V P – V M )G DM + V OST G N Where: VCM = Op Amp’s Common Mode Input Voltage VDD VIN+ G N = 1 + G DM GN = Noise Gain VREF = VDD/2 VP V CM = V P ( 1 – 1 ⁄ G N ) + V REF ( 1 ⁄ G N ) GDM = Differential Mode Gain RF 100 kΩ CB2 1 µF VIN– (V/V) (V/V) VM RG 100 kΩ RL 10 kΩ RF 100 kΩ VOUT CL 60 pF (V) (mV) CF 6.8 pF VL FIGURE 1-1: AC and DC Test Circuit for Most Specifications. DS22196A-page 5 MCP6286 NOTES: DS22196A-page 6 © 2009 Microchip Technology Inc. MCP6286 2.0 TYPICAL PERFORMANCE CURVES Note: The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. 14% 800 Input Offset Voltage (µV) -600 600 VDD = 5.5V 600 Representative Part 400 200 0 -200 -400 -600 TA = +125°C TA = +85°C TA = +25°C TA = -40°C -800 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Common Mode Input Voltage (V) FIGURE 2-3: Input Offset Voltage vs. Common Mode Input Voltage with VDD = 5.5V. © 2009 Microchip Technology Inc. FIGURE 2-5: Output Voltage. Input Offset Voltage (µV) Input Offset Voltage (µV) 800 1.5 1.7 5.5 5.0 4.5 4.0 Output Voltage (V) Input Offset Drift with Temperature (µV/°C) Input Offset Voltage Drift. 3.5 0.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 0% VDD = 5.5V 3.0 5% 2.5 10% 2.0 15% VDD = 2.2V 1.5 20% 1.0 25% 500 400 300 200 100 0 -100 -200 -300 -400 -500 0.5 Input Offset Voltage (µV) 30% FIGURE 2-2: 1.3 FIGURE 2-4: Input Offset Voltage vs. Common Mode Input Voltage with VDD = 2.2V. 1360 Samples -3.5 Percentage of Occurrences Input Offset Voltage. 40% 35% 1.1 -0.5 Common Mode Input Voltage (V) Input Offset Voltage (µV) FIGURE 2-1: 0.9 -800 800 600 500 400 300 200 0 100 -100 -200 -300 -400 -500 -600 0% TA = +125 °C TA = +85°C TA = +25°C TA = -40°C -400 0.7 2% 0 -200 0.5 4% 200 0.3 6% 400 0.1 8% -0.1 10% Representative Part VDD = 2.2V 600 -0.3 1360 Samples 12% -800 Percentage of Occurrences Note: Unless otherwise indicated, TA = +25°C, VDD = +2.2V to +5.5V, VSS = GND, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2, RL = 10 kΩ to VL and CL = 60 pF. Input Offset Voltage vs. VCM = VCMR-L Representative Part 400 200 0 TA = +125°C TA = +85°C TA = +25°C TA = -40°C -200 -400 -600 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Power Supply Voltage (V) 5.5 6.0 FIGURE 2-6: Input Offset Voltage vs. Power Supply Voltage with VCM = VCMR_L. DS22196A-page 7 MCP6286 Note: Unless otherwise indicated, TA = +25°C, VDD = +2.2V to +5.5V, VSS = GND, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2, RL = 10 kΩ to VL and CL = 60 pF. VCM = VCMR-H 400 Representative Part CMRR, PSRR (dB) Input Offset Voltage (µV) 600 200 0 -200 TA = +125°C TA = +85°C TA = +25°C TA = -40°C -400 -600 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Power Supply Voltage (V) 5.5 120 110 100 90 80 70 60 50 40 30 20 100 1k 10k 100000 100k 1E+06 1M 100 1000 10000 Frequency (Hz) CMRR, PSRR vs. CMRR @ VDD = 5.5V @ VDD = 2.2V 105 CMRR, PSRR (dB) Input Noise Voltage Density (nV/√ Hz) 10 10 110 100 10 100 95 90 PSRR 85 80 75 1 0.1 1.E+0 1 10 100 1.E+3 1k 10k 100k 1M 1.E-1 1.E+1 1.E+2 1.E+4 1.E+5 1.E+6 Frequency (Hz) FIGURE 2-8: vs. Frequency. Input Noise Voltage Density -50 7.0 6.5 f = 10 kHz 6.0 VDD = 5.5 V 5.5 5.0 4.5 VDD = 2.2 V 4.0 3.5 -0.3 0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6 3.9 4.2 4.5 3.0 Common Mode Input Voltage (V) FIGURE 2-9: Input Noise Voltage Density vs. Common Mode Input Voltage. DS22196A-page 8 -25 0 25 50 75 Ambient Temperature (°C) FIGURE 2-11: Temperature. Common Mode Input Voltage Headroom (V) Input Voltage Noise Density (nV/√ Hz) CMRR FIGURE 2-10: Frequency. 1,000 Representative Part PSRR+ 11 6.0 FIGURE 2-7: Input Offset Voltage vs. Power Supply Voltage with VCM = VCMR_H. PSRR- 100 125 CMRR, PSRR vs. Ambient 1.20 1.05 0.90 0.75 0.60 0.45 0.30 0.15 0.00 -0.15 -0.30 VDD - VCMR_H @ VDD = 5.5V @ VDD = 2.2V VCMR_L - VSS @ VDD = 2.2V VOL - VSS @ VDD = 5.5V V V -50 -25 0 25 50 75 100 Ambient Temperature (°C) 125 FIGURE 2-12: Common Mode Input Voltage Headroom vs. Ambient Temperature. © 2009 Microchip Technology Inc. MCP6286 700 10000 Quiescent Current (uA) VDD = 5.5V 1000 Input Bias Current 10 100 -150 0 VDD = 5.5V 500 VDD = 2.2V 400 350 300 250 -25 0 25 50 75 Ambient Temperature (°C) 100 FIGURE 2-15: Quiescent Current vs Ambient Temperature. © 2009 Microchip Technology Inc. 1 1.0E+01 10 125 6.0 -210 1.0E+02 1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 100 1k 10k 100k 1M 10M Frequency (Hz) 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Open-Loop Gain, Phase vs. 100 90 80 70 60 50 40 30 20 10 0 Gain Bandwidth Product Phase Margin VDD = 5.5V 0.8 600 450 1.0E+00 0.2 650 -0.4 Gain Bandwidth Product (MHz) 700 550 -180 VDD = 5.5V -20 1.0E-01 0.1 Open-Loop Phase (°) 20 FIGURE 2-17: Frequency. FIGURE 2-14: Input Bias Current vs. Common Mode Input Voltage. 5.5 -120 Phase (°) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Common Mode Input Votlage (V) -90 40 4.4 TA = +85°C 200 60 3.8 400 -60 Open-Loop Phase 3.2 600 -30 80 2.6 800 100 2.0 TA = +125°C 0 Open-Loop Gain 1.4 Open-Loop Gain (dB) 1000 5.0 4.5 4.0 3.5 FIGURE 2-16: Quiescent Current vs. Power Supply Voltage. 120 0 Quiescent Current (µA) 3.0 Power Supply Voltage (V) VDD = 5.5V 1200 -50 2.5 45 55 65 75 85 95 105 115 125 Ambient Temperature (°C) 2.0 0 FIGURE 2-13: Input Bias, Offset Currents vs. Ambient Temperature. Input Bias Current (pA) 200 1.5 35 TA = +125°C TA = +85°C TA = +25°C TA = -40°C 300 1.0 25 1400 400 Input Offset Current 1 1600 500 0.5 100 600 0.0 Input Bias, Offset Currents (pA) Note: Unless otherwise indicated, TA = +25°C, VDD = +2.2V to +5.5V, VSS = GND, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2, RL = 10 kΩ to VL and CL = 60 pF. Common Mode Input Voltage (V) FIGURE 2-18: Gain Bandwidth Product, Phase Margin vs. Common Mode Input Voltage with VDD = 5.5V. DS22196A-page 9 MCP6286 VDD = 5.5V -50 -25 0 25 50 75 100 Ambient Temperature (°C) 90 85 80 75 70 65 60 55 50 45 40 125 3.0 2.5 0.5 0.0 80 75 70 65 2.0 1.5 1.0 Phase Margin VDD = 2.2V -50 -25 0 25 50 75 100 Ambient Temperature (°C) 60 55 50 45 40 125 FIGURE 2-21: Gain Bandwidth Product, Phase Margin vs. Ambient Temperature with VDD = 2.2V. DS22196A-page 10 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 VDD = 5.5V VDD = 2.2V 1 100 100 1k 1000 FIGURE 2-23: Frequency. 10k 100k 10000 100000 Frequency (Hz) 1M 1000000 10M 10000000 Output Voltage Swing vs. 1000 Phase (°) Gain Bandwidth Product (MHz) Gain Bandwidth Product TA = +125°C TA = +85°C TA = +25°C TA = -40°C 5 0.1 90 85 4.0 3.5 10 10 FIGURE 2-20: Gain Bandwidth Product, Phase Margin vs. Ambient Temperature with VDD = 5.5V. 5.0 4.5 15 FIGURE 2-22: Ouput Short Circuit Current vs. Power Supply Voltage. Output Voltage Swing (VP-P) Phase Margin 20 Power Supply Voltage (V) Phase (°) Gain Bandwidth Product (MHz) Gain Bandwidth Product 25 1.1 FIGURE 2-19: Gain Bandwidth Product, Phase Margin vs. Common Mode Input Voltage with VDD = 2.2V. 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Output Short Circuit Current (mA) 100 90 80 70 60 50 40 30 20 10 0 Output Voltage Headroom (mV) 5.0 4.5 Gain Bandwidth Product 4.0 3.5 3.0 2.5 Phase Margin 2.0 1.5 1.0 0.5 VDD = 2.2V 0.0 -0.4 -0.1 0.2 0.5 0.8 Common Mode Input Voltage (V) Phase (°) Gain Bandwidth Product (MHz) Note: Unless otherwise indicated, TA = +25°C, VDD = +2.2V to +5.5V, VSS = GND, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2, RL = 10 kΩ to VL and CL = 60 pF 100 10 VOL - VSS VDD - VOH 1 0.01 0.1 1 Output Current (mA) 10 FIGURE 2-24: Output Voltage Headroom vs. Output Current. © 2009 Microchip Technology Inc. MCP6286 60 55 50 45 40 35 30 25 20 15 10 5 0 Output Voltage (50 mV/div) Output Voltage Headroom VDD - VOH, VOL - VSS (mV) Note: Unless otherwise indicated, TA = +25°C, VDD = +2.2V to +5.5V, VSS = GND, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2, RL = 10 kΩ to VL and CL = 60 pF. VDD - VOH @ RL = 2kΩ VOL - VSS @ RL = 2kΩ VDD - VOH @ RL = 10kΩ VOL - VSS @ RL = 10kΩ -50 -25 0 25 50 75 100 Ambient Temperature (°C) 125 FIGURE 2-25: Output Voltage Headroom vs. Ambient Temperature. Time (1 µs/div) FIGURE 2-28: Response. 3.0 2.8 Slew Rate (V/µs) 2.4 Output Voltage (V) Falling Edge, VDD = 5.5V Rising Edge, VDD = 5.5V 2.6 2.2 2.0 1.8 1.6 Falling Edge, VDD = 2.2V Rising Edge, VDD = 2.2V 1.4 1.2 1.0 -25 Output Voltage (50 mV/div) FIGURE 2-26: Temperature. 0 25 50 75 Temperature (°C) 100 125 Slew Rate vs. Ambient VDD = 5.5V G = +1 V/V Time (1 µs/div) FIGURE 2-27: Pulse Response. Small Signal Non-Inverting © 2009 Microchip Technology Inc. 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 FIGURE 2-29: Pulse Response. Output Voltage (V) -50 VDD = 5.5V G = -1 V/V 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Small Signal Inverting Pulse VDD = 5.5V G = +2 V/V Time (5 µs/div) Large Signal Non-Inverting VDD = 5.5V G = -2 V/V Time (5 µs/div) FIGURE 2-30: Response. Large Signal Inverting Pulse DS22196A-page 11 MCP6286 Note: Unless otherwise indicated, TA = +25°C, VDD = +1.8V to +6.0V, VSS = GND, VCM = VDD/3, VOUT ≈ VDD/2, VL = VDD/2, RL = 10 kΩ to VL and CL = 60 pF. 1m 1m 1m 1000000000 5.0 100 µ 100000000 100 100 µµ 10000000 10µ 10µ 10µ 1µ 1000000 1µ 1µ VOUT 4.0 VIN -I IN (A) Input, Output Voltages (V) 6.0 3.0 100000 100n 100n 10000 10n 10n 1000 1n 1n 100 100p 100p 2.0 1.0 VDD = 5.5V G = +2 V/V 0.0 10p 10p10 1p1 1p -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 -1.0 V IN (V) Time (1 ms/div) FIGURE 2-31: Phase Reversal. The MCP6286 Shows No FIGURE 2-33: Measured Input Current vs. Input Voltage (below VSS). Closed Loop Output Impedance (Ω) 1000 100 10 GN: 101 V/V 11 V/V 1 V/V 1 0.1 10 10 100 100 1k 1000 10k 100000 100k 1E+06 1M 10M 10000 1E+07 Frequency (Hz) FIGURE 2-32: Closed Loop Output Impedance vs. Frequency. DS22196A-page 12 © 2009 Microchip Technology Inc. MCP6286 3.0 PIN DESCRIPTIONS Descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE MCP6286 SOT-23-5 3.1 Symbol 1 VOUT 2 VSS 3 VIN+ Non-inverting Input 4 VIN– Inverting Input 5 VDD Positive Power Supply Analog Output The output pin is low-impedance voltage source. 3.2 Description Analog Inputs The non-inverting and inverting inputs are high-impedance CMOS inputs with low bias currents. © 2009 Microchip Technology Inc. Analog Output Negative Power Supply 3.3 Power Supply Pins The positive power supply (VDD) is 2.2V to 5.5V higher than the negative power supply (VSS). For normal operation, the other pins are at voltages between VSS and VDD. Typically, these parts are used in a single (positive) supply configuration. In this case, VSS is connected to ground and VDD is connected to the supply. VDD will need bypass capacitors. DS22196A-page 13 MCP6286 NOTES: DS22196A-page 14 © 2009 Microchip Technology Inc. MCP6286 4.0 APPLICATION INFORMATION VDD The MCP6286 op amp is manufactured using Microchip’s state-of-the-art CMOS process and is specifically designed for low-power, low-noise applications. 4.1 D1 R1 Input 4.1.1 MCP6286 V2 PHASE REVERSAL R2 The MCP6286 op amp is designed to prevent phase reversal when the input pins exceed the supply voltages. Figure 2-31 shows the input voltage exceeding the supply voltage without any phase reversal. 4.1.2 D2 V1 INPUT VOLTAGE AND CURRENT LIMITS The ESD protection on the inputs can be depicted as shown in Figure 4-1. This structure was chosen to protect the input transistors and to minimize input bias current (IB). The input ESD diodes clamp the inputs when they try to go more than one diode drop below VSS. They also clamp any voltage that goes too far above VDD; their breakdown voltage is high enough to allow normal operation and low enough to bypass ESD events within the specified limits. R3 VSS – (minimum expected V1) 2 mA VSS – (minimum expected V2) R2 > 2 mA R1 > FIGURE 4-2: Inputs. Protecting the Analog It is also possible to connect the diodes to the left of the resistors R1 and R2. In this case, the currents through the diodes D1 and D2 need to be limited by some other mechanism. The resistors then serve as in-rush current limiters; the DC currents into the input pins (VIN+ and VIN-) should be very small. A significant amount of current can flow out of the inputs when the common mode voltage (VCM) is below ground (VSS). (See Figure 2-33). VDD Bond Pad 4.1.3 VIN+ Bond Pad The input stage of the MCP6286 op amp uses a PMOS input stage. It operates at low common mode input voltage (VCM), including ground. With this topology, the device operates with a VCM up to VDD - 1.2V and 0.3V below VSS. (See Figure 2-12).The input offset voltage is measured at VCM = VSS – 0.3V and VDD - 1.2V to ensure proper operation. Input Stage Bond VIN– Pad VSS Bond Pad FIGURE 4-1: Structures. Simplified Analog Input ESD In order to prevent damage and/or improper operation of these op amps, the circuit they are in must limit the voltages and currents at the VIN+ and VIN- pins (see Absolute Maximum Ratings at the beginning of Section 1.0 “Electrical Characteristics”). Figure 4-2 shows the recommended approach to protecting these inputs. The internal ESD diodes prevent the input pins (VIN+ and VIN-) from going too far below ground, and the resistors R1 and R2 limit the possible current drawn out of the input pins. Diodes D1 and D2 prevent the input pins (VIN+ and VIN-) from going too far above VDD. When implemented as shown, resistors R1 and R2 also limit the current through D1 and D2. © 2009 Microchip Technology Inc. NORMAL OPERATION For a unity gain buffer, since VOUT is the same voltage as the inverting input, VOUT must be maintained below VDD –1.2V for correct operation. 4.2 Rail-to-Rail Output The output voltage range of the MCP6286 op amp is VSS + 15 mV (minimum) and VDD – 15 mV (maximum) when RL = 10 kΩ is connected to VDD/2 and VDD = 5.5V. Refer to Figure 2-24 and Figure 2-25 for more information. DS22196A-page 15 MCP6286 4.3 Capacitive Loads 4.4 Driving large capacitive loads can cause stability problems for voltage feedback op amps. As the load capacitance increases, the feedback loop’s phase margin decreases and the closed-loop bandwidth is reduced. This produces gain peaking in the frequency response, with overshoot and ringing in the step response. While a unity-gain buffer (G = +1 V/V) is the most sensitive to capacitive loads, all gains show the same general behavior. When driving large capacitive loads with these op amps (e.g., > 100 pF when G = +1 V/V), a small series resistor at the output (RISO in Figure 4-3) improves the feedback loop’s phase margin (stability) by making the output load resistive at higher frequencies. The bandwidth will be generally lower than the bandwidth with no capacitance load. – RISO MCP6286 + VIN VOUT CL Supply Bypass MCP6286 op amp’s power supply pin (VDD for single-supply) should have a local bypass capacitor (i.e., 0.01 µF to 0.1 µF) within 2 mm for good high frequency performance. It can use a bulk capacitor (i.e., 1 µF or larger) within 100 mm to provide large, slow currents. This bulk capacitor can be shared with other analog parts. 4.5 PCB Surface Leakage In applications where low input bias current is critical, Printed Circuit Board (PCB) surface leakage effects need to be considered. Surface leakage is caused by humidity, dust or other contamination on the board. Under low humidity conditions, a typical resistance between nearby traces is 1012Ω. A 5V difference would cause 5 pA of current to flow; which is greater than the MCP6286 op amp’s bias current at +25°C (±1 pA, typical). The easiest way to reduce surface leakage is to use a guard ring around sensitive pins (or traces). The guard ring is biased at the same voltage as the sensitive pin. An example of this type of layout is shown in Figure 4-5. FIGURE 4-3: Output Resistor, RISO Stabilizes Large Capacitive Loads. Guard Ring VIN– VIN+ VSS Figure 4-4 gives recommended RISO values for different capacitive loads and gains. The x-axis is the normalized load capacitance (CL/GN), where GN is the circuit's noise gain. For non-inverting gains, GN and the Signal Gain are equal. For inverting gains, GN is 1+|Signal Gain| (e.g., -1 V/V gives GN = +2 V/V). FIGURE 4-5: for Inverting Gain. Recommended RISO (Ω) 1000 VDD = 5.5 V RL = 10 kΩ 1. 100 10 GN: 1 V/V 2 V/V ≥ 5 V/V 1 10p 100p 1n 10n 0.1µ 1µ 1.E-11 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 Normalized Load Capacitance; CL/GN (F) FIGURE 4-4: Recommended RISO Values for Capacitive Loads. After selecting RISO for your circuit, double check the resulting frequency response peaking and step response overshoot. Modify RISO’s value until the response is reasonable. Bench evaluation and simulations with the MCP6286 SPICE macro model are very helpful. DS22196A-page 16 2. Example Guard Ring Layout Non-inverting Gain and Unity-Gain Buffer: a. Connect the non-inverting pin (VIN+) to the input with a wire that does not touch the PCB surface. b. Connect the guard ring to the inverting input pin (VIN–). This biases the guard ring to the common mode input voltage. Inverting Gain and Transimpedance Gain Amplifiers (convert current to voltage, such as photo detectors): a. Connect the guard ring to the non-inverting input pin (VIN+). This biases the guard ring to the same reference voltage as the op amp (e.g., VDD/2 or ground). b. Connect the inverting pin (VIN–) to the input with a wire that does not touch the PCB surface. © 2009 Microchip Technology Inc. MCP6286 4.6 4.6.1 Application Circuits 4.6.2 ACTIVE LOW-PASS FILTER The MCP6286 op amp’s low input bias current makes it possible for the designer to use larger resistors and smaller capacitors for active low-pass filter applications. However, as the resistance increases, the noise generated also increases. Parasitic capacitances and the large value resistors could also modify the frequency response. These trade-offs need to be considered when selecting circuit elements. Figure 4-6 and Figure 4-7 show low-pass, second-order, Butterworth filters with a cut-off frequency of 10 Hz. The filter in Figure 4-6 has a non-inverting gain of +1 V/V, and the filter in Figure 4-7 has an inverting gain of -1 V/V. PHOTO DETECTION The MCP6286 op amps can be used to easily convert the signal from a sensor that produces an output current (such as a photo diode) into a voltage (a transimpedance amplifier). This is implemented with a single resistor (R2) in the feedback loop of the amplifiers shown in Figure 4-8 and Figure 4-9. The optional capacitor (C2) sometimes provides stability for these circuits. A photodiode configured in the Photovoltaic mode has zero voltage potential placed across it (Figure 4-8). In this mode, the light sensitivity and linearity is maximized, making it best suited for precision applications. The key amplifier specifications for this application are: low input bias current, low noise, common mode input voltage range (including ground), and rail-to-rail output. G = +1 V/V fP = 10 Hz C1 47 nF C2 R2 R2 R1 382 kΩ 641 kΩ VOUT ID1 + VIN MCP6286 C2 22 nF VOUT D1 Light – VDD MCP6286 – + VOUT = ID1*R2 FIGURE 4-6: Second-Order, Low-Pass Butterworth Filter with Sallen-Key Topology. G = -1 V/V fP = 10 Hz R2 618 kΩ C1 8.2 nF R3 R1 618 kΩ 1.00 MΩ VOUT VIN C2 47 nF FIGURE 4-8: Photovoltaic Mode Detector. In contrast, a photodiode that is configured in the Photoconductive mode has a reverse bias voltage across the photo-sensing element (Figure 4-9). This decreases the diode capacitance, which facilitates high-speed operation (e.g., high-speed digital communications). The design trade-off is increased diode leakage current and linearity errors. The op amp needs to have a wide Gain Bandwidth Product (GBWP). – C2 MCP6286 VDD/2 + FIGURE 4-7: Second-Order, Low-Pass Butterwork Filter with Multiple-Feedback Topology. R2 ID1 D1 Light VBIAS – VDD VOUT MCP6286 + VOUT = ID1*R2 VBIAS < 0V FIGURE 4-9: Detector. © 2009 Microchip Technology Inc. Photoconductive Mode DS22196A-page 17 MCP6286 NOTES: DS22196A-page 18 © 2009 Microchip Technology Inc. MCP6286 5.0 DESIGN AIDS Microchip provides the basic design tools needed for the MCP6286 op amp. 5.1 SPICE Macro Model The latest SPICE macro model for the MCP6286 op amp is available on the Microchip web site at www.microchip.com. The model was written and tested in official Orcad (Cadence) owned PSPICE. For the other simulators, it may require translation. The model covers a wide aspect of the op amp's electrical specifications. Not only does the model cover voltage, current, and resistance of the op amp, but it also covers the temperature and noise effects on the behavior of the op amp. The model has not been verified outside of the specification range listed in the op amp data sheet. The model behaviors under these conditions can not be guaranteed that it will match the actual op amp performance. Moreover, the model is intended to be an initial design tool. Bench testing is a very important part of any design and cannot be replaced with simulations. Also, simulation results using this macro model need to be validated by comparing them to the data sheet specifications and characteristic curves. 5.2 FilterLab® Software Microchip’s FilterLab® software is an innovative software tool that simplifies analog active filter (using op amps) design. Available at no cost from the Microchip web site at www.microchip.com/filterlab, the FilterLab design tool provides full schematic diagrams of the filter circuit with component values. It also outputs the filter circuit in SPICE format, which can be used with the macro model to simulate actual filter performance. 5.3 Mindi™ Circuit Designer & Simulator Microchip’s Mindi™ Circuit Designer & Simulator aids in the design of various circuits useful for active filter, amplifier and power-management applications. It is a free online circuit designer & simulator available from the Microchip web site at www.microchip.com/mindi. This interactive circuit designer & simulator enables designers to quickly generate circuit diagrams, simulate circuits. Circuits developed using the Mindi Circuit Designer & Simulator can be downloaded to a personal computer or workstation. 5.4 Microchip Advanced Part Selector (MAPS) MAPS is a software tool that helps semiconductor professionals efficiently identify Microchip devices that fit a particular design requirement. Available at no cost from the Microchip website at www.microchip.com/ maps, the MAPS is an overall selection tool for Microchip’s product portfolio that includes Analog, Memory, MCUs and DSCs. Using this tool you can define a filter to sort features for a parametric search of devices and export side-by-side technical comparison reports. Helpful links are also provided for Datasheets, Purchase, and Sampling of Microchip parts. 5.5 Analog Demonstration and Evaluation Boards Microchip offers a broad spectrum of Analog Demonstration and Evaluation Boards that are designed to help you achieve faster time to market. For a complete listing of these boards and their corresponding user’s guides and technical information, visit the Microchip web site at www.microchip.com/ analogtools. Some boards that are especially useful are: • • • • • • MCP6XXX Amplifier Evaluation Board 1 MCP6XXX Amplifier Evaluation Board 2 MCP6XXX Amplifier Evaluation Board 3 MCP6XXX Amplifier Evaluation Board 4 Active Filter Demo Board Kit 5/6-Pin SOT-23 Evaluation Board, P/N VSUPEV2 5.6 Application Notes The following Microchip Analog Design Note and Application Notes are available on the Microchip web site at www.microchip.com/appnotes and are recommended as supplemental reference resources. • ADN003: “Select the Right Operational Amplifier for your Filtering Circuits”, DS21821 • AN722: “Operational Amplifier Topologies and DC Specifications”, DS00722 • AN723: “Operational Amplifier AC Specifications and Applications”, DS00723 • AN884: “Driving Capacitive Loads With Op Amps”, DS00884 • AN990: “Analog Sensor Conditioning Circuits – An Overview”, DS00990 • AN1177: “Op Amp Precision Design: DC Errors”, DS01177 • AN1228: “Op Amp Precision Design: Random Noise”, DS01228 These application notes and others are listed in the design guide: • “Signal Chain Design Guide”, DS21825 © 2009 Microchip Technology Inc. DS22196A-page 19 MCP6286 NOTES: DS22196A-page 20 © 2009 Microchip Technology Inc. MCP6286 6.0 PACKAGING INFORMATION 6.1 Package Marking Information Example: 5-Lead SOT-23 5 4 5 WENN XXNN 1 2 3 Legend: XX...X Y YY WW NNN e3 * Note: 4 1 2 3 Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information. © 2009 Microchip Technology Inc. DS22196A-page 21 MCP6286 .# #$# /!- 0 # 1/ %##!# ## +22--- 2 / b N E E1 3 2 1 e e1 D A2 A c φ A1 L L1 3# 4# 5$8%1 44"" 5 56 7 5 ( 4!1# ()* 6$# !4!1# 6,9# : !!1// ; : #!%% : ( 6,<!# " : !!1/<!# " : ; 6,4# : )* ( .#4# 4 : = .# # 4 ( : ; .# > : > 4!/ ; : = 4!<!# 8 : ( !"!#$!!% #$ !% #$ #&! ! !# "'( )*+ ) #&#,$ --#$## - *) DS22196A-page 22 © 2009 Microchip Technology Inc. MCP6286 APPENDIX A: REVISION HISTORY Revision A (August 2009) • Original Release of this Document. © 2009 Microchip Technology Inc. DS22196A-page 23 MCP6286 NOTES: DS22196A-page 24 © 2009 Microchip Technology Inc. MCP6286 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. X /XX Device Temperature Range Package Device: MCP6286T: Temperature Range: E Package: OT = Plastic Small Outline Transistor, 5-lead Examples: a) MCP6286T-E/OT: Tape and Reel, 5-LD SOT-23 package Single Op Amp (Tape and Reel) = -40°C to +125°C © 2009 Microchip Technology Inc. DS22196A-page 25 MCP6286 NOTES: DS22196A-page 26 © 2009 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, rfPIC and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Omniscient Code Generation, PICC, PICC-18, PICkit, PICDEM, PICDEM.net, PICtail, PIC32 logo, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 2009, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. © 2009 Microchip Technology Inc. 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