MCP6441 450 nA, 9 kHz Op Amp Features: Description: • • • • • • • • • The MCP6441 device is a single nanopower operational amplifier (op amp), which has low quiescent current (450 nA, typical) and rail-to-rail input and output operation. This op amp is unity gain stable and has a gain bandwidth product of 9 kHz (typical). These devices operate with a single supply voltage as low as 1.4V. These features make the family of op amps well suited for single-supply, battery-powered applications. Low Quiescent Current: 450 nA (typical) Gain Bandwidth Product: 9 kHz (typical) Supply Voltage Range: 1.4V to 6.0V Rail-to-Rail Input and Output Unity Gain Stable Slew Rate: 3V/ms (typical) Extended Temperature Range: -40°C to +125°C No Phase Reversal Small Packages Applications: • • • • • • Portable Equipment Battery Powered System Data Acquisition Equipment Sensor Conditioning Battery Current Sensing Analog Active Filters Package Types MCP6441 SC70-5, SOT-23-5 Design Aids: • • • • • • The MCP6441 op amp is designed with Microchip’s advanced CMOS process and offered in the 5-pin SC70 and SOT-23 single packages. All devices are available in the extended temperature range, with a power supply range of 1.4V to 6.0V. SPICE Macro Models FilterLab® Software Mindi™ Circuit Designer and Simulator Microchip Advanced Part Selector (MAPS) Analog Demonstration and Evaluation Boards Application Notes VOUT 1 VSS 2 VIN+ 3 5 VDD 4 VIN– Typical Application IDD 1.4V to 6.0V 10Ω 100 kΩ To load VDD MCP6441 VOUT 1 MΩ V DD – V OUT I DD = -----------------------------------------( 10 V/V ) ⋅ ( 10 Ω ) Battery Current Sensing © 2010 Microchip Technology Inc. DS22257A-page 1 MCP6441 NOTES: DS22257A-page 2 © 2010 Microchip Technology Inc. MCP6441 1.0 ELECTRICAL CHARACTERISTICS 1.1 Absolute Maximum Ratings † † 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. 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 †† See Section 4.1.2 “Input Voltage Limits”. Current at Output and Supply Pins ............................±30 mA 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 = +1.4V to +6.0V, VSS= GND, TA= +25°C, VCM = VDD/2, VOUT ≈ VDD/2, VL = VDD/2 and RL = 1 MΩ to VL. (Refer to Figure 1-1). Parameters Sym Min Typ Max Units VOS -4.5 — +4.5 mV ΔVOS/ΔTA — ±2.5 — PSRR 65 86 — dB IB — ±1 — pA Conditions Input Offset Input Offset Voltage Input Offset Drift with Temperature Power Supply Rejection Ratio VCM = VSS µV/°C TA= -40°C to +125°C, VCM = VSS VCM = VSS Input Bias Current and Impedance Input Bias Current — 20 — pA TA = +85°C — 400 — pA TA = +125°C Input Offset Current IOS — ±1 — pA Common Mode Input Impedance ZCM — 1013||6 — Ω||pF Differential Input Impedance ZDIFF — 1013||6 — Ω||pF Common Mode Input Voltage Range VCMR VSS-0.3 — VDD+0.3 V Common Mode Rejection Ratio CMRR 60 76 — dB VCM = -0.3V to 6.3V, VDD = 6.0V AOL 90 110 — dB VOUT = 0.1V to VDD-0.1V RL = 10 kΩ to VL VOL, VOH VSS+20 — VDD–20 mV VDD = 6.0V, RL = 10 kΩ 0.5V input overdrive Common Mode Open-Loop Gain DC Open-Loop Gain (Large Signal) Output Maximum Output Voltage Swing Output Short-Circuit Current — ±3 — mA VDD = 1.4V — ±22 — mA VDD = 6.0V VDD 1.4 — 6.0 V IQ 250 450 650 nA ISC Power Supply Supply Voltage Quiescent Current per Amplifier © 2010 Microchip Technology Inc. IO = 0, VDD = 5.0V DS22257A-page 3 MCP6441 AC ELECTRICAL SPECIFICATIONS Electrical Characteristics: Unless otherwise indicated, TA = +25°C, VDD = +1.4V to +6.0V, VSS = GND, VCM = VDD/2, VOUT ≈ VDD/2, VL = VDD/2, RL = 1 MΩ to VL and CL = 60 pF. (Refer to Figure 1-1). Parameters Sym Min Typ Max Units kHz Conditions AC Response Gain Bandwidth Product GBWP — 9 — Phase Margin PM — 65 — ° Slew Rate SR — 3 — V/ms Input Noise Voltage Eni — 5 — µVp-p f = 0.1 Hz to 10 Hz Input Noise Voltage Density eni — 190 — nV/√Hz f = 1 kHz Input Noise Current Density ini — 0.6 — fA/√Hz f = 1 kHz G = +1 V/V Noise TEMPERATURE SPECIFICATIONS Electrical Characteristics: Unless otherwise indicated, VDD = +1.4V to +6.0V and VSS = GND. Parameters Sym Min Typ Max Units Operating Temperature Range TA -40 — +125 °C Storage Temperature Range TA -65 — +150 °C Thermal Resistance, 5L-SC70 θJA — 331 — °C/W Thermal Resistance, 5L-SOT-23 θJA — 220.7 — °C/W Conditions Temperature Ranges Note 1 Thermal Package Resistances Note 1: 1.2 The internal junction temperature (TJ) must not exceed the absolute maximum specification of +150°C. Test Circuits The circuit used for most DC and AC tests is shown in Figure 1-1. This circuit can independently set VCM and VOUT (see Equation 1-1). Note that VCM is not the circuit’s Common Mode voltage ((VP + VM)/2), and that VOST includes VOS plus the effects (on the input offset error, VOST) of the temperature, CMRR, PSRR and AOL. EQUATION 1-1: CF 6.8 pF RG 100 kΩ VP VIN+ V CM = ( V P + VDD ⁄ 2 ) ⁄ 2 CB1 100 nF VDD/2 CB2 1 µF VIN– V OST = V IN– – VIN+ V OUT = ( V DD ⁄ 2 ) + ( V P – V M ) + VOST ( 1 + G DM ) Where: GDM = Differential Mode Gain (V/V) VCM = Op Amp’s Common Mode Input Voltage (V) DS22257A-page 4 VDD MCP6441 G DM = RF ⁄ RG VOST = Op Amp’s Total Input Offset Voltage RF 100 kΩ (mV) VM RG 100 kΩ RL 1 MΩ RF 100 kΩ CF 6.8 pF VOUT CL 60 pF VL FIGURE 1-1: AC and DC Test Circuit for Most Specifications. © 2010 Microchip Technology Inc. MCP6441 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. Note: Unless otherwise indicated, TA = +25°C, VDD = +1.4V to +6.0V, VSS = GND, VCM = VDD/2, VOUT ≈ VDD/2, VL = VDD/2, RL = 1 MΩ to VL and CL = 60 pF. 4000 Input Offset Voltage (µV) Common Mode Input Voltage (V) FIGURE 2-3: Input Offset Voltage vs. Common Mode Input Voltage with VDD = 6.0V. © 2010 Microchip Technology Inc. 1.7 1.5 1.3 1.1 0.9 6.0 5.5 4.5 4.0 5.0 6.5 6.0 5.5 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -500 Representative Part 5.0 0 +125°C +85°C +25°C -40°C 4.5 500 TA = TA = TA = TA = 4.0 1000 1.0 TA = +125°C TA = +85°C TA = +25°C TA = -40°C 2000 1600 1200 800 400 0 -400 -800 -1200 -1600 -2000 3.0 VDD = 6.0V Representative Part Input Offset Voltage (µV) Input Offset Voltage (µV) 3000 Input Offset Voltage vs. 3.5 FIGURE 2-5: Output Voltage. 2.5 Input Offset Voltage Drift. 1500 3.5 Output Voltage (V) Input Offset Voltage Drift (µV/°C) 2000 3.0 0.0 10 8 6 4 2 0 -2 -4 -6 -10 -8 0% Representative Part 2.5 5% 2.0 10% VDD = 6.0V 1.5 15% VDD = 1.4V 1.0 20% 1000 800 600 400 200 0 -200 -400 -600 -800 -1000 0.5 Input Offset Voltage (µV) Percentage of Occurences 1700 Samples VCM = VSS TA = -40°C to +125°C FIGURE 2-2: 0.7 FIGURE 2-4: Input Offset Voltage vs. Common Mode Input Voltage with VDD = 1.4V. 30% 2500 0 Common mode input voltage (V) Input Offset Voltage. 25% 500 -0.3 Input Offset Voltage (mV) FIGURE 2-1: 1000 -500 4.5 3.5 2.5 1.5 0.5 -0.5 -1.5 -2.5 -3.5 0% 1500 0.5 5% 2000 0.3 10% 2500 0.1 15% 3000 -0.1 20% VDD = 1.4V Representative Part TA = +125°C TA = +85°C TA = +25°C TA = -40°C 2.0 25% 3500 1.5 30% 1700 Samples VCM = VSS -4.5 Percentage of Occurences 35% Power Supply Voltage (V) FIGURE 2-6: Input Offset Voltage vs. Power Supply Voltage. DS22257A-page 5 MCP6441 Note: Unless otherwise indicated, TA = +25°C, VDD = +1.4V to +6.0V, VSS = GND, VCM = VDD/2, VOUT ≈ VDD/2, VL = VDD/2, RL = 1 MΩ to VL and CL = 60 pF. CMRR,PSRR (dB) Input Noise Voltage Density (nV/Hz) 1,000 100 0.1 0.1 11 10 100 10 100 Frequency (Hz) 10k 10000 Input Noise Voltage Density PSRR (VDD = 1.4V to 6.0V, VCM = VSS) CMRR (VDD = 6.0V, VCM = -0.3V to 6.3V) CMRR (VDD = 1.4V, VCM = -0.3V to 1.7V) -50 -25 100 125 CMRR, PSRR vs. Ambient 1000 350 300 250 VDD = 6.0V 100 200 150 100 f = 1 kHz VDD = 6.0 V 50 Input Bias Current 10 Input Offset Current 1 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 0 25 45 65 85 105 Ambient Temperature (°C) Common Mode Input Voltage (V) FIGURE 2-8: Input Noise Voltage Density vs. Common Mode Input Voltage. 100 125 FIGURE 2-11: Input Bias, Offset Current vs. Ambient Temperature. 1000 Input Bias Current (pA) Representative Part PSRR- 90 80 PSRR+ 70 CMRR 60 c 50 40 30 TA = +125°C 100 TA = +85°C 10 VDD = 6.0V FIGURE 2-9: Frequency. DS22257A-page 6 CMRR, PSRR vs. 6.0 5.5 5.0 4.5 4.0 3.5 3.0 1000 2.5 100 2.0 10 Frequency (Hz) 1.5 1 1.0 0.1 0.5 1 20 0.0 CMRR, PSRR (dB) 0 25 50 75 Ambient Temperature (°C) FIGURE 2-10: Temperature. Input Bias and Offset Currents (pA) Input Noise Voltage Density (nV/Hz) FIGURE 2-7: vs. Frequency. 1k 1000 100 95 90 85 80 75 70 65 60 55 50 Common Mode Input Voltage (V) FIGURE 2-12: Input Bias Current vs. Common Mode Input Voltage. © 2010 Microchip Technology Inc. MCP6441 Note: Unless otherwise indicated, TA = +25°C, VDD = +1.4V to +6.0V, VSS = GND, VCM = VDD/2, VOUT ≈ VDD/2, Ω VL = VDD/2, RL = 1 MΩ to VL and CL = 60 pF. 130 DC Open-Loop Gain (dB) 600 VDD = 6.0V 500 450 400 350 VDD = 1.4V 300 250 90 80 RL = 10 kΩ VSS + 0.1V < VOUT < VDD - 0.1V 70 6.0 5.5 5.0 4.5 4.0 3.5 3.0 125 2.5 0 25 50 75 100 Ambient Temperature (°C) 2.0 -25 FIGURE 2-13: Quiescent Current vs. Ambient Temperature. Power Supply Voltage (V) FIGURE 2-16: DC Open-Loop Gain vs. Power Supply Voltage. 700 130 DC Open-Loop Gain (dB) 600 500 400 TA = TA = TA = TA = 200 100 +125°C +85°C +25°C -40°C 7.0 6.5 6.0 5.5 4.5 5.0 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 Power Supply Voltage (V) FIGURE 2-14: Quiescent Current vs. Power Supply Voltage. Open-Loop Gain 100 80 Open-Loop Phase 40 -90 -180 -210 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 1.0E+05 1m 10m 0.1 1 10 100 1k 10k 100k Frequency (Hz) Open-Loop Gain, Phase vs. © 2010 Microchip Technology Inc. RL = 10k Ω 60 0.00 -30 -20 FIGURE 2-15: Frequency. Large Signal AOL 70 16 -150 VDD = 6.0V 80 18 -120 20 VDD = 1.4V 90 0 -60 60 100 0.05 0.10 0.15 0.20 Output Voltage Headroom (V) 0.25 FIGURE 2-17: DC Open-Loop Gain vs. Output Voltage Headroom. Open-Loop Phase (°) 120 110 90 Phase Margin 80 14 70 12 60 10 50 8 40 Gain Bandwidth Product 6 30 4 20 VDD = 6.0V 2 10 0 -50 Phase Margin (°) 300 VDD = 6.0V 120 Gain Bandwidth Product (kHz) Quiescent Current (nA/Amplifier) 100 1.0 -50 Open-Loop Gain (dB) 110 60 200 0 120 1.5 Quiescent Current (nA/Amplifier) 550 -25 0 25 50 75 100 Ambient Temperature (°C) 0 125 FIGURE 2-18: Gain Bandwidth Product, Phase Margin vs. Ambient Temperature. DS22257A-page 7 MCP6441 90 Phase Margin 16 80 14 70 12 60 10 50 Gain Bandwidth Product 8 40 6 30 4 20 VDD = 1.4V 2 10 0 -50 -25 Phase Margin (°) Gain Bandwidth Product (kHz) 18 0 25 50 75 100 Ambient Temperature (°C) 0 125 1000 10 RL = 10 kΩ 0.1 0.01 10 0.1 1 100 1000 Output Current (mA) 10 10000 FIGURE 2-22: Output Voltage Headroom vs. Output Current. Output Voltage Headroom VDD - VOH or VOL - VSS (mV) TA = -40°C TA = +25°C TA = +85°C TA = +125°C 25 20 15 10 5 15 10 5 FIGURE 2-20: Output Short Circuit Current vs. Power Supply Voltage. VDD - VOH @ VDD = 1.4V VOL - VSS @ VDD = 1.4V 0 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 VDD - VOH @ VDD = 6.0V VOL - VSS @ VDD = 6.0V 20 -50 Power Supply Voltage (V) -25 0 25 50 75 100 Ambient Temperature (°C) 125 FIGURE 2-23: Output Voltage Headroom vs. Ambient Temperature. 6 VDD = 6.0V Falling Edge, VDD = 6.0V Rising Edge, VDD = 6.0V 5 Slew Rate (V/ms) Output Voltage Swing (V P-P) VDD - VOH @ VDD = 6.0V VOL - VSS @ VDD = 6.0V 1 25 30 10 VDD - VOH @ VDD = 1.4V VOL - VSS @ VDD = 1.4V 100 35 0.0 Output Short Circuit Current (mA) FIGURE 2-19: Gain Bandwidth Product, Phase Margin vs. Ambient Temperature. Output Voltage Headroom (mV) Note: Unless otherwise indicated, TA = +25°C, VDD = +1.4V to +6.0V, VSS = GND, VCM = VDD/2, VOUT ≈ VDD/2, VL = VDD/2, RL = 1 MΩ to VL and CL = 60 pF. VDD = 1.4V 1 4 3 2 Falling Edge, VDD = 1.4V Rising Edge, VDD = 1.4V 1 0 0.1 10 FIGURE 2-21: Frequency. DS22257A-page 8 100 1k 100 1000 Frequency (Hz) 10k 10000 Output Voltage Swing vs. -50 -25 FIGURE 2-24: Temperature. 0 25 50 75 Ambient Temperature (°C) 100 125 Slew Rate vs. Ambient © 2010 Microchip Technology Inc. MCP6441 VDD = 6.0V G = +1 V/V 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Output Voltage (V) Output Voltage (20 mv/div) Note: Unless otherwise indicated, TA = +25°C, VDD = +1.4V to +6.0V, VSS = GND, VCM = VDD/2, VOUT ≈ VDD/2, VL = VDD/2, RL = 1 MΩ to VL and CL = 60 pF. Time (200 µs/div) FIGURE 2-25: Pulse Response. Small Signal Non-Inverting VDD = 6.0V G = -1 V/V Time (2 ms/div) FIGURE 2-28: Response. Large Signal Inverting Pulse VDD = 6.0V G = -1 V/V Input,Output Voltage (V) Output Voltage (20 mv/div) 7.0 6.0 5.0 VOUT VIN 4.0 3.0 2.0 1.0 VDD = 6.0V G = +2 V/V 0.0 -1.0 Time (2 ms/div) Time (200 µs/div) 6.0 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 1M 1000000 VDD = 6.0V G = +1 V/V Time (2 ms/div) FIGURE 2-27: Pulse Response. FIGURE 2-29: The MCP6441 Device Shows No Phase Reversal. Large Signal Non-Inverting © 2010 Microchip Technology Inc. Closed Loop Output Impedance (Ω) Output Voltage (V) FIGURE 2-26: Response. 100k 100000 10k 10000 1k 1000 G N: 101 V/V 11 V/V 1 V/V 100 100 10 10 1 1 1 1 10 10 100 100 1000 1k 10000 10k Frequency (Hz) FIGURE 2-30: Closed Loop Output Impedance vs. Frequency. DS22257A-page 9 MCP6441 Note: Unless otherwise indicated, TA = +25°C, VDD = +1.4V to +6.0V, VSS = GND, VCM = VDD/2, VOUT ≈ VDD/2, VL = VDD/2, RL = 1 MΩ to VL and CL = 60 pF. 1m 1.E-03 100µ 1.E-04 -IIN (A) 10µ 1.E-05 1µ 1.E-06 100n 1.E-07 10n 1.E-08 1n 1.E-09 100p 1.E-10 10p 1.E-11 TA = -40°C TA = +25°C TA = +85°C TA = +125°C 1p 1.E-12 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 Input Voltage (V) FIGURE 2-31: Measured Input Current vs. Input Voltage (below VSS). DS22257A-page 10 © 2010 Microchip Technology Inc. MCP6441 3.0 PIN DESCRIPTIONS Descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE MCP6441 SC70-5, SOT-23-5 3.1 Symbol Description Analog Output 1 VOUT 2 VSS Negative Power Supply 3 VIN+ Non-inverting Input 4 VIN– Inverting Input 5 VDD Positive Power Supply Analog Output (VOUT) The output pin is a low-impedance voltage source. 3.2 Power Supply Pins (VDD, VSS) The positive power supply (VDD) is 1.4V to 6.0V 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. 3.3 Analog Inputs (VIN+, VIN-) The non-inverting and inverting inputs are highimpedance CMOS inputs with low bias currents. © 2010 Microchip Technology Inc. DS22257A-page 11 MCP6441 NOTES: DS22257A-page 12 © 2010 Microchip Technology Inc. MCP6441 4.0 APPLICATION INFORMATION The MCP6441 op amp is manufactured using Microchip’s state-of-the-art CMOS process, specifically designed for low power applications. 4.1 In some applications, it may be necessary to prevent excessive voltages from reaching the op amp inputs; Figure 4-2 shows one approach to protecting these inputs. VDD Rail-to-Rail Input 4.1.1 PHASE REVERSAL The MCP6441 op amp is designed to prevent phase reversal, when the input pins exceed the supply voltages. Figure 2-29 shows the input voltage exceeding the supply voltage with no phase reversal. 4.1.2 D1 D2 U1 V1 MCP6441 VOUT V2 INPUT VOLTAGE LIMITS In order to prevent damage and/or improper operation of the amplifier, the circuit must limit the voltages at the input pins (see Section 1.1 “Absolute Maximum Ratings †”). The Electrostatic Discharge (ESD) protection on the inputs can be depicted as shown in Figure 4-1. This structure was chosen to protect the input transistors against many, but not all, over-voltage conditions, and to minimize the input bias current (IB). VDD Bond Pad VIN+ Bond Pad Input Stage Bond V – IN Pad FIGURE 4-2: Inputs. Protecting the Analog A significant amount of current can flow out of the inputs when the Common Mode voltage (VCM) is below ground (VSS); See Figure 2-31. 4.1.3 INPUT CURRENT LIMITS In order to prevent damage and/or improper operation of the amplifier, the circuit must limit the currents into the input pins (see Section 1.1 “Absolute Maximum Ratings †”). Figure 4-3 shows one approach to protecting these inputs. The resistors R1 and R2 limit the possible currents in or out of the input pins (and the ESD diodes, D1 and D2). The diode currents will go through either VDD or VSS. VDD VSS Bond Pad FIGURE 4-1: Structures. D1 Simplified Analog Input ESD The input ESD diodes clamp the inputs when they try to go more than one diode drop below VSS. They also clamp any voltages that go well above VDD; their breakdown voltage is high enough to allow normal operation, but not low enough to protect against slow over-voltage (beyond VDD) events. Very fast ESD events that meet the spec are limited so that damage does not occur. © 2010 Microchip Technology Inc. D2 U1 V1 R1 MCP6441 VOUT V2 R2 min(R1,R2) > VSS – min(V1, V2) 2 mA min(R1,R2) > max(V1,V2) – VDD 2 mA FIGURE 4-3: Inputs. Protecting the Analog DS22257A-page 13 MCP6441 NORMAL OPERATION The input stage of the MCP6441 op amp uses two differential input stages in parallel. One operates at a low Common Mode input voltage (VCM), while the other operates at a high VCM. With this topology, the device operates with a VCM up to 300 mV above VDD and 300 mV below VSS. The input offset voltage is measured at VCM = VSS – 0.3V and VDD + 0.3V, to ensure proper operation. Figure 4-5 gives the recommended RISO values for the 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). 1000000 1M Recommended RISO (Ω) 4.1.4 The transition between the input stages occurs when VCM is near VDD – 0.6V (see Figures 2-3 and 2-4). For the best distortion performance and gain linearity, with non-inverting gains, avoid this region of operation. 4.2 Rail-to-Rail Output The output voltage range of the MCP6441 op amp is VSS + 20 mV (minimum) and VDD – 20 mV (maximum) when RL = 10 kΩ is connected to VDD/2 and VDD = 6.0V. Refer to Figures 2-22 and 2-23 for more information. 4.3 Capacitive Loads 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 the capacitive loads, all gains show the same general behavior. When driving large capacitive loads with the MCP6441 op amp (e.g., > 100 pF when G = +1 V/V), a small series resistor at the output (RISO in Figure 4-4) 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 MCP6441 VIN + VOUT CL 100k 100000 10k 10000 G N: 1 V/V 2 V/V ≥ 5 V/V 1k 1000 10p 1.E-10 100p 1.E-09 1n 10n 0.1µ 1µ 1.E-11 1.E-08 1.E-07 1.E-06 Normalized Load Capacitance; CL/GN (F) FIGURE 4-5: 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 MCP6441 SPICE macro model are very helpful. 4.4 Supply Bypass The MCP6441 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 MCP6441 op amp’s bias current at +25°C (±1 pA, typical). FIGURE 4-4: Output Resistor, RISO Stabilizes Large Capacitive Loads. DS22257A-page 14 © 2010 Microchip Technology Inc. MCP6441 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 4-6. Guard Ring FIGURE 4-6: for Inverting Gain. 1. 2. VIN– VIN+ VSS 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. © 2010 Microchip Technology Inc. 4.6 4.6.1 Application Circuits BATTERY CURRENT SENSING The MCP6441 op amp’s Common Mode Input Range, which goes 0.3V beyond both supply rails, supports their use in high-side and low-side battery current sensing applications. The low quiescent current (450 nA, typical) helps prolong battery life, and the rail-to-rail output supports detection of low currents. Figure 4-7 shows a high side battery current sensor circuit. The 10Ω resistor is sized to minimize power losses. The battery current (IDD) through the 10Ω resistor causes its top terminal to be more negative than the bottom terminal. This keeps the Common Mode input voltage of the op amp below VDD, which is within its allowed range. The output of the op amp will also be below VDD, within its Maximum Output Voltage Swing specification. IDD 1.4V to 6.0V To load 10Ω 100 kΩ VDD MCP6441 VOUT 1 MΩ VDD – VOUT I DD = -----------------------------------------( 10 V/V ) ⋅ ( 10 Ω ) FIGURE 4-7: Battery Current Sensing. DS22257A-page 15 MCP6441 4.6.2 PRECISION HALF-WAVE RECTIFIER 4.6.3 The precision half-wave rectifier, which is also known as a super diode, is a configuration obtained with an operational amplifier in order to have a circuit behaving like an ideal diode and rectifier. It effectively cancels the forward voltage drop of the diode in such way that very low level signals can still be rectified, with minimal error. This can be useful for high-precision signal processing. The MCP6441 op amp has high input impedance, low input bias current and rail-to-rail input/output, which makes this device suitable for precision rectifier applications. Figure 4-8 shows a precision half-wave rectifier and its transfer characteristic. The rectifier’s input impedance is determined by the input resistor R1. To avoid the loading effect, it must be driven from a low-impedance source. When VIN is greater than zero, D1 is OFF, D2 is ON, and VOUT is zero. When VIN is less than zero, D1 is ON, D2 is OFF, and VOUT is the VIN with an amplification of -R2/R1. The rectifier circuit shown in Figure 4-8 has the benefit that the op amp never goes in saturation, so the only thing affecting its frequency response is the amplification and the gain bandwidth product. INSTRUMENTATION AMPLIFIER The MCP6441 op amp is well suited for conditioning sensor signals in battery-powered applications. Figure 4-9 shows a two op amp instrumentation amplifier, using the MCP6441 device, that works well for applications requiring rejection of Common Mode noise at higher gains. The reference voltage (VREF) is supplied by a low-impedance source. In single supply applications, VREF is typically VDD/2. RG VREF R1 R2 R2 R1 VOUT V2 MCP6441 MCP6441 V1 R1 2R 1 VOUT = ( V1 – V 2 ) ⎛⎝ 1 + ------ + ---------⎞⎠ + VREF R2 RG FIGURE 4-9: Two Op Amp Instrumentation Amplifier. . R2 D2 VIN R1 VOUT MCP6441 D1 Precision Half-Wave Rectifier VOUT -R2/R1 VIN Transfer Characteristic FIGURE 4-8: Rectifier. DS22257A-page 16 Precision Half-Wave © 2010 Microchip Technology Inc. MCP6441 5.0 DESIGN AIDS Microchip provides the basic design tools needed for the MCP6441 op amp. 5.1 SPICE Macro Model The latest SPICE macro model for the MCP6441 op amp is available on the Microchip web site at www.microchip.com. The model was written and tested in the official OrCAD (Cadence®) owned PSpice®. For the other simulators, translation may be required. 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 the 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 cannot ensure 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 design using op amps. 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 the actual filter performance. 5.3 5.4 Microchip Advanced Part Selector (MAPS) MAPS is a software tool that helps semiconductor professionals efficiently identify the 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 Data Sheets, 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 Mindi™ Circuit Designer and Simulator Microchip’s Mindi Circuit Designer and Simulator aids in the design of various circuits useful for active filter, amplifier and power-management applications. It is a free online circuit designer and simulator, available from the Microchip web site at www.microchip.com/mindi. This interactive circuit designer and simulator enables designers to quickly generate circuit diagrams and simulate circuits. Circuits developed using the Mindi Circuit Designer and Simulator can be downloaded to a personal computer or workstation. © 2010 Microchip Technology Inc. DS22257A-page 17 MCP6441 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 • AN1297 – “Microchip’s Op Amp SPICE Macro Models”, DS01297 These application notes and others are listed in the design guide: • “Signal Chain Design Guide”, DS21825 DS22257A-page 18 © 2010 Microchip Technology Inc. MCP6441 6.0 PACKAGING INFORMATION 6.1 Package Marking Information 5-Lead SC70 XXNN 5-Lead SOT-23 XXNN DG25 Example: WU25 Legend: XX...X Y YY WW NNN e3 * Note: Example: 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. © 2010 Microchip Technology Inc. DS22257A-page 19 MCP6441 . # #$#/!- 0 # 1/%# #!# ##+22--- 2/ D b 3 1 2 E1 E 4 5 e A e A2 c A1 L 3# 4# 5$8 %1 44"" 5 5 56 7 ( 1# 6,:# ; 9()* < !!1// ; < #! %% < 6,=!# " ; !!1/=!# " ( ( ( 6,4# ; ( . #4# 4 9 4!/ ; < 9 4!=!# 8 ( < !"! #$! !% #$ !% #$ #&! ! !# "'( )*+ ) #&#,$ --# $## - *9) DS22257A-page 20 © 2010 Microchip Technology Inc. MCP6441 . # #$#/!- 0 # 1/%# #!# ##+22--- 2/ © 2010 Microchip Technology Inc. DS22257A-page 21 MCP6441 ! . # #$#/!- 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,:# < !!1// ; < #! %% < ( 6,=!# " < !!1/=!# " < ; 6,4# < )* ( . #4# 4 < 9 . ## 4 ( < ; . # I > < > 4!/ ; < 9 4!=!# 8 < ( !"! #$! !% #$ !% #$ #&! ! !# "'( )*+ ) #&#,$ --# $## - *) DS22257A-page 22 © 2010 Microchip Technology Inc. MCP6441 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging © 2010 Microchip Technology Inc. DS22257A-page 23 MCP6441 NOTES: DS22257A-page 24 © 2010 Microchip Technology Inc. MCP6441 APPENDIX A: REVISION HISTORY Revision A (September 2010) • Original Release of this Document. © 2010 Microchip Technology Inc. DS22257A-page 25 MCP6441 NOTES: DS22257A-page 26 © 2010 Microchip Technology Inc. MCP6441 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. Device Device: T -X /XX Tape and Reel Temperature Package Range MCP6441: = -40°C to +125°C Package: = Plastic Package (SC70), 5-lead = Plastic Small Outline Transistor (SOT-23), 5-lead © 2010 Microchip Technology Inc. a) MCP6441T-E/LT: b) MCP6441T-E/OT: Tape and Reel, 5LD SC70 Package Tape and Reel, 5LD SOT-23 Package Single Op Amp (Tape and Reel) (SC70, SOT-23) Temperature Range: E LT OT Examples: DS22257A-page 27 MCP6441 NOTES: DS22257A-page 28 © 2010 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, PIC32 logo, 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, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver, 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. © 2010, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. ISBN: 978-1-60932-513-8 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. © 2010 Microchip Technology Inc. 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