3PEAK TP1541A/ TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Features Description Stable 1.3MHz GBWP Over Temperature Range Stable 1.3MHz GBWP in VCM from 0V to VDD 0.7V/s Slew Rate Only 80A of Supply Current per Amplifier Excellent EMIRR: 80dB(1GHz) Offset Voltage: 400uV Maximum Offset Voltage Temperature Drift: 1uV/C Input Bias Current: 1pA Typical THD+Noise: -105dB at 1kHz, -90dB at 10kHz High CMRR/PSRR: 95dB/90dB Beyond the Rails Input Common-Mode Range High Output Current: 100mA No Phase Reversal for Overdriven Inputs Drives 2k Resistive Loads Shutdown Current: 0.2A (TP1541NA) Single +2.1V to +6.0V Supply Voltage Range -40C to 125C Operation Temperature Range ESD Rating: Robust 8KV - HBM, 2KV - CDM and 500V - MM Green, Popular Type Package TP154xA series are CMOS single/dual/quad op-amps with low offset, stable high frequency response, low power, low supply voltage, and rail-to-rail inputs and outputs. They incorporate 3PEAKs proprietary and patented design techniques to achieve best in-class performance among all micro-power CMOS amplifiers in its power class. The TP154xA family can be used as plug-in replacements for many commercially available op-amps to reduce power and improve input/output range and performance. TP154xA are unity gain stable with Any Capacitive load with a constant 1.3MHz GBWP, 0.7V/s slew rate while consuming only 80A of quiescent current per amplifier. Analog trim and calibration routine reduce input offset voltage to below 0.4mV, and proprietary precision temperature compensation technique makes offset voltage temperature drift at 1V/C. Adaptive biasing and dynamic compensation enables the TP154xA to achieve THD+Noise for 1kHz/10kHz 2VPP signal at -105dB and -90dB, respectively. Beyond the rails input and rail-to-rail output characteristics allow the full power-supply voltage to be used for signal range. This combination of features makes the TP154xA ideal choices for battery-powered applications because they minimize errors due to power supply voltage variations over the lifetime of the battery and maintain high CMRR even for a rail-to-rail input op-amp. General audio output, remote batterypowered sensors, and smoke detector can benefit from the features of the TP154xA op-amps. Applications Audio Output Active Filters, ASIC Input or Output Amplifier Portable Instruments and Mobile Equipment Battery or Solar Powered Systems Smoke/Gas/Environment Sensors Piezo Electrical Transducer Amplifier Medical Equipment PCMCIA Cards For applications that require power-down, the TP1541NA in popular type packages has a low-power shutdown mode that reduces supply current to 0.2A, and forces the output into a high-impedance state. 3PEAK and the 3PEAK logo are registered trademarks of 3PEAK INCORPORATED. All other trademarks are the property of their respective owners. Pin Configuration (Top View) TP1541A TP1542A 5-Pin SOT23/SC70 8-Pin SOIC/TSSOP/MSOP (-T and -C Suffixes) (-S, -T and -V Suffixes) Out 1 Vs 2 +In 3 5 Vs 4 -In Out A 1 In A 2 In A 3 Vs 4 TP1541NA A B 7 Out B 6 In B 5 In B 8-Pin DFN 1 6 +VS -VS 2 5 SHDN -In 3 4 Out (-S and -T Suffixes) Out A 1 In A 2 A Out A 1 8 Vs In A 2 7 Out B In A 3 6 In B Vs 4 5 In B 14 Out D 13 In D D In A 3 12 In D Vs 4 11 Vs In B 5 10 In C B (-F Suffix) +In 14-Pin SOIC/TSSOP Vs TP1542A 6-Pin SC70 (-C Suffix) www.3peakic.com.cn TP1544A 8 C In B 6 9 In C Out B 7 8 Out C Rev. B.04 1 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Absolute Maximum Ratings Note 1 + - Supply Voltage: V - V ....................................7.0V - + Output Short-Circuit Duration Note 3............... Infinite Input Voltage............................. V - 0.3 to V + 0.3 Operating Temperature Range.......-40C to 125C Input Current: +IN, -IN, SHDN Note 2.............. 10mA Maximum Junction Temperature................... 150C Differential Input Voltage................................ 7V - + SHDN Pin Voltage.................................V to V Storage Temperature Range.......... -65C to 150C Lead Temperature (Soldering, 10 sec) ......... 260C Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The inputs are protected by ESD protection diodes to each power supply. If the input extends more than 500mV beyond the power supply, the input current should be limited to less than 10mA. Note 3: A heat sink may be required to keep the junction temperature below the absolute maximum. This depends on the power supply voltage and how many amplifiers are shorted. Thermal resistance varies with the amount of PC board metal connected to the package. The specified values are for short traces connected to the leads. ESD, Electrostatic Discharge Protection Symbol Parameter Condition Minimum Level Unit HBM Human Body Model ESD MIL-STD-883H Method 3015.8 8 kV MM Machine Model ESD JEDEC-EIA/JESD22-A115 500 V CDM Charged Device Model ESD JEDEC-EIA/JESD22-C101E 2 kV Order Information Model Name TP1541A TP1541NA TP1542A TP1544A 2 Order Number TP1541A-TR TP1541NA-CR TP1542A-SR TP1542A-VR TP1542A-FR TP1544A-SR TP1544A-TR Rev. B.04 Package 5-Pin SOT23 6-Pin SC70 8-Pin SOIC 8-Pin MSOP 8-Pin DFN 14-Pin SOIC 14-Pin TSSOP Transport Media, Quantity Tape and Reel, 3000 Tape and Reel, 3000 Tape and Reel, 4000 Tape and Reel, 3000 Tape and Reel, 3000 Tape and Reel, 2500 Tape and Reel, 3000 Marking Information 541 54N 1542A 1542A 542 1544A 1544A www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Electrical Characteristics The specifications are at TA = 27 C. VS = 5V, VCM = 2.5V, RL = 2k, CL =100pF, Unless otherwise noted. SYMBOL VOS VOS TC PARAMETER CONDITIONS MIN TYP MAX UNITS -400 50 +400 V Input Offset Voltage VCM = 0V to 3V Input Offset Voltage Drift -40 C to 125 C 1 TA = 27 C 1 TA = 85 C 25 pA V/ C 10 pA IB Input Bias Current IOS Input Offset Current 0.001 pA Input Voltage Noise f = 0.1Hz to 10Hz 7 VPP f = 1kHz f = 1kHz Differential Common Mode VCM = 0.1V to 2.6V 27 nV/Hz fA/Hz Vn en in Input Voltage Noise Density Input Current Noise CIN Input Capacitance CMRR PSRR Common Mode Rejection Ratio Common-mode Input Voltage Range Power Supply Rejection Ratio AVOL VCM 85 2 7.76 6.87 95 V- -0.3 pF dB V++0.3 V VCM = 2.5V, VS = 3V to 5V 77 90 dB Open-Loop Large Signal Gain RLOAD = 10k 98 120 dB VOL, VOH Output Swing from Supply Rail RLOAD = 10k ROUT Closed-Loop Output Impedance G = 1, f =1kHz, IOUT = 0 RO Open-Loop Output Impedance f = 1kHz, IOUT = 0 ISC Output Short-Circuit Current Sink or source current IO Output Current Sink or source current, Output 1V Drop VDD Supply Voltage IQ 3 90 6 mV 0.002 125 100 mA 50 mA 2.1 6.0 V 110 A Quiescent Current per Amplifier VS = 5V 80 PM Phase Margin RLOAD = 1k, CLOAD = 60pF 65 GM Gain Margin RLOAD = 1k, CLOAD = 60pF 15 dB Gain-Bandwidth Product f = 1kHz AV = 1, VOUT = 1.5V to 3.5V, CLOAD = 60pF, RLOAD = 1k 1.3 MHz 0.7 V/s AV = -1, VOUT = 1V Step 3.7 4.9 s f = 1kHz, AV =1, RL = 2k, VOUT = 1Vp-p -105 dB f = 1kHz, RL = 2k 110 dB VS = 5V 0.2 A VSHDN = 0.5V -0.15 A VSHDN = 1.5V -0.15 A GBWP SR tS THD+N Xtalk Slew Rate Settling Time, 0.1% Settling Time, 0.01% Total Harmonic Distortion and Noise Channel Separation IQ(OFF) Supply Current in Shutdown ISHDN Shutdown Pin Current ILEAK Output Leakage Current in Shutdown VSHDN = 0V, VOUT = 0V -20 pA VSHDN = 0V, VOUT = 5V 20 pA VIL SHDN Input Low Voltage Disable VIH SHDN Input High Voltage Enable tON Turn-On Time SHDN Toggle from 0V to 5V 20 ms tOFF Turn-Off Time SHDN Toggle from 5V to 0V 20 ms www.3peakic.com.cn 0.5 1.0 V V Rev. B.04 3 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Typical Performance Characteristics VS = 2.75V, VCM = 0V, RL = Open, unless otherwise specified. Offset Voltage Production Distribution Unity Gain Bandwidth vs. Temperature 2.0 3000 Number =46247pcs 1.8 2500 1.3 GBW(MHz) Population 1.5 2000 1500 1000 1.0 0.8 0.5 500 0.3 0.0 400 350 300 250 200 150 100 0 50 -50 -100 -150 -200 -250 -300 -350 -400 0 -50 0 Offset Voltage(V) 100 150 Temperature() Open-Loop Gain and Phase Input Voltage Noise Spectral Density 140 1000 200 120 Phase 60 50 40 Gain 0 20 0 Phase () 100 80 Noise(nV/Hz) 150 100 Gain(dB) 50 100 10 -50 -20 -100 -40 -60 0.1 10 1k 100k 1 -150 1000M 10M 1 10 Input Bias Current vs. Temperature 10k 100k 1M 0 40 -5 Input Bias Current(pA) Input Bias Current(pA) 1k Input Bias Current vs. Input Common Mode Voltage 50 30 20 10 -10 -15 -20 0 -10 -40 -20 0 20 40 60 Temperature() 4 100 Frequency(Hz) Frequency (Hz) Rev. B.04 80 100 120 -25 0 1 2 3 4 5 Common Mode Voltage(V) www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Typical Performance Characteristics VS = 2.75V, VCM = 0V, RL = Open, unless otherwise specified. (Continued) Common Mode Rejection Ratio CMRR vs. Frequency 160 140 140 120 120 CMRR(dB) CMRR(dB) 100 80 60 40 100 80 60 40 20 20 0 0 0 1 2 3 4 5 1 10 100 Common-mode Voltage(V) Quiescent Current vs. Temperature 10k 100k 1M Short Circuit Current vs. Temperature 120 140 VCM= 2.5V 120 Current(mA) 100 Supply current(A) 1k Frequency(Hz) VCM= 5.0V 80 60 VCM= 0V ISOURCE 100 ISINK 80 60 40 40 20 20 0 0 -50 -50 0 50 100 0 100 150 Temperature() Temperature() Power-Supply Rejection Ratio Quiescent Current vs. Supply Voltage 120 120 PSRR+ 100 Supply current (uA) 100 PSRR- 80 PSRR(dB) 50 150 60 40 20 80 60 40 20 0 0 -20 1.5 0.1 10 1k Frequency(Hz) www.3peakic.com.cn 100k 2 2.5 3 3.5 4 4.5 5 Supply Voltage (V) Rev. B.04 5 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Typical Performance Characteristics VS = 2.75V, VCM = 0V, RL = Open, unless otherwise specified. (Continued) PSRR vs. Temperature CMRR vs. Temperature 140 120 120 CMRR(-dB) PSRR(-dB) 100 80 60 100 80 60 40 40 20 20 0 0 -50 0 50 100 -50 150 0 50 100 150 Temperature() Temperature() EMIRR IN+ vs. Frequency Large-Scale Step Response 90 Gain = 1 RL = 10k 2V/div 80 EMIRR IN+ (dB) 70 60 50 40 30 2V/div 20 10 0 1 10 100 1000 Time (50s/div) Frequency (MHz) Gain = +10 V = 2.5V 1V/div Time (50s/div) 6 Positive Over-Voltage Recovery 2V/div Gain = +10 V = 2.5V 1V/div 2V/div Negative Over-Voltage Recovery Rev. B.04 Time (50s/div) www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Typical Performance Characteristics VS = 2.75V, VCM = 0V, RL = Open, unless otherwise specified. (Continued) 0.1 Hz TO 10 Hz Input Voltage Noise Offset Voltage vs Common-Mode Voltage 200 100 5V/div Offset voltage(V) 0 -100 -200 -300 -400 -500 -600 -700 -800 -900 0 Time (1s/div) 2 3 4 5 Common-mode voltage(V) Positive Output Swing vs. Load Current Negative Output Swing vs. Load Current 120 0 100 -20 25 -40 125 -40 80 -60 Iout(mA) Iout(mA) 1 60 -80 40 25 -100 -40 20 -120 125 0 -140 0 1 2 3 4 5 0 1 2 3 4 5 Vout Dropout (V) Vout Dropout (V) Offset Voltage vs. Temperature 80 Offset voltage(V) 70 60 50 40 30 20 10 0 -50 0 50 100 150 Temperature() www.3peakic.com.cn Rev. B.04 7 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Pin Functions -IN: Inverting Input of the Amplifier. Voltage range - + of this pin can go from V - 0.3V to V + 0.3V. +IN: Non-Inverting Input of Amplifier. This pin has the same voltage range as -IN. +VS: Positive Power Supply. Typically the voltage is from 2.1V to 6V. Split supplies are possible as long as the voltage between V+ and V- is between 2.1V and 6V. A bypass capacitor of 0.1F as close to the part as possible should be used between power supply pins or between supply pins and ground. -VS: Negative Power Supply. It is normally tied to ground. It can also be tied to a voltage other than + - ground as long as the voltage between V and V is from 2.1V to 6V. If it is not connected to ground, bypass it with a capacitor of 0.1F as close to the part as possible. SHDN: Active Low Shutdown. Shutdown threshold is 1.0V above negative supply rail. If unconnected, the amplifier is automatically enabled. OUT: Amplifier Output. The voltage range extends to within millivolts of each supply rail. N/C: No Connection. Operation The TP154xA family input signal range extends beyond the negative and positive power supplies. The output can even extend all the way to the negative supply. The input stage is comprised of two CMOS differential amplifiers, a PMOS stage and NMOS stage that are active over different ranges of common mode input voltage. The Class-AB control buffer and output bias stage uses a proprietary compensation technique to take full advantage of the process technology to drive very high capacitive loads. This is evident from the transient over shoot measurement plots in the Typical Performance Characteristics. Applications Information Low Supply Voltage and Low Power Consumption The TP154xA family of operational amplifiers can operate with power supply voltages from 2.1V to 6.0V. Each amplifier draws only 80A quiescent current. The low supply voltage capability and low supply current are ideal for portable applications demanding HIGH CAPACITIVE LOAD DRIVING CAPABILITY and CONSTANT WIDE BANDWIDTH. The TP154xA family is optimized for wide bandwidth low power applications. They have an industry leading high GBWP to power ratio and are unity gain stable for ANY CAPACITIVE load. When the load capacitance increases, the increased capacitance at the output pushed the non-dominant pole to lower frequency in the open loop frequency response, lowering the phase and gain margin. Higher gain configurations tend to have better capacitive drive capability than lower gain configurations due to lower closed loop bandwidth and hence higher phase margin. Low Input Referred Noise The TP154xA family provides a low input referred noise density of 27nV/Hz at 1kHz. The voltage noise will grow slowly with the frequency in wideband range, and the input voltage noise is typically 7VP-P at the frequency of 0.1Hz to 10Hz. Low Input Offset Voltage The TP154xA family has a low offset voltage of 400V maximum which is essential for precision applications. The offset voltage is trimmed with a proprietary trim algorithm to ensure low offset voltage for precision signal processing requirement. 8 Rev. B.04 www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Low Input Bias Current The TP154xA family is a CMOS OPA family and features very low input bias current in pA range. The low input bias current allows the amplifiers to be used in applications with high resistance sources. Care must be taken to minimize PCB Surface Leakage. See below section on "PCB Surface Leakage" for more details. 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 12 humidity conditions, a typical resistance between nearby traces is 10 . A 5V difference would cause 5pA of current to flow, which is greater than the TP154xA OPAs input bias current at +27C (1pA, typical). It is recommended to use multi-layer PCB layout and route the OPAs -IN and +IN signal under the PCB surface. The effective 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 1 for Inverting Gain application. 1. For 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. 2. For Inverting Gain and Trans-impedance 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. Guard Ring VIN+ VIN- +VS Figure 1 Ground Sensing and Rail to Rail Output The TP154xA family has excellent output drive capability, delivering over 100mA of output drive current. The output stage is a rail-to-rail topology that is capable of swinging to within 10mV of either rail. Since the inputs can go 300mV beyond either rail, the op-amp can easily perform true ground sensing. The maximum output current is a function of total supply voltage. As the supply voltage to the amplifier increases, the output current capability also increases. Attention must be paid to keep the junction temperature of the IC below 150C when the output is in continuous short-circuit. The output of the amplifier has reverse-biased ESD diodes connected to each supply. The output should not be forced more than 0.5V beyond either supply, otherwise current will flow through these diodes. ESD The TP154xA family has reverse-biased ESD protection diodes on all inputs and output. not be biased more than 300mV beyond either supply rail. Input and out pins can Shut-down The single channel OPA versions have SHDN pins that can shut down the amplifier to less than 0.2A supply current. The SHDN pin voltage needs to be within 0.5V of V- for the amplifier to shut down. During shutdown, the output will be in high output resistance state, which is suitable for multiplexer applications. When left floating, the SHDN pin is internally pulled up to the positive supply and the amplifier remains enabled. www.3peakic.com.cn Rev. B.04 9 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Driving Large Capacitive Load The TP154xA family of OPA is designed to drive large capacitive loads. Refer to Typical Performance Characteristics for "Phase Margin vs. Load Capacitance". As always, larger load capacitance decreases overall phase margin in a feedback system where internal frequency compensation is utilized. As the load capacitance increases, the feedback loops phase margin decreases, and the closed-loop bandwidth is reduced. This produces gain peaking in the frequency response, with overshoot and ringing in output step response. The unity-gain buffer (G = +1V/V) is the most sensitive to large capacitive loads. When driving large capacitive loads with the TP154xA OPA family (e.g., > 200 pF when G = +1V/V), a small series resistor at the output (RISO in Figure 3) improves the feedback loops phase margin and stability by making the output load resistive at higher frequencies. Riso Vout Vin Cload Figure 3 Power Supply Layout and Bypass The TP154xA OPAs power supply pin (VDD for single-supply) should have a local bypass capacitor (i.e., 0.01F to 0.1F) within 2mm for good high frequency performance. It can also use a bulk capacitor (i.e., 1F or larger) within 100mm to provide large, slow currents. This bulk capacitor can be shared with other analog parts. Ground layout improves performance by decreasing the amount of stray capacitance and noise at the OPAs inputs and outputs. To decrease stray capacitance, minimize PC board lengths and resistor leads, and place external components as close to the op amps pins as possible. Proper Board Layout To ensure optimum performance at the PCB level, care must be taken in the design of the board layout. To avoid leakage currents, the surface of the board should be kept clean and free of moisture. Coating the surface creates a barrier to moisture accumulation and helps reduce parasitic resistance on the board. Keeping supply traces short and properly bypassing the power supplies minimizes power supply disturbances due to output current variation, such as when driving an ac signal into a heavy load. Bypass capacitors should be connected as closely as possible to the device supply pins. Stray capacitances are a concern at the outputs and the inputs of the amplifier. It is recommended that signal traces be kept at least 5mm from supply lines to minimize coupling. A variation in temperature across the PCB can cause a mismatch in the Seebeck voltages at solder joints and other points where dissimilar metals are in contact, resulting in thermal voltage errors. To minimize these thermocouple effects, orient resistors so heat sources warm both ends equally. Input signal paths should contain matching numbers and types of components, where possible to match the number and type of thermocouple junctions. For example, dummy components such as zero value resistors can be used to match real resistors in the opposite input path. Matching components should be located in close proximity and should be oriented in the same manner. Ensure leads are of equal length so that thermal conduction is in equilibrium. Keep heat sources on the PCB as far away from amplifier input circuitry as is practical. The use of a ground plane is highly recommended. A ground plane reduces EMI noise and also helps to maintain a constant temperature across the circuit board. Instrumentation Amplifier The TP154xA OPA series is well suited for conditioning sensor signals in battery-powered applications. Figure 4 shows a two op-amp instrumentation amplifier, using the TP154xA OPA. The circuit 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 voltage supply applications, VREF is typically VDD/2. 10 Rev. B.04 www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps RG R1 Vref R2 R2 R1 Vout V2 V2 VOUT =(V1 V2 )(1 R1 2 R1 ) VREF R2 RG Figure 4 Gain-of-100 Amplifier Circuit Figure 5 shows a Gain-of-100 amplifier circuit using two TP154xA OPAs. supply rail, and has a -3dB frequency at 100kHz. It draws 160uA total current from Figure 6 shows the small signal frequency response of the circuit. +0.9V Vin Vout -0.9V 90.9K 10K 90.9K 10K Figure 5: 100kHz, 160A Gain-of-100 Amplifier Figure 6: Frequency response of 100kHz, 160uA Gain-of-100 Amplifier Buffered Chemical Sensor (pH) Probe The TP154xA OPA has input bias current in the pA range. This is ideal in buffering high impedance chemical sensors such as pH probe. As an example, the circuit in Figure 7 eliminates expansive low-leakage cables that that is required to connect pH probe to metering ICs such as ADC, AFE and/or MCU. A TP154xA OPA and a lithium battery are housed in the probe assembly. A conventional low-cost coaxial cable can be used to carry OPAs output signal to subsequent ICs for pH reading. www.3peakic.com.cn Rev. B.04 11 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps BATTERY 3V (DURACELL DL1620) GENERAL PURPOSE COMBINATION pH PROBE (CORNING 476540) R1 10M COAX To ADC/AFE/MCU pH PROBE R2 10M ALL COMPONENTS CONTAJNED WITHIN THE pH PROBE Figure 7: Buffer pH Probe Two-Pole Micro-power Sallen-Key Low-Pass Filter Figure 8 shows a micro-power two-pole Sallen-Key Low-Pass Filter with 400Hz cut-off frequency. For best results, the filters cut-off frequency should be 8 to 10 times lower than the OPAs crossover frequency. Additional OPAs phase margin shift can be avoided if the OPAs bandwidth-to-signal ratio is greater than 8. The design equations for the 2-pole Sallen-Key low-pass filter are given below with component values selected to set a 400Hz low-pass filter cutoff frequency: C1 400pF Vin R1 1MOhm R2 1MOhm Vout C2 400pF R1 = R 2 = R = 1M C1 = C2 = C = 400pF Q = Filter Peaking Factor = 1 f -3dB = 1/(2 RC ) = 400Hz R3 2MOhm R4 2MOhm R 3 = R 4 /(2-1/Q) ; with Q = 1, R 3 =R 4 Figure 8 Portable Gas Sensor Amplifier Gas sensors are used in many different industrial and medical applications. Gas sensors generate a current that is proportional to the percentage of a particular gas concentration sensed in an air sample. This output current flows through a load resistor and the resultant voltage drop is amplified. Depending on the sensed gas and sensitivity of the sensor, the output current can be in the range of tens of microamperes to a few milli-amperes. Gas sensor datasheets often specify a recommended load resistor value or a range of load resistors from which to choose. There are two main applications for oxygen sensors - applications which sense oxygen when it is abundantly present (that is, in air or near an oxygen tank) and those which detect traces of oxygen in parts-per-million concentration. In medical applications, oxygen sensors are used when air quality or oxygen delivered to a patient needs to be monitored. In fresh air, the concentration of oxygen is 20.9% and air samples containing less than 18% oxygen are considered dangerous. In industrial applications, oxygen sensors are used to detect the absence of oxygen; for example, vacuum-packaging of food products. The circuit in Figure 9 illustrates a typical implementation used to amplify the output of an oxygen detector. With the components shown in the figure, the circuit consumes less than 37A of supply current ensuring that small form-factor single- or button-cell batteries (exhibiting low mAh charge ratings) could last beyond the operating life of the oxygen sensor. The precision specifications of these amplifiers, such as their low offset voltage, low TC-VOS, 12 Rev. B.04 www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps low input bias current, high CMRR, and high PSRR are other factors which make these amplifiers excellent choices for this application. 10MOhm 1% 100KOhm 1% Vout Oxygen Sensor City Technology 4OX2 I O2 100KOhm 1% 100Ohm 1% VOUT 1Vin Air ( 21% O2 ) I DD 0.7uA Figure 9 www.3peakic.com.cn Rev. B.04 13 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Package Outline Dimensions SC70-5(SC70-6) Dimensions Dimensions In Millimeters In Inches Min Max Min Max A 0.900 1.100 0.035 0.043 A1 0.000 0.100 0.000 0.004 A2 0.900 1.000 0.035 0.039 b 0.150 0.350 0.006 0.014 C 0.080 0.150 0.003 0.006 D 2.000 2.200 0.079 0.087 E 1.150 1.350 0.045 0.053 E1 2.150 2.450 0.085 0.096 e 0.650TYP 0.026TYP e1 1.200 0.047 L 0.525REF 0.021REF L1 0.260 0.460 0.010 0.018 0 8 0 8 Symbol 1.400 0.055 SOT23-5(SOT23-6) Dimensions Dimensions In Millimeters In Inches Min Max Min Max A 1.050 1.250 0.041 0.049 A1 0.000 0.100 0.000 0.004 A2 1.050 1.150 0.041 0.045 b 0.300 0.400 0.012 0.016 C 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1.500 1.700 0.059 0.067 E1 2.650 2.950 0.104 0.116 e 0.950TYP 0.037TYP e1 1.800 0.071 L 0.700REF 0.028REF L1 0.300 0.460 0.012 0.024 0 8 0 8 Symbol 14 Rev. B.04 2.000 0.079 www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Package Outline Dimensions SOIC-8 Dimensions Dimensions In In Millimeters Inches Min Max Min Max A 1.350 1.750 0.053 0.069 A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 B 0.330 0.510 0.013 0.020 C 0.190 0.250 0.007 0.010 D 4.780 5.000 0.188 0.197 E 3.800 4.000 0.150 0.157 E1 5.800 6.300 0.228 0.248 e 1.270TYP L1 0.400 1.270 0.016 0.050 0 8 0 8 Symbol 0.050TYP MSOP-8 www.3peakic.com.cn Symbol Dimensions In Millimeters Min Max Dimensions In Inches Min Max A 0.800 1.200 0.031 0.047 A1 0.000 0.200 0.000 0.008 A2 0.760 0.970 0.030 0.038 b 0.30 TYP 0.012 TYP C 0.15 TYP 0.006 TYP D 2.900 e 0.65 TYP E 2.900 3.100 0.114 0.122 E1 4.700 5.100 0.185 0.201 L1 0.410 0.650 0.016 0.026 0 6 0 6 3.100 0.114 0.122 0.026 Rev. B.04 15 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Package Outline Dimensions DFN-8 Dimensions Symbol Min Nom Max Min Nom Max A 0.80 0.85 0.9 0.031 0.033 0.035 A1 0.00 0.02 0.05 0.000 0.001 0.002 A2 0.153 0.203 0.253 0.006 0.008 0.010 b 0.18 0.24 0.30 0.007 0.009 0.012 D 1.9 2.0 2.1 0.075 0.079 0.083 E 1.9 2.0 2.1 0.075 0.079 0.083 D1 0.5 0.6 0.7 0.020 0.024 0.028 E1 1.1 1.2 1.3 0.043 0.047 0.051 e 16 Rev. B.04 Dimensions In Inches In Millimeters 0.50 k 0.2 L 0.25 0.20 0.008 0.35 0.45 0.010 0.014 0.018 www.3peakic.com.cn TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Package Outline Dimensions SOIC-14 Dimensions In Millimeters Symbol MIN MAX A 1.35 1.60 1.75 A1 0.10 0.15 0.25 A2 1.25 1.45 1.65 A3 0.55 0.65 0.75 b 0.36 b1 0.35 c 0.16 c1 0.15 0.20 0.25 D 8.53 8.63 8.73 E 5.80 6.00 6.20 E1 3.80 3.90 4.00 e L www.3peakic.com.cn NOM 0.49 0.40 0.45 0.25 1.27 BSC 0.45 0.60 L1 1.04 REF L2 0.25 BSC 0.80 R 0.07 R1 0.07 h 0.30 0 1 6 8 10 2 6 8 10 3 5 7 9 4 5 7 9 0.40 0.50 8 Rev. B.04 17 TP1541A/TP1541NA/TP1542A/TP1544A Stable 1.3MHz, Precision, RRIO, Op Amps Package Outline Dimensions TSSOP-14 Dimensions In Millimeters Symbol MIN Rev. B.04 MAX A - - 1.20 A1 0.05 - 0.15 A2 0.90 1.00 1.05 A3 0.34 0.44 0.54 b 0.20 - 0.28 b1 0.20 0.22 0.24 c 0.10 - 0.19 c1 0.10 0.13 0.15 D 4.86 4.96 5.06 E 6.20 6.40 6.60 E1 4.30 4.40 4.50 e 18 NOM 0.65 BSC L 0.45 0.60 0.75 L1 1.00 REF L2 0.25 BSC R 0.09 - - R1 0.09 - - s 0.20 - 1 0 - 8 2 10 12 14 3 10 12 14 www.3peakic.com.cn