TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Features Description Supply Current: 950nA Maximum /Amplifier Stable 18kHz GBWP with 10mV/s Slew Rate Offset Voltage: 1.5mV Maximum Ultra-low VOS TC: 0.5V/C Ultra-low Input Bias Current: 1fA Typical High 120dB Open-Loop Voltage Gain Unity Gain Stable for 1,000nF Capacitive Load Rail-to-Rail Input/Output Voltage Range Outputs Source and Sink 20mA of Load Current No Phase Reversal for Overdriven Inputs Ultra-low Single-Supply Operation Down to +1.8V Shutdown Current: 3nA Typical (TP2121N) -40C to 125C Operation Range Robust 8kV - HBM and 2kV - CDM ESD Rating Green, Popular Type Package Applications Handsets and Mobile Accessories Current Sensing Wireless Remote Sensors, Active RFID Readers Environment/Gas/Oxygen Sensors Threshold Detectors/Discriminators Low Power Filters Battery or Solar Powered Devices Sensor Network Powered by Energy Scavenging The TP212x are ultra-low power, precision CMOS op-amps featuring a maximum supply current of 950nA per amplifier with an ultra-low typical input bias current of 1fA. Analog trim and calibration routine reduce input offset voltage to below 1.5mV, and the precision temperature compensation technique makes offset voltage temperature drift at 0.5V/C, which allowing use of the TP212x in systems with high gain without creating excessively large output offset errors. The TP212x are unity gain stable with 1,000nF capacitive load with a constant 18kHz GBWP, 10mV/s slew rate, which make them appropriate for low frequency applications, such as battery current monitoring and sensor conditioning. The TP212x can operate from a single-supply voltage of +1.8V to +6.0V or a dual-supply voltage of 0.9V to 3.0V. Beyond the rails input and rail-to-rail output characteristics allow the full power-supply voltage to be used for signal range. The combined features make the TP212x 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. Mobile accessories, wireless remote sensing, backup battery sensors, and single-Li+ or 2-cell NiCd/Alkaline battery powered systems can benefit from the features of the TP212x op-amps. For applications that require power-down, the TP2121N has a low-power shutdown mode that reduces supply current to 3nA, 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. Ultra-low Supply Current Op-amps: VOUT I CC R3 ( Supply Current 0.3 A 0.6 A 4 A GBWP 10 kHz 18 kHz 150 kHz Single TP2111 TP2121 TP1511 With Shut-down TP2111N TP2121N TP1511N Dual TP2112 TP2122 TP1512 Quad TP2114 TP2124 TP1514 R1 1) R2 TP2121 in Low Side Battery Current Sensor www.3peakic.com REV1.2 1 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Pin Configuration (Top View) Order Information Model Name TP2121 TP2121U TP2121N TP2122 TP2124 Order Number Package Transport Media, Quantity Marking Information TP2121-TR 5-Pin SOT23 Tape and Reel, 3,000 B2TYW (1) TP2121-CR 5-Pin SC70 Tape and Reel, 3,000 B2CYW (1) TP2121-SR 8-Pin SOIC Tape and Reel, 4,000 2121S TP2121U-TR 5-Pin SOT23 Tape and Reel, 3,000 B2UYW (1) TP2121N-TR 6-Pin SOT23 Tape and Reel, 3,000 B2NYW (1) TP2121N-VR 8-Pin MSOP Tape and Reel, 3,000 2121N TP2121N-SR 8-Pin SOIC Tape and Reel, 4,000 2121NS TP2122-SR 8-Pin SOIC Tape and Reel, 4,000 B22S TP2122-VR 8-Pin MSOP Tape and Reel, 3,000 B22V TP2124-SR 14-Pin SOIC Tape and Reel, 2,500 B24S TP2124-TR 14-Pin TSSOP Tape and Reel, 3,000 B24T Note (1): `YW' is date coding scheme. 'Y' stands for calendar year, and 'W' stands for single workweek coding scheme. Absolute Maximum Ratings Note 1 Supply Voltage: V+ - V-....................................6.0V - + Input Voltage............................. V - 0.3 to V + 0.3 Input Current: +IN, -IN, SHDN Note 2.............. 10mA - Output Short-Circuit Duration Note 3............ Indefinite Operating Temperature Range.......-40C to 125C Maximum Junction Temperature................... 150C + SHDN Pin Voltage.................................V to V Storage Temperature Range.......... -65C to 150C Output Current: OUT.................................... 20mA 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. 2 REV1.2 www.3peakic.com TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps 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 CDM Charged Device Model ESD JEDEC-EIA/JESD22-C101E 2 kV www.3peakic.com REV1.2 3 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps 5V Electrical Characteristics The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 27C. VSUPPLY = 5V, VCM = VOUT = VSUPPLY/2, RL = 100k, CL =60pF, VSHDN is unconnected. SYMBOL PARAMETER VOS VOS TC Input Offset Voltage Input Offset Voltage Drift CONDITIONS VCM = VDD/2 and VCM = GND IB Input Bias Current TA=27 oC TA=85 oC TA=125 oC IOS Vn en RIN Input Offset Current Input Voltage Noise Input Voltage Noise Density Input Resistance f = 0.1Hz to 10Hz f = 1kHz CIN Input Capacitance CMRR Common Mode Rejection Ratio Common-mode Input Voltage Range Power Supply Rejection Ratio VCM PSRR AVOL Open-Loop Large Signal Gain VOL, VOH ROUT RO ISC VDD IQ PM GM GBWP Output Swing from Supply Rail Closed-Loop Output Impedance Open-Loop Output Impedance Output Short-Circuit Current Supply Voltage Quiescent Current per Amplifier Phase Margin Gain Margin Gain-Bandwidth Product Settling Time, 1.5V to 3.5V, Unity Gain Settling Time, 2.45V to 2.55V, Unity Gain tS SR Slew Rate FPBW IQ(off) Full Power Bandwidth Note 2 Supply Current in Shutdown Note 1 ISHDN Shutdown Pin Current Note 1 ILEAK VIL VIH Output Leakage Current in Shutdown Note 1 SHDN Input Low Voltage Note 1 SHDN Input High Voltage Note 1 Differential Common Mode VCM = 0.1V to 4.9V VOUT = 2.5V, RLOAD = 100k VOUT = 0.1V to 4.9V, RLOAD = 100k RLOAD = 100k G = 1, f = 1kHz, IOUT = 0 f = 1kHz, IOUT = 0 Sink or source current MIN TYP MAX UNITS -1.5 0.1 0.5 1 700 45 1 6.5 170 >1 2.9 5 130 +1.5 mV V/C fA fA pA fA VP-P nV/Hz T 80 V--0.3 60 80 80 92 120 120 5 0.4 2.6 20 600 61 -10 18 0.25 0.253 0.035 0.038 RLOAD = 100k, CLOAD = 60pF RLOAD = 100k, CLOAD = 60pF f = 1kHz 0.1% 0.01% 0.1% 0.01% AV = 1, VOUT = 1.5V to 3.5V, CLOAD = 60pF, RLOAD = 100k 2VP-P VSHDN = 0.5V VSHDN = 1.5V VSHDN = 0V, VOUT = 0V VSHDN = 0V, VOUT = 5V Disable Enable dB V++0.3 1.8 pF 6.0 950 V dB dB dB mV mA V nA dB kHz ms 10 mV/s 600 3 -10 -10 -3.6 3.6 Hz nA pA pA 0.5 1.0 Note 1: Specifications apply to the TP2121N with shutdown. Note 2: Full power bandwidth is calculated from the slew rate FPBW = SR/ * VP-P. 4 REV1.2 www.3peakic.com V V TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Typical Performance Characteristics Small-Signal Step Response, 100mV Step Large-Signal Step Response, 2V Step 4 2.60 3 Gain = +1 VIN Step = 100mV CLOAD = 60pF 2.50 Gain = +1 CLOAD = 60pF RLOAD = 100k 1V/div 50mV/div 2.55 2 2.45 2.40 3 5 7 9 1 2 5 2ms/div Open-Loop Gain and Phase 80 100 Gain = +1 RLOAD = 100k 60 Phase Phase (dB) GAIN AND PHASE (dB) 11 Phase Margin vs. CLOAD (Stable for Any CLOAD) 150 Gain 50 40 Gain = 1 RLOAD = 100k CLOAD = 60pF 0 -50 1E-3 1E-1 1E+1 20 1E+3 1E+5 1E+7 0 1E+0 1E+1 FREQUENCY (Hz) Input Voltage Noise Spectral Density 1E+2 1E+3 1E+4 Load Capacitance (pF) 1E+5 1E+6 Common-Mode Rejection Ratio 150 10k 120 CMRR (dB) Input Noise Voltage (nV/Hz) 8 3ms/div 1k 90 60 100 1E-1 1E+0 1E+1 1E+2 FREQUENCY (Hz) www.3peakic.com 1E+3 30 1E-3 1E-1 1E+1 1E+3 1E+5 1E+7 Frequency (Hz) REV1.2 5 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Typical Performance Characteristics Over-Shoot Voltage, CLOAD = 40nF, Gain = +1, RFB=100k Over-Shoot % vs. CLOAD, Gain = +1, RFB = 1M 60% Overshoot and Undershoot (%) 2.6 50mV/div 2.55 2.5 Gain = +1 VIN Step = 100mV CLOAD = 40nF 2.45 Gain = +1 VIN Step = 200mV 50% 40% Overshoot 30% Undershoot 20% 10% 2.4 0% 2 4 6 8 10 1E+1 1E+2 1E+3 2ms/div Over-Shoot Voltage, CLOAD=40nF, Gain= -1, RFB=100k 1E+5 1E+6 1E+7 Over-Shoot % vs. CLOAD, Gain = -1, RFB = 1M 60% Overshoot and Undershoot (%) 2.6 2.55 50mV/div 1E+4 Load Capacitance (pF) Gain = -1 VIN Step = 100mV CLOAD = 40nF 2.5 2.45 Gain = -1 VIN Step = 200mV 50% Undershoot 40% 30% Overshoot 20% 10% 2.4 6 8 10 12 0% 1E+0 14 1E+2 1E+4 1E+6 Load Capacitance (pF) 2ms/div Power-Supply Rejection Ratio VIN = -0.2V to 5.7V, No Phase Reversal 80 6.0 PSRRP 40 AMPLITUDE (V) PSRRN/PSRRP (dB) 5.0 60 PSRRN 20 4.0 3.0 2.0 1.0 0.0 -1.0 0 0 1E-3 1E-2 1E-1 1E+0 1E+1 Frequency (Hz) 6 REV1.2 1E+2 1E+3 1E+4 10 20 30 40 50 60 1E+5 TIME (ms) www.3peakic.com TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Typical Performance Characteristics Quiescent Supply Current vs. Temperature Open-Loop Gain vs. Temperature 750.0 130 OPEN LOOP GAIN (dB) CURRENT (nA) 700.0 650.0 600.0 550.0 500.0 -40 -20 0 20 40 60 80 120 110 100 100 -40 -20 750.0 700.0 85OC CURRENT (nA) 27OC 550.0 -40OC 500.0 450.0 400.0 1.8 2.6 3.4 60 80 100 4.2 30 25 20 15 10 5 0 1.8 5 2.8 3.8 4.8 POWER SUPPLY VOLTAGE (V) POWER SUPPLY VOLTAGE (V) Input Offset Voltage Distribution Input Offset Voltage vs. Common Mode Input Voltage 400 0.4 Production Package Units VDD=5V, VCM<VDD1V, 2000 Samples 0.3 Input Offset Voltage(mV) 300 Smpeles 40 Short-Circuit Current vs. Supply Voltage SHORT-CIRCUIT CURRENT (mA) Quiescent Supply Current vs. Supply Voltage 600.0 20 TEMPERATURE (OC) TEMPERATURE (OC) 650.0 0 200 100 TA = +85OC TA = +27OC 0.2 TA = - 40OC 0.1 0 -0.1 0 -1.6 -1.2 -0.8 -0.4 0 Offset Voltage (mV) www.3peakic.com 0.4 0.8 1.2 1.6 0 1 2 3 4 5 Common Mode Input Voltage(V) REV1.2 7 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Typical Performance Characteristics Closed-Loop Output Impedance vs. Frequency 0.1Hz to 10Hz Time Domain Output Voltage Noise 5 100k PEAK-TO-PEAK Voltage (V) OUTPUT IMPEDANCE () 4 10k 1k 100 3 2 1 0 -1 -2 10 -3 1 -4 1 10 100 1k 10k -5 -6 FREQUENCY (Hz) -4 -2 0 2 4 6 TIME (Seconds) 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. V+ or +VS: Positive Power Supply. Typically the voltage is from 1.8V to 5.5V. Split supplies are possible as long as the voltage between V+ and V- is between 1.8V and 5.5V. 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. N/C: No Connection. V- or -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 1.8V to 5.5V. 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 milli-volts of each supply rail. Operation The TP212x 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 8 REV1.2 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. www.3peakic.com TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Applications Information Low Supply Voltage and Low Power Consumption The TP212x family of operational amplifiers can operate with power supply voltages from 1.8V to 6.0V. Each amplifier draws only 600nA 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 TP212x 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 1,000nF 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 TP212x family provides a low input referred noise density of 170nV/Hz at 1kHz. The voltage noise will grow slowly with the frequency in wideband range, and the input voltage noise is typically 6.5VP-P at the frequency of 0.1Hz to 10Hz. Low Input Offset Voltage The TP212x family has a low offset voltage of 1.5mV 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. Low Input Bias Current The TP212x 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 humidity conditions, a typical resistance between nearby traces is 1012. A 5V difference would cause 5pA of current to flow, which is greater than the TP212x OPA's input bias current at +27C (1fA, typical). It is recommended to use multi-layer PCB layout and route the OPA's -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. Figure 1 Ground Sensing and Rail to Rail Output The TP212x family has excellent output drive capability, delivering over 10mA of output drive current. The output stage is a rail-to-rail topology that is capable of swinging to within 5mV of either rail. Since the inputs can go 300mV beyond either rail, the op-amp can easily perform `true ground' sensing. www.3peakic.com REV1.2 9 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps 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 TP212x family has reverse-biased ESD protection diodes on all inputs and output. Input and out pins can not be biased more than 300mV beyond either supply rail. Shut-down The single channel OPA versions have SHDN pins that can shut down the amplifier to typical 3nA 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. Driving Large Capacitive Load The TP212x 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 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 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 TP212x OPA family (e.g., > 200 pF when G = +1V/V), a small series resistor at the output (RISO in Figure 2) improves the feedback loop's phase margin and stability by making the output load resistive at higher frequencies. Figure 2 Power Supply Layout and Bypass The TP212x OPA's 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 OPA's 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. 10 REV1.2 www.3peakic.com TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps 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. BATTERY CURRENT SENSING The Common Mode Input voltage Range of TP212x OPA series, 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 (600nA, typical) helps prolong battery life, and the rail-to-rail output supports detection of low currents. The battery current (IDD) through the 10 resistor causes its top terminal to be more negative than the bottom terminal. This keeps the Common Mode Input voltage below VDD, which is within its allowed range. The output of the OPA will also be blow VDD, within its Maximum Output Voltage Swing specification. I DD VDD VOUT R1 R3 R2 Figure 3 Instrumentation Amplifier The TP212x OPA series is well suited for conditioning sensor signals in battery-powered applications. Figure 4 shows a two op-amp instrumentation amplifier, using the TP212x 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. VOUT =(V1 V2 )(1 R1 2 R1 ) VREF R2 RG Figure 4 Buffered Chemical Sensor (pH) Probe The TP212x 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 5 eliminates expansive low-leakage cables that that is required to connect pH probe to metering ICs such as ADC, AFE and/or MCU. A TP212x OPA and a lithium battery are housed in the probe assembly. A conventional low-cost coaxial cable can be used to carry OPA's output signal to subsequent ICs for pH reading. www.3peakic.com REV1.2 11 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Figure 5: Buffer pH Probe 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 6 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 600nA 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 VOS TC, low input bias current, high CMRR, and high PSRR are other factors which make these amplifiers excellent choices for this application. I O2 VOUT 1Vin Air ( 21% O 2 ) I DD 0.7uA Figure 6 12 REV1.2 www.3peakic.com TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Package Outline Dimensions SOT23-5 / SOT23-6 Symbol Dimensions Dimensions In Millimeters In Inches Min Max Min Max 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 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 www.3peakic.com 0.950TYP 0.037TYP e1 1.800 2.000 0.071 0.079 L1 0.300 0.460 0.012 0.024 0 8 0 8 REV1.2 13 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Package Outline Dimensions SC-70-5 / SC-70-6 (SOT353 / SOT363) Symbol Dimensions Dimensions In In Millimeters Inches Min Max Min Max 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 14 REV1.2 0.650TYP 0.026TYP e1 1.200 1.400 0.047 0.055 L1 0.260 0.460 0.010 0.018 0 8 0 8 www.3peakic.com TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Package Outline Dimensions SO-8 (SOIC-8) A2 C L1 A1 e E D Symbol E1 Dimensions Dimensions In In Millimeters Inches Min Max Min Max 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 b 1.270TYP 0.050TYP L1 0.400 1.270 0.016 0.050 0 8 0 8 Package Outline Dimensions www.3peakic.com REV1.2 15 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps MSOP-8 Dimensions Dimensions In In Millimeters Inches Min Max 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 Symbol E E1 e b D 3.100 0.114 0.122 0.026 A1 R1 R L1 16 REV1.2 L L2 www.3peakic.com TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Package Outline Dimensions SO-14 (SOIC-14) Dimensions In Millimeters Symbol MIN TYP MAX A 1.35 1.60 1.75 A1 0.10 0.15 0.25 A2 1.25 1.45 1.65 b 0.36 D 8.53 8.63 8.73 E 5.80 6.00 6.20 E1 3.80 3.90 4.00 e L 1.27 BSC 0.45 0.60 L1 1.04 REF L2 0.25 BSC www.3peakic.com 0.49 0 0.80 8 REV1.2 17 TP2121/TP2121N/TP2122/TP2124 1.8V, 600nA Nanopower, Rail-to-Rail Input/Output Op-amps Package Outline Dimensions TSSOP-14 Dimensions E1 E A A2 e c D Symbol In Millimeters MIN TYP MAX A - - 1.20 A1 0.05 - 0.15 A2 0.90 1.00 1.05 b 0.20 - 0.28 c 0.10 - 0.19 D 4.86 4.96 5.06 E 6.20 6.40 6.60 E1 4.30 4.40 4.50 e L A1 R1 R 0.65 BSC 0.45 0.60 L1 1.00 REF L2 0.25 BSC 0.75 R 0.09 - - 0 - 8 L1 18 REV1.2 L L2 www.3peakic.com