COS8551TRA

COS8551 1.8V, 1.5MHz, RRIO Zero-Drift Operational Amplifiers Features General Description ■ Low offset Voltage: 10µV (Max.) The COS8551 is a single channel, micro power, ■ Zero Drift: 0.005µV/ºC zero-drift operational amplifiers operated on 1.8 ■ Low Quiescent Current: 55μA to 5.5 supplies. It uses chopper stabilized ■ Gain Bandwidth Product: 1.5MHz technique to provide very low offset voltage ■ Operates on 1.8V ~ 5.5V Supplies and near zero drift over temperature. Low ■ Slew Rate: 0.9V/µs quiescent supply current of 55µA per amplifier ■ Rail-to-Rail Input and Output (RRIO) and very low input bias current make the ■ Unity Gain Stable devices an ideal choice for low offset, low ■ No Phase Reversal power ■ Extended Temperature Ranges applications. consumption and high impedance From -40°C to +125°C ■ Small Packaging: Despite its low quiescent current, the COS8551 COS8551 available in SOT23-5 provides excellent overall performance and versatility. It has both rail-to-rail input and output range. The output voltage swing extends Applications ■ Sensor Conditioning ■ Temperature Measurements ■ Transducers ■ Test Equipment ■ Medical Instrumentation ■ Battery Powered Instruments ■ A/D converters www.cosine-ic.com to within 5mV of each rail, providing the maximum output dynamic range with excellent overdrive recovery. COS855x family is unity gain stable and has a gain bandwidth product of 1.5MHz (typical). Rev1.0 Copyright@2018 Cosine Nanoelectronics Inc. All rights reserved The information provided here is believed to be accurate and reliable. Cosine Nanoelectronics assumes no reliability for inaccuracies and omissions. Specifications described and contained here are subjected to change without notice on the purpose of improving the design and performance. All of this information described herein should not be implied or granted for any third party. 1 COS8551 1. Pin Configuration and Functions COS8551 Pin Functions Name Pin No. +Vs 5 -Vs 2 -IN 4 +IN 3 OUT 1 Description Note A bypass capacitor of 0.1μF as close to the part as possible should be placed between power supply pins or between supply pins and ground. Negative power supply If it is not connected to ground, bypass it with a or ground capacitor of 0.1μF as close to the part as possible. Inverting input of the amplifier. Voltage range of this Negative input pin can go from -Vs -0.3V to +Vs + 0.3V. Non-inverting input of the amplifier. This pin has the Positive input same voltage range as –IN. The output voltage range extends to within millivolts Output of each supply rail. Positive power supply 2. Package and Ordering Information Model Channel COS8551 1 COS8552 2 COS8554 4 www.cosine-ic.com Order Number Package Package Option Marking Information COS8551TR SOT23-5 Tape and Reel, 3000 C8551 COS8551SR SOP-8 Tape and Reel, 3000 COS8551 COS8552SR SOP-8 Tape and Reel, 3000 COS8552 COS8552MR MSOP-8 Tape and Reel, 3000 COS8552 COS8554SR SOP-14 Tape and Reel, 3000 COS8554 COS8554TR TSSOP-14 Tape and Reel, 3000 COS8554 2 COS8551 3. Product Specification 3.1 Absolute Maximum Ratings (1) Parameter Power Supply: +Vs to -Vs Input Voltage Input Current (2) Storage Temperature Range Junction Temperature Operating Temperature Range ESD Susceptibility, HBM Rating Units 7.5 V -Vs -0.5V to +Vs + 0.5V V 10 mA -65 to 150 °C 150 °C -40 to 125 °C 2000 V (1) Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. (2) Input terminals are diode-clamped to the power-supply rails. Input signals that can swing more than 0.5V beyond the supply rails should be current-limited to 10mA or less. 3.2 Thermal Data Parameter Rating Unit Package Thermal Resistance 190 (SOT23-5) 206 (MSOP8) 155 (SOP8) 105 (TSSOP14) 82 (SOP14) °C/W Rating Unit 1.8V ~ 5.5V V Input common-mode voltage range -Vs ~ +Vs V Operating ambient temperature -40 to +85 °C 3.3 Recommended Operating Conditions Parameter DC Supply Voltage www.cosine-ic.com 3 COS8551 3.4 Electrical Characteristics (+VS=+5V, -VS=0, VCM=VS/2, TA=+25°C, RL=10kΩ to VS/2, unless otherwise noted) Parameter Symbol Conditions Min Typ Max Unit Input Characteristics Input Offset Voltage VOS COS8551A 10 COS8551B 20 COS8551C 50 -40 to 125°C 0.005 Input Offset Voltage Drift ΔVOS/ΔT Input Bias Current IB ±3 pA Input Offset Current IOS ±3 pA Common-Mode Voltage Range VCM VS = 5.5V Common-Mode Rejection Ratio CMRR VCM =0.1V to 4.9V 120 dB Open-Loop Voltage Gain AOL VO=0.2V to 4.8V 145 dB RL=100kΩ 5 mV RL=10kΩ 15 mV ISR Sourcing 7 mA ISK Sinking -7 mA -0.1 0.05 μV 5.6 μV/°C V Output Characteristics Output Voltage Swing from Rail Short-Circuit Current Power Supply Operating Voltage Range 1.8 Power Supply Rejection Ratio PSRR VS = 1.8V to 5.5V Quiescent Current / Amplifier IQ Gain Bandwidth Product Slew Rate 80 5.5 V 100 dB VS = 3.0V 55 μA GBWP G=+1 1.5 MHz SR G = +1 , 2V Output Step 0.9 V/μs en f=1kHz 50 nV/√Hz Dynamic Performance Noise Performance Voltage Noise Density www.cosine-ic.com 4 COS8551 4.0 Application Notes Driving 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. A unity gain buffer (G = +1) is the most sensitive to capacitive loads, but all gains show the same general behavior. When driving large capacitive loads with these op amps (e.g., > 100 pF when G = +1), a small series resistor at the output (RISO in Figure 1) improves the feedback loop’s phase margin (stability) by making the output load resistive at higher frequencies. It does not, however, improve the bandwidth. To select RISO, check the frequency response peaking (or step response overshoot) on the bench. If the response is reasonable, you do not need RISO. Otherwise, start RISO at 1 kΩ and modify its value until the response is reasonable. RISO VOUT VIN CL Figure 1. Indirectly Driving Heavy Capacitive Load An improvement circuit is shown in Figure 2. It provides DC accuracy as well as AC stability. RF provides the DC accuracy by connecting the inverting signal with the output, CF and RISO serve to counteract the loss of phase margin by feeding the high frequency component of the output signal back to the amplifier’s inverting input, thereby preserving phase margin in the overall feedback loop. Figure 2. Indirectly Driving Heavy Capacitive Load with DC Accuracy www.cosine-ic.com 5 COS8551 For noninverting configuration, there are two others ways to increase the phase margin: (a) by increasing the amplifier’s gain or (b) by placing a capacitor in parallel with the feedback resistor to counteract the parasitic capacitance associated with inverting node, as shown in Figure 3. Figure 3. Adding a Feedback Capacitor in the Noninverting Configuration Power-Supply Bypassing and Layout The COS855x operates from a single +1.8V to +5.5V supply or dual ±0.9V to ±2.75V supplies. For single-supply operation, bypass the power supply +Vs with a 0.1μF ceramic capacitor which should be placed close to the +Vs pin. For dual-supply operation, both the +Vs and the -Vs supplies should be bypassed to ground with separate 0.1μF ceramic capacitors. 2.2μF tantalum capacitor can be added for better performance. The length of the current path is directly proportional to the magnitude of parasitic inductances and thus the high frequency impedance of the path. High speed currents in an inductive ground return create an unwanted voltage noise. Broad ground plane areas will reduce the parasitic inductance. Thus a ground plane layer is important for high speed circuit design. Typical Application Circuits Differential Amplifier The circuit shown in Figure 4 performs the differential function. If the resistors ratios are equal (R4 / R3 = R2 / R1), then VOUT = (VIP – VIN) × R2 / R1 + VREF. www.cosine-ic.com 6 COS8551 Figure 4. Differential Amplifier Low Pass Active Filter When receiving low-level signals, limiting the bandwidth of the incoming signals into the system is often required. The simplest way to establish this limited bandwidth is to place an RC filter at the noninverting terminal of the amplifier. If even more attenuation is needed, a multiple pole filter is required. The Sallen-Key filter can be used for this task, as Figure 5. For best results, the amplifier should have a bandwidth that is 8 to 10 times the filter frequency bandwidth. Failure to follow this guideline can result in reduction of phase margin. The large values of feedback resistors can couple with parasitic capacitance and cause undesired effects such as ringing or oscillation in high-speed amplifiers. Keep resistors value as low as possible and consistent with output loading consideration. Figure 5. Two-Pole Low-Pass Sallen-Key Active Filter www.cosine-ic.com 7 COS8551 5. Package Information 5.1 SOT23-5 (Package Outline Dimensions) 6. Related Parts Part Number Description COS6041/2/4 24kHz, 0.5μA, RRIO Op Amps, 1.8 to 5.5V Supply COS1347/2347/4347 350kHz, 15μA, RRIO Op Amps, 1.8 to 5.5V Supply COS6001/2/4 1.5MHz, 50μA, RRIO Op Amps, 1.8 to 5.5V Supply COS1314/2314/4314 3MHz, 150μA, RRIO Op Amps, 1.8 to 5.5V Supply COS821/2/4 5MHz, 300μA, RRIO Op Amps, 1.8 to 5.5V Supply COS1374/2374/4374 7MHz, 500μA, RRIO Op Amps, 1.8 to 5.5V Supply COS721/2/4 10MHz, 650μA, RRIO Op Amps, 2.1 to 5.5V Supply COS1333/2333/4333 www.cosine-ic.com 0.35MHz, 18μA, RRIO Op Amps, 1.8 to 5.5V Supply, Zero Drift, Vos