COS27DT

COS27 36V, 8MHz, Precision Low-Noise Operational Amplifiers General Description Features The COS27 is low power, precision operational ■ Low Offset Voltage: 50µV (Max.) amplifiers operated on ±2.25V to ±18V supplies. ■ Low Drift: 0.2µV/ºC It has very low input offset voltage (50μV) ■ Gain Bandwidth Product: 8MHz maximum that is obtained by trimming at the ■ Wide Supply Range：±2.25V ~ ±18V wafer ■ Low Quiescent Current: 1.2mA ■ Slew Rate: 2.8V/µs ■ Unity Gain Stable ■ Input Over-Voltage Protection ■ Extended Temperature Ranges From -40°C to +125°C ■ stage. These low offset voltages generally eliminate any need for external nulling. COS27 also features low input bias current and high open-loop gain. The low offset and high open-loop gain make COS27 particularly useful for high gain instrumentation applications. Available in SOP-8/MSOP-8/DIP-8 The wide input voltage range of ±13 V Applications minimum combined with a high CMRR of 110dB and high input impedance provide high Sensors and Controls accuracy in the noninverting circuit config- Thermocouples uration. Excellent linearity and gain accuracy Resistor thermal detectors (RTDs) can be maintained even at high closed-loop Strain bridges gains. Stability of offsets and gain with time or Shunt current measurements variations in temperature is excellent. The ■ Precision Filters accuracy and stability of the COS27, even at ■ Data Acquisition high gain, combined with the freedom from ■ Medical Instrumentation external nulling have made the COS27 an ideal ■ Optical Network Control Circuits choice for instrumentation applications. ■ Wireless Base Station Control Circuits ■ 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. www.cosine-ic.com 1 COS27 1. Pin Configuration and Functions Pin Functions Name Description Note A bypass capacitor of 0.1μF as close to the part as Positive power supply 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 to +Vs 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. Optional, place a offset nulling resistor (e.g. 20kΩ) VOS Trim between pin 1 & 8 +Vs -Vs -IN +IN OUT TRIM NC No connection 2. Package and Ordering Information Model COS27 Channel 1 www.cosine-ic.com Order Number Package Package Option Marking Information COS27SR SOP-8 Tape and Reel, 3000 COS27SR COS27MR MSOP-8 Tape and Reel, 3000 COS27MR COS27DR DIP-8 Tape and Reel, 1500 COS27DR COS27DT DIP-8 Tube, 50 COS27DT 2 COS27 3. Product Specification 3.1 Absolute Maximum Ratings (1) Parameter Power Supply: +Vs to -Vs Differential Input Voltage Range Common Mode Input voltage Range(2) Output Current Storage Temperature Range Junction Temperature Operating Temperature Range ESD Susceptibility, HBM Rating Units 36 V ±0.5 V -Vs to +Vs V 50 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 DC Supply Voltage ±2.25V ~ ±18V V Input common-mode voltage range -Vs+2 ~ +Vs-2 V -40 to +85 °C 3.3 Recommended Operating Conditions Parameter Operating ambient temperature www.cosine-ic.com 3 COS27 3.4 Electrical Characteristics (+VS=+15V, -VS=-15V, TA=+25°C, RL=10kΩ to VS/2, unless otherwise noted) Parameter Symbol Conditions Min Typ Max Unit ±15 ±50 μV 0.2 0.7 μV/°C Input Characteristics Input Offset Voltage VOS Input Offset Voltage Drift ΔVOS/ΔT Input Bias Current IB ±4 ±8 nA Input Offset Current IOS ±0.5 ±2 nA Common-Mode Voltage Range VCM ±13 ±14 V Common-Mode Rejection Ratio CMRR 80 110 dB Open-Loop Voltage Gain AOL RL ≥ 2kΩ, VO = ±10V 90 120 dB Output Voltage Swing VO(PP) RL ≥ 10kΩ ±12 ±13.8 V Short-Circuit Current ISC ±28 mA -40 to 125°C Out Characteristics Power Supply Operating Voltage Range ±2.25 Power Supply Rejection Ratio PSRR Quiescent Current / Amplifier IQ 100 ±18 120 1.2 V dB 1.5 mA Dynamic Performance Gain Bandwidth Product GBWP CL=100pF, RL=10kΩ Slew Rate SR en 5.0 8.0 MHz CL=100pF, RL=10kΩ, Av=1 2.8 V/μs f=1kHz 3.0 nV/√Hz Noise Performance Voltage Noise Density www.cosine-ic.com 4 COS27 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 COS27 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 COS27 operates from a single +4.5V to +36V supply or dual ±2.25V to ±18V 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 COS27 R2 R1 VIN VOUT VIP R3 R4 VREF 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 COS27 5. Package Information 5.1 SOP8 (Package Outline Dimensions) 5.2 MSOP8 (Package Outline Dimensions) www.cosine-ic.com 8 COS27 5.3 DIP8 (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 0.35MHz, 18μA, RRIO Op Amps, 1.8 to 5.5V Supply, Zero Drift, Vos