COS1177MR

COS1177/2177/4177 36V, Precision Low-Noise Operational Amplifiers Features General Description ■ Low Offset Voltage: 50µV (Max.) The COS1177 (single), COS2177 (dual) and ■ Low Drift: 0.2µV/ºC COS4177 (quad) are low power, precision ■ Low Input Bias Current: 2nA (Max.) operational amplifiers operated on ±2.25V to ■ Gain Bandwidth Product: 2MHz ±18V supplies. The COSx177 family has very ■ Wide Supply Range：±2.25V ~ ±18V low input offset voltage (50μV) maximum that is ■ Low Quiescent Current: 330µA obtained by trimming at the wafer stage. These ■ Slew Rate: 0.7V/µs low offset voltages generally eliminate any ■ Unity Gain Stable need for external nulling. The COSx177 also ■ Input Over-Voltage Protection features low input bias current and high ■ Extended Temperature Ranges open-loop gain. The low offset and high From -40°C to +125°C open-loop gain make the COSx177 particularly Small Packaging useful COS1177 available in SOP8/MSOP8 applications. ■ for high gain instrumentation COS2177 available in SOP8/MSOP8 COS4177 available in SOP14/TSSOP14 The wide input voltage range of ±13 V minimum combined with a high CMRR of Applications 125dB and high input impedance provide high accuracy in the noninverting circuit config- ■ Sensors and Controls uration. Excellent linearity and gain accuracy ■ Precision Filters can be maintained even at high closed-loop ■ Data Acquisition gains. Stability of offsets and gain with time or ■ Medical Instrumentation variations in temperature is excellent. The ■ Optical Network Control Circuits accuracy and stability of the COSx177, even at ■ Wireless Base Station Control Circuits high gain, combined with the freedom from external nulling have made the COSx177 an Rev1.0 Copyright@2018 Cosine Nanoelectronics Inc. All rights reserved ideal choice for instrumentation applications. 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 COS1177/2177/4177 1. Pin Configuration and Functions COS1177 COS2177 COS4177 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. +Vs -Vs -IN +IN OUT NC No connection 2. Package and Ordering Information Model Channel COS1177 1 COS2177 2 COS4177 4 www.cosine-ic.com Order Number Package Package Option Marking Information COS1177SR SOP-8 Tape and Reel, 3000 COS1177 COS1177MR MSOP-8 Tape and Reel, 3000 COS1177 COS2177SR SOP-8 Tape and Reel, 3000 COS2177 COS2177MR MSOP-8 Tape and Reel, 3000 COS2177 COS4177SR SOP-14 Tape and Reel, 3000 COS4177 COS4177TR TSSOP-14 Tape and Reel, 3000 COS4177 2 COS1177/2177/4177 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 ±2.5V ~ ±18V V Input common-mode voltage range -Vs+1 ~ +Vs-1 V -40 to +85 °C 3.3 Recommended Operating Conditions Parameter Operating ambient temperature www.cosine-ic.com 3 COS1177/2177/4177 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 ±0.5 ±2 nA Input Offset Current IOS ±0.2 ±1 nA Common-Mode Voltage Range VCM ±13 ±14 V Common-Mode Rejection Ratio CMRR 120 125 dB Open-Loop Voltage Gain AOL 100 120 dB +14 +14.1 V -40 to 125°C RL ≥ 2kΩ, VO = ±10V Output Characteristics Output Voltage High VOH Output Voltage Low VOL Output Current IOUT Short-Circuit Current ISC -14.1 VDROPOUT < 1.2 V -13.9 V ±10 mA ±28 mA Power Supply Operating Voltage Range ±2.5 Power Supply Rejection Ratio PSRR Quiescent Current / Amplifier IQ 120 ±18 130 330 V dB 430 μA Dynamic Performance Gain Bandwidth Product GBWP CL=100pF, RL=10kΩ 2.0 MHz Slew Rate SR CL=100pF, RL=10kΩ, Av=1 0.7 V/μs en f=1kHz 8.0 nV/√Hz Noise Performance Voltage Noise Density www.cosine-ic.com 4 COS1177/2177/4177 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 COS1177/2177/4177 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 COSx177 operates from a single +5V to +36V supply or dual ±2.5V 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 COS1177/2177/4177 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 COS1177/2177/4177 5. Package Information 5.1 SOP8 (Package Outline Dimensions) 5.2 MSOP8 (Package Outline Dimensions) www.cosine-ic.com 8 COS1177/2177/4177 5.3 SOP14 (Package Outline Dimensions) 5.4 TSSOP14 (Package Outline Dimensions) www.cosine-ic.com 9