COS721SR

COS721/722/724 10MHz, Rail-to-Rail Input/Output Low Power Operational Amplifiers Features General Description ■ Low Quiescent Current: 650μA The COS721 (single), COS722 (dual) and ■ Gain Bandwidth Product: 10MHz COS724 (quad) are low power, rail-to-rail input ■ Operates on 2.1V ~ 5.5V Supplies and output amplifiers operated on 1.8 to 5.5 ■ Slew Rate: 7.5V/µs supplies. Despite their low quiescent current, ■ Rail-to-Rail Input and Output (RRIO) the COS72x family provides excellent overall ■ Unity Gain Stable performance and versatility. They have both ■ No Phase Reversal rail-to-rail input and output range. The output ■ Extended Temperature Ranges voltage swing extends to within 10mV of each From -40°C to +125°C rail, providing the maximum output dynamic Small Packaging range with excellent overdrive recovery. ■ COS721 available in SOT23-5/SOP-8 COS722 available in SOP-8/MSOP-8 COS721/2/4 family is unity gain stable and has COS724 available in SOP14/TSSOP14 a gain bandwidth product of 10MHz (typical). They Applications provide high CMRR and PRSS performance and can operate from a single supply voltage as low as 1.8V. These features ■ Battery or Solar Powered Systems make the COS721/2/4 family well suited for ■ Portable Equipment single-supply, ■ Sensor Conditioning They can be used as plus-in replacements for ■ Analog Active Filters many commercially available op-amps to ■ Medical Equipment reduce power and improve input/output range ■ Audio Output and performance. ■ White Goods ■ Smoke/Gas/Environment Sensors www.cosine-ic.com battery-powered applications. 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 COS721/722/724 1. Pin Configuration and Functions COS721 COS721 COS722 COS724 Pin Functions Name 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. +Vs Positive power supply -Vs -IN +IN OUT NC No connection 2. Package and Ordering Information Model Channel COS721 1 COS722 2 COS724 4 www.cosine-ic.com Order Number Package Package Option Marking Information COS721TR SOT23-5 Tape and Reel, 3000 C721 COS721SR SOP-8 Tape and Reel, 3000 COS721 COS722SR SOP-8 Tape and Reel, 3000 COS722 COS722MR MSOP-8 Tape and Reel, 3000 COS722 COS724SR SOP-14 Tape and Reel, 3000 COS724 COS724TR TSSOP-14 Tape and Reel, 3000 COS724 2 COS721/722/724 3. Product Specification 3.1 Absolute Maximum Ratings (1) Parameter Power Supply: +Vs to -Vs Input Voltage Rating Units 6.0 V -Vs -0.5V to +Vs + 0.5V V (2) 10 mA Storage Temperature Range -65 to 150 °C 150 °C -40 to 125 °C 2000 V Input Current Junction Temperature Operating Temperature Range ESD Susceptibility, HBM (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 2.1V ~ 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 COS721/722/724 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 ±0.6 ±5 mV Input Characteristics Input Offset Voltage VOS Input Offset Voltage Drift ΔVOS/ΔT Input Bias Current -40 to 125°C ±2.0 μV/°C IB ±2.5 pA Input Offset Current IOS ±2.5 pA Common-Mode Voltage Range VCM VS = 5.5V Common-Mode Rejection Ratio CMRR VCM =0.1V to 4.9V 125 dB Open-Loop Voltage Gain AOL VO=0.2V to 4.8V 120 dB RL=100kΩ 1 mV RL=10kΩ 8 mV RL=2kΩ 40 mV Sourcing 21 mA Sinking 22 mA -0.1 5.6 V Out Characteristics Output Voltage Swing from Rail Short-Circuit Current IOUT Power Supply Operating Voltage Range 2.1 Power Supply Rejection Ratio PSRR Quiescent Current / Amplifier IQ VS = +1.8V to +5.5V 80 5.5 V 100 dB 650 μA Dynamic Performance Gain Bandwidth Product GBWP G=+1 10 MHz Slew Rate SR G = +1 , 2V Output Step 7.5 V/μs en f=1kHz 12 nV/√Hz Noise Performance Voltage Noise Density www.cosine-ic.com 4 COS721/722/724 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 COS721/722/724 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 COS721/2/4 operates from a single +2.1V to +5.5V supply or dual ±1.05V 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 COS721/722/724 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 COS721/722/724 5. Package Information 5.1 SOT23-5 (Package Outline Dimensions) 5.2 SOP8 (Package Outline Dimensions) www.cosine-ic.com 8 COS721/722/724 5.3 MSOP8 (Package Outline Dimensions) 5.4 SOP14 (Package Outline Dimensions) www.cosine-ic.com 9 COS721/722/724 5.5 TSSOP14 (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 COS374/2374/4374 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 0.5MHz, 18μA, RRIO Op Amps, 1.8 to 5.5V Supply, Zero Drift, Vos