1 Pcs Analog Devices Ad822arz Dual Precision, Low Power Fet Input Op Amp. Ad822

US $3.00

Longmont, Colorado, United States
Jan 29th

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AD822 Single Supply, Rail-to-Rail Low Power FET-Input Op Amp FEATURES TRUE SINGLE SUPPLY OPERATION Output Swings Rail to Rail Input Voltage Range Extends Below Ground Single Supply Capability from +3 V to +36 V Dual Supply Capability from1.5 V to 18 V HIGH LOAD DRIVE Capacitive Load Drive of 350 pF, G = 1 Minimum Output Current of 15 mA EXCELLENT AC PERFORMANCE FOR LOW POWER 800 uA Max Quiescent Current per Amplifier Unity Gain Bandwidth: 1.8 MHz Slew Rate of 3.0 V/us GOOD DC PERFORMANCE 800 mV Max Input Offset Voltage 2 uV/C Typ Offset Voltage Drift 25 pA Max Input Bias Current LOW NOISE 13 nV/?Hz@ 10 kHz NO PHASE INVERSION APPLICATIONS Battery Powered Precision Instrumentation Photodiode Preamps Active Filters 12- to 14-Bit Data Acquisition Systems Medical Instrumentation Low Power References and Regulators ABSOLUTE MAXIMUM RATINGS Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±18 V Internal Power Dissipation Plastic DIP (N) . . . . . . . . . . . . . . Observe Derating Curves Cerdip (Q) . . . . . . . . . . . . . . . . . . Observe Derating Curves SOIC (R) . . . . . . . . . . . . . . . . . . . Observe Derating Curves Input Voltage . . . . . . . . . . . . . . (+VS+ 0.2 V) to –(20 V + VS) Output Short Circuit Duration . . . . . . . . . . . . . . . . Indefinite Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . .±30 V Storage Temperature Range (N) . . . . . . . . . –65°C to +125°C Storage Temperature Range (Q) . . . . . . . . . –65°C to +150°C Storage Temperature Range (R) . . . . . . . . . –65°C to +150°C Operating Temperature Range AD822A/B . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C AD822S . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C Lead Temperature Range (Soldering 60 sec) . . . . . . . +260°C APPLICATION NOTES INPUT CHARACTERISTICS In the AD822, n-channel JFETs are used to provide a low offset, low noise, high impedance input stage. Minimum input common-mode voltage extends from 0.2 V below –VSto 1 Vless than +VS. Driving the input voltage closer to the positive rail will cause a loss of amplifier bandwidth (as can be seen by comparing the large signal responses shown in Figures 31 and 34) and increased common-mode voltage error as illustrated in Figure 17. The AD822 does not exhibit phase reversal for input voltages up to and including +VS. Figure 39a shows the response of an AD822 voltage follower to a 0 V to +5 V (+VS) square wave input. The input and output arc superimposed. The output tracks the input up to +VS without phase reversal. The reduced bandwidth above a 4 V input causes the rounding of the output wave form. For input voltages greater than +VS, a resistor in series with the AD822’s noninverting input will prevent phase reversal, at the expense of greater input voltage noise. This is illustrated in Figure 39b Since the input stage uses n-channel JFETs, input current during normal operation is negative; the current flows out from the input terminals. If the input voltage is driven more positive than +VS– 0.4 V, the input current will reverse direction as internal device junctions become forward biased. This is illustrated in Figure 4. A current limiting resistor should be used in series with the input of the AD822 if there is a possibility of the input voltage exceeding the positive supply by more than 300 mV, or if an input voltage will be applied to the AD822 when ±VS= 0. The amplifier will be damaged if left in that condition for more than 10 seconds. A 1 k? resistor allows the amplifier to withstand up to 10 volts of continuous overvoltage, and increases the input voltage noise by a negligible amount. Input voltages less than –VS are a completely different story. The amplifier can safely withstand input voltages 20 volts below the minus supply voltage as long as the total voltage from the positive supply to the input terminal is less than 36 volts. In addition, the input stage typically maintains picoamp level input currents across that input voltage range.