Part A
AD822AR
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 6939 PCS
- Package
- SOIC-8
- Series
- Linear - Amplifiers - Instrumentation, OP Amps, Buffer Amps
Replacement verdict
Not a drop-in replacement
The AD822AR and AD8221BR-REEL7 are not drop-in replacements for one another. The AD822AR is a dual-channel, general-purpose JFET-input operational amplifier in an 8-lead SOIC package, while the AD8221BR-REEL7 is a single-channel, high-performance instrumentation amplifier in an 8-lead SOIC package with a different pinout and gain-setting architecture. Their channel count, amplifier topology, pin configuration, and gain configuration differ fundamentally, so neither part can be substituted for the other without a board redesign.
Different channel count
Different amplifier topology
Different pin configuration
Different gain configuration
Parts at a glance
Part B
AD8221BR-REEL7
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 6216 PCS
- Package
- SOIC-8
- Series
- Linear - Amplifiers - Instrumentation, OP Amps, Buffer Amps
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD822AR | AD8221BR-REEL7 | Why it matters |
|---|---|---|---|
| Amplifier Type | General Purpose, Dual | Instrumentation Amplifier, Single | Determines the fundamental function and channel count; a dual op-amp is not a drop-in for a single instrumentation amplifier. |
| Number of Channels | 2 | 1 | Channel count affects circuit topology and board layout; the two parts cannot be substituted without redesign. |
| Input Offset Voltage (Max) | 0.8 mV | 0.025 mV | Lower offset improves DC accuracy; the instrumentation amp offers far better precision for low-level signal measurement. |
| Gain Bandwidth Product | 1.9 MHz | 825 kHz (G=1) | Sets the usable frequency range; the general-purpose op-amp has wider small-signal bandwidth. |
| Input Bias Current (Typ) | 2 pA | 0.5 nA | Affects error in high-impedance sources; the JFET-input op-amp has significantly lower bias current. |
| Supply Voltage Range | ±2.5 V to ±15 V (5 V to 30 V) | ±2.3 V to ±18 V (4.6 V to 36 V) | Determines compatibility with the system power rails; the instrumentation amp tolerates a wider supply range. |
| CMRR (Typ) | 80 dB | 130 dB (G=100) | Common-mode rejection is critical for rejecting noise; the instrumentation amp provides far superior CMRR. |
| Package / Mounting | 8-Lead SOIC (Surface Mount) | 8-Lead SOIC (Surface Mount, Tape & Reel) | Physical footprint and assembly method must match; both share SOIC-8 but differ in packaging format for production. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Ensures both parts meet the same environmental requirements for industrial applications. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD822AR | AD8221BR-REEL7 |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Obsolete | Obsolete |
| Amplifier Type | General Purpose | Instrumentation |
| Number of Circuits | 2 | 1 |
| Slew Rate | 3V/µs | 2V/µs |
| -3 dB Bandwidth | 1.9 MHz | 825 kHz |
| Current - Input Bias | 2 pA | 200 pA |
| Voltage - Input Offset | 400 µV | 25 µV |
| Supply Current | 1.24mA | 900µA |
| Current - Output / Channel | 20 mA | 18 mA |
| Voltage - Supply Span(Min) | 5 V | 4.6 V |
| Voltage - Supply Span(Max) | 30 V | 36 V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Output Type | Rail-to-Rail | - |
| Gain Bandwidth Product | 1.9 MHz | - |
Frequently asked questions
Are the AD822AR and AD8221BR-REEL7 interchangeable in an existing design?
No, they are not directly interchangeable. The AD822AR is a dual, general-purpose, low-power operational amplifier, while the AD8221BR-REEL7 is a single, high-performance instrumentation amplifier. They differ in function, channel count, pinout, and package, so a direct drop-in substitution is not possible without redesigning the circuit and PCB layout.
What are the fundamental functional differences between the AD822AR and AD8221BR-REEL7?
The AD822AR is a dual operational amplifier intended for general signal conditioning, filtering, and amplification tasks. The AD8221BR-REEL7 is a monolithic instrumentation amplifier designed for precision differential signal acquisition with a single external gain resistor. The AD8221BR-REEL7 provides a single channel with laser-trimmed gain accuracy, whereas the AD822AR provides two independent op-amp channels.
How do the package and pinout of the AD822AR and AD8221BR-REEL7 compare?
The AD822AR is offered in an 8-lead SOIC package (among other options), with the standard dual op-amp pinout (two inputs, two outputs, and supply pins). The AD8221BR-REEL7 is supplied in an 8-lead SOIC package with an instrumentation amplifier pinout (two differential inputs, a gain-setting resistor pair, a reference pin, an output, and supply pins). Although both may use an 8-lead SOIC footprint, the pin functions are not compatible, so the PCB layout must be redesigned.
Which part is better suited for precision differential signal measurement?
The AD8221BR-REEL7 is the appropriate choice for precision differential signal measurement. It is a dedicated instrumentation amplifier with high common-mode rejection ratio (CMRR), low offset voltage, and gain set by a single external resistor. The AD822AR, as a general-purpose dual op-amp, would require an external resistor network to build a discrete instrumentation amplifier, resulting in lower precision and more components.
Do the AD822AR and AD8221BR-REEL7 have the same supply voltage requirements?
Both devices support dual-supply operation, but their specified ranges differ. The AD822AR operates on supplies from ±2.5 V to ±15 V (or 5 V to 30 V single supply). The AD8221BR-REEL7 operates on supplies from ±2.3 V to ±18 V. Designers must verify the actual supply rails against the respective datasheet limits before use.
Can the AD8221BR-REEL7 replace one channel of the AD822AR in a dual op-amp circuit?
No. The AD8221BR-REEL7 is a single instrumentation amplifier with a fixed pinout that includes a gain resistor connection and a reference pin, which are not present on the AD822AR. Replacing one channel of a dual op-amp with an instrumentation amplifier requires a new PCB layout and a review of the surrounding circuit topology, gain configuration, and reference connections.
What gain-setting method does each device use?
The AD822AR, as an operational amplifier, uses external feedback resistors to set closed-loop gain for each channel. The AD8221BR-REEL7 uses a single external resistor (R_G) connected between its gain-setting pins to program the gain, with the gain equation specified in the manufacturer datasheet. This difference affects both the bill of materials and the achievable gain accuracy.
Which part is more appropriate for multi-channel general-purpose amplification?
The AD822AR is more appropriate for multi-channel general-purpose amplification because it integrates two independent op-amp channels in a single package, reducing board space and component count. The AD8221BR-REEL7 provides only one instrumentation amplifier channel per package and is intended for precision differential measurement rather than general-purpose multi-channel signal conditioning.