Part A
AD8422BRZ
ADI公司
- Lifecycle
- Active
- Stock
- 3871 件
- Package
- SOIC-8
- Series
- 線性放大器-儀器、運算放大器、緩衝放大器
Replacement verdict
Compatible functional replacement candidate
The AD8422BRZ and AD8421BRZ-RL are both precision instrumentation amplifiers in the same SOIC-8 package with identical pinout, making them a viable functional replacement candidate. However, the AD8422BRZ offers lower supply current and wider supply range, while the AD8421BRZ-RL provides higher bandwidth and faster settling. Designers should validate gain-setting resistor values and AC performance requirements before substituting.
Package Type
High match
Pin Configuration
High match
Supply Voltage Range
Validation required
Bandwidth and Slew Rate
Validation required
Parts at a glance
Part B
AD8421BRZ-RL
ADI公司
- Lifecycle
- Active
- Stock
- 9374 件
- Package
- SOIC-8
- Series
- 線性放大器-儀器、運算放大器、緩衝放大器
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8422BRZ | AD8421BRZ-RL | Why it matters |
|---|---|---|---|
| Gain Bandwidth Product (GBP) | 1 MHz | 10 MHz | Determines the maximum frequency at which the amplifier can provide useful gain; the AD8421 offers roughly 10x the bandwidth, enabling higher-speed signal conditioning. |
| Input Voltage Noise (1 kHz) | 8 nV/√Hz | 3 nV/√Hz | Lower input voltage noise improves signal-to-noise ratio for low-level signals; the AD8421 is significantly quieter, benefiting precision low-amplitude measurements. |
| Input Offset Voltage (max) | 70 µV | 60 µV | Offset voltage directly adds DC error to the amplified signal; a lower maximum offset reduces measurement error in high-gain precision applications. |
| Supply Current per Amplifier (typ) | 300 µA | 2.3 mA | Quiescent current affects power budget and thermal load; the AD8422 is far more power-efficient, making it preferable for battery-powered or low-power designs. |
| CMRR (DC to 60 Hz, G=1000) | 120 dB | 134 dB | Common-mode rejection ratio determines how well the amplifier rejects unwanted common-mode signals; higher CMRR improves accuracy in noisy or high-common-mode environments. |
| Input Bias Current (max) | 1 nA | 2 nA | Bias current flowing through source impedance creates offset errors; lower bias current is advantageous for high-impedance sensor interfaces. |
| Slew Rate | 0.8 V/µs | 35 V/µs | Slew rate limits how fast the output can respond to large signal changes; the AD8421 supports much faster transient response for dynamic signals. |
| Supply Voltage Range | ±2.3 V to ±18 V (4.6 V to 36 V) | ±2.5 V to ±18 V (5 V to 36 V) | Defines the allowable power supply window; the slightly wider low-end range of the AD8422 permits operation at marginally lower supply voltages. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Specifies the ambient temperature window for guaranteed operation; identical ranges mean both suit the same industrial environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8422BRZ | AD8421BRZ-RL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Active | Active |
| Amplifier Type | Instrumentation | Instrumentation |
| Number of Circuits | 1 | 1 |
| Slew Rate | 0.8V/µs | 35V/µs |
| -3 dB Bandwidth | 2.2 MHz | 10 MHz |
| Current - Input Bias | 200 pA | 100 pA |
| Voltage - Input Offset | 25 µV | 25 µV |
| Supply Current | 300µA | 2mA |
| Current - Output / Channel | 20 mA | 65 mA |
| Voltage - Supply Span(Min) | 4.6 V | 5 V |
| Voltage - Supply Span(Max) | 36 V | 36 V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Output Type | Rail-to-Rail | - |
Frequently asked questions
What are the primary differences between the AD8422BRZ and AD8421BRZ-RL?
The AD8422BRZ is an instrumentation amplifier with a supply range of ±2.3 V to ±18 V (or 4.6 V to 36 V single-supply), a gain bandwidth product of 2.2 MHz, and a maximum input offset voltage of 25 µV in the B grade. The AD8421BRZ-RL is a lower-noise instrumentation amplifier with a supply range of ±2.25 V to ±18 V (or 4.5 V to 36 V single-supply), a gain bandwidth product of 10 MHz, and a maximum input offset voltage of 60 µV in the B grade. The AD8421BRZ-RL is supplied in a 500-unit reel (RL suffix), while the AD8422BRZ is supplied in a tube.
Are the AD8422BRZ and AD8421BRZ-RL pin-compatible?
Both devices are offered in an 8-lead SOIC package (R-8 suffix) with the same pinout: -IN, RG, RG, +IN, -VS, REF, VOUT, +VS. This allows them to share the same PCB land pattern, but electrical differences must be validated before substitution.
Which device offers lower input voltage noise?
The AD8421BRZ-RL specifies an input voltage noise density of 3 nV/√Hz at 1 kHz (G = 1), while the AD8422BRZ specifies 8 nV/√Hz at 1 kHz. The AD8421BRZ-RL is therefore the lower-noise option for low-level signal amplification.
How do the gain bandwidth products of these two amplifiers compare?
The AD8421BRZ-RL has a gain bandwidth product of 10 MHz, whereas the AD8422BRZ has a gain bandwidth product of 2.2 MHz. The AD8421BRZ-RL therefore provides wider closed-loop bandwidth at a given gain.
What are the supply voltage ranges for the AD8422BRZ and AD8421BRZ-RL?
The AD8422BRZ operates from ±2.3 V to ±18 V dual supplies or 4.6 V to 36 V single supply. The AD8421BRZ-RL operates from ±2.25 V to ±18 V dual supplies or 4.5 V to 36 V single supply. Both support a broad range of industrial and instrumentation supply rails.
How do the input offset voltage specifications compare?
The AD8422BRZ (B grade) specifies a maximum input offset voltage of 25 µV. The AD8421BRZ-RL (B grade) specifies a maximum input offset voltage of 60 µV. The AD8422BRZ offers tighter DC offset accuracy, while the AD8421BRZ-RL offers lower noise and higher bandwidth.
What is the significance of the RL suffix on the AD8421BRZ-RL?
The RL suffix indicates the device is supplied in a 500-unit tape-and-reel packaging format, which is suitable for automated surface-mount assembly. The AD8422BRZ is supplied in a tube. The electrical specifications are identical to the corresponding non-reel B-grade part.
Can the AD8422BRZ and AD8421BRZ-RL be used interchangeably in an existing design?
They are not electrically identical. The AD8421BRZ-RL has lower voltage noise (3 nV/√Hz vs 8 nV/√Hz) and higher gain bandwidth (10 MHz vs 2.2 MHz), while the AD8422BRZ has lower maximum input offset voltage (25 µV vs 60 µV). Substitution requires verification of noise, bandwidth, offset, and stability against the target design requirements and manufacturer datasheets.