Part A
AD8422ARZ
아날로그 디바이스(주)
- Lifecycle
- Active
- Stock
- 3872 PCS
- Package
- SOIC-8
- Series
- 선형 증폭기 - 계측기, 연산 증폭기, 완충 증폭기
Replacement verdict
Compatible functional replacement candidate
The AD8429ARZ and AD8422ARZ are both precision instrumentation amplifiers in the same SOIC-8 package and pinout, making them functionally interchangeable in many designs. However, the AD8429ARZ offers substantially higher bandwidth and faster slew rate, while the AD8422ARZ delivers lower power consumption and lower input bias current. Designers should validate noise, bandwidth, and supply current requirements against the target application before substituting one for the other.
Package and Pinout
High match
Gain Range and Configuration
High match
Bandwidth and Slew Rate
Validation required
Supply Current and Noise
Validation required
Parts at a glance
Part B
AD8429ARZ
아날로그 디바이스(주)
- Lifecycle
- Active
- Stock
- 7143 PCS
- Package
- SOIC-8
- Series
- 선형 증폭기 - 계측기, 연산 증폭기, 완충 증폭기
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8429ARZ | AD8422ARZ | Why it matters |
|---|---|---|---|
| Number of Channels | 1 | 1 | Both are single-channel instrumentation amplifiers, so channel count is functionally equivalent. |
| Gain Bandwidth Product (GBW) | 15 MHz | 2.2 MHz | Higher GBW allows the AD8429 to handle wider signal bandwidths at a given gain, affecting high-frequency performance. |
| Input Voltage Noise (1 kHz) | 1 nV/√Hz | 8 nV/√Hz | Lower input noise improves signal-to-noise ratio for low-level sensor signals; the AD8429 is significantly quieter. |
| Input Offset Voltage (max) | 50 µV | 70 µV | Lower offset voltage reduces DC error at the output, important for precision measurement applications. |
| Supply Current per Amplifier | 4.5 mA | 0.3 mA | The AD8422 draws far less supply current, making it preferable for low-power and battery-operated designs. |
| Supply Voltage Range | ±4 V to ±18 V | ±2.3 V to ±18 V | The AD8422 supports lower supply voltages, enabling operation in low-voltage systems where the AD8429 cannot be used. |
| CMRR (G=1000, DC to 60 Hz) | 130 dB | 120 dB | Higher common-mode rejection suppresses interference; the AD8429 offers better rejection for precision instrumentation. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +85 °C | The AD8429 supports a wider temperature range, making it suitable for harsher environments. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Identical package and pinout allow direct board-level substitution without layout changes. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8422ARZ | AD8429ARZ |
|---|---|---|
| Part Status | Active | Active |
| Amplifier Type | Instrumentation | Instrumentation |
| Number of Circuits | 1 | 1 |
| Output Type | Rail-to-Rail | - |
| Slew Rate | 0.8V/µs | 22V/µs |
| -3 dB Bandwidth | 2.2 MHz | 15 MHz |
| Current - Input Bias | 500 pA | 300 nA |
| Voltage - Input Offset | 60 µV | 150 µV |
| Supply Current | 300µA | 6.7mA |
| Current - Output / Channel | 20 mA | 35 mA |
| Voltage - Supply Span(Min) | 4.6 V | 8 V |
| Voltage - Supply Span(Max) | 36 V | 36 V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the key differences between the AD8429ARZ and AD8422ARZ instrumentation amplifiers?
The AD8429ARZ is a low-noise instrumentation amplifier optimized for high gain accuracy and low noise (1 nV/√Hz at 1 kHz) with a gain range of 1 to 10,000, while the AD8422ARZ is a micropower, high-precision instrumentation amplifier with lower supply current (typically 300 µA) and a gain range of 1 to 1,000. The AD8429ARZ targets low-noise signal acquisition, whereas the AD8422ARZ targets power-sensitive precision applications.
Are the AD8429ARZ and AD8422ARZ pin-compatible in the SOIC-8 package?
Both devices are offered in an 8-lead SOIC package (R-8 suffix), and their pinouts follow the standard instrumentation amplifier configuration (gain resistor pins, +IN, -IN, REF, OUT, +VS, -VS). However, designers should verify the exact pin function assignments and gain-setting resistor connections against the respective manufacturer datasheets before substituting one for the other.
How do the noise specifications of the AD8429ARZ and AD8422ARZ compare?
The AD8429ARZ specifies an input voltage noise of approximately 1 nV/√Hz at 1 kHz, making it suitable for low-level signal amplification. The AD8422ARZ specifies higher input voltage noise (approximately 8 nV/√Hz at 1 kHz) but consumes significantly less supply current. The choice depends on whether noise performance or power consumption is the dominant design constraint.
What are the supply voltage and quiescent current differences between the AD8429ARZ and AD8422ARZ?
The AD8429ARZ operates from dual supplies typically ranging from ±4 V to ±18 V and draws a higher quiescent current (on the order of several mA). The AD8422ARZ operates from supplies as low as ±2.3 V (or 4.6 V single supply) up to ±18 V and draws a much lower quiescent current of approximately 300 µA, making it preferable for battery-powered or low-power systems.
Can the AD8422ARZ replace the AD8429ARZ in an existing low-noise design?
Direct replacement is not recommended without validation. The AD8422ARZ has higher input voltage noise and a lower maximum gain (1,000 versus 10,000 for the AD8429ARZ), so a design requiring the AD8429ARZ's low noise floor or high gain range would not meet specifications with the AD8422ARZ. Gain-setting resistor values and bandwidth must also be recalculated.
What are the gain ranges and gain-setting methods for the AD8429ARZ and AD8422ARZ?
Both devices set gain using a single external resistor connected between the RG pins. The AD8429ARZ supports gains from 1 to 10,000, while the AD8422ARZ supports gains from 1 to 1,000. The gain equation and recommended resistor values differ between the two devices and must be taken from the respective datasheets.
Which device is better suited for high-precision, low-power portable instrumentation?
The AD8422ARZ is better suited for low-power portable instrumentation due to its approximately 300 µA supply current and low offset voltage, while still providing precision DC performance. The AD8429ARZ is preferred when ultralow input noise is the primary requirement and higher supply current is acceptable.