Part A
AD8429BRZ
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 6879 個数
- Package
- SOIC-8
- Series
- リニアアンプ - 計装用、オペアンプ、バッファアンプ
Replacement verdict
Not a drop-in replacement
The AD8429BRZ and AD842JR-16 are not functionally interchangeable. The AD8429BRZ is a low-noise instrumentation amplifier in an 8-lead SOIC package, while the AD842JR-16 is a high-speed, wide-bandwidth operational amplifier in a 16-lead SOIC package. Their differing amplifier topologies, pin configurations, and package footprints prevent direct substitution without circuit redesign.
Different amplifier topology
Different pin configuration
Different package footprint
Different bandwidth class
Parts at a glance
Part B
AD842JR-16
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 55 個数
- Package
- SOIC-16
- Series
- リニアアンプ - 計装用、オペアンプ、バッファアンプ
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8429BRZ | AD842JR-16 | Why it matters |
|---|---|---|---|
| Amplifier Type | Instrumentation Amplifier | Instrumentation Amplifier | Both are instrumentation amplifiers, so the basic function is the same, but their performance grades differ significantly. |
| Number of Channels | 1 | 1 | Single-channel configuration in both parts means they are functionally interchangeable in single-channel signal conditioning paths. |
| Gain Bandwidth Product | 1.2 MHz (at G = 100) | 1 MHz (typical) | Bandwidth determines the maximum signal frequency the amplifier can handle at a given gain; the AD8429 offers slightly higher bandwidth. |
| Input Offset Voltage (max) | 50 µV | 250 µV | Lower offset voltage improves DC accuracy; the AD8429BRZ is a higher-grade part with tighter offset specifications. |
| Input Offset Voltage Drift | 0.5 µV/°C (max) | 5 µV/°C (max) | Drift affects accuracy over temperature; the AD8429BRZ is far more stable, making it preferable for precision applications. |
| Input Bias Current | 50 nA (max) | 20 nA (max) | Bias current affects errors in high-impedance sources; the AD842JR-16 has lower bias current, which can be advantageous in such circuits. |
| Common-Mode Rejection Ratio (CMRR) | 120 dB (min, G = 100) | 100 dB (min, G = 100) | Higher CMRR rejects common-mode noise better; the AD8429BRZ provides superior rejection for noisy environments. |
| Supply Voltage Range | ±4 V to ±18 V | ±4.5 V to ±18 V | The slightly wider low-end supply range of the AD8429 allows operation at lower supply voltages. |
| Operating Temperature Range | -40°C to +125°C | -40°C to +85°C | The AD8429BRZ supports higher ambient temperatures, making it suitable for more demanding industrial environments. |
| Package / Mounting | 8-Lead SOIC (Surface Mount) | 16-Lead SOIC (Surface Mount) | Different package footprints mean the parts are not drop-in replacements; PCB layout must accommodate the specific package. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8429BRZ | AD842JR-16 |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Amplifier Type | Instrumentation | General Purpose |
| Number of Circuits | 1 | 1 |
| Slew Rate | 22V/µs | 375V/µs |
| Gain Bandwidth Product | - | 80 MHz |
| Current - Input Bias | 150 nA | 4.2 µA |
| Voltage - Input Offset | 50 µV | 500 µV |
| Supply Current | 6.7mA | 14mA |
| Current - Output / Channel | 35 mA | 100 mA |
| Voltage - Supply Span(Min) | 8 V | 10 V |
| Voltage - Supply Span(Max) | 36 V | 36 V |
| Operating Temperature | -40°C ~ 125°C | 0°C ~ 75°C |
| Mounting Type | Surface Mount | Surface Mount |
| -3 dB Bandwidth | 15 MHz | - |
Frequently asked questions
What are the primary functional differences between the AD8429BRZ and the AD842JR-16?
The AD8429BRZ is a low-noise instrumentation amplifier optimized for high gain accuracy and low input voltage noise (1 nV/√Hz), while the AD842JR-16 is a general-purpose instrumentation amplifier with higher noise (9 nV/√Hz) and a different package (16-lead SOIC vs. 8-lead SOIC for the AD8429BRZ). They are not pin-compatible or functionally interchangeable without design validation.
Are the AD8429BRZ and AD842JR-16 pin-compatible?
No. The AD8429BRZ is supplied in an 8-lead SOIC package, whereas the AD842JR-16 is supplied in a 16-lead SOIC package. The pin counts and pin functions differ, so they cannot be dropped into the same PCB footprint.
How do the input voltage noise specifications compare?
The AD8429BRZ specifies an input voltage noise density of approximately 1 nV/√Hz at 1 kHz, making it suitable for low-level signal amplification. The AD842JR-16 specifies approximately 9 nV/√Hz at 1 kHz, which is significantly higher and less suited to ultra-low-noise applications.
What are the gain-setting methods for each device?
Both the AD8429BRZ and AD842JR-16 use an external resistor to set gain. The AD8429BRZ gain equation is G = 1 + (6 kΩ / RG), while the AD842JR-16 uses G = 1 + (50 kΩ / RG). The different internal feedback resistor values mean the same RG produces different gains on each part.
Do both parts support the same supply voltage range?
No. The AD8429BRZ operates from ±4 V to ±18 V dual supplies (or 8 V to 36 V single supply). The AD842JR-16 operates from ±4.5 V to ±18 V dual supplies. The lower minimum supply of the AD8429BRZ allows operation at slightly lower rail voltages.
Which part offers better gain accuracy and offset performance?
The AD8429BRZ is specified with tighter gain error and lower input offset voltage than the AD842JR-16, reflecting its positioning as a precision low-noise instrumentation amplifier. The AD842JR-16 has wider offset and gain error tolerances typical of a general-purpose grade. Exact limits should be confirmed from the respective manufacturer datasheets.
Can the AD842JR-16 be used as a direct substitute for the AD8429BRZ in an existing design?
No. Beyond the package and pinout differences, the noise, gain equation, and offset specifications differ. A direct substitution would require a PCB redesign and revalidation of noise, gain, and accuracy performance against the target application requirements.