Part A
AD847ARZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 6367 PCS
- Package
- SOIC-8
- Series
- Linear - Amplificadores - Instrumentação, OP Amps, Buffer Amps
Replacement verdict
Not a drop-in replacement
The AD847ARZ and AD8479BRZ-RL are not interchangeable despite sharing a similar function name. The AD847ARZ is a high-speed, low-power operational amplifier, while the AD8479BRZ-RL is a precision high common-mode voltage difference amplifier. Their input structures, gain configurations, supply requirements, and package options differ fundamentally, so substituting one for the other is not feasible without a complete circuit redesign.
Different amplifier function
Different input topology
Different gain configuration
Different package and pinout
Parts at a glance
Part B
AD8479BRZ-RL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5855 PCS
- Package
- SOIC-8
- Series
- Linear - Amplificadores - Instrumentação, 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 | AD847ARZ | AD8479BRZ-RL | Why it matters |
|---|---|---|---|
| Amplifier Type | General Purpose Voltage Feedback Op Amp | High Common-Mode Voltage Difference Amplifier | The two parts serve fundamentally different functions; one is a standard op amp and the other is a specialized difference amplifier, so they are not direct substitutes. |
| Number of Channels | 1 | 1 | Both are single-channel devices, so channel count alone does not differentiate them for substitution. |
| Gain Bandwidth Product | 50 MHz | 1 MHz (fixed gain of 1) | Bandwidth determines the maximum signal frequency the amplifier can handle; the AD847ARZ supports much higher-frequency signals. |
| Slew Rate | 300 V/µs | 1 V/µs | Slew rate limits how fast the output can respond to large signal changes; the AD847ARZ is far faster for high-speed applications. |
| Input Offset Voltage (max) | 0.5 mV | 1 mV | Offset voltage affects DC accuracy; lower offset gives better precision in low-level signal measurement. |
| Supply Voltage Range | ±4.5 V to ±18 V (dual) | ±5 V to ±18 V (dual) | The supply range determines compatibility with the system power rails; the AD847ARZ tolerates slightly lower minimum supplies. |
| Common-Mode Input Voltage Range | Limited to supply rails (standard op amp) | ±600 V (high voltage) | The AD8479BRZ-RL can measure signals far above its supply rails, which is essential for high-side current sensing; the AD847ARZ cannot. |
| Input Bias Current (typ) | 3.3 µA | 1 µA | Bias current affects accuracy in high-impedance source applications; lower bias current reduces error. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +125 °C | The wider temperature range of the AD8479BRZ-RL suits harsher environments and industrial applications. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Both use the same SOIC footprint, so board layout compatibility is maintained even though the parts are functionally different. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD847ARZ | AD8479BRZ-RL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Active | Active |
| Amplifier Type | General Purpose | General Purpose |
| Number of Circuits | 1 | 1 |
| Output Type | - | Rail-to-Rail |
| Slew Rate | 300V/µs | 8V/µs |
| -3 dB Bandwidth | - | 130 kHz |
| Voltage - Input Offset | 500 µV | 500 µV |
| Supply Current | 5.3mA | 550µA |
| Current - Output / Channel | 32 mA | 55 mA |
| Voltage - Supply Span(Min) | 9 V | 5 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 |
| Gain Bandwidth Product | 50 MHz | - |
| Current - Input Bias | 3.3 µA | - |
Frequently asked questions
Are the AD847ARZ and AD8479BRZ-RL functionally interchangeable?
No. The AD847ARZ is a high-speed, low-power operational amplifier, while the AD8479BRZ-RL is a precision high common-mode voltage difference amplifier. They serve different signal-conditioning roles and are not direct substitutes.
What are the key differences in function between the AD847ARZ and AD8479BRZ-RL?
The AD847ARZ is a general-purpose voltage-feedback op amp intended for amplification and active filtering. The AD8479BRZ-RL is a difference amplifier designed to measure differential signals riding on very high common-mode voltages, with a fixed gain of 1.
Do the AD847ARZ and AD8479BRZ-RL use the same package and pinout?
Both devices are offered in an 8-lead SOIC package, but their pin functions differ because the AD847ARZ is an op amp and the AD8479BRZ-RL is a difference amplifier. PCB layouts and pin assignments must be verified against each device's datasheet before any substitution.
How do the supply voltage requirements compare between the AD847ARZ and AD8479BRZ-RL?
The AD847ARZ operates on dual supplies typically up to ±15 V, while the AD8479BRZ-RL is specified for operation on ±5 V to ±18 V dual supplies. Designers should confirm the exact supply range and headroom requirements in the respective manufacturer datasheets.
Which device is better suited for high common-mode voltage sensing?
The AD8479BRZ-RL is specifically designed for high common-mode voltage difference measurement, supporting common-mode voltages far beyond its supply rails. The AD847ARZ is not intended for this function and should not be used for high common-mode sensing.
Can the AD847ARZ be used as a drop-in replacement for the AD8479BRZ-RL in an existing design?
No. Because the two parts have different internal topologies, pin functions, and intended applications, the AD847ARZ cannot be used as a drop-in replacement for the AD8479BRZ-RL. Any change requires full schematic and layout review against the manufacturer datasheets.
What role does the "BRZ-RL" suffix play on the AD8479BRZ-RL?
The suffix indicates the device grade, package type, and packaging option as defined by the manufacturer. Designers should consult the official AD8479 datasheet ordering guide to confirm the exact grade, temperature range, and reel packaging associated with the BRZ-RL suffix.