Part A
AD847AR
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 7655 PCS
- Series
- Linear - Amplifiers - Instrumentation, Op Amps, Buffer Amps
Replacement verdict
Not a drop-in replacement
The AD8479ARZ-RL and AD847AR are not functionally interchangeable. The AD8479ARZ-RL is a high common-mode voltage difference amplifier with a fixed gain of 1 and a ±600 V common-mode input range, while the AD847AR is a low-power, high-speed operational amplifier with a 50 MHz gain-bandwidth product. Their input architectures, gain configurations, and application roles differ fundamentally, so the AD847AR cannot directly replace the AD8479ARZ-RL in high-voltage sensing circuits, nor vice versa.
Different amplifier function
Different gain configuration
Different input architecture
Different application role
Parts at a glance
Part B
AD8479ARZ-RL
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 2479 PCS
- Package
- SOIC-8
- Series
- Amplificateurs linéaires - instruments, amplificateurs opérationnels, amplificateurs tampons
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8479ARZ-RL | AD847AR | Why it matters |
|---|---|---|---|
| Amplifier Type | Difference Amplifier | High Speed Operational Amplifier | The two parts serve fundamentally different functions; a difference amplifier extracts a differential signal, while a general-purpose op amp requires external circuitry to do so, so they are not directly substitutable. |
| Number of Channels | 1 | 1 | Both are single-channel devices, so channel count does not differentiate them for single-signal designs. |
| Gain Bandwidth Product | Not specified (fixed gain difference amplifier) | 50 MHz | GBW determines the maximum signal frequency the amplifier can handle at a given closed-loop gain; the AD847AR offers a defined high-speed bandwidth while the AD8479ARZ-RL is a fixed-gain difference stage. |
| Slew Rate | Not specified | 300 V/µs | Slew rate limits how fast the output can respond to large signal steps; the AD847AR's high slew rate suits fast transient applications. |
| Input Offset Voltage | ±0.5 mV (typical) | ±0.5 mV (typical) | Offset voltage directly affects DC accuracy; both parts offer comparable typical offset, though their application contexts differ. |
| Supply Voltage Range | ±5 V to ±18 V (dual supply) | ±4.5 V to ±18 V (dual supply) | The supply range determines compatibility with the system power rails; the AD847AR tolerates a slightly lower minimum supply. |
| Package / Mounting | 8-Lead SOIC (surface mount) | 8-Lead SOIC (surface mount) | Matching package and mounting style allows both parts to fit the same PCB footprint, easing layout substitution. |
| Operating Temperature Range | -40°C to +125°C | -40°C to +85°C | The wider temperature range of the AD8479ARZ-RL supports harsher environments, while the AD847AR is limited to standard industrial temperatures. |
| Input Common-Mode Voltage Range | ±600 V (high voltage difference input) | Limited to supply rails | The AD8479ARZ-RL is designed for high common-mode voltage sensing, whereas the AD847AR's inputs are constrained near its supply rails, making them unsuitable as direct substitutes in high-voltage sensing. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD847AR | AD8479ARZ-RL |
|---|---|---|
| Part Status | Obsolete | Active |
| Base Product Number | AD847 | - |
| Amplifier Type | Standard (General Purpose) | General Purpose |
| Number of Circuits | 1 | 1 |
| Slew Rate | 300V/µs | 8V/µs |
| Gain Bandwidth Product | 50 MHz | - |
| Current - Input Bias | 3.3 µA | - |
| Voltage - Input Offset | 500 µV | 500 µV |
| Supply Current | 5.3mA | 550µA |
| Voltage - Supply Span (Min) | 9 V | - |
| Voltage - Supply Span (Max) | 36 V | - |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Packaging | Tube | - |
| Current - Output / Channel | 32 mA | 55 mA |
| Output Type | - | Rail-to-Rail |
| -3 dB Bandwidth | - | 130 kHz |
| Voltage - Supply Span(Min) | - | 5 V |
| Voltage - Supply Span(Max) | - | 36 V |
Frequently asked questions
What are the primary functional differences between the AD8479ARZ-RL and the AD847AR?
The AD8479ARZ-RL is a precision, high common-mode voltage difference amplifier designed for applications requiring a very high common-mode input range (up to ±600 V), while the AD847AR is a high-speed, low-power operational amplifier. They serve fundamentally different circuit functions and are not functionally interchangeable.
Are the AD8479ARZ-RL and AD847AR pin-compatible or package-compatible?
No. The AD8479ARZ-RL is supplied in an 8-lead SOIC package (SOIC-8), whereas the AD847AR is supplied in an 8-lead PDIP (N) or 8-lead SOIC package depending on the specific ordering variant. Pin functions and internal architecture differ, so PCB land patterns and pin assignments must be verified against the respective datasheets before any layout reuse.
Can the AD847AR be used as a direct substitute for the AD8479ARZ-RL in a high common-mode voltage sensing application?
No. The AD8479ARZ-RL is specifically designed as a difference amplifier with an internal resistor network that allows it to handle common-mode voltages up to ±600 V, whereas the AD847AR is a general-purpose op amp with a standard supply voltage range and no integrated high-voltage difference amplifier network. Substitution would require a complete redesign of the signal conditioning stage.
What are the key AC performance specifications of the AD847AR?
The AD847AR is a high-speed operational amplifier with a unity-gain bandwidth of approximately 50 MHz and a slew rate of approximately 300 V/µs, making it suitable for video and high-speed signal processing applications. These parameters should be confirmed against the latest Analog Devices datasheet for the specific grade.
What is the common-mode voltage range of the AD8479ARZ-RL?
The AD8479ARZ-RL supports a very wide common-mode input voltage range of ±600 V, which is its primary distinguishing feature for high-voltage current sensing and industrial measurement applications. This specification should be verified against the official Analog Devices datasheet.
Do the AD8479ARZ-RL and AD847AR share the same supply voltage requirements?
No. The AD8479ARZ-RL operates from dual supplies typically in the ±5 V to ±18 V range (with specific limits per datasheet), while the AD847AR operates from dual supplies typically in the ±5 V to ±15 V range. Designers must confirm exact supply limits and absolute maximum ratings from the respective manufacturer datasheets before use.
Which part is better suited for precision current sensing in motor control or power supply designs?
The AD8479ARZ-RL is the appropriate choice for precision current sensing in high-voltage motor control or power supply designs because of its integrated difference amplifier topology and ±600 V common-mode range. The AD847AR is not designed for high common-mode voltage sensing and would not provide the required input range or integrated resistor matching.