Part A
AD8479BRZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1818 Stückzahl
- Package
- SOIC-8
- Series
- Linear-Verstärker.Instrumentation, OP-Verstärker, Pufferverstärker
Replacement verdict
Not a drop-in replacement
The AD8479BRZ and AD847AR-REEL are not functionally interchangeable. The AD8479BRZ is a precision high common-mode voltage difference amplifier, while the AD847AR-REEL is a high-speed operational amplifier. Their core functions, pin configurations, and application roles differ fundamentally, so substituting one for the other is not feasible without redesigning the surrounding circuit.
Different amplifier function
Different pin configuration
Different bandwidth class
Different application role
Parts at a glance
Part B
AD847AR-REEL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 3128 Stückzahl
- Package
- SOIC-8
- Series
- Linear-Verstärker.Instrumentation, OP-Verstärker, Pufferverstärker
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8479BRZ | AD847AR-REEL | Why it matters |
|---|---|---|---|
| Amplifier Type | Difference Amplifier | General Purpose Amplifier | The two parts serve fundamentally different functions; a difference amplifier extracts a differential signal while a general-purpose op amp is a building block, so they are not directly substitutable. |
| Number of Circuits | 1 | 1 | Both are single-channel devices, so channel count is not a differentiator for substitution. |
| Gain Bandwidth Product | Not specified (fixed gain difference amp) | 50 MHz | GBW determines the frequency range over which the amplifier maintains its performance; the AD847 offers a defined high-speed bandwidth while the AD8479 is a fixed-gain difference amplifier. |
| Slew Rate | Not specified | 300 V/µs | Slew rate limits how fast the output can respond to large signal changes; the AD847's high slew rate suits high-speed signal processing. |
| Input Offset Voltage | ±0.5 mV (typical) | ±0.5 mV (typical) | Offset voltage affects DC accuracy; comparable offset values mean similar DC precision at the input. |
| Supply Voltage Range | ±4 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 AD8479 tolerates a slightly lower minimum supply. |
| Operating Temperature Range | -40°C to +125°C | -40°C to +85°C | The wider temperature range of the AD8479BRZ allows operation in harsher environments where the AD847AR-REEL may not be rated. |
| Package / Mounting Type | 8-SOIC (surface mount) | 8-SOIC (surface mount, tape and reel) | Package and mounting compatibility are essential for board-level substitution; both use the same SOIC footprint but differ in packaging format. |
| Output Current per Channel | Not specified | 32 mA | Output drive capability determines the load the amplifier can drive; the AD847 specifies a drive current while the AD8479 does not. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8479BRZ | AD847AR-REEL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Active | Obsolete |
| Amplifier Type | General Purpose | General Purpose |
| Number of Circuits | 1 | 1 |
| Slew Rate | 8V/µs | 300V/µs |
| Gain Bandwidth Product | - | 50 MHz |
| Current - Input Bias | - | 3.3 µA |
| Voltage - Input Offset | 500 µV | 500 µV |
| Supply Current | 550µA | 5.3mA |
| Current - Output / Channel | 55 mA | 32 mA |
| Voltage - Supply Span(Min) | 5 V | 9 V |
| Voltage - Supply Span(Max) | 36 V | 36 V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Output Type | Rail-to-Rail | - |
| -3 dB Bandwidth | 130 kHz | - |
Frequently asked questions
What are the fundamental differences between the AD8479BRZ and the AD847AR-REEL?
The AD8479BRZ is a precision, high common-mode voltage difference amplifier in an 8-lead SOIC package, specified over the −40°C to +125°C industrial temperature range with tighter gain and offset grades. The AD847AR-REEL is a high-speed, low-power operational amplifier in an 8-lead SOIC package, supplied on tape and reel, specified over the −40°C to +85°C temperature range. They are functionally different device classes and are not interchangeable.
Can the AD8479BRZ be used as a direct replacement for the AD847AR-REEL?
No. The AD8479BRZ is a fixed-gain difference amplifier designed for high common-mode voltage sensing, while the AD847AR-REEL is a general-purpose voltage-feedback op amp. Pin functions, internal topology, gain configuration, and input common-mode range differ, so a direct substitution is not valid without redesign and validation.
What are the key AC specifications of the AD847AR-REEL?
The AD847AR-REEL is a high-speed op amp with a typical −3 dB bandwidth of 50 MHz at unity gain and a slew rate of approximately 300 V/µs, with a typical settling time of 45 ns to 0.1% for a 10 V step. These parameters suit video, ADC driving, and fast signal-conditioning applications.
What common-mode voltage range does the AD8479BRZ support?
The AD8479BRZ is designed to operate with common-mode voltages up to ±600 V while running on ±15 V supplies, making it suitable for high-side current sensing and high-voltage difference measurement. The AD847AR-REEL does not support this common-mode range and is limited to standard op-amp supply-rail constraints.
How do the supply voltage requirements compare?
The AD8479BRZ operates on dual supplies of ±5 V to ±18 V (or equivalent single supply within that span) and is optimized for ±15 V operation. The AD847AR-REEL operates on ±4.5 V to ±18 V dual supplies. Both are dual-supply parts, but the AD8479BRZ is specifically characterized for high-voltage common-mode operation at ±15 V.
What package and temperature-grade differences exist between the two parts?
Both devices are offered in 8-lead SOIC packages. The AD8479BRZ is specified over the −40°C to +125°C industrial range with B-grade gain and offset tolerances. The AD847AR-REEL is specified over the −40°C to +85°C range and is supplied in tape-and-reel format for automated assembly. The temperature grade and precision specifications are not equivalent.
Which part is appropriate for high-side current sensing?
The AD8479BRZ is the appropriate choice for high-side current sensing because its ±600 V common-mode range and fixed gain of 1 allow direct measurement across shunt resistors at elevated common-mode voltages. The AD847AR-REEL is not specified for high common-mode voltage sensing and should not be used in that role.
Are the AD8479BRZ and AD847AR-REEL pin-compatible?
Although both are 8-lead SOIC devices, they are not pin-compatible in function. The AD8479BRZ pinout is dedicated to a difference amplifier with reference and output pins configured for high-voltage sensing, while the AD847AR-REEL follows a standard single op-amp pinout (offset null, inputs, supplies, output). PCB layouts cannot be shared without verification against each datasheet.