Part A
AD8655ARZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 7253 PCS
- Package
- SOIC-8
- Series
- Linear - Amplifiers - Instrumentation, OP Amps, Buffer Amps
Replacement verdict
Compatible functional replacement candidate
The AD8655ARZ and AD8651AR are both single-channel, 5 V, rail-to-rail input/output CMOS operational amplifiers in the same 8-lead SOIC package, making them strong functional replacement candidates. The AD8655ARZ offers lower voltage noise and lower offset voltage, while the AD8651AR provides higher gain bandwidth and faster slew rate. Designers should validate bandwidth, noise, and settling requirements against the target application before substituting.
Amplifier Channel Count
High match
Package Type
High match
Supply Voltage Range
High match
Gain Bandwidth Product
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8655ARZ | AD8651AR | Why it matters |
|---|---|---|---|
| Number of Amplifiers | 1 | 1 | Both are single-channel op-amps, so channel count is functionally equivalent for single-signal designs. |
| Gain Bandwidth Product | 28 MHz | 50 MHz | Higher GBW allows the AD8651AR to handle faster signals and wider closed-loop bandwidths than the AD8655ARZ. |
| Input Offset Voltage (Max) | 250 µV | 350 µV | Lower offset voltage improves DC accuracy; the AD8655ARZ offers tighter precision in low-frequency measurement circuits. |
| Input Voltage Noise Density | 5 nV/√Hz | 6 nV/√Hz | Lower noise density benefits low-level signal amplification; the AD8655ARZ provides slightly better noise performance. |
| Supply Voltage Range | 2.7 V to 5.5 V | 2.7 V to 5.5 V | Identical supply range means both can operate from the same single-supply rails without redesign. |
| Quiescent Current (per amplifier) | 4.5 mA | 7.5 mA | Lower quiescent current in the AD8655ARZ reduces power consumption, which matters for battery-powered or thermally constrained designs. |
| Slew Rate | 11 V/µs | 22 V/µs | Higher slew rate in the AD8651AR supports faster large-signal transitions and better performance in high-frequency applications. |
| Input Bias Current (Typ) | 1 pA | 1 pA | Both are CMOS inputs with negligible bias current, making them suitable for high-impedance sensor interfaces. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical temperature ratings ensure both parts are interchangeable in industrial and automotive environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8655ARZ | AD8651AR |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | DigiTrim® | DigiTrim® |
| Part Status | Active | Obsolete |
| Amplifier Type | General Purpose | Voltage Feedback |
| Number of Circuits | 1 | 1 |
| Output Type | Rail-to-Rail | Rail-to-Rail |
| Slew Rate | 11V/µs | 41V/µs |
| Gain Bandwidth Product | 28 MHz | 50 MHz |
| Current - Input Bias | 1 pA | 1 pA |
| Voltage - Input Offset | 50 µV | 100 µV |
| Supply Current | 3.7mA | 9.5mA |
| Current - Output / Channel | 220 mA | 40 mA |
| Voltage - Supply Span(Min) | 2.7 V | 2.7 V |
| Voltage - Supply Span(Max) | 5.5 V | 5.5 V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the primary differences between the AD8655ARZ and the AD8651AR?
The AD8655ARZ is a single, low-noise, precision CMOS operational amplifier specified with a 28 nV/√Hz voltage noise density and a 5 V to 5.5 V supply range, while the AD8651AR is a single, high-speed CMOS op amp with a 70 MHz gain-bandwidth product and a 2.7 V to 5.5 V supply range. The AD8655ARZ targets low-noise precision signal chains, whereas the AD8651AR targets wideband signal processing.
Are the AD8655ARZ and AD8651AR pin-compatible in the SOIC-8 package?
Both devices are offered in an 8-lead SOIC package with the standard single op amp pinout (1 = NC, 2 = -IN, 3 = +IN, 4 = V-, 5 = NC, 6 = OUT, 7 = V+, 8 = NC), so the package footprint and pin functions are compatible. Electrical differences must still be validated for the target design.
What is the gain-bandwidth product of each device?
The AD8655ARZ has a 28 MHz gain-bandwidth product, while the AD8651AR has a 70 MHz gain-bandwidth product. The AD8651AR therefore provides wider closed-loop bandwidth for a given gain.
How do the voltage noise specifications compare?
The AD8655ARZ is specified with a low voltage noise density of 28 nV/√Hz at 1 kHz, making it suitable for precision low-noise applications. The AD8651AR is a high-speed amplifier whose noise specification is higher and is not intended for low-noise precision front ends.
What supply voltage ranges do the AD8655ARZ and AD8651AR support?
The AD8655ARZ operates from a 5 V to 5.5 V single supply (or ±2.5 V to ±2.75 V dual supply). The AD8651AR operates from a 2.7 V to 5.5 V single supply (or ±1.35 V to ±2.75 V dual supply), giving it a wider low-voltage operating range.
Which device is better suited for low-noise precision signal conditioning?
The AD8655ARZ is the better choice for low-noise precision signal conditioning because of its 28 nV/√Hz voltage noise density and precision CMOS input characteristics. The AD8651AR is optimized for high-speed applications rather than low-noise precision.
Which device is better suited for high-speed signal processing?
The AD8651AR is better suited for high-speed signal processing due to its 70 MHz gain-bandwidth product, compared with 28 MHz for the AD8655ARZ. The higher bandwidth supports wider closed-loop signal chains.
Can the AD8655ARZ and AD8651AR be used interchangeably in an existing design?
They should not be treated as drop-in interchangeable without validation. Although both are single CMOS op amps in an 8-lead SOIC package with the same pinout, their gain-bandwidth product, voltage noise, and minimum supply voltage differ, so stability, bandwidth, noise, and supply headroom must be verified against the manufacturer datasheets for the specific circuit.