Part A
AD8138AR
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 3049 Stückzahl
- Package
- SOP-8
- Series
- Linear-Verstärker
Replacement verdict
Compatible functional replacement candidate
The AD8138AR and AD8131AR-REEL7 are both high-speed differential amplifiers from Analog Devices in the same SOIC-8 package, sharing a common functional role in differential signal processing. However, they differ in key electrical characteristics such as gain configuration, bandwidth, and supply current, so the AD8131AR-REEL7 can serve as a functional substitute only after the circuit's gain, bandwidth, and power budget requirements are validated against the AD8138AR's specifications.
Gain Configuration
Validation required
Bandwidth
Validation required
Supply Current
Validation required
Package Type
High match
Parts at a glance
Part B
AD8131AR-REEL7
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5949 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 | AD8138AR | AD8131AR-REEL7 | Why it matters |
|---|---|---|---|
| Amplifier Type | Differential ADC Driver | Fixed-Gain Differential Receiver/Driver | Determines the core function; the AD8138 is a general-purpose differential driver while the AD8131 is a fixed-gain line receiver, so they are not drop-in substitutes. |
| Gain Configuration | External resistors (user-selectable gain) | Fixed gain of 2 (internal resistors) | The AD8138 allows arbitrary gain setting via external feedback, whereas the AD8131 has a fixed gain of 2, limiting design flexibility. |
| -3 dB Bandwidth | 320 MHz | 400 MHz | Bandwidth affects the maximum signal frequency the amplifier can handle with acceptable attenuation. |
| Slew Rate | 1150 V/µs | 2000 V/µs | Higher slew rate supports faster large-signal transitions and reduces distortion at high frequencies. |
| Input Voltage Noise | 5 nV/√Hz | 12 nV/√Hz | Lower input noise improves signal-to-noise ratio, which is critical for high-resolution ADC driving. |
| Supply Voltage Range | ±1.4 V to ±5.5 V (2.8 V to 11 V) | ±1.5 V to ±5.5 V (3 V to 11 V) | The supply range determines compatibility with the system power rails; slight differences affect low-voltage operation. |
| Quiescent Supply Current | 19 mA | 11 mA | Lower quiescent current reduces power consumption, important for power-sensitive designs. |
| Output Voltage Swing | ±3.5 V (on ±5 V supplies) | ±3.5 V (on ±5 V supplies) | Output swing determines the maximum signal amplitude deliverable to the load; both are similar here. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Package compatibility affects PCB footprint and assembly; identical packages ease board-level substitution. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range confirms suitability for industrial environments; both cover the same range. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8138AR | AD8131AR-REEL7 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Part Status | Obsolete | Obsolete |
| Amplifier Type | - | Differential |
| Number of Circuits | - | 1 |
| Output Type | - | Differential |
| Slew Rate | - | 2000V/µs |
| -3 dB Bandwidth | - | 400 MHz |
| Current - Input Bias | - | 500 nA |
| Voltage - Input Offset | - | 1.5 mV |
| Supply Current | - | 11.5mA |
| Current - Output / Channel | - | 60 mA |
| Voltage - Supply Span(Min) | - | 2.8 V |
| Voltage - Supply Span(Max) | - | 11 V |
| Operating Temperature | - | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Type | ADC Driver | - |
| Applications | Data Acquisition | - |
Frequently asked questions
What are the primary functional differences between the AD8138AR and AD8131AR-REEL7?
The AD8138AR is a differential ADC driver with an adjustable output common-mode voltage and external gain-setting resistors, allowing user-defined gain configurations. The AD8131AR-REEL7 is a fixed-gain differential amplifier with a preset gain of 2, intended for driving differential ADCs without external gain resistors. Both are manufactured by Analog Devices in an 8-lead SOIC package.
Are the AD8138AR and AD8131AR-REEL7 pin-compatible?
Both devices are offered in an 8-lead SOIC (R-8) package, but pin functions differ. The AD8138AR uses the package pins for feedback and gain-setting resistor connections, while the AD8131AR-REEL7 has internally fixed gain and uses its pins accordingly. A direct drop-in substitution should not be assumed without verifying the pinout against the respective datasheets.
What is the gain configuration of each device?
The AD8138AR is a fully differential amplifier whose gain is set by external resistors, enabling flexible closed-loop gain design. The AD8131AR-REEL7 provides a fixed gain of 2 (6 dB) internally, eliminating the need for external gain resistors.
Do both parts support adjustable output common-mode voltage?
Yes. Both the AD8138AR and AD8131AR-REEL7 feature a VOCM pin that allows the output common-mode voltage to be set independently via an external reference, which is useful for matching the input common-mode requirements of differential ADCs.
How do the bandwidth specifications compare?
The AD8138AR provides a -3 dB bandwidth of approximately 320 MHz. The AD8131AR-REEL7 provides a -3 dB bandwidth of approximately 400 MHz. Designers should confirm these values against the latest Analog Devices datasheets for the specific grade and test conditions.
What is the significance of the -REEL7 suffix on the AD8131AR-REEL7?
The -REEL7 suffix indicates the packaging format: the devices are supplied on a 7-inch tape-and-reel for automated surface-mount assembly. It does not denote a different silicon die or performance grade compared with the standard AD8131AR.
Can the AD8138AR and AD8131AR-REEL7 be used interchangeably in an existing design?
Not without design review. Because the AD8138AR requires external gain resistors and the AD8131AR-REEL7 has a fixed internal gain of 2, the surrounding circuit topology, gain, and PCB layout differ. Substitution requires validating gain, bandwidth, pinout, and common-mode behavior against the manufacturer datasheets.