Part A
AD8221ARZ
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 4567 PCS
- Package
- SOIC-8
- Series
- Amplificateurs linéaires - instruments, amplificateurs opérationnels, amplificateurs tampons
Replacement verdict
Compatible functional replacement candidate
The AD8227ARZ-RL is a viable functional replacement candidate for the AD8221ARZ in many instrumentation amplifier applications, sharing the same SOIC-8 footprint, similar supply range, and comparable gain-bandwidth performance. However, the AD8227 offers wider input common-mode range and higher slew rate while the AD8221 provides superior CMRR and lower noise, so designers should validate gain accuracy, noise budget, and common-mode requirements before substituting in precision measurement circuits.
Package Type
High match
Supply Voltage Range
High match
Gain Bandwidth Product
Validation required
Input Noise Density
Validation required
Parts at a glance
Part B
AD8227ARZ-RL
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 5490 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 | AD8221ARZ | AD8227ARZ-RL | Why it matters |
|---|---|---|---|
| Number of Amplifiers | 1 | 1 | Both are single instrumentation amplifiers, so channel count is equivalent for substitution. |
| Gain Bandwidth Product | 825 kHz | 250 kHz | Higher bandwidth in the AD8221 supports wider signal frequency ranges; the AD8227 is limited to lower-frequency applications. |
| Input Offset Voltage (max) | 60 µV | 200 µV | Lower offset voltage improves DC accuracy, making the AD8221 preferable for precision measurement front ends. |
| Input Bias Current (max) | 1.5 nA | 27 nA | Lower bias current reduces errors with high-impedance sources; the AD8221 is better suited for high source impedance sensors. |
| Input Voltage Noise (1 kHz) | 8 nV/√Hz | 22 nV/√Hz | Lower voltage noise improves signal-to-noise ratio in low-level signal amplification; the AD8221 offers better noise performance. |
| Supply Voltage Range | ±2.3 V to ±18 V | ±2.25 V to ±18 V | Nearly identical supply ranges allow both parts to operate in similar power rails, supporting functional interchangeability. |
| Supply Current (per amplifier, max) | 1.0 mA | 0.35 mA | The AD8227 draws significantly less supply current, making it preferable for low-power or battery-operated designs. |
| CMRR (G=100, min) | 110 dB | 100 dB | Higher common-mode rejection in the AD8221 better suppresses interference in noisy environments. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +125 °C | The AD8227 supports a wider temperature range, making it suitable for harsher environments where the AD8221 may not be rated. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Identical package and pinout allow drop-in replacement on the same PCB footprint. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD8221ARZ | AD8227ARZ-RL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Active | Active |
| Amplifier Type | Instrumentation | Instrumentation |
| Number of Circuits | 1 | 1 |
| Output Type | - | Rail-to-Rail |
| Slew Rate | 2V/µs | 0.8V/µs |
| -3 dB Bandwidth | 825 kHz | 250 kHz |
| Current - Input Bias | 500 pA | 20 nA |
| Voltage - Input Offset | 60 µV | 200 µV |
| Supply Current | 900µA | 350µA |
| Current - Output / Channel | 18 mA | 13 mA |
| Voltage - Supply Span(Min) | 4.6 V | 2.2 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 |
Frequently asked questions
What are the key differences between the AD8221ARZ and AD8227ARZ-RL instrumentation amplifiers?
The AD8221ARZ is a high-performance instrumentation amplifier with a gain range of 1 to 1000, specified for operation from ±2.3 V to ±18 V (or 4.6 V to 36 V single supply), and offers a typical CMRR of 90 dB at G=1 (up to 130 dB at G=1000) with a typical input offset voltage of 60 µV. The AD8227ARZ-RL is a lower-power, lower-cost instrumentation amplifier with a gain range of 1 to 1000, specified for operation from ±2.3 V to ±18 V (or 4.6 V to 36 V single supply), and offers a typical CMRR of 80 dB at G=1 (up to 120 dB at G=1000) with a typical input offset voltage of 200 µV. The AD8221ARZ is supplied in an 8-lead SOIC package in tube form, while the AD8227ARZ-RL is supplied in an 8-lead SOIC package in tape-and-reel form.
Are the AD8221ARZ and AD8227ARZ-RL pin-compatible?
Yes. Both devices are offered in an 8-lead SOIC package with the same pinout: pin 1 = -IN, pin 2 = RG, pin 3 = RG, pin 4 = -VS, pin 5 = REF, pin 6 = VOUT, pin 7 = +VS, and pin 8 = +IN. This pin compatibility allows the AD8227ARZ-RL to be used as a drop-in replacement for the AD8221ARZ in existing 8-lead SOIC layouts, provided the performance differences are acceptable for the application.
How do the gain-setting resistor requirements compare between the AD8221ARZ and AD8227ARZ-RL?
Both devices use a single external resistor RG connected between pins 2 and 3 to set the gain according to the same transfer function: G = 1 + (49.4 kΩ / RG). This identical gain equation means that a given RG value produces the same nominal gain on either device, simplifying evaluation and substitution between the AD8221ARZ and AD8227ARZ-RL.
Which device offers better DC accuracy, the AD8221ARZ or the AD8227ARZ-RL?
The AD8221ARZ offers better DC accuracy. Its typical input offset voltage is 60 µV (maximum 100 µV at 25°C) with a typical input offset drift of 0.3 µV/°C, whereas the AD8227ARZ-RL has a typical input offset voltage of 200 µV (maximum 500 µV at 25°C) with a typical input offset drift of 1 µV/°C. The AD8221ARZ also specifies a typical input bias current of 1 nA, compared with 20 nA typical for the AD8227ARZ-RL.
How do the noise and bandwidth specifications of the AD8221ARZ and AD8227ARZ-RL differ?
The AD8221ARZ specifies a typical input voltage noise of 8 nV/√Hz at 1 kHz and a typical -3 dB bandwidth of 825 kHz at G=1 (825 kHz at G=1, 110 kHz at G=10, 11 kHz at G=100, and 1.1 kHz at G=1000). The AD8227ARZ-RL specifies a typical input voltage noise of 22 nV/√Hz at 1 kHz and a typical -3 dB bandwidth of 800 kHz at G=1 (800 kHz at G=1, 80 kHz at G=10, 8 kHz at G=100, and 0.8 kHz at G=1000). The AD8221ARZ therefore provides lower input noise and wider bandwidth at higher gains.
What are the supply current and power consumption differences between the AD8221ARZ and AD8227ARZ-RL?
The AD8221ARZ typically draws 1.0 mA of supply current (maximum 1.5 mA) over its specified temperature range. The AD8227ARZ-RL typically draws 350 µA of supply current (maximum 500 µA). The AD8227ARZ-RL therefore consumes roughly one-third the supply current of the AD8221ARZ, making it preferable for low-power or battery-operated designs where the reduced DC accuracy and higher noise are acceptable.
What are the operating temperature ranges and package options for the AD8221ARZ and AD8227ARZ-RL?
Both the AD8221ARZ and AD8227ARZ-RL are specified over the industrial temperature range of -40°C to +85°C and are offered in an 8-lead SOIC package (the "RZ" suffix denotes the RoHS-compliant SOIC package). The AD8221ARZ is supplied in tube packaging, while the AD8227ARZ-RL is supplied in tape-and-reel packaging (the "RL" suffix denotes tape-and-reel).
Can the AD8227ARZ-RL be used as a direct substitute for the AD8221ARZ in an existing design?
Because both devices share the same 8-lead SOIC pinout and the same gain equation (G = 1 + 49.4 kΩ / RG), the AD8227ARZ-RL can be considered a functional substitute for the AD8221ARZ. However, the substitution is only acceptable if the design can tolerate the AD8227ARZ-RL's higher input offset voltage (200 µV typical vs. 60 µV typical), higher input bias current (20 nA typical vs. 1 nA typical), higher input voltage noise (22 nV/√Hz vs. 8 nV/√Hz), and lower CMRR (80 dB vs. 90 dB at G=1). The lower supply current of the AD8227ARZ-RL (350 µA typical vs. 1.0 mA typical) may be an advantage in power-sensitive applications.