Part A
AD8221ARMZ
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 2550 個数
- Package
- MSOP-8
- Series
- リニアアンプ - 計装用、オペアンプ、バッファアンプ
Replacement verdict
Compatible functional replacement candidate
The AD8221ARMZ and AD8220ARMZ-RL are both precision instrumentation amplifiers in the same 8-lead MSOP package and share a closely related gain-setting architecture, making the AD8220ARMZ-RL a viable functional replacement candidate for the AD8221ARMZ in many designs. However, the two devices differ in their input bias current, supply voltage range, and bandwidth characteristics, so the replacement should be validated against the specific application requirements before adoption.
Package Type
High match
Input Bias Current
Validation required
Supply Voltage Range
Validation required
Bandwidth
Validation required
Parts at a glance
Part B
AD8220ARMZ-RL
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 3523 個数
- Package
- TSSOP-8
- Series
- リニアアンプ - 計装用、オペアンプ、バッファアンプ
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD8221ARMZ | AD8220ARMZ-RL | Why it matters |
|---|---|---|---|
| Amplifier Type | Instrumentation Amplifier | Instrumentation Amplifier with JFET Input | The AD8220 uses a JFET input stage, giving it much lower input bias current, which is critical for high-impedance sensor interfaces. |
| Input Bias Current | 0.5 nA (typ) | 10 pA (typ) | Lower input bias current reduces errors in high-source-impedance applications such as pH or photodiode sensing. |
| Input Offset Voltage | 60 µV (max) | 250 µV (max) | Lower offset voltage improves DC accuracy and reduces the need for calibration in precision measurement systems. |
| Input Voltage Noise | 8 nV/√Hz (typ, 1 kHz) | 14 nV/√Hz (typ, 1 kHz) | Lower voltage noise improves signal-to-noise ratio for low-level signal amplification. |
| Gain Bandwidth Product | 825 kHz (G=1) | 1.5 MHz (G=1) | Higher bandwidth allows the amplifier to handle faster signals and wider frequency content. |
| CMRR (G=1) | 80 dB (min) | 80 dB (min) | Common-mode rejection ratio determines how well the amplifier rejects unwanted common-mode signals; both parts are comparable here. |
| Supply Voltage Range | ±2.3 V to ±18 V | ±2.25 V to ±18 V | Wide supply range enables use in both low-voltage portable and high-voltage industrial systems. |
| Supply Current | 1.0 mA (typ) | 1.0 mA (typ) | Quiescent current affects power budget in battery-powered and low-power designs; both parts are similar. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Industrial temperature range ensures reliable operation across harsh environments; both parts match. |
| Package | 8-Lead MSOP | 8-Lead MSOP | Identical package allows drop-in PCB compatibility between the two parts. |
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 | AD8221ARMZ | AD8220ARMZ-RL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Active | Obsolete |
| Amplifier Type | Instrumentation | Instrumentation |
| Number of Circuits | 1 | 1 |
| Output Type | - | Rail-to-Rail |
| Slew Rate | 2V/µs | 2V/µs |
| -3 dB Bandwidth | 825 kHz | 1.5 MHz |
| Current - Input Bias | 500 pA | 25 pA |
| Voltage - Input Offset | 60 µV | 250 µV |
| Supply Current | 900µA | 750µA |
| Current - Output / Channel | 18 mA | 15 mA |
| Voltage - Supply Span(Min) | 4.6 V | 4.5 V |
| Voltage - Supply Span(Max) | 36 V | 36 V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the primary functional differences between the AD8221ARMZ and AD8220ARMZ-RL?
The AD8221ARMZ is a high-performance instrumentation amplifier with a fixed gain of 1 to 1000 set by a single external resistor, featuring a typical CMRR of 90 dB at G=1 (up to 110 dB at G=1000) and a typical input offset voltage of 60 µV. The AD8220ARMZ-RL is a JFET-input instrumentation amplifier with a fixed gain of 1 to 1000 set by a single external resistor, offering rail-to-rail output, a typical input bias current of 10 pA, and a typical CMRR of 80 dB at G=1 (up to 100 dB at G=1000). The AD8221 is optimized for low offset and high CMRR with bipolar input stages, while the AD8220 is optimized for low input bias current and rail-to-rail output using JFET inputs.
Are the AD8221ARMZ and AD8220ARMZ-RL pin-compatible in the MSOP-8 package?
Yes, both devices are offered in an 8-lead MSOP package with the same pinout: pin 1 = -IN, pin 2 = +IN, pin 3 = V-, pin 4 = RG, pin 5 = REF, pin 6 = VOUT, pin 7 = V+, and pin 8 = RG. This pin compatibility allows the same PCB land pattern to accommodate either device, though electrical differences must be validated for the target design.
How do the input bias currents of the AD8221ARMZ and AD8220ARMZ-RL compare?
The AD8221ARMZ uses bipolar input transistors and specifies a typical input bias current of 0.5 nA (maximum 2.5 nA at 25°C). The AD8220ARMZ-RL uses JFET input transistors and specifies a typical input bias current of 10 pA (maximum 20 pA at 25°C). The AD8220 is therefore preferable for high-impedance sensor interfaces where input bias current errors must be minimized.
What are the supply voltage ranges for the AD8221ARMZ and AD8220ARMZ-RL?
Both devices operate from dual supplies of ±2.3 V to ±18 V or single supplies of 4.6 V to 36 V. The AD8220ARMZ-RL additionally features a rail-to-rail output stage, which allows its output to swing close to both supply rails, whereas the AD8221ARMZ output swing is limited to approximately 1.2 V from each rail under typical load conditions.
Which device is better suited for high-impedance sensor applications?
The AD8220ARMZ-RL is generally better suited for high-impedance sensor applications because its JFET inputs provide a typical input bias current of 10 pA, compared to 0.5 nA for the AD8221ARMZ. Lower input bias current reduces voltage errors across high source impedances, making the AD8220 preferable for pH sensors, photodiode interfaces, and other high-impedance transducers.
How do the gain-setting configurations differ between the AD8221ARMZ and AD8220ARMZ-RL?
Both devices use a single external resistor connected between the RG pins to set gain from 1 to 1000. For the AD8221ARMZ, the gain equation is G = 1 + (49.4 kΩ / RG). For the AD8220ARMZ-RL, the gain equation is G = 1 + (49.4 kΩ / RG). The gain-setting resistor value for a given gain is therefore identical for both devices, though the resistor tolerance and temperature coefficient should be selected according to the desired gain accuracy.
What are the package and ordering differences between the AD8221ARMZ and AD8220ARMZ-RL?
The AD8221ARMZ is supplied in an 8-lead MSOP tube or reel package and is specified over the -40°C to +85°C industrial temperature range. The AD8220ARMZ-RL is supplied in an 8-lead MSOP tape-and-reel package (the -RL suffix denotes reel packaging) and is also specified over the -40°C to +85°C industrial temperature range. Both are RoHS-compliant. The primary ordering difference is the packaging format, not the electrical specification.