Part A
AD8420ARMZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1829 Stückzahl
- Package
- MSOP-8
- Series
- Linear-Verstärker.Instrumentation, OP-Verstärker, Pufferverstärker
Replacement verdict
Compatible functional replacement candidate
The AD8422ARMZ and AD8420ARMZ share the same SOIC-8 package, dual-supply architecture, and instrumentation amplifier function, making the AD8420ARMZ a viable functional substitute for the AD8422ARMZ in many designs. However, the two devices differ in supply voltage range, quiescent current, and gain-bandwidth characteristics, so the replacement should be validated against the target application's power budget and signal bandwidth requirements before adoption.
Package Type
High match
Supply Voltage Range
Validation required
Quiescent Current
Validation required
Gain-Bandwidth Product
Validation required
Parts at a glance
Part B
AD8422ARMZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4335 Stückzahl
- Package
- MSOP-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 | AD8422ARMZ | AD8420ARMZ | Why it matters |
|---|---|---|---|
| Amplifier Type | Instrumentation Amplifier | Instrumentation Amplifier (micropower, indirect current mode) | Both are instrumentation amplifiers, but the AD8420 uses an indirect current-mode architecture optimized for very low power, which affects noise, bandwidth, and input behavior. |
| Supply Current (typical) | 300 µA | 85 µA | Supply current directly impacts power budget; the AD8420 draws substantially less, making it preferable for battery-powered or low-power designs. |
| Input Offset Voltage (max) | 70 µV | 250 µV | Lower offset voltage improves DC accuracy; the AD8422 offers tighter offset, which matters for precision measurement applications. |
| Input Voltage Noise (1 kHz, typical) | 8 nV/√Hz | 55 nV/√Hz | Lower input voltage noise enables better resolution of small signals; the AD8422 is significantly quieter than the AD8420. |
| Gain Bandwidth Product / -3 dB Bandwidth | 2.2 MHz (G = 1) | 250 kHz (G = 1) | Bandwidth determines the maximum signal frequency the amplifier can handle; the AD8422 supports much higher frequencies than the AD8420. |
| Gain Range | 1 to 1000 (set by single resistor) | 1 to 1000 (set by single resistor) | Both allow resistor-programmable gain from 1 to 1000, so gain flexibility is comparable for functional substitution. |
| Supply Voltage Range | ±2.3 V to ±18 V (4.6 V to 36 V single supply) | ±2.0 V to ±18 V (4.0 V to 36 V single supply) | The AD8420 can operate at a slightly lower minimum supply, which can matter in low-voltage systems, though both cover a wide range. |
| CMRR (G = 100, typical) | 120 dB | 100 dB | Higher common-mode rejection improves rejection of interference and ground noise; the AD8422 provides better CMRR for demanding precision applications. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Both share the same industrial temperature range, so environmental compatibility is equivalent for substitution purposes. |
| Package | 8-Lead MSOP (RMZ) | 8-Lead MSOP (RMZ) | Identical package and pinout simplify board-level replacement, though electrical differences still require design review. |
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 | AD8420ARMZ | AD8422ARMZ |
|---|---|---|
| Part Status | Active | Active |
| Amplifier Type | Instrumentation | Instrumentation |
| Number of Circuits | 1 | 1 |
| Output Type | Rail-to-Rail | Rail-to-Rail |
| Slew Rate | 1V/µs | 0.8V/µs |
| -3 dB Bandwidth | 250 kHz | 2.2 MHz |
| Current - Input Bias | 20 nA | 500 pA |
| Voltage - Input Offset | 250 µV | 70 µV |
| Supply Current | 85µA | 300µA |
| Current - Output / Channel | 10 mA | 20 mA |
| Voltage - Supply Span(Min) | 2.7 V | 4.6 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 differences between the AD8422ARMZ and AD8420ARMZ instrumentation amplifiers?
The AD8422ARMZ is a high-precision, low-power instrumentation amplifier with a typical input offset voltage of 70 µV, a gain bandwidth product of 2.2 MHz, and a supply current of 300 µA. The AD8420ARMZ is a micropower instrumentation amplifier with a typical input offset voltage of 125 µV, a gain bandwidth product of 1.1 MHz, and a supply current of 85 µA. The AD8422ARMZ offers higher bandwidth and lower offset voltage, while the AD8420ARMZ consumes significantly less supply current.
Are the AD8422ARMZ and AD8420ARMZ pin-compatible in the same package?
Both devices are offered in an 8-lead MSOP (RMZ) package and share the same pinout: pin 1 = -IN, pin 2 = RG, pin 3 = RG, pin 4 = -VS, pin 5 = REF, pin 6 = VOUT, pin 7 = +VS, pin 8 = +IN. This pin compatibility allows evaluation of either device on the same PCB footprint, but electrical differences must be validated for the target design.
How do the supply current and power consumption of the AD8422ARMZ and AD8420ARMZ compare?
The AD8422ARMZ draws a typical supply current of 300 µA, while the AD8420ARMZ draws a typical supply current of 85 µA. For battery-powered or micropower applications, the AD8420ARMZ provides substantially lower quiescent power consumption, whereas the AD8422ARMZ trades higher supply current for improved bandwidth and offset performance.
Which device offers better bandwidth for high-frequency signal conditioning?
The AD8422ARMZ provides a gain bandwidth product of 2.2 MHz, compared with 1.1 MHz for the AD8420ARMZ. For applications requiring wider closed-loop bandwidth at a given gain, the AD8422ARMZ is the higher-bandwidth option, while the AD8420ARMZ is optimized for low-power operation.
How do the input offset voltage specifications of the AD8422ARMZ and AD8420ARMZ differ?
The AD8422ARMZ specifies a typical input offset voltage of 70 µV, whereas the AD8420ARMZ specifies a typical input offset voltage of 125 µV. The AD8422ARMZ therefore offers lower typical offset voltage, which can be advantageous in precision DC signal acquisition where offset error must be minimized.
What supply voltage ranges are supported by the AD8422ARMZ and AD8420ARMZ?
Both the AD8422ARMZ and AD8420ARMZ operate from dual supplies of ±2.3 V to ±18 V (or single supply of 4.6 V to 36 V). Designers should verify the specific supply range and output swing requirements against the respective manufacturer datasheets for the intended operating conditions.
Can the AD8420ARMZ be used as a drop-in replacement for the AD8422ARMZ in an existing design?
Although both devices share the same 8-lead MSOP pinout, they are not electrically identical. The AD8420ARMZ has lower supply current but also lower bandwidth and higher typical input offset voltage than the AD8422ARMZ. A drop-in replacement is only appropriate after verifying that the reduced bandwidth, offset, and noise performance meet the application requirements.