AD8421ARMZ Equivalent & Substitute Parts

Part Overview

The AD8421ARMZ is an instrumentation amplifier manufactured by Analog Devices Inc., designed for precision signal conditioning applications. This single-circuit device operates across a wide supply voltage range of 5V to 36V and delivers a slew rate of 35V/µs with a -3dB bandwidth of 10 MHz. The part is currently in active production status with 1280 pieces available in new original inventory. Substitute parts are identified when the primary device is unavailable, when supply chain constraints occur, or when application requirements permit operation with alternative amplifier topologies that meet or exceed the electrical specifications of the original design.

Substiute Parts

AD8421ARMZ

Analog Devices Inc.In Stock: 1388AD8421ARMZ Datasheet

Current PartRFQ

OPA656UB/2K5

Texas InstrumentsIn Stock: 3279OPA656UB/2K5 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AD8421ARMZ is based on functional equivalence within the linear amplifier category. The primary substitution criterion is the ability to perform single-circuit amplification with compatible electrical performance across the operating temperature range of -40°C to 85°C. Both the main part and identified substitutes operate as surface-mount devices in 8-pin packages and maintain compliance with ROHS3 and REACH regulations.

The AD8421ARMZ operates as an instrumentation amplifier with a supply voltage range of 5V to 36V. Substitute parts must maintain active product status and surface-mount packaging to ensure manufacturing continuity and assembly compatibility. The key electrical parameters that define substitution eligibility include slew rate, bandwidth, input bias current, input offset voltage, supply current, and output current capability. Parts meeting these criteria within the specified operating temperature range are considered functionally equivalent for applications where the instrumentation amplifier topology is not a mandatory requirement.

Parameter Comparison

Engineering Selection Recommendations

Both the AD8421ARMZ and OPA656UB/2K5 maintain active product status with ROHS3 compliance and REACH unaffected designation, ensuring regulatory alignment for current manufacturing environments. The AD8421ARMZ is the primary selection when instrumentation amplifier topology is required and when supply voltage operation above 12V is necessary. The OPA656UB/2K5 operates as a voltage feedback amplifier with superior slew rate and bandwidth performance, suitable for applications where higher frequency response is beneficial and supply voltage remains within the 8V to 12V range.

Package differences exist between the two devices: the AD8421ARMZ uses an 8-MSOP package with 3.00mm width, while the OPA656UB/2K5 uses an 8-SOIC package with 3.90mm width. This distinction affects printed circuit board layout and assembly considerations. The AD8421ARMZ maintains lower supply current consumption at 2mA compared to the OPA656UB/2K5 at 14mA, which is relevant for power-constrained applications. The OPA656UB/2K5 exhibits lower input bias current at 1pA versus 1nA for the AD8421ARMZ, providing superior input impedance characteristics.

Moisture sensitivity differs between the parts: the AD8421ARMZ carries MSL 1 (unlimited shelf life), while the OPA656UB/2K5 carries MSL 3 (168-hour limit), affecting storage and handling protocols.

Frequently Asked Questions (FAQ)

Q: Can the OPA656UB/2K5 directly replace the AD8421ARMZ in all applications?

A: Direct replacement depends on application-specific requirements. Both devices are single-circuit amplifiers in 8-pin surface-mount packages with identical operating temperature ranges and regulatory compliance. However, the OPA656UB/2K5 operates as a voltage feedback amplifier rather than an instrumentation amplifier, and its supply voltage range is limited to 8V to 12V compared to the AD8421ARMZ range of 5V to 36V. Package footprints differ, requiring circuit board layout modification. Applications requiring instrumentation amplifier topology or supply voltages outside the 8V to 12V range must use the AD8421ARMZ.

Q: What are the key electrical differences between these parts?

A: The OPA656UB/2K5 provides significantly higher slew rate (295V/µs versus 35V/µs) and bandwidth (500 MHz versus 10 MHz), making it suitable for high-frequency applications. The AD8421ARMZ consumes less supply current (2mA versus 14mA) and operates across a wider supply voltage range. Input offset voltage is lower on the AD8421ARMZ (60µV versus 250µV), while input bias current is lower on the OPA656UB/2K5 (1pA versus 1nA).

Q: Are there package compatibility concerns?

A: Yes. The AD8421ARMZ uses an 8-MSOP package (3.00mm width) while the OPA656UB/2K5 uses an 8-SOIC package (3.90mm width). These packages have different footprints and pin spacing, requiring circuit board redesign for substitution. Automated assembly equipment settings must be adjusted accordingly.

Q: Do both parts meet current regulatory requirements?

A: Both the AD8421ARMZ and OPA656UB/2K5 are ROHS3 compliant and REACH unaffected, meeting current environmental and hazardous substance regulations. Both maintain active product status with established supply chains.

Q: What is the significance of the moisture sensitivity level difference?

A: The AD8421ARMZ carries MSL 1, indicating unlimited shelf life under standard storage conditions. The OPA656UB/2K5 carries MSL 3, requiring storage in controlled humidity environments with a 168-hour limit after packaging opening. This affects inventory management, storage protocols, and component handling procedures.

Q: Which part should be selected for low-power applications?

A: The AD8421ARMZ is the appropriate choice for power-constrained designs, consuming 2mA supply current compared to 14mA for the OPA656UB/2K5. This 7-fold reduction in supply current is significant for battery-powered or energy-limited systems.

Q: Can the AD8421ARMZ operate at 48V supply voltage?

A: No. The AD8421ARMZ maximum supply voltage is 36V. The OPA656UB/2K5 maximum supply voltage is 12V. Neither device operates at 48V.