Analog Devices Inc. ADA4625-2ARDZ

Overview

ADA4625-2ARDZ from Analog Devices is a dual-channel, precision JFET-input operational amplifier optimized for high-voltage, low-noise, fast-settling applications. It delivers 18 MHz gain bandwidth, 48 V/µs slew rate, and 3.3 nV/√Hz voltage noise density at 1 kHz, operating from 5 V to 36 V single supply or ±2.5 V to ±18 V dual supply. It serves as a rail-to-rail output (RRO) amplifier in PLL filter stages and photodiode sensor interfaces where signal integrity and speed are critical.

For engineers reviewing the ADA4625-2ARDZ datasheet, ADA4625-2ARDZ pinout, ADA4625-2ARDZ application, or ADA4625-2ARDZ equivalent, key selection criteria include its 75° phase margin at unity gain, −40°C to +125°C extended industrial temperature range, and confirmed capability to drive 1000 pF capacitive loads without instability-critical for active loop filters and transimpedance amplifiers.

Technical Context

The ADA4625-2ARDZ employs a dual JFET input stage with extended common-mode range (down to V− and up to V+ + 0.2 V), eliminating phase reversal beyond supply rails by 200 mV. Its architecture integrates a virtual cascode gain structure and rail-to-rail output stage with ±46 mA short-circuit current capability.

It features two independent amplifiers sharing a common exposed-pad SOIC-8 package, with differential input capacitance of 13.8 pF (CDM) and common-mode capacitance of 13.3 pF (CCM). Channel separation is 108 dB at 1 kHz, supporting high-fidelity dual-channel signal conditioning in compact layouts.

Key Specifications

Pinout & Package

The ADA4625-2ARDZ is housed in an 8-lead SOIC package with exposed pad (RD-8-4), rated for θJA = 52.8°C/W with proper PCB thermal design. The exposed pad must be connected to GND, V+, or V− for optimal thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision JFET op amp applications.

Compared with ADA4622-2ARMZ and AD8620ARZ, the ADA4625-2ARDZ provides superior speed-noise trade-off, guaranteed rail-overvoltage tolerance, and tighter DC specifications-making it the preferred choice for demanding PLL, sensor, and DAC interface applications where signal fidelity and reliability are non-negotiable.

Availability

ADA4625-2ARDZ is available at Aetrix Electronics and suitable for PLL filter design, photodiode sensor interfaces, and precision DAC output buffering requiring stable component supply across industrial, test & measurement, and aerospace programs.

Supply support for ADA4625-2ARDZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The ADA4625 family targets high-voltage, low-noise, fast-settling precision signal conditioning-specifically engineered for PLL loop filters, photodiode interfaces, and charge amplifiers where JFET input performance meets demanding speed and accuracy requirements.

FAQ

What is the maximum capacitive load the ADA4625-2ARDZ can drive stably?

The ADA4625-2ARDZ is specified to drive loads up to 1000 pF without requiring external isolation resistors or compensation. This capability is validated across supply voltages (±18 V and 5 V) and temperature ranges (−40°C to +125°C), making it suitable for direct connection to photodiode junction capacitance or long PCB traces in DAC output paths. Stability is maintained due to its 75° phase margin and internal compensation optimized for unity-gain operation.

Does the ADA4625-2ARDZ support true single-supply operation from 5 V?

Yes, the ADA4625-2ARDZ operates fully specified from 5 V single supply, with input common-mode range extending from −0.2 V to +1.5 V and rail-to-rail output swing from 0.17 V to 4.82 V (at 2 kΩ load). Its JFET input stage maintains low bias current (±15 pA typical) and low noise (3.3 nV/√Hz) even at 5 V, enabling precision signal conditioning in battery-powered or low-voltage industrial systems without negative rail generation.

How does the ADA4625-2ARDZ prevent phase reversal when inputs exceed supply rails?

The ADA4625-2ARDZ prevents phase reversal by incorporating a secondary input pair (M3/M4) that activates when the input exceeds V+ or falls below V− by more than 200 mV. This auxiliary stage maintains correct polarity and avoids latch-up, unlike conventional RRO op amps. The datasheet guarantees no phase inversion under this condition across the full −40°C to +125°C temperature range, critical for robust operation in noisy or transient-prone environments.

What is the typical settling time of the ADA4625-2ARDZ to 0.01% for a 10 V step?

At ±18 V supply, the ADA4625-2ARDZ settles to 0.01% in 1200 ns for a 10 V step under standard test conditions (RL = 2 kΩ, CL = 15 pF, AV = −1). At 5 V supply, settling to 0.01% takes 1350 ns for a 4 V step. These values reflect its fast-settling architecture and are measured with verified load and gain conditions-enabling precise timing in high-speed data acquisition and control loop applications.

Is the exposed pad on the ADA4625-2ARDZ package electrically connected or thermal-only?

The exposed pad on the ADA4625-2ARDZ (SOIC-8 EPAD) is both thermally and electrically functional. While it may be left floating, Analog Devices specifies that it must be connected to GND, V+, or V− for proper thermal management and EMI suppression. Connection to GND is most common and improves noise immunity and junction temperature control-reducing θJA from 52.8°C/W to lower effective values with adequate PCB copper area.