Analog Devices Inc. ADA4691-2ACPZ-R7

Overview

ADA4691-2ACPZ-R7 from Analog Devices is a dual, rail-to-rail output, micropower operational amplifier optimized for low-noise, high-impedance sensor interfaces and portable instrumentation. It delivers 3.6 MHz gain bandwidth, 16 nV/√Hz voltage noise density at 1 kHz, 0.5 pA typical input bias current, 180 µA per amplifier supply current, and operates from 2.7 V to 5 V single supply - enabling precision signal conditioning in photodiode amplifiers and low-side current sense circuits.

For engineers reviewing the ADA4691-2ACPZ-R7 datasheet, ADA4691-2ACPZ-R7 pinout, ADA4691-2ACPZ-R7 application, or ADA4691-2ACPZ-R7 equivalent, key selection criteria include its shutdown-enabled dual architecture, 10-lead 2 mm × 2 mm LFCSP package, −40°C to +125°C extended industrial temperature rating, and verified performance in ADC driver and active filter topologies requiring low THD+N (0.003% typ) and rail-to-rail output swing.

Technical Context

The ADA4691-2ACPZ-R7 integrates two independent CMOS-input op-amps with dedicated shutdown pins (SD A and SD B), enabling per-amplifier power gating to reduce total system current to 10 nA in shutdown mode. Its input stage uses ultra-low-leakage P-channel JFET-like transistors, delivering sub-picoampere bias current stable over temperature and common-mode voltage.

It features unity-gain-stable compensation with 49° phase margin at 1 MHz, supports capacitive loads up to 35 pF without oscillation, and maintains rail-to-rail output swing within 24 mV of V– and 2.65 V of V+ (at 2.7 V supply, RL = 2 kΩ), making it suitable for single-supply data acquisition front-ends where headroom and dynamic range are constrained.

Key Specifications

Pinout & Package

The ADA4691-2ACPZ-R7 is housed in a 10-lead, 2 mm × 2 mm lead frame chip scale package (LFCSP, CP-10-11) with exposed thermal pad connected to V– for optimal thermal performance and EMI suppression.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual operational amplifier applications.

Compared with ADA4692-2ARMZ-R7 and AD8617ARMZ-R7, the ADA4691-2ACPZ-R7 uniquely combines per-amplifier shutdown, 10-lead compact LFCSP packaging, and guaranteed 0.5 pA input bias - making it the only option among the three for space-constrained, battery-operated systems requiring adaptive power management and femtoampere-level precision.

Availability

ADA4691-2ACPZ-R7 is available at Aetrix Electronics and suitable for photodiode amplifiers, portable medical instrumentation, and low-side current sense applications requiring stable component supply, long-term manufacturability, and guaranteed extended temperature performance.

Supply support for ADA4691-2ACPZ-R7 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, headquartered in Norwood, MA.

The ADA4691-2ACPZ-R7 belongs to the ADA4691/ADA4692 family of micropower, rail-to-rail output op-amps designed specifically for high-impedance, low-power sensor signal conditioning in portable and industrial instrumentation.

FAQ

What is the maximum supply voltage for the ADA4691-2ACPZ-R7?

The ADA4691-2ACPZ-R7 has an absolute maximum supply voltage rating of 6 V. Operation beyond this limit risks permanent damage. For reliable long-term use, Analog Devices specifies a recommended operating range of 2.7 V to 5 V single supply (or ±1.35 V to ±2.5 V dual supply). The ADA4691-2ACPZ-R7 maintains full rail-to-rail output swing and specified AC performance across this entire range.

Does the ADA4691-2ACPZ-R7 support true rail-to-rail input?

No, the ADA4691-2ACPZ-R7 features rail-to-rail *output* only. Its input common-mode voltage range is specified as −0.3 V to +1.6 V at 2.7 V supply and −0.3 V to +3.9 V at 5 V supply - meaning it does not accept signals at the positive rail. This limitation is inherent to its CMOS input stage architecture and must be accounted for in level-shifting design when interfacing with full-rail sensors.

How does the shutdown function work on the ADA4691-2ACPZ-R7?

The ADA4691-2ACPZ-R7 provides two independent CMOS-compatible shutdown pins (SD A and SD B). Driving either pin below 0.5 V (at 2.7 V supply) disables its corresponding amplifier, reducing that channel's supply current to 10 nA. Both pins must be pulled low to achieve full 20 nA system shutdown. Rise/fall times should be <10 µs to avoid transient current spikes during transition - slow RC edges are discouraged per the datasheet.

Can the ADA4691-2ACPZ-R7 drive capacitive loads?

Yes, the ADA4691-2ACPZ-R7 is unity-gain stable and characterized to drive up to 35 pF capacitive loads without oscillation when configured as a voltage follower (AV = +1). For larger loads (e.g., >100 pF), external isolation resistance (≥100 Ω) between the output and capacitor is recommended to maintain phase margin above 45° and prevent peaking or ringing in step response.

What is the thermal resistance (θJA) of the ADA4691-2ACPZ-R7 package?

The ADA4691-2ACPZ-R7 uses a 10-lead 2 mm × 2 mm LFCSP (CP-10-11) package with a specified junction-to-ambient thermal resistance (θJA) of 115°C/W under JEDEC-standard 4-layer board conditions. Its junction-to-case (θJC) is 40°C/W. The exposed thermal pad must be soldered to a solid V– copper plane to realize these values; inadequate thermal land area increases effective θJA and may limit continuous output current at high ambient temperatures.