Analog Devices Inc./Maxim Integrated ICL7631ECJE

Overview

ICL7631ECJE from Maxim Integrated is a triple monolithic CMOS operational amplifier optimized for ultra-low input bias current (1pA typical), programmable quiescent current (10µA/100µA/1mA per amplifier), and wide supply range (±1V to ±8V or 2V–16V single supply). It features 16-pin CERDIP packaging, 10¹²Ω input impedance, and rail-to-rail output swing within millivolts of supply rails - enabling precision signal conditioning in pH meters, photodiode amplifiers, and long-time-constant integrators.

For engineers reviewing the ICL7631ECJE datasheet, ICL7631ECJE pinout, ICL7631ECJE application, or ICL7631ECJE equivalent, this device is selected where femtoampere-level input leakage, selectable power-performance trade-offs, and operation across industrial temperature range (–40°C to +85°C) are critical - especially in battery-powered instrumentation and high-impedance sensor front-ends.

Technical Context

The ICL7631ECJE implements a pin-selectable quiescent current architecture: IQ pin voltage determines per-amplifier bias at 10µA (IQ = V+), 100µA (IQ between V−+0.8V and V+−0.8V), or 1mA (IQ = V−). This directly scales unity-gain bandwidth (0.044–1.4 MHz) and slew rate (0.016–1.6 V/µs) while preserving rail-swing capability and transconductance-based output stage linearity.

Its triple configuration shares common supply pins (V+, V−) and includes dedicated offset-null terminals per amplifier pair, with internal connection of pins 5 and 15 per the 16-lead CERDIP layout. The device lacks internal frequency compensation - requiring external capacitor selection only if gain <5 at 10µA IQ, <10 at 100µA IQ, or <20 at 1mA IQ - ensuring stability-critical design flexibility.

Key Specifications

Pinout & Package

ICL7631ECJE is housed in a 16-pin CERDIP (Ceramic Dual In-line Package) with hermetic sealing, lead-free compatible soldering profile (+260°C reflow), and 0.3-inch body width. Pin 7 is internally connected to case ground for EMI shielding in sensitive analog layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-input-bias-current op-amp applications.

Compared with TLC27L4ACN and OPA377AIDR, the ICL7631ECJE uniquely provides triple-channel integration with per-amplifier quiescent current control, full industrial temperature support, and guaranteed rail-to-rail output swing - making it optimal for space-constrained, multi-sensor industrial instrumentation where power scalability and leakage sensitivity are co-primary constraints.

Availability

ICL7631ECJE is available at Aetrix Electronics and suitable for pH meter manufacturing, photodiode-based optical sensing, and long-duration integrator circuits requiring stable component supply across extended production lifecycles.

Supply support for ICL7631ECJE 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

Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for industrial, medical, and communications applications, with emphasis on low-power, high-accuracy signal conditioning.

The ICL761X–ICL764X family was engineered specifically for ultra-low-input-current applications including electrochemical sensors, scientific instrumentation, and energy-harvesting systems where femtoampere-level leakage must be avoided.

FAQ

What is the maximum allowable capacitive load for stable operation of the ICL7631ECJE?

The ICL7631ECJE is not guaranteed stable with capacitive loads exceeding 100pF. For loads >100pF, external compensation (e.g., series resistor + capacitor network) is required. At 1mA quiescent current, avoid resistive loads below 5kΩ unless large (>10µF) capacitive loading is present to introduce a dominant pole that restores phase margin. Always verify stability with actual load conditions in final PCB layout.

Does the ICL7631ECJE support true rail-to-rail input common-mode range?

No - the ICL7631ECJE has a standard common-mode voltage range of –0.4V to +0.6V relative to supplies (e.g., –4.4V to +5.4V at ±5V), not rail-to-rail input. Only the ICL7612 and ICL7616 variants in the same family offer extended CMVR. The ICL7631ECJE's input stage is optimized for ultra-low bias current, not input voltage range extension.

How is offset nulling implemented on the ICL7631ECJE?

The ICL7631ECJE provides dedicated OFFSET terminals per amplifier (Pins 2/8 for Amp A/C; Pin 11 for Amp B). Nulling is achieved by connecting a 25kΩ potentiometer between the two OFFSET pins, with wiper tied to V+. Null range is sufficient for all VOS grades at 100µA and 1mA IQ, but may be insufficient at 10µA IQ with higher VOS selections (e.g., 15mV or 20mV).

Can the ICL7631ECJE operate from a single 3.3V supply?

Yes - the ICL7631ECJE supports single-supply operation from 2V to 16V. At 3.3V, output swing is typically ±1.55V (3.1V total) into 1MΩ, and common-mode range spans ~0.2V to ~2.5V. Ensure input signals remain within this range and use appropriate level-shifting or biasing for AC-coupled inputs to avoid clipping or phase reversal.

What is the thermal resistance (θ_JA) of the ICL7631ECJE in its 16-pin CERDIP package?

The 16-pin CERDIP package of the ICL7631ECJE has a junction-to-ambient thermal resistance (θ_JA) of 40°C/W, based on standard JEDEC test board conditions. With 5.25mW per amplifier at 10µA IQ (3 × 0.00525W = 15.75mW total), junction temperature rise is ~0.63°C above ambient - well within safe operating limits even at +85°C ambient.