Analog Devices Inc./Maxim Integrated MAX4123ESA

Overview

MAX4123ESA from Maxim Integrated is a single-channel, rail-to-rail input/output operational amplifier optimized for low-voltage, low-power precision signal conditioning. It features 5MHz gain-bandwidth product, 650µA quiescent current per amplifier, ±200µV input offset voltage (max), shutdown mode reducing supply current to 25µA, and operates from +2.7V to +6.5V single supply. It is used in battery-powered data-acquisition front-ends where rail-to-rail swing and low power are critical.

For engineers reviewing the MAX4123ESA datasheet, MAX4123ESA pinout, MAX4123ESA application, or MAX4123ESA equivalent, this page delivers verified electrical specs, SO-8 package terminal mapping, real-world use cases in portable instrumentation, and two validated alternative op amps with documented functional trade-offs.

Technical Context

The MAX4123ESA employs a dual-input-stage architecture-NPN and PNP differential pairs-to achieve rail-to-rail common-mode input range extending 250mV beyond VEE and VCC. Its output stage delivers rail-to-rail swing into 250Ω loads while maintaining stability with up to 500pF capacitive loads.

It integrates a dedicated SHDN pin that places the output in high-impedance state and reduces quiescent current to 25µA per amplifier when pulled low (<0.8V). The device is unity-gain stable and specified across –40°C to +85°C industrial temperature range in 8-pin SO package.

Key Specifications

Pinout & Package

MAX4123ESA is housed in an 8-pin SO (Small Outline) package, 150mil width, with standard JEDEC MS-012AC footprint. Pin 1 is marked by a beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar rail-to-rail, low-power op amp applications.

Compared with TLV2461CDR and AD8601ARZ, the MAX4123ESA uniquely combines 5MHz bandwidth, true rail-to-rail input *and* output, shutdown capability, and sub-200µV offset in a single SO-8 package - making it optimal for battery-constrained, precision, rail-sensing applications where all four attributes are required simultaneously.

Availability

MAX4123ESA is available at Aetrix Electronics and suitable for battery-powered instruments, portable medical sensors, and industrial sensor transmitters requiring stable component supply across extended production lifecycles.

Supply support for MAX4123ESA 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 high-performance analog and mixed-signal ICs for industrial, automotive, communications, and consumer applications.

The MAX4122–MAX4129 family was engineered specifically for low-voltage, low-power, rail-to-rail signal conditioning in portable and battery-operated systems - emphasizing precision, speed, and supply flexibility without sacrificing robustness.

FAQ

What is the maximum capacitive load the MAX4123ESA can drive stably?

The MAX4123ESA is specified to remain stable with capacitive loads up to 500pF without external compensation. This is confirmed in the datasheet's "Capacitive Load Stability" section and typical operating characteristics (Figure 4). Driving larger loads may require an isolation resistor (e.g., 39Ω) in series with the output to restore phase margin. The MAX4123ESA's internal compensation enables this robustness without sacrificing bandwidth or requiring layout changes.

Does the MAX4123ESA support true rail-to-rail input operation?

Yes, the MAX4123ESA supports true rail-to-rail input operation: its common-mode input voltage range extends from (VEE − 0.25V) to (VCC + 0.25V), as stated in the Absolute Maximum Ratings and DC Electrical Characteristics tables. This is achieved via complementary NPN/PNP input stages. The MAX4123ESA maintains low distortion and consistent CMRR across this full range, making it suitable for sensing signals directly at the supply rails - a key advantage over op amps with limited CMVR.

What happens to the output of the MAX4123ESA during shutdown mode?

During shutdown mode (SHDN pin < 0.8V), the MAX4123ESA's output enters a high-impedance (high-Z) state - effectively disconnecting it from the load. This is explicitly documented in the General Description and Applications Information sections. The output does not clamp, short, or assume a defined voltage; instead, it floats. This behavior prevents unintended loading of downstream circuitry and is essential for multiplexed or shared-bus analog signal paths. The MAX4123ESA's shutdown current drops to 25µA per amplifier under this condition.

Can the MAX4123ESA operate from a 1.8V supply?

Although the absolute minimum rated supply is +2.7V, the MAX4123ESA typically operates down to 1.8V, as noted in the General Description ("Although the minimum operating voltage is specified at 2.7V, the devices typically operate down to 1.8V"). However, performance parameters - including gain-bandwidth, slew rate, and output swing - are not guaranteed below 2.7V. For production designs requiring guaranteed operation, the MAX4123ESA must be used within its specified +2.7V to +6.5V range. The 1.8V figure reflects characterization data, not specification.

What is the input bias current behavior of the MAX4123ESA near mid-supply?

The MAX4123ESA exhibits polarity reversal of input bias current near VCC/2 due to its dual NPN/PNP input stage architecture. As described in the Applications Information section, the PNP stage dominates near VEE and the NPN stage near VCC, with a transition region centered at mid-supply. This causes bias current to change sign - potentially introducing offset errors if source impedances are mismatched. To mitigate this, the datasheet recommends matching the Thévenin-equivalent impedance at IN+ and IN− (e.g., using R3 = R1∥R2 in Figure 1a/1b). The MAX4123ESA's typical input bias current is ±1nA at 25°C but varies with common-mode voltage.