Analog Devices Inc./Maxim Integrated MAX931CSA+T

Overview

MAX931CSA+T from Maxim Integrated is a single micropower comparator with integrated 1.182V ±2% bandgap reference, programmable hysteresis via HYST pin, TTL/CMOS-compatible output that sources up to 40mA and sinks ≥5mA, and operates from +2.5V to +11V single supply (or ±1.25V to ±5.5V dual supply). It targets ultra-low-power battery-powered threshold detection in portable instrumentation and sensor interfaces.

For engineers reviewing the MAX931CSA+T datasheet, MAX931CSA+T pinout, MAX931CSA+T application, or MAX931CSA+T equivalent, key selection considerations include its 4µA max quiescent current over –40°C to +85°C, rail-to-rail input range (V– to V+ – 1.3V), 12µs propagation delay at 10mV overdrive, absence of crowbar current during switching, and compatibility with 8-pin plastic DIP package at 0°C to +70°C ambient.

Technical Context

The MAX931CSA+T integrates a precision 1.182V reference referenced to V– (not GND), enabling self-contained threshold generation without external components. Its unique output stage eliminates switching crowbar current, reducing parasitic supply feedback and improving stability in noisy or poorly decoupled layouts.

It supports hysteresis programming via the HYST pin using two resistors-no external feedback loop required-and guarantees operation down to +2.5V supply while maintaining full functionality across its specified temperature range. Input common-mode range extends from V– to (V+ – 1.3V), supporting detection near the positive rail in single-supply systems.

Key Specifications

Pinout & Package

MAX931CSA+T is housed in an 8-pin plastic DIP package with through-hole mounting and 0°C to +70°C operating range.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar comparator applications.

Compared with MAX921CSA+T, the MAX931CSA+T trades 1% reference accuracy for lower cost and sufficient precision for most battery-monitoring and alarm applications; versus TLV3701CDR, it delivers 5× higher output drive and eliminates external reference dependency at the cost of ~2.5× higher quiescent current.

Availability

MAX931CSA+T is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, oscillator circuits, and alarm circuits requiring stable component supply with long-term manufacturability.

Supply support for MAX931CSA+T 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, mixed-signal, and power-management ICs for industrial, automotive, communications, and computing markets.

The MAX931CSA+T belongs to the MAX931–MAX934 micropower comparator family, engineered specifically for ultra-low-power, single-supply sensing and decision-making in portable and energy-constrained systems.

FAQ

What is the maximum supply voltage for MAX931CSA+T in single-supply operation?

The MAX931CSA+T supports a single-supply voltage range of +2.5V to +11V. At +11V, it remains within Absolute Maximum Ratings and maintains full electrical performance per datasheet specifications. Exceeding +11V risks permanent damage, and operation below +2.5V degrades reference accuracy and propagation delay.

Does MAX931CSA+T require external bypass capacitors on V+ and REF pins?

No bypass capacitor is required on the REF pin-datasheet explicitly warns against bypassing it. For V+, a 100nF ceramic capacitor is recommended only if supply impedance is high or leads are long; low-impedance lab supplies often operate reliably without it. The absence of crowbar current reduces sensitivity to supply noise.

Can MAX931CSA+T drive an LED directly without a series resistor?

No. Although MAX931CSA+T sources ≥40mA continuously, driving an LED without a current-limiting resistor risks exceeding forward current ratings and damaging the LED or stressing the output stage. A series resistor must be used to set safe LED current-e.g., 330Ω for ~15mA with 5V V+ and 2V LED drop.

Is the internal reference of MAX931CSA+T referenced to GND or V–?

The internal 1.182V reference of MAX931CSA+T is referenced to V–, not GND. When V– is tied to GND in single-supply operation, REF = 1.182V relative to GND. In dual-supply configurations (e.g., ±5V), REF = 1.182V above V–, so with V– = –5V, REF = –3.818V relative to GND.

How is hysteresis implemented on MAX931CSA+T without external feedback?

MAX931CSA+T implements hysteresis via the HYST pin: connect R1 between REF and HYST, and R2 between HYST and V–. This creates a voltage divider that shifts the effective threshold based on output state. The hysteresis band (VHB) ≈ 2 × (REF – VHYST), with VHYST adjustable from REF down to (REF – 50mV), yielding up to 100mV total hysteresis.