Analog Devices Inc./Maxim Integrated MAX977ESD

Overview

The MAX977ESD from Maxim Integrated is a dual high-speed/low-power comparator with auto-standby functionality, designed for +2.7V to +5.25V single-supply operation in battery-constrained systems. It delivers 28ns propagation delay in high-speed mode, 3µA supply current per comparator in low-power mode, and independently adjustable timeout periods via external capacitors on STOA/STOB pins - enabling adaptive power management in IR receivers and threshold detection circuits.

For engineers reviewing the MAX977ESD datasheet, MAX977ESD pinout, MAX977ESD application, or MAX977ESD equivalent, this page provides verified functional identity, validated SO-14 package mapping, confirmed dual-comparator timing behavior, real-world auto-standby timeout calibration (t_ASB = 10 × C_STO µs), and design-meaningful parameter interpretation for low-overdrive signal conditioning and rail-to-rail CMOS/TTL interfacing.

Technical Context

The MAX977ESD implements two independent comparators sharing a single LP control input but featuring separate STOA/STOB timing inputs and STAT A/B status outputs. Each comparator uses parallel high-speed and low-power paths, with transition monitoring logic that enables automatic mode switching based on output stability.

In high-speed mode, internal hysteresis (±0.3–4mV) prevents oscillation near trip points, while rail-to-rail outputs drive CMOS/TTL loads without pull-ups. In auto-standby, the device disables the high-speed path after an externally timed idle period (programmable from ~10µs to >1s), reducing ICC to ≤5µA while retaining output state and STAT-driven auxiliary power capability.

Key Specifications

Pinout & Package

MAX977ESD is housed in a 14-pin Small Outline (SO-14) package with standard JEDEC MO-001AC footprint (5.3mm × 10.2mm, 1.27mm pitch). Pin 1 is marked with a beveled corner or dot; pin numbering follows counterclockwise convention from pin 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM393DR and TLV3702IDR, the MAX977ESD uniquely combines sub-µA standby, nanosecond-speed response, and hardware-programmable idle adaptation - making it the only option for battery-powered systems requiring both event-triggered wake-up and sustained low-noise discrimination.

Availability

MAX977ESD is available at Aetrix Electronics and suitable for battery-powered systems, RFID tag readers, IR receivers, and threshold detectors requiring stable component supply across industrial temperature ranges (–40°C to +85°C).

Supply support for MAX977ESD 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 power, sensing, and interface applications in industrial, automotive, and consumer markets.

The MAX975/MAX977 family was engineered specifically for energy-aware signal conditioning - delivering nanosecond-speed comparison with µA-level standby current and hardware-configurable power-state transitions.

FAQ

What is the function of the STOA and STOB pins on the MAX977ESD?

The STOA and STOB pins on the MAX977ESD are independent timeout programming inputs for Comparator A and Comparator B, respectively. Each accepts an external capacitor to set the idle duration before entering auto-standby mode using the formula t_ASB = 10 × C_STO µs (C in pF). This enables asymmetric power management - for example, configuring one comparator for fast wake-up on transient events while the other remains in low-power mode for background monitoring. The MAX977ESD requires separate capacitors on STOA and STOB; sharing a single capacitor invalidates timing behavior.

How does the MAX977ESD achieve rail-to-rail output operation without external pull-up resistors?

The MAX977ESD integrates complementary P-channel and N-channel MOSFETs in its output stage, enabling true rail-to-rail voltage swing from GND to V_CC under load. This architecture delivers ≥2mA sink/source capability while maintaining logic compatibility with 1.8V, 3.3V, and 5V CMOS/TTL families. Unlike open-drain comparators, the MAX977ESD requires no external pull-up resistors - reducing component count, board space, and potential noise coupling from resistor thermal effects. Output voltage levels are specified as VOL ≤ 0.4V and VOH ≥ 0.7×V_CC across temperature and load conditions.

Can the MAX977ESD operate from a 2.7V supply, and what performance changes occur?

Yes, the MAX977ESD is fully specified for operation from +2.7V to +5.25V. At 2.7V, propagation delay increases slightly (28ns typical becomes ~32ns in high-speed mode), and output drive strength decreases (VOH drops to ≥0.7×2.7V ≈ 1.89V, sufficient for 1.8V logic). Input common-mode range shifts to –0.2V to +1.5V, preserving ground-sensing capability. Supply current remains stable: 250µA in high-speed mode and 3µA in low-power mode. All timing parameters - including auto-standby timeout and wake-up delays - retain accuracy across the full voltage range, as confirmed by Typical Operating Characteristics graphs in the datasheet.

What is the purpose of the STAT pins on the MAX977ESD, and how should they be used?

The STAT pins (STATA and STATB) on the MAX977ESD indicate real-time operating mode: high during auto-standby, low-power, or transition states; low only in confirmed high-speed mode. Critically, each STAT pin can source up to 3mA, allowing direct powering of external circuitry - such as LED status indicators, bias networks for downstream amplifiers, or gate drivers for power FETs - only when the comparator is active or transitioning. This eliminates the need for separate enable logic and improves system-level power efficiency. For example, connecting an IR LED's anode to STATB ensures illumination only during valid signal detection, conserving battery energy in remote-control receivers.

How does the MAX977ESD handle input signals outside its common-mode voltage range?

The MAX977ESD specifies a guaranteed common-mode input range of –0.2V to (V_CC – 1.2V), but its inputs tolerate rail-to-rail differential voltage (GND to V_CC). If either input exceeds the common-mode limits while the other remains within range, the output retains correct logic state. However, if both inputs fall outside the common-mode range simultaneously, input-stage current saturation occurs and output behavior becomes unpredictable. Therefore, design practices must ensure at least one input stays within –0.2V to (V_CC – 1.2V) - for instance, by referencing the inverting input to a stable divider and applying the signal to the noninverting input. This constraint is explicitly documented in the Absolute Maximum Ratings and Electrical Characteristics tables for the MAX977ESD.