Analog Devices Inc./Maxim Integrated MAX16040LLA44+T

Overview

The MAX16040LLA44+T from Maxim Integrated is an 8-pin μDFN battery-backup supervisory IC with auxiliary adjustable-reset input (RESETIN), active-low push-pull reset output, and power-fail comparator. It operates from 1.2V to 5.5V, features a factory-set 4.38V reset threshold (±0.13V), 140ms minimum reset timeout, and draws only 13µA quiescent current at 2.8V - enabling reliable µP reset and SRAM backup in portable industrial controllers.

For engineers reviewing the MAX16040LLA44+T datasheet, MAX16040LLA44+T pinout, MAX16040LLA44+T application, or MAX16040LLA44+T equivalent, key selection criteria include its RESETIN-comparator interface for secondary supply monitoring, battery switchover behavior below VTH, push-pull reset drive capability up to 20mA, and operation down to 1.2V supply voltage.

Technical Context

The MAX16040LLA44+T integrates a precision 1.235V internal reference to set the RESETIN threshold, supporting external resistor-divider configuration for custom voltage monitoring. Its reset generator asserts active-low RESET for ≥140ms after VCC rises above 4.38V or after RESETIN recovers from <1.235V, with propagation delay under 1.5µs.

It includes a dedicated power-fail comparator (PFI/PFO) with 1.235V trip point and 1% hysteresis, independent of the main reset threshold. The device implements automatic battery switchover when VCC falls below both VTH and VBATT, with 40mV hysteresis on the BATT-to-OUT MOSFET control to prevent oscillation during slow brownouts.

Key Specifications

Pinout & Package

Package: 2mm × 2mm, 8-pin μDFN (pin pitch: 0.5mm), RoHS-compliant, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX16036LLA44+T, the MAX16040LLA44+T saves board space with its 8-pin μDFN and removes unused CE gating logic, reducing complexity. Against TPS3808G33DBVR, it adds critical battery switchover, RESETIN monitoring, and PFI/PFO - making it the only viable choice for SRAM-retention systems requiring auxiliary supply supervision.

Availability

MAX16040LLA44+T is available at Aetrix Electronics and suitable for industrial controllers, point-of-sale terminals, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX16040LLA44+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 and mixed-signal ICs for industrial, automotive, and communications applications - emphasizing reliability, low power, and small form factor.

The MAX16033–MAX16040 family targets µP-based systems needing integrated reset, battery backup, and multi-rail monitoring in space-constrained environments - specifically optimized for portable and industrial equipment with stringent power and footprint requirements.

FAQ

What is the factory-set reset threshold voltage for MAX16040LLA44+T?

The MAX16040LLA44+T has a factory-set reset threshold of 4.38V (minimum 4.25V, maximum 4.50V) over the full -40°C to +85°C temperature range. This value is laser-trimmed during production and does not require external components. The 'A44' suffix in the part number explicitly denotes this 4.38V threshold variant within the MAX16040 family.

Does MAX16040LLA44+T support battery backup for SRAM, and what is its switchover behavior?

Yes, the MAX16040LLA44+T supports battery backup for SRAM via its BATT and OUT pins. It automatically switches OUT from VCC to BATT when VCC falls below both the 4.38V reset threshold and VBATT, with 40mV hysteresis to prevent oscillation. During backup mode, OUT is sourced from the higher of VCC or BATT, and RESET remains asserted until VCC recovers and holds for ≥140ms.

How is the RESETIN input used on MAX16040LLA44+T, and what voltage does it monitor?

The RESETIN input on MAX16040LLA44+T monitors an external voltage using an internal 1.235V precision reference comparator. When the voltage at RESETIN falls below 1.235V (±50mV), RESET asserts. Users configure the monitored voltage (e.g., 3.3V, 2.5V) with a two-resistor divider: VRTH = 1.235V × (R1/R2 + 1). Input bias current is ≤25nA, allowing use of high-value resistors without accuracy loss.

What type of RESET output does MAX16040LLA44+T provide, and what is its drive strength?

The MAX16040LLA44+T provides an active-low push-pull RESET output, as indicated by the 'L' in its part number suffix (LLA44+T). It can sink up to 20mA while maintaining VOL ≤ 0.3V at ISINK = 1.6mA and VCC ≥ 2.1V. This eliminates the need for an external pull-up resistor and ensures robust interfacing with µP reset inputs across varying supply voltages from 1.2V to 5.5V.

Can MAX16040LLA44+T monitor a second power supply independently of its main reset function?

Yes, the MAX16040LLA44+T independently monitors a second power supply using its RESETIN input and PFI input. RESETIN uses a dedicated 1.235V comparator to supervise auxiliary rails (e.g., 3.3V, 2.5V), while PFI provides a separate 1.235V power-fail comparator for early warning. Both functions operate concurrently with the main 4.38V reset, enabling comprehensive multi-rail supervision in a single 8-pin package.