Analog Devices Inc./Maxim Integrated MAX16021LTET+

Overview

MAX16021LTET+ from Maxim Integrated is a low-power microprocessor supervisory circuit with integrated battery-backup switchover, chip-enable (CE) gating, watchdog timer, and power-fail monitoring. It monitors 3.3V systems (reset threshold 3.010V–3.190V), delivers 145ms min reset timeout, supports 1.53V–5.5V operation, and provides CEIN-to-CEOUT propagation delay of 1.5ns for SRAM write protection in GPS modules and industrial controllers.

For engineers reviewing the MAX16021LTET+ datasheet, MAX16021LTET+ pinout, MAX16021LTET+ application, or MAX16021LTET+ equivalent, key selection criteria include its 16-pin TQFN package, dual reset output polarity (active-low RESET and active-high RESET), battery-OK/Battery-On indicators, and guaranteed -40°C to +85°C operation for embedded backup-power systems.

Technical Context

The MAX16021LTET+ integrates four core supervisory functions: precise VCC monitoring with fixed 3.100V typical reset threshold, seamless VCC-to-battery switchover via internal MOSFET (RON ≤ 5.5Ω at 1.91V), on-board CE signal gating with 12µs hold time during reset, and independent watchdog timer (1.235s typical timeout) with WDI edge-triggered clear logic.

It implements a dual-threshold comparator architecture: one for reset (VTH), one for early warning (LL at ~2.5% above VTH), and a third for power-fail detection (PFI at 0.590V ±30mV). All outputs-including PFO, WDO, BATTON, BATTOK, and LL-are specified for push-pull or open-drain configurations per variant, with supply current as low as 0.25µA in battery-backup mode.

Key Specifications

Pinout & Package

MAX16021LTET+ uses a 16-pin TQFN package (3mm × 3mm, 0.5mm pitch) with exposed thermal pad (EP) internally connected to GND. The package supports reflow soldering at +240°C and provides 2000mW max continuous power dissipation at +70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX16021LTET+, MAX16020LTET+ removes BATT_TEST but retains identical CE gating and switchover functionality, while TPS3808G33DBVR offers lower cost and smaller footprint at the expense of integrated battery management and memory write protection.

Availability

MAX16021LTET+ is available at Aetrix Electronics and suitable for GPS tracking modules, industrial PLC controllers, point-of-sale terminals, and portable medical monitors requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX16021LTET+ 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 connectivity applications in industrial, automotive, and communications markets.

The MAX160xx family was engineered specifically for microprocessor-based systems needing integrated power supervision, battery backup, and memory write protection-targeting GPS, POS, and industrial control equipment with stringent reliability and low-power demands.

FAQ

What is the reset threshold voltage range for MAX16021LTET+?

The MAX16021LTET+ has a fixed reset threshold range of 3.010V (min) to 3.190V (max), with a typical value of 3.100V. This is optimized for reliable monitoring of standard 3.3V power rails and is factory-trimmed-no external resistor divider is needed. The threshold remains stable over temperature, with normalized variation ≤±0.5% across -40°C to +85°C.

Does MAX16021LTET+ support both active-high and active-low reset outputs?

Yes, MAX16021LTET+ provides two independent reset outputs: an active-high RESET pin and an active-low RESET pin. This dual-polarity capability allows direct interfacing with µPs that require either logic level for reset assertion-eliminating the need for external inverters or level translators in mixed-platform designs.

How does the CE gating function protect memory during brownout?

The MAX16021LTET+ disables the CE path during reset assertion by holding CEOUT low for 12µs after reset begins. If CEIN is low when reset triggers, CEOUT stays low for that duration to complete the current memory access; if CEIN is high, CEOUT remains high. This prevents partial writes and ensures SRAM data integrity during power transitions.

What is the purpose of the BATT_TEST output on MAX16021LTET+?

The BATT_TEST output on MAX16021LTET+ pulses low for 1.3 seconds every 24 hours to activate an external test load, verifying battery voltage under load. When combined with BATTOK monitoring, it enables autonomous battery health validation without host processor involvement-critical for unattended remote devices like GPS trackers.

Can MAX16021LTET+ operate with a 1.8V main supply?

No, MAX16021LTET+ is not rated for 1.8V VCC operation. Its minimum operating voltage is 1.53V, but its reset threshold variants (including the LTET+ suffix) are specified for 3.3V systems (3.010V–3.190V). For 1.8V rails, use MAX16021 variants with 'R' or 'Z' suffixes (2.568V–2.716V or 2.260V–2.390V thresholds) and confirm VCC ≥ 1.53V in all operating conditions.