Analog Devices Inc./Maxim Integrated MAX16021LTES+T

Overview

MAX16021LTES+T from Maxim Integrated is a low-power microprocessor supervisory circuit with integrated battery-backup switchover, chip-enable (CE) gating, and power-fail monitoring. It provides active-low reset output, 145ms minimum reset timeout, 1.2µA supply current, and supports 3.0V system monitoring (typical threshold 3.100V). It is used in RTC and SRAM backup systems where reliable brownout detection and memory write protection are required.

For engineers reviewing the MAX16021LTES+T datasheet, MAX16021LTES+T pinout, MAX16021LTES+T application, or MAX16021LTES+T equivalent, key selection criteria include its 16-pin TQFN package, push-pull reset output, CEIN/CEOUT propagation delay of 1.5ns, battery-OK and battery-on indicators, and support for 3.0V supply supervision with ±2.5% threshold accuracy over temperature.

Technical Context

The MAX16021LTES+T implements a dual-path power-switching architecture: VCC connects to OUT during normal operation, while BATT automatically takes over when VCC falls below the 3.0V reset threshold and VBATT > VCC. Its internal CE gating logic disables CEIN-to-CEOUT conduction during reset assertion, holding CEOUT low for 12µs if CEIN is low at reset onset - preventing spurious writes to SRAM.

It integrates a 1.2s watchdog timer with WDI edge-triggered clear, a 0.590V power-fail comparator (PFI) with 30mV hysteresis, and a low-line (LL) output that asserts 2.5% above the reset threshold to enable early NMI-based shutdown. All supervisory outputs (RESET, PFO, WDO, LL, BATTON, BATTOK) are push-pull, and the device operates across -40°C to +85°C.

Key Specifications

Pinout & Package

MAX16021LTES+T is housed in a 16-pin 4mm × 4mm TQFN-EP package with exposed pad (EP) internally connected to GND. Thermal resistance θJA = 40°C/W enables stable operation at full load in compact industrial PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX16021LTES+T, MAX16020LTES+T omits BATT_TEST but retains identical timing, accuracy, and packaging - ideal for cost-sensitive designs without autonomous battery diagnostics. TPS3808G33DBVR offers footprint reduction but sacrifices all battery-management and CE-gating capabilities required for RTC/SRAM backup systems.

Availability

MAX16021LTES+T is available at Aetrix Electronics and suitable for real-time clock backup, industrial control panels, portable medical devices, and GPS systems requiring stable component supply with guaranteed long-term availability and RoHS-compliant packaging.

Supply support for MAX16021LTES+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.

The MAX160xx family was designed specifically for microprocessor-based systems needing integrated power supervision, battery switchover, and memory write protection - targeting applications where data integrity during power failure is mission-critical.

FAQ

What is the reset threshold voltage for MAX16021LTES+T?

The MAX16021LTES+T has a nominal reset threshold of 3.100V, with a guaranteed range of 3.010V (min) to 3.190V (max) across temperature and process variation. This threshold is factory-trimmed and stable over the full -40°C to +85°C operating range, making it suitable for precise 3.0V system supervision without external resistor networks.

Does MAX16021LTES+T support battery-backed SRAM write protection?

Yes, MAX16021LTES+T provides hardware-enforced SRAM write protection via its CEIN/CEOUT gating function. When RESET asserts, CEOUT is held low for 12µs if CEIN is low - blocking spurious writes during power transition. The 1.5ns propagation delay ensures compatibility with high-speed µPs and DSPs without timing violations.

How does the BATT_TEST output work on MAX16021LTES+T?

The BATT_TEST output on MAX16021LTES+T pulses low for 1.3 seconds once every 24 hours to activate an external test load. This verifies battery health without continuous drain. If VBATT drops below 2.6V during the test, BATTOK deasserts, signaling imminent battery failure - enabling predictive maintenance in unattended equipment.

Can MAX16021LTES+T operate with a 1.8V main supply?

No, MAX16021LTES+T is not rated for 1.8V VCC operation. Its minimum operating voltage is 1.53V, but its 3.100V reset threshold requires VCC ≥ ~3.0V to function as intended. For 1.8V systems, use MAX16021 variants with suffix 'R' (2.640V threshold) or 'Z' (2.323V threshold), not the 'TES' variant.

What is the purpose of the LL (Low-Line) output on MAX16021LTES+T?

The LL output on MAX16021LTES+T asserts low when VCC falls to 2.5% above the reset threshold - providing early warning of impending power failure. This allows the microprocessor to trigger a nonmaskable interrupt (NMI) and execute an orderly shutdown sequence before RESET asserts, preserving volatile data and system state.