Analog Devices Inc./Maxim Integrated MAX793TCSE+

Overview

MAX793TCSE+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with fixed reset threshold (3.00V–3.15V), backup-battery switchover, active-low/open-drain RESET output, and integrated watchdog timer (1.6s timeout). It monitors VCC supply integrity, asserts reset during brownout or manual trigger, and gates chip-enable signals to protect CMOS RAM in embedded controllers and portable equipment.

For engineers reviewing the MAX793TCSE+ datasheet, MAX793TCSE+ pinout, MAX793TCSE+ application, or MAX793TCSE+ equivalent, key selection criteria include guaranteed reset assertion down to VCC = 1V, battery-switching capability with VBATT > VCC (e.g., 3.6V Li), low-line early-warning (LOWLINE) output, and CE IN-to-CE OUT propagation delay ≤7ns - all critical for reliable power-fail response and RAM write protection in battery-backed systems.

Technical Context

The MAX793TCSE+ implements a precision voltage-monitoring comparator with 10mV typical hysteresis and fixed 3.00V–3.15V reset threshold (T-suffix), ensuring robust immunity to supply noise during power-up/down. Its internal p-channel MOSFET switch enables seamless VCC-to-BATT switchover when VCC falls below VSW (2.55V–2.68V), with <15mV hysteresis to prevent oscillation.

It integrates a 1.6s watchdog timer (WDI input, WDO output), manual reset input (MR) with 70µA internal pullup and 200ms timeout, and chip-enable gating logic that disables CE IN-to-CE OUT path during reset - preserving RAM integrity with ≤10µs hold time on CE OUT when CE IN is low at reset assertion.

Key Specifications

Pinout & Package

MAX793TCSE+ is housed in a 16-pin narrow SO (SOIC-16) package with 1.27mm pitch, RoHS-compliant and lead-free (+ suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX793SCSE+, MAX793TCSE+ asserts reset later (≥3.00V vs ≥2.85V), offering tighter alignment with 3.3V ±5% supplies; versus MAX795TCSE+, it adds LOWLINE, BATT OK, and watchdog - increasing functionality but requiring 16-pin layout and higher BOM cost.

Availability

MAX793TCSE+ is available at Aetrix Electronics and suitable for industrial data loggers, medical patient monitors, POS terminals, and ruggedized handheld computers requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX793TCSE+ 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 demanding industrial, medical, and communications applications.

The MAX793 family targets 3.0V/3.3V microprocessor supervision with integrated battery switchover, RAM protection, and watchdog - optimized for reliability-critical portable and embedded systems where power integrity cannot be compromised.

FAQ

What is the reset threshold voltage range for MAX793TCSE+?

The MAX793TCSE+ has a fixed reset threshold range of 3.00V to 3.15V (VCC falling), corresponding to the 'T' suffix. This range is designed for 3.3V ±5% power supplies, guaranteeing reset assertion before VCC falls below 3.0V and preventing spurious resets above 3.15V. The threshold includes 10mV typical hysteresis to suppress noise-induced toggling.

Does MAX793TCSE+ support backup batteries with voltage higher than VCC?

Yes, MAX793TCSE+ supports VBATT up to 6.0V - exceeding typical 3.0V/3.3V VCC rails. Its internal p-channel MOSFET switch enables seamless switchover to battery when VCC falls below VSW (2.55V–2.68V), permitting use of standard 3.6V lithium cells. The device also features a battery freshness seal that isolates BATT until first power-on, minimizing shelf-life leakage.

How does the watchdog function work in MAX793TCSE+?

The MAX793TCSE+ includes a 1.6s watchdog timer monitored via WDI. If WDI remains static (high or low) beyond 1.6s, WDO goes low. A transition on WDI resets the timer. WDO is pulled high when reset is asserted or VCC < VSW. For automatic recovery, WDO can be diode-OR'd to MR - causing a 200ms reset pulse on each watchdog timeout. The function cannot be disabled.

What is the purpose of the LOWLINE output on MAX793TCSE+?

The LOWLINE output on MAX793TCSE+ is an active-low early power-fail warning signal, asserted when VCC falls to approximately VRST − 25mV (e.g., ~2.975V for T-suffix). It provides programmable advance notice before reset assertion, enabling systems to trigger non-maskable interrupts (NMI) for last-chance data saves, state preservation, or controlled shutdown - improving system resilience during gradual brownout.

Can MAX793TCSE+ gate chip-enable signals to protect CMOS RAM during undervoltage?

Yes, MAX793TCSE+ provides dedicated CE IN and CE OUT pins with internal transmission-gate logic. During normal operation, CE IN passes through to CE OUT with ≤7ns delay. When reset is asserted, the path disables immediately - and if CE IN is low at reset, CE OUT remains low for ≤10µs to complete the current write cycle. This prevents corrupted writes to battery-backed RAM during power collapse.