Analog Devices Inc./Maxim Integrated MAX6357TWUT+

Overview

MAX6357TWUT+ from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with triple-monitor capability (VCC1, VCC2, and RSTIN), featuring active-low push-pull reset referenced to VCC2, factory-set 3.08V/1.67V thresholds, 20µA supply current, and guaranteed RESET validity down to VCC1 or VCC2 ≥ 1.0V. It is used in multivoltage embedded systems requiring reliable power-on reset and third-voltage monitoring.

For engineers reviewing the MAX6357TWUT+ datasheet, MAX6357TWUT+ pinout, MAX6357TWUT+ application, or MAX6357TWUT+ equivalent, key selection criteria include its VCC2-referenced RST output, 1.22V adjustable RSTIN threshold, 100ms min reset pulse width, and SOT23-6 package compatibility with industrial temperature range operation.

Technical Context

The MAX6357TWUT+ monitors two primary supply rails (VCC1 and VCC2) with independent precision thresholds (3.08V and 1.67V), and includes a dedicated RSTIN input for monitoring a third voltage via external resistive divider. Its reset logic asserts RST low whenever either VCC1 drops below 3.08V or VCC2 drops below 1.67V-or when RSTIN falls below 1.22V.

Reset assertion is sustained as long as at least one supply remains ≥ 1.0V; the push-pull RST output is referenced to VCC2 and sinks ≥1.2mA at VCC2 ≥ 2.7V. The device operates over –40°C to +85°C and requires no external components for dual-supply supervision.

Key Specifications

Pinout & Package

MAX6357TWUT+ is housed in a 6-pin SOT23-6 package with gull-wing leads, 1.27mm pitch, and JEDEC MO-178AC outline. Pin 1 is RST (active-low push-pull output referenced to VCC2), Pin 2 is GND, Pin 3 is MR (debounced manual reset input), Pin 4 is VCC2, Pin 5 is RSTIN (third-voltage monitor input), and Pin 6 is VCC1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-voltage supervisory applications.

Compared with MAX6357TTUT+, MAX6357TWUT+ provides lower VCC2 threshold (1.67V vs. 2.93V) essential for +1.8V domain supervision, while retaining identical RSTIN functionality and SOT23-6 footprint; TPS3808G33DBVR lacks dual-supply monitoring and adjustable third-input capability entirely.

Availability

MAX6357TWUT+ is available at Aetrix Electronics and suitable for industrial PLCs, portable medical devices, automotive body controllers, and motor drive systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6357TWUT+ 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, communications, computing, and consumer applications.

The MAX6351–MAX6360 family delivers multivoltage µP supervision with integrated reset generation, manual reset debouncing, and optional third-voltage monitoring-targeting space-constrained, high-reliability embedded systems.

FAQ

What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6357TWUT+?

The MAX6357TWUT+ has factory-set thresholds of 3.08V for VCC1 and 1.67V for VCC2, each with ±1.5% tolerance over –40°C to +85°C. These values are laser-trimmed during production and documented in Maxim's Electrical Characteristics table under "VTH1" and "VTH2" for suffix "TW". The 3.08V threshold reliably supervises standard +3.3V logic rails, while the 1.67V threshold matches common +1.8V I/O or core supplies. MAX6357TWUT+ does not support user adjustment of these primary thresholds.

How does the RSTIN pin function on the MAX6357TWUT+ and what voltage can it monitor?

The RSTIN pin on MAX6357TWUT+ is a high-impedance input with a fixed 1.22V internal threshold, enabling monitoring of a third voltage via an external resistive divider. When the divided voltage at RSTIN falls below 1.22V, the device asserts RST. For example, to monitor a +2.5V rail, use R1 = 100kΩ and R2 = 165kΩ to scale it to 1.22V. RSTIN is powered from VCC1, so its input voltage must not exceed VCC1. This feature is unique to MAX6355/MAX6356/MAX6357 variants and is fully supported in MAX6357TWUT+.

Is the RST output of the MAX6357TWUT+ push-pull or open-drain, and what is its drive strength?

The RST output of MAX6357TWUT+ is an active-low push-pull driver referenced to VCC2-not open-drain. It can sink ≥1.2mA when VCC2 ≥ 2.7V and VCC2 ≥ 4.5V, sinking ≥3.2mA. Its VOL is guaranteed ≤0.3V under those conditions. This allows direct connection to µP reset inputs without external pull-up resistors. The push-pull architecture ensures fast, rail-to-rail reset transitions and eliminates timing uncertainty associated with RC-based pull-ups. MAX6357TWUT+ does not offer an open-drain variant in the TW suffix.

Does the MAX6357TWUT+ include a watchdog timer function?

No, the MAX6357TWUT+ does not include a watchdog timer. Watchdog functionality is exclusive to the MAX6358/MAX6359/MAX6360 variants (suffixes ending in "U", "V", or "W" with WDI pin). MAX6357TWUT+ belongs to the MAX6355/MAX6356/MAX6357 subgroup, which adds the RSTIN third-voltage monitor but omits WDI and watchdog circuitry. Its pin 5 is RSTIN-not WDI-and no watchdog timeout specifications apply to MAX6357TWUT+.

What is the minimum supply voltage required for valid reset operation on the MAX6357TWUT+?

MAX6357TWUT+ guarantees valid RST output as long as either VCC1 ≥ 1.0V or VCC2 ≥ 1.0V-documented in the Electrical Characteristics table as "Guaranteed RESET Valid to VCC1 = 1V or VCC2 = 1V". This brownout resilience ensures reset remains asserted during deep supply sags, preventing premature µP release. Operation below 1.0V on both rails invalidates RST behavior; the device is not specified for sub-1.0V operation. This specification applies across the full –40°C to +85°C temperature range.