Analog Devices Inc./Maxim Integrated DS1705ESA/T&R

Overview

DS1705ESA/T&R from Maxim Integrated is a 5V ±5% supply voltage supervisor IC with active-low reset (/RST), watchdog status output (/WDS), and non-maskable interrupt (NMI) for microprocessor systems. It monitors VCC, detects power transients, debounces pushbutton reset, and provides 130 ms minimum reset pulse width and 1.0 s watchdog timeout. Used in industrial embedded controllers requiring reliable power-up sequencing and fail-safe recovery.

For engineers reviewing the DS1705ESA/T&R datasheet, DS1705ESA/T&R pinout, DS1705ESA/T&R application, or DS1705ESA/T&R equivalent, key selection criteria include VCC trip point accuracy (4.50–4.75 V), guaranteed 130 ms reset assertion time, NMI early-warning capability at IN pin, and compatibility with 8-pin SOIC layout constraints.

Technical Context

The DS1705ESA/T&R implements three independent monitoring functions: precision VCC threshold detection using an internal bandgap reference, pushbutton reset debouncing with 130 ms minimum active pulse, and a 1.0 s watchdog timer triggered by ST input strobes. Its NMI output activates when the IN pin voltage falls below 1.25 V, enabling early power-fail warning before reset assertion.

All logic outputs are CMOS-compatible with VCC-referenced thresholds: /RST and /WDS drive low with 10 mA sink capability, while NMI is open-drain. The device operates across full industrial temperature range (−40°C to +85°C) with 50 µA typical supply current at VCC < 3.6 V and 60 µA at VCC < 5.5 V.

Key Specifications

Pinout & Package

DS1705ESA/T&R is housed in an 8-pin SOIC (150-mil) package with gull-wing leads, JEDEC MS-012AC compliant, body size 3.9 mm × 4.9 mm × 1.75 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor applications.

Compared with MAX705ESA+ and TPS3808G15DBVR, DS1705ESA/T&R uniquely combines VCC supervision, NMI-based early warning, and hardware watchdog in one SOIC-8 footprint-enabling compact, fault-tolerant designs where system-level diagnostics and deterministic recovery are required.

Availability

DS1705ESA/T&R is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and telecommunications infrastructure requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for DS1705ESA/T&R 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, medical, and communications applications, emphasizing reliability, integration, and performance under harsh conditions.

The DS1705ESA/T&R belongs to the MicroMonitor™ family of voltage supervisors engineered for fail-safe microprocessor supervision in mission-critical embedded systems where power integrity and software execution monitoring are essential.

FAQ

What is the VCC trip point specification for DS1705ESA/T&R?

The DS1705ESA/T&R has a guaranteed VCC trip point of 4.50 V (min), 4.65 V (typ), and 4.75 V (max) - corresponding to a nominal 5.0 V ±5% monitoring window. This specification is tested across the full −40°C to +85°C operating temperature range and ensures consistent reset activation when the supply falls outside tolerance. DS1705ESA/T&R uses an internal bandgap reference to maintain accuracy without external calibration.

Does DS1705ESA/T&R provide both active-high and active-low reset outputs?

No, DS1705ESA/T&R provides only an active-low reset output (/RST) and an active-low watchdog status output (/WDS). Unlike some DS1706 variants (e.g., DS1706LESA), it does not include an active-high RST output. The /RST pin drives low with 10 mA sink capability and remains asserted for a minimum of 130 ms during power-up or brownout recovery. DS1705ESA/T&R is specifically configured for /RST, /WDS operation per its ordering code.

How does the NMI function work in DS1705ESA/T&R?

The NMI output in DS1705ESA/T&R activates when the voltage at the IN pin falls below 1.25 V (1.20–1.30 V range), triggering a low pulse ≥200 ns with 100 µV hysteresis to reject noise. This allows users to monitor upstream rails via a resistor divider. DS1705ESA/T&R's NMI gives early warning before /RST asserts, enabling firmware-controlled shutdown. DS1705ESA/T&R requires VCC ≥ VCCTP before NMI becomes active during power-up.

Can DS1705ESA/T&R be used with 3.3 V systems?

No, DS1705ESA/T&R is specified exclusively for 5.0 V ±5% systems, with a VCC trip point centered at 4.65 V. It is not rated for reliable operation with 3.3 V supplies. For 3.3 V applications, DS1706TESA (3.3 V ±5%) or DS1706RESA (3.3 V ±20%) variants are appropriate alternatives. DS1705ESA/T&R's internal reference and comparator thresholds are optimized for 5 V operation, and using it at 3.3 V would result in premature or failed reset assertion.

What is the watchdog timeout period for DS1705ESA/T&R?

The watchdog timeout for DS1705ESA/T&R is 1.0 s (min), 1.6 s (typ), and 2.2 s (max), measured from the last ST input strobe. The timer starts when /RST goes inactive after power-up or reset release. A high-to-low transition on ST resets the timer; failure to strobe within the timeout causes /WDS to assert low for ≥130 ms. DS1705ESA/T&R's watchdog is fully self-contained and requires no external components.