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

Overview

DS1705ESA+T&R from Maxim Integrated is a 5V ±5% microprocessor supervisory circuit that monitors VCC, provides pushbutton reset control, and delivers watchdog timer functionality with non-maskable interrupt (NMI) output. It halts and restarts out-of-control microprocessors during power transients, guarantees ≥130 ms active-low reset pulse width, and operates across -40°C to +85°C in 8-pin SOIC package.

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 (4.50–4.75 V), NMI response time (≤8 µs), watchdog timeout (1.0–2.2 s), and compatibility with 5V systems requiring precise reset timing and early power-fail warning.

Technical Context

The DS1705ESA+T&R implements three independent monitoring functions: precision VCC threshold detection using an internal bandgap reference and comparator, debounced pushbutton reset with guaranteed 130 ms minimum active-low RST pulse, and a 1-second watchdog timer triggered by ST input transitions. All functions operate without external components.

Its IN pin accepts user-defined voltage sense points via resistor divider (trip point = 1.25 V), enabling upstream power rail monitoring; NMI asserts for ≥200 µs with 100 µV hysteresis to reject noise; and RST remains active ≥130 ms after VCC recovery to ensure system stabilization.

Key Specifications

Pinout & Package

DS1705ESA+T&R is housed in an 8-pin SOIC (150-mil) package, RoHS-compliant and tape-and-reel packaged per T&R suffix.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX705ESA+, DS1705ESA+ provides identical supervision functionality with enhanced manufacturability and RoHS compliance; versus TPS3808G33DBVR, DS1705ESA+ adds critical NMI and configurable watchdog features essential for robust embedded systems requiring graceful failure handling.

Availability

DS1705ESA+T&R is available at Aetrix Electronics and suitable for industrial automation, medical diagnostics, automotive infotainment, and network infrastructure applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.

The DS1705ESA+T&R belongs to the MicroMonitor family, designed specifically for microprocessor system supervision-combining power monitoring, watchdog, and interrupt functions in a single 8-pin package for space-constrained embedded designs.

FAQ

What is the exact VCC trip point range for DS1705ESA+T&R?

The DS1705ESA+T&R has a specified VCC trip point range of 4.50 V (minimum) to 4.75 V (maximum) at -40°C to +85°C, corresponding to a nominal 5V supply with ±5% tolerance. This threshold is internally temperature-compensated and applies directly to the VCC pin; it triggers the RST output and initiates the reset sequence when the supply falls below this window. The DS1705ESA+T&R datasheet confirms this range under DC Electrical Characteristics.

Does DS1705ESA+T&R support both active-high and active-low reset outputs?

No, DS1705ESA+T&R provides only an active-low reset output (RST). The part marking "DS1705" indicates the /RST variant (active-low), distinct from DS1706L or DS1706P which offer active-high RST. The DS1705ESA+T&R datasheet explicitly lists RST as "Active Low Reset Output" and does not include *RST (active-high) functionality. Designers requiring active-high reset must select a DS1706L or DS1706P variant instead.

Can DS1705ESA+T&R monitor a 12V supply rail?

Yes, DS1705ESA+T&R can monitor a 12V supply rail using its IN pin with an external resistor divider. The IN pin has a fixed 1.25 V trip threshold; selecting R1 and R2 such that V_IN = 12V × R2/(R1+R2) = 1.25 V satisfies this requirement. The DS1705ESA+T&R datasheet provides the equation and example calculation (Figure 5), confirming compatibility with higher-voltage rails as long as the IN voltage stays within VCC. For 12V monitoring, R2 = 10 kΩ and R1 ≈ 86 kΩ yields correct scaling.

What is the watchdog timeout accuracy of DS1705ESA+T&R?

The DS1705ESA+T&R watchdog timeout is specified as 1.0 s (minimum), 1.6 s (typical), and 2.2 s (maximum) over -40°C to +85°C. This variation arises from process and temperature dependencies in the internal RC oscillator. The DS1705ESA+T&R datasheet states the timeout is tested at 4.5 V for 5V devices, and the 1.0–2.2 s range reflects worst-case timing across voltage, temperature, and unit-to-unit variation-critical for designing reliable heartbeat intervals in safety-critical firmware.

Is DS1705ESA+T&R pin-compatible with MAX705/MAX706 devices?

Yes, DS1705ESA+T&R is explicitly pin-compatible with the MAX705 and MAX706 in 8-pin DIP, SOIC, and µSOP packages, as confirmed in the "Features" section of the DS1705/DS1706 datasheet. All signal names (PBRST, VCC, GND, IN, NMI, ST, RST, WDS), pin positions, and electrical behavior match. This allows direct replacement in existing MAX705/MAX706-based PCB layouts without modification, provided the DS1705ESA+T&R's 5V ±5% trip point meets the system's reset threshold requirement.