Analog Devices Inc./Maxim Integrated DS1705ESA+

Overview

DS1705ESA+ 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 features 130 ms minimum reset pulse width, 1.25 V precision sense threshold at IN pin, and operates across -40°C to +85°C in 8-pin SOIC package for embedded power management in industrial microcontroller systems.

For engineers reviewing the DS1705ESA+ datasheet, DS1705ESA+ pinout, DS1705ESA+ application, or DS1705ESA+ equivalent, this page delivers verified electrical parameters, validated pin functions, confirmed watchdog timeout (1.0–2.2 s), precise VCC trip point (4.50–4.75 V), and real-world use cases in power-fail recovery and firmware crash mitigation.

Technical Context

The DS1705ESA+ integrates three independent monitoring functions: (1) VCC supply monitoring with comparator-based reset generation at 4.50–4.75 V trip point and 130–285 ms active-low RST assertion; (2) debounced pushbutton reset input (PBRST) guaranteeing ≥130 ms reset pulse on release; (3) watchdog timer with 1.0–2.2 s timeout triggered by ST strobe edge, driving WDS low upon timeout.

Its NMI output provides early power-fail warning via high-impedance IN pin sensing (1.20–1.30 V threshold), with built-in 100 µV hysteresis and 5 µs noise immunity. All logic outputs are TTL/CMOS-compatible, with RST sinking 10 mA and sourcing 350 µA, and operating current as low as 50 µA at VCC < 3.6 V.

Key Specifications

Pinout & Package

DS1705ESA+ is housed in an 8-pin SOIC (150-mil) package per Maxim's S8-2 outline, with gull-wing leads and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX705ESA+, DS1705ESA+ adds critical WDS output for autonomous watchdog fault reporting; versus TPS3808G33DBVR, it retains full 5 V compatibility, NMI capability, and drop-in replacement for Maxim-based legacy designs-making it optimal for industrial retrofit and long-lifecycle programs.

Availability

DS1705ESA+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, smart energy meters, and automotive telematics gateways requiring stable component supply across extended product lifecycles.

Supply support for DS1705ESA+ 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 industrial, medical, and communications applications.

The DS1705ESA+ belongs to Maxim's MicroMonitor family-engineered specifically for robust microprocessor supervision in harsh environments where power integrity, firmware reliability, and deterministic reset behavior are mission-critical.

FAQ

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

The DS1705ESA+ has a guaranteed VCC trip point range of 4.50 V to 4.75 V at -40°C to +85°C, with typical value 4.65 V. This ±5% tolerance is calibrated for 5 V systems and ensures reset activation before the microprocessor enters undefined operation. The DS1705ESA+ datasheet specifies this parameter under DC Electrical Characteristics, Table 3, and it is measured with VCC ramped at controlled slew rate.

Does DS1705ESA+ provide both active-high and active-low reset outputs?

No, DS1705ESA+ provides only active-low reset output (RST). Unlike some DS1706 variants (e.g., DS1706LESA+), the DS1705ESA+ does not include *RST (active-high) output. Its RST pin is open-drain, active-low, and asserts for a minimum of 130 ms during power-up or failure. This matches the reset input polarity of most 8051, ARM Cortex-M, and PIC microcontrollers.

How does the watchdog timer in DS1705ESA+ interact with the reset function?

The DS1705ESA+ watchdog timer starts timing only after RST becomes inactive (i.e., after power-up stabilization). If the ST input is not strobed low within 1.0–2.2 s, WDS goes active-low for ≥130 ms-but WDS does not directly assert RST. To trigger reset on timeout, external logic (e.g., connecting WDS to PBRST) or firmware must be used. This decoupling allows flexible fault-handling strategies without automatic hard reset.

Can DS1705ESA+ monitor voltages other than its own VCC supply?

Yes, DS1705ESA+ can monitor external voltages via its IN pin, which has a precise 1.20–1.30 V threshold. Using a resistor divider (e.g., R1 = 26 kΩ, R2 = 10 kΩ), users can scale higher voltages (e.g., 12 V) down to the IN threshold. The DS1705ESA+ datasheet Figure 5 provides the calculation method, and the IN pin's high impedance (<1 µA leakage) ensures minimal loading on the source.

Is DS1705ESA+ RoHS-compliant and lead-free?

Yes, DS1705ESA+ is RoHS-compliant and lead-free. The "+" suffix in the part number explicitly denotes Maxim's lead(Pb)-free/RoHS-compliant packaging. It meets JEDEC J-STD-020 moisture sensitivity level (MSL) 1 and is qualified for reflow soldering at peak temperature +260°C, as confirmed in the Absolute Maximum Ratings table of the official DS1705/DS1706 datasheet Rev 4/10.