Analog Devices Inc./Maxim Integrated DS1818R-5-U

Overview

DS1818R-5-U from Maxim Integrated is a 3.3V fixed-threshold supervisory IC with pushbutton reset capability, active-low open-drain reset output, 150ms reset timeout, and 35µA max quiescent current. It monitors VCC for out-of-tolerance conditions and asserts reset during power-up, power-down, or manual pushbutton release in embedded microprocessor systems.

For engineers reviewing the DS1818R-5-U datasheet, DS1818R-5-U pinout, DS1818R-5-U application, or DS1818R-5-U equivalent, key selection considerations include its 3.06V typical trip point (±5% tolerance), internal 5.5kΩ pullup resistor, -40°C to +85°C operation, pushbutton-synchronized reset timing, and SOT-23/TO-92 package compatibility.

Technical Context

The DS1818R-5-U implements a precision temperature-compensated voltage reference and comparator to detect VCC deviations against a fixed 3.3V threshold. Its reset assertion logic includes dual-trigger behavior: automatic response to VCC dropout and edge-triggered response to external RST line pull-down.

Reset deassertion is delayed by a guaranteed 100–250ms window after VCC returns to tolerance or after pushbutton release, ensuring processor stabilization. The open-drain output supports flexible interface with external pullups and direct connection to microcontroller reset inputs requiring active-low assertion.

Key Specifications

Pinout & Package

SOT-23-3 and TO-92 packages both used for DS1818R-5-U; pinout identical across variants: Pin 1 = RST (active-low open-drain reset output), Pin 2 = VCC (power supply input), Pin 3 = GND (ground reference).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD1T and TPS3808G33DBVR, the DS1818R-5-U uniquely integrates pushbutton synchronization and internal pullup in a 3-pin SOT-23, offering lowest component count for cost-sensitive 3.3V reset applications requiring manual override capability.

Availability

DS1818R-5-U is available at Aetrix Electronics and suitable for industrial control panels, portable medical devices, smart metering systems, and automotive body electronics requiring stable component supply and long-term lifecycle support.

Supply support for DS1818R-5-U 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, automotive, and computing applications.

The DS1818R-5-U belongs to the EconoReset™ family of supervisory ICs engineered for cost-effective, reliable power-on reset and manual reset functions in resource-constrained embedded systems.

FAQ

What is the exact reset threshold voltage for DS1818R-5-U?

The DS1818R-5-U has a nominal reset threshold of 3.06V with ±5% tolerance, meaning it asserts reset when VCC falls below 2.98V (min) and releases reset when VCC rises above 3.15V (max). This specification is guaranteed across the full -40°C to +85°C operating range and is derived from its internal temperature-compensated reference.

Does DS1818R-5-U require an external pullup resistor on the RST pin?

No, DS1818R-5-U includes an internal 5.5kΩ pullup resistor on the RST pin, eliminating the need for an external component in most standard microcontroller reset interfaces. However, if interfacing with high-capacitance buses or logic families requiring stronger drive, an external pullup may still be added per system requirements.

How does DS1818R-5-U handle pushbutton reset events?

DS1818R-5-U detects any low pulse ≥1µs on the RST pin and generates a clean, timed reset pulse upon release. After button release, it holds RST low for 100–250ms (typical 150ms), providing hardware-debounced manual reset without external circuitry - a core differentiator versus basic reset supervisors.

What package options are available for DS1818R-5-U?

DS1818R-5-U is offered in both SOT-23-3 and TO-92 packages, with identical pinout (RST-VCC-GND) and electrical specifications. The SOT-23 variant supports automated assembly and space-constrained layouts, while TO-92 suits through-hole prototyping and legacy board designs.

Can DS1818R-5-U operate from a 1.8V supply rail?

Yes, DS1818R-5-U operates with VCC from 1.0V to 5.5V, enabling use with 1.8V, 2.5V, 3.3V, and 5V systems. Its internal reference and comparator function correctly down to 1.0V, and the 3.06V threshold remains valid regardless of supply voltage - making it suitable for monitoring higher rails from lower-voltage supplies.