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, active-low open-drain reset output, 150ms reset timeout, and 35µA max quiescent current-used for reliable microprocessor power-fail detection and stabilization in embedded control systems.

For engineers reviewing the DS1818R-5-U+ datasheet, DS1818R-5-U+ pinout, DS1818R-5-U+ application, or DS1818R-5-U+ equivalent, key selection criteria include its fixed 3.3V trip point (±5%), internal 5.5kΩ pullup, -40°C to +85°C operation, pushbutton monitoring capability, and TO-92/SOT-23 package compatibility.

Technical Context

The DS1818R-5-U+ implements a precision temperature-compensated voltage reference and comparator to monitor VCC against a fixed 3.3V threshold (2.98V–3.15V). It asserts RST low on out-of-tolerance detection and holds reset active for 100–250ms after VCC recovery.

It supports dual reset initiation modes: automatic power-up/power-down detection and manual pushbutton reset via the RST pin-where pulling RST low for ≥1µs triggers a 100–250ms reset pulse upon release. Its open-drain output includes an internal 3.5–7.5kΩ pullup resistor.

Key Specifications

Pinout & Package

DS1818R-5-U+ is available in both TO-92 and SOT-23 packages. Both variants share identical pin assignment: Pin 1 = RST (active-low open-drain reset output), Pin 2 = VCC (1.0V–5.5V 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 MAX809TRD2+T and TPS3808G33DBVR, DS1818R-5-U+ uniquely integrates pushbutton monitoring on the RST pin and offers TO-92 packaging-making it suitable for legacy designs, cost-sensitive applications, and systems requiring single-pin manual reset without added components.

Availability

DS1818R-5-U+ is available at Aetrix Electronics and suitable for industrial PLC controllers, smart metering systems, and embedded gateway devices requiring stable component supply, long-lifecycle support, and proven reset reliability under voltage transients.

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, communications, and computing applications.

The DS1818R-5-U+ belongs to Maxim's EconoReset™ family of supervisory ICs-engineered for cost-effective, low-component-count power monitoring and reset generation in resource-constrained embedded systems.

FAQ

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

The DS1818R-5-U+ has a guaranteed VCC trip point of 2.98V (min), 3.06V (typ), and 3.15V (max) at room temperature, corresponding to a nominal 3.3V threshold with ±5% tolerance. This specification is validated across the full -40°C to +85°C operating range and is based on internal temperature-compensated reference circuitry-not external resistors or trimming.

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

No, DS1818R-5-U+ includes an internal pullup resistor of 3.5–7.5kΩ (typical 5.5kΩ) connected between VCC and the RST pin. This eliminates the need for an external pullup in most microcontroller reset interfaces, reducing component count and PCB area-though an external pullup may be added if stronger drive or different voltage translation is required.

How does the pushbutton reset function work on DS1818R-5-U+?

DS1818R-5-U+ monitors the RST pin directly: pulling RST low for ≥1µs (e.g., via momentary switch to GND) initiates a reset cycle. Upon release, the DS1818R-5-U+ holds RST low for 100–250ms-providing a clean, debounced reset pulse without external RC networks or firmware intervention.

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

DS1818R-5-U+ is offered in both TO-92 and SOT-23 packages. The TO-92 variant uses standard through-hole mounting and is marked "818" with tolerance code "D" (for ±5%). The SOT-23 version is surface-mount, pin-compatible, and shares identical electrical behavior and pinout (RST-VCC-GND).

Is DS1818R-5-U+ compatible with 1.8V or 2.5V supply rails?

Yes-DS1818R-5-U+ operates with VCC from 1.0V to 5.5V, and its internal reference and comparator remain functional across this range. However, its reset threshold remains fixed at 3.3V ±5%, so it is intended for monitoring 3.3V rails. For lower-voltage rails, a different variant (e.g., DS1818R-10-U+) or alternate supervisor should be selected.