Analog Devices Inc./Maxim Integrated DS1818R-20+T&R

Overview

DS1818R-20+T&R 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 internal 5.5kΩ pullup resistor. It monitors VCC for out-of-tolerance conditions in microprocessor power systems and ensures stable boot-up in industrial embedded controllers.

For engineers reviewing the DS1818R-20+T&R datasheet, DS1818R-20+T&R pinout, DS1818R-20+T&R application, or DS1818R-20+T&R equivalent, key selection factors include its fixed 3.3V trip point (±20% tolerance), 35µA max quiescent current, -40°C to +85°C operation, pushbutton-synchronized reset timing, and TO-92/SOT-23 package compatibility.

Technical Context

The DS1818R-20+T&R implements a precision temperature-compensated voltage reference and comparator to detect VCC deviations beyond ±20% of 3.3V. Its internal power-fail detection logic asserts RST within 5µs of threshold violation and holds it active for 100–250ms after VCC recovery.

It supports dual reset initiation modes: automatic power-supply monitoring and manual pushbutton override. When RST is externally pulled low ≥1µs, the device generates a synchronized 100–250ms reset pulse upon release-enabling reliable human-initiated system recovery without external timing components.

Key Specifications

Pinout & Package

DS1818R-20+T&R is supplied in SOT-23 and TO-92 packages. Both share identical 3-pin configuration and pin functions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD2+T and TPS3808G33DBVR, the DS1818R-20+T&R uniquely integrates pushbutton synchronization and a ±20% tolerance window optimized for cost-sensitive industrial systems where absolute precision is secondary to robustness and minimal external components.

Availability

DS1818R-20+T&R is available at Aetrix Electronics and suitable for industrial PLC I/O modules, smart energy meters, medical handheld diagnostics, and factory automation gateways requiring stable component supply and long-term production continuity.

Supply support for DS1818R-20+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, mixed-signal, and power management ICs for industrial, automotive, and communications applications.

The DS1818R-20+T&R belongs to the EconoReset™ family of supervisory ICs engineered for cost-effective, reliable power monitoring and reset control in resource-constrained embedded systems.

FAQ

What is the exact reset threshold voltage for DS1818R-20+T&R?

The DS1818R-20+T&R has a nominal 3.3V reset threshold with ±20% tolerance, meaning it asserts reset when VCC falls below 2.47V (min) and releases reset when VCC rises above 2.64V (max). This range is specified in the DC Electrical Characteristics table under VCCTP for the "-20" variant and is temperature-compensated across -40°C to +85°C.

Does DS1818R-20+T&R require an external pullup resistor on the RST pin?

No, DS1818R-20+T&R includes an internal 5.5kΩ pullup resistor on the RST pin, eliminating the need for an external component in standard 3.3V microcontroller interfaces. The datasheet confirms this design feature under "Efficient Open-Drain Output" and specifies RP = 3.50–7.5kΩ, with 5.5kΩ as the typical value.

How does the pushbutton reset function work on DS1818R-20+T&R?

The DS1818R-20+T&R monitors the RST pin for external low pulses. When RST is pulled low for ≥1µs, the device detects the pushbutton press and, upon release, holds RST active low for 100–250ms. This synchronized timing eliminates mechanical bounce issues and requires no external RC network-unlike generic reset ICs that lack built-in pushbutton logic.

What is the maximum supply voltage for DS1818R-20+T&R?

The DS1818R-20+T&R supports a supply voltage range of 1.0V to 5.5V on the VCC pin, with absolute maximum rating of +7.0V. Operation above 5.5V is not guaranteed and may damage the device. All electrical characteristics-including trip point accuracy and quiescent current-are validated for VCC = 1.2V to 5.5V per the Recommended DC Operating Conditions table.

Is DS1818R-20+T&R pin-compatible with other DS1818 variants?

Yes, all DS1818 variants-including DS1818R-5, DS1818R-10, and DS1818R-20-share identical pinout, package dimensions, and functional interface. The only difference is the reset threshold tolerance (±5%, ±10%, or ±20%). This allows direct substitution in existing layouts when adjusting trip point accuracy requirements without PCB revision.