Analog Devices Inc./Maxim Integrated DS1818-20

Overview

DS1818-20 from Maxim Integrated is a fixed-threshold, temperature-compensated microprocessor supervisory circuit with active-low open-drain reset output, 2.55 V ±20% VCC trip point, 150 ms reset timeout, and pushbutton reset monitoring capability. It ensures reliable power-up/power-down sequencing in embedded microcontroller systems operating from 1.2 V to 5.5 V supply rails.

For engineers reviewing the DS1818-20 datasheet, DS1818-20 pinout, DS1818-20 application, or DS1818-20 equivalent, key selection considerations include its 2.47–2.64 V trip window, 35 µA max quiescent current, 150 ms guaranteed reset pulse width, pushbutton debounce support, and dual TO-92/SOT-23 package availability.

Technical Context

The DS1818-20 implements a precision bandgap reference and comparator to detect VCC deviations beyond its factory-trimmed 20% tolerance window (2.47–2.64 V). Upon detection, it asserts RST low for ≥100 ms and ≤250 ms-guaranteed 150 ms typical-to allow processor stabilization after power recovery.

Its open-drain RST output includes an internal 5.5 kΩ pullup resistor, enabling direct interface to microcontroller reset inputs without external components. The device also detects and debounces manual reset via the same RST pin, generating a 150 ms reset pulse upon button release after ≥1 µs low assertion.

Key Specifications

Pinout & Package

DS1818-20 is available in both TO-92 and SOT-23 packages, sharing identical 3-pin configuration and terminal functions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809SEUR+T and TPS3808G12DBVR, the DS1818-20 uniquely combines factory-trimmed 20% tolerance, integrated pushbutton reset, and internal pullup in a single 3-pin package-reducing component count and simplifying layout for cost-sensitive industrial controllers.

Availability

DS1818-20 is available at Aetrix Electronics and suitable for industrial PLC controllers, smart metering modules, medical sensor nodes, and POS terminal power management requiring stable component supply and long-term lifecycle assurance.

Supply support for DS1818-20 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 DS1818-20 belongs to Maxim's EconoReset™ family of supervisory circuits, engineered to deliver reliable, low-cost power monitoring and reset control for resource-constrained microcontroller-based systems.

FAQ

What is the exact VCC trip point range for DS1818-20?

The DS1818-20 has a guaranteed VCC trip point range of 2.47 V (minimum) to 2.64 V (maximum), corresponding to a nominal 2.55 V threshold with ±20% tolerance. This window is factory-trimmed and temperature-compensated to ensure consistent brownout detection across −40°C to +85°C operation. The DS1818-20 does not require external calibration or adjustment to maintain this specification.

Does DS1818-20 require an external pullup resistor on the RST pin?

No, the DS1818-20 includes an internal 5.5 kΩ pullup resistor on the RST pin, eliminating the need for an external component in most standard microcontroller reset applications. The open-drain output sinks ≥10 mA at 0.4 V, ensuring compatibility with common CMOS reset inputs. External pullups may still be used if stronger drive strength or different logic thresholds are required-but they are not necessary for basic DS1818-20 operation.

How does DS1818-20 handle manual reset via pushbutton?

The DS1818-20 monitors the RST pin for manual reset: pulling RST low for ≥1 µs triggers a reset cycle, and the DS1818-20 holds RST active low for 100–250 ms (typically 150 ms) after the button is released. This built-in debounce and timing eliminates external RC networks or firmware polling. The DS1818-20 performs this function using the same pin used for power-fail reset output-enabling single-wire reset control.

What is the maximum supply voltage the DS1818-20 can tolerate?

The DS1818-20 supports a recommended DC operating supply voltage range of 1.0 V to 5.5 V on the VCC pin. Its absolute maximum rating is +7.0 V, but operation above 5.5 V is not functional or guaranteed. The DS1818-20 maintains specified trip accuracy and reset timing only within the 1.2 V to 5.5 V range per its electrical characteristics table, and exceeding 5.5 V risks permanent damage or parametric shift.

Is DS1818-20 available in both TO-92 and SOT-23 packages?

Yes, the DS1818-20 is offered in both TO-92 and SOT-23 packages, with identical pinout (RST–VCC–GND) and fully interchangeable electrical specifications. Both variants share the same 2.47–2.64 V trip point, 150 ms reset timeout, and pushbutton reset functionality. The DS1818-20's mechanical drawings for each package are published in Maxim's official datasheet revision 1 (3/15), confirming pin-for-pin compatibility across form factors.