Analog Devices Inc./Maxim Integrated DS1817R-20-U

Overview

DS1817R-20-U from Maxim Integrated (now Analog Devices) is a precision voltage-monitoring reset IC with active-high push-pull output, designed for power-fail detection and microprocessor reset supervision in 3.0V systems. It features 20% V_CC trip tolerance (2.47V–2.64V), 150ms guaranteed reset pulse width after power recovery, and operates from -40°C to +85°C in SOT-23 package.

For engineers reviewing the DS1817R-20-U datasheet, DS1817R-20-U pinout, DS1817R-20-U application, or DS1817R-20-U equivalent, key selection criteria include its fixed 20% trip point for 3.0V rails, guaranteed 100–250ms reset assertion window, push-pull output drive capability (350µA high, +10mA low), ultra-low 28–35µA operating current, and TO-92/SOT-23 dual-package availability.

Technical Context

The DS1817R-20-U integrates a temperature-compensated voltage reference and comparator to detect V_CC deviations beyond ±20% of nominal 3.0V (trip range: 2.47V–2.64V). Its internal timing circuit ensures RST remains asserted for ≥100ms and ≤250ms after V_CC returns to tolerance, with typical 150ms duration.

It delivers a CMOS-compatible push-pull output capable of sourcing 350µA at V_CC–0.5V and sinking +10mA at 0.4V, eliminating need for external pull-up resistors. Operating current stays within 28–35µA across full V_CC range (1.2V–5.5V), supporting low-power embedded supervision.

Key Specifications

Pinout & Package

SOT-23 surface-mount package (3-pin, JEDEC MO-178AA); compact footprint ideal for space-constrained PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage-monitoring reset applications.

Compared with MAX6326–UR29 and TPS3808G12DBVR, the DS1817R-20-U offers factory-trimmed 20% tolerance specifically for 3.0V rails, eliminates pull-up dependency via push-pull output, and achieves lowest quiescent current-making it optimal for cost-sensitive, space-constrained, fixed-voltage supervision.

Availability

DS1817R-20-U is available at Aetrix Electronics and suitable for industrial control, smart metering, IoT edge nodes, and portable medical devices requiring stable component supply and long-lifecycle availability.

Supply support for DS1817R-20-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

Analog Devices (via acquisition of Maxim Integrated) designs precision analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.

The DS1817R-20-U belongs to Maxim's EconoReset™ family-engineered for low-cost, reliable power-supply monitoring and microprocessor reset in resource-constrained embedded systems.

FAQ

What is the exact V_CC trip voltage range for DS1817R-20-U?

The DS1817R-20-U has a factory-set 20% tolerance trip point for nominal 3.0V systems, with guaranteed V_CC trip range of 2.47V (min) to 2.64V (max) across -40°C to +85°C. This is verified per datasheet AC/DC electrical characteristics table and applies specifically to the DS1817R-20-U variant-not the -5 or -10 versions.

Does DS1817R-20-U require an external pull-up resistor on the RST pin?

No. The DS1817R-20-U features a push-pull active-high output stage capable of sourcing 350µA and sinking +10mA, allowing direct connection to CMOS/TTL inputs without external components. This reduces BOM count and PCB area versus open-drain alternatives like the MAX6326 series.

What is the guaranteed reset pulse width after V_CC recovery for DS1817R-20-U?

The DS1817R-20-U guarantees a reset pulse width between 100ms and 250ms after V_CC returns to tolerance, with typical duration of 150ms. This window ensures sufficient stabilization time for both power supply regulation and microprocessor clock circuitry before releasing the reset signal.

Can DS1817R-20-U operate from a 1.8V supply?

Yes. DS1817R-20-U supports V_CC from 1.2V to 5.5V per recommended operating conditions. However, its 20% trip threshold remains referenced to nominal 3.0V (2.47V–2.64V), so it functions as a fixed 3.0V supervisor even when powered from lower rails-provided the monitored rail meets that voltage range.

Is DS1817R-20-U available in TO-92 package?

No. DS1817R-20-U is specified and marked for SOT-23 package only. While the base DS1817 family includes TO-92 variants (e.g., DS1817R-20+), the "U" suffix denotes SOT-23 packaging per Maxim's part numbering convention and mechanical drawings.