Analog Devices Inc./Maxim Integrated DS1817R-20/T&R

Overview

DS1817R-20/T&R 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% VCC 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/T&R datasheet, DS1817R-20/T&R pinout, DS1817R-20/T&R application, or DS1817R-20/T&R equivalent, key selection criteria include trip point accuracy, reset timeout stability, push-pull drive capability, supply current (<35µA), and compatibility with low-voltage 3.0V microcontroller power rails.

Technical Context

The DS1817R-20/T&R integrates a temperature-compensated voltage reference and comparator to detect VCC deviations beyond ±20% of nominal 3.0V. Its internal circuitry asserts RST immediately on undervoltage and holds it active for 100–250ms after VCC returns to tolerance - ensuring reliable processor initialization.

It uses CMOS output stage with VOH ≥ VCC−0.1V at 0–500µA load and IOL = +10mA sink capability, enabling direct interface with TTL/CMOS inputs without external pull-ups. No external components are required for basic reset functionality.

Key Specifications

Pinout & Package

SOT-23-3 surface-mount package (3.0mm × 1.7mm × 1.3mm height), RoHS-compliant, tape-and-reel format (T&R).

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1817R-20/T&R, MAX6326UT29D+T offers lower quiescent current but lacks push-pull drive, while TPS3808G12DBVR provides programmability at the cost of added external components - making DS1817R-20/T&R optimal for fixed 3.0V systems prioritizing simplicity and robustness.

Availability

DS1817R-20/T&R is available at Aetrix Electronics and suitable for industrial control panels, smart utility meters, embedded gateways, and IoT sensor hubs requiring stable component supply and long-term manufacturability.

Supply support for DS1817R-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

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/T&R belongs to the EconoReset™ family of supervisory circuits, engineered specifically for cost-sensitive, high-volume applications needing reliable power-on reset and brownout protection without external components.

FAQ

What is the exact VCC trip voltage range for DS1817R-20/T&R?

The DS1817R-20/T&R has a guaranteed VCC trip point range of 2.47V (minimum) to 2.64V (maximum) at -40°C to +85°C, corresponding to ±20% tolerance around a nominal 3.0V supply. This range is factory-trimmed and temperature-compensated, ensuring consistent brownout detection across operating conditions without external calibration. The DS1817R-20/T&R datasheet specifies VCCTP under DC electrical characteristics with test conditions explicitly defined.

Does DS1817R-20/T&R require an external pull-up resistor on the RST pin?

No, DS1817R-20/T&R does not require an external pull-up resistor because it features a push-pull active-high output stage. The RST pin drives high (VOH ≥ VCC−0.1V) and low (VOL ≤ 0.4V at 10mA) directly, enabling direct connection to microcontroller reset inputs without additional components. This simplifies layout and reduces BOM count - a key advantage confirmed in the DS1817R-20/T&R pin assignment and electrical specifications.

Can DS1817R-20/T&R be used with a 3.3V microcontroller supply?

Yes, DS1817R-20/T&R can supervise a 3.3V system if configured for appropriate trip margin, but its 20%-tolerance variant (2.47V–2.64V) is optimized for 3.0V nominal rails. Using it on 3.3V may result in premature reset assertion. For 3.3V systems, consider DS1817R-10/T&R (2.80V–2.97V) instead. The DS1817R-20/T&R datasheet explicitly defines trip points per variant code and warns against mismatched voltage targeting.

What is the maximum capacitive load the RST output of DS1817R-20/T&R can drive?

The DS1817R-20/T&R RST output is characterized for COUT ≤ 10pF, and its drive strength supports up to +10mA sink current and ≥ VCC−0.1V high-level output at 500µA load. While not rated for heavy capacitive loads, it reliably interfaces with standard CMOS/TTL inputs and typical MCU reset pins (typically < 5pF). Exceeding 10pF may degrade timing margins - verified in AC electrical characteristics and timing diagrams of the DS1817R-20/T&R datasheet.

Is DS1817R-20/T&R compatible with lead-free reflow soldering processes?

Yes, DS1817R-20/T&R in SOT-23 package is rated for lead-free reflow with peak soldering temperature of 260°C for 10 seconds, as specified in the Absolute Maximum Ratings table. Its packaging meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for surface-mount assembly. This qualification is documented in the DS1817R-20/T&R mechanical drawings and packaging section.