Analog Devices Inc./Maxim Integrated DS1819CR-20+T&R

Overview

DS1819CR-20+T&R from Maxim Integrated is a 3.3V microprocessor supervisory circuit in SOT-23-5 package, providing precision power monitoring (20% trip point at 2.55–2.70 V), watchdog timer (1.12 s timeout), and pushbutton reset with 140 ms active-low reset pulse. It halts and restarts out-of-control microprocessors during power transients or software lockup in embedded control systems.

For engineers reviewing the DS1819CR-20+T&R datasheet, DS1819CR-20+T&R pinout, DS1819CR-20+T&R application, or DS1819CR-20+T&R equivalent, key selection criteria include VCC trip accuracy (±20% for 3.0 V systems), watchdog strobe timing compatibility, pushbutton debounce behavior, and SOT-23-5 footprint constraints in space-constrained industrial controllers.

Technical Context

The DS1819CR-20+T&R implements a precision voltage monitor with 5 mV hysteresis, a 1.12 s watchdog timer triggered by ST input transitions, and a debounced PBRST input that generates a minimum 140 ms active-low RST pulse upon button release. Its push-pull RST output remains valid down to 1.0 V VCC, and supports 0 V operation with external pull-down.

It belongs to the DS1819 'C' variant family, featuring both active-low RST (Pin 1) and active-high RST (Pin 3), plus PBRST (Pin 4) - distinguishing it from 'A' (RST + PBRST) and 'B' (RST + RST + ST) variants. The -20 suffix confirms ±20% VCC trip tolerance optimized for 3.0 V nominal systems.

Key Specifications

Pinout & Package

SOT-23-5 surface-mount package (1.6 mm × 2.9 mm × 1.1 mm), lead-free and RoHS-compliant, optimized for high-density PCB layouts in compact embedded systems.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX823SEUK+T and TPS3808G33DBVR, the DS1819CR-20+T&R uniquely integrates power monitoring, watchdog timer, and pushbutton reset in one SOT-23-5 package - reducing BOM count and PCB area while enabling full system-level fault recovery without external logic.

Availability

DS1819CR-20+T&R is available at Aetrix Electronics and suitable for industrial PLC controllers, smart metering modules, medical handheld diagnostics, and automotive body control units requiring stable component supply and long-term lifecycle assurance.

Supply support for DS1819CR-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 DS1819CR-20+T&R belongs to the MicroMonitor™ supervisory product line, engineered to provide integrated power, watchdog, and reset control for resource-constrained microprocessor systems operating at 3.0 V.

FAQ

What is the exact VCC trip voltage range for DS1819CR-20+T&R?

The DS1819CR-20+T&R has a guaranteed VCC trip point of 2.55 V to 2.70 V, corresponding to ±20% tolerance around a nominal 3.0 V supply. This range is specified over the full industrial temperature range (−40 °C to +85 °C) and ensures reliable reset assertion before brownout-induced MCU malfunction. The DS1819CR-20+T&R achieves this using an internal temperature-compensated voltage reference and comparator circuit.

Does DS1819CR-20+T&R support both active-low and active-high reset outputs?

Yes, the DS1819CR-20+T&R provides two independent reset outputs: Pin 1 (RST) is active-low, and Pin 3 (RST) is active-high. This dual-output capability allows direct interfacing with MCUs requiring either polarity without external inverters. Both outputs are asserted simultaneously during power failure, watchdog timeout, or PBRST activation, and remain active for a minimum of 140 ms.

Can the watchdog timer in DS1819CR-20+T&R be disabled?

Yes, the watchdog timer in DS1819CR-20+T&R can be disabled by leaving the ST (strobe) input floating or tri-stated. When ST is not toggled within the 1.12 s timeout window, the watchdog forces reset outputs active. Disabling it removes this software-execution monitoring function while preserving power monitoring and pushbutton reset. The DS1819CR-20+T&R datasheet confirms this behavior applies to all 'A' and 'B' variants - and since DS1819CR-20+T&R is a 'C' variant, ST is not assigned, so watchdog is inherently disabled.

What is the function of Pin 4 (PBRST) on DS1819CR-20+T&R?

Pin 4 (PBRST) on DS1819CR-20+T&R is a debounced pushbutton reset input. It accepts an active-low signal, internally pulls up to VCC (~50 kΩ), and generates a clean 140 ms minimum active-low reset pulse on RST (Pin 1) upon button release. This eliminates mechanical switch bounce and EMI-induced false triggers, making DS1819CR-20+T&R suitable for front-panel reset interfaces in industrial and medical equipment.

Is DS1819CR-20+T&R pin-compatible with MAX823 series devices?

Yes, DS1819CR-20+T&R is explicitly stated as pin- and function-compatible with the MAX823/24/25 family. It shares the same SOT-23-5 footprint and identical pin assignments (RST, GND, RST, PBRST, VCC), enabling direct substitution in existing designs. However, note that MAX823 variants are 5 V–only and lack PBRST - so DS1819CR-20+T&R offers enhanced functionality while maintaining backward compatibility where PBRST is unused.