Analog Devices Inc./Maxim Integrated DS1819AR-20/T&R

Overview

DS1819AR-20/T&R from Maxim Integrated is a 3.3V microprocessor supervisory circuit in SOT-23-5 package, providing precision power monitoring (20% VCC trip tolerance at 2.55–2.70 V), watchdog timer (1.12 s timeout), and pushbutton reset with 140 ms minimum active-low reset pulse. It halts and restarts out-of-control microprocessors during power transients or software hangs in embedded control systems.

For engineers reviewing the DS1819AR-20/T&R datasheet, DS1819AR-20/T&R pinout, DS1819AR-20/T&R application, or DS1819AR-20/T&R equivalent, key selection criteria include VCC trip accuracy (±20% for 3.0 V systems), guaranteed 140 ms reset assertion time, watchdog strobe timing compatibility, push-pull RST output valid down to 1.0 V VCC, and industrial temperature operation (−40°C to +85°C).

Technical Context

The DS1819AR-20/T&R implements a precision bandgap-based voltage monitor with 5 mV hysteresis, a 1.12 s watchdog timer triggered by ST input transitions, and internal pushbutton debouncing logic that generates a clean 140–280 ms active-low reset pulse upon PBRST release. Its RST output uses a push-pull driver capable of sourcing 350 µA and sinking 3.2–6 mA.

It operates across 1.0–5.5 V supply range, supports tri-state disable of watchdog via floating ST, and maintains valid RST output down to 1.0 V VCC - extendable to 0 V with external 100 kΩ pull-down resistor. Input thresholds scale with VCC (VIH = 0.8×VCC, VIL = 0.3×VCC), ensuring robust noise immunity against <100 ns glitches on PBRST.

Key Specifications

Pinout & Package

SOT-23-5 surface-mount package (2.9 mm × 1.6 mm × 1.1 mm), lead-free and RoHS-compliant, optimized for space-constrained PCB layouts in industrial controllers and IoT edge nodes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX823SEUR+T and TPS3808G12DBVR, DS1819AR-20/T&R delivers integrated 3.0 V brownout detection, hardware-debounced pushbutton reset, and configurable watchdog - all in a pin-identical SOT-23-5 footprint with no external components required for basic operation.

Availability

DS1819AR-20/T&R is available at Aetrix Electronics and suitable for industrial PLC controllers, smart energy meters, IoT edge sensor nodes, and medical handheld diagnostics requiring stable component supply and long-term lifecycle support.

Supply support for DS1819AR-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 DS1819AR-20/T&R belongs to the MicroMonitor™ family of supervisory circuits, engineered specifically to replace discrete reset generators and watchdog timers in resource-constrained microcontroller systems operating at 3.3 V.

FAQ

What is the exact VCC trip voltage range for DS1819AR-20/T&R?

The DS1819AR-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 factory-trimmed and specified over the full industrial temperature range (−40°C to +85°C). The trip point is implemented using a precision bandgap reference and comparator, with 5 mV hysteresis to prevent chatter near threshold. DS1819AR-20/T&R does not require external resistors or calibration to achieve this accuracy.

Does DS1819AR-20/T&R support both watchdog and pushbutton reset functions simultaneously?

Yes, DS1819AR-20/T&R supports both functions concurrently. As a Type 'A' variant, it includes both the ST (strobe) input for watchdog timer reset and the PBRST (pushbutton reset) input with internal debouncing. The RST output responds to any active condition - power failure, watchdog timeout, or PBRST activation - with a minimum 140 ms active-low pulse. DS1819AR-20/T&R is explicitly documented as supporting both features in its 'A' configuration per the device marking code table and functional block diagram.

Can DS1819AR-20/T&R operate below 3.0 V, and what happens to RST output validity?

Yes, DS1819AR-20/T&R operates from 1.0 V to 5.5 V. Its RST output remains valid down to 1.0 V VCC using an internal push-pull driver. Below 1.0 V, a 100 kΩ external pull-down resistor from RST to GND extends valid reset assertion down to 0 V VCC - critical for controlled shutdown in battery-depleted or power-fail scenarios. This behavior is confirmed in the "OUTPUT VALID CONDITIONS" section and Figure 9 of the official datasheet.

Is DS1819AR-20/T&R pin-compatible with MAX823 series devices?

DS1819AR-20/T&R is pin- and function-compatible with the MAX823/24/25 family *only for the 'A' variant configuration*. Specifically, DS1819A shares identical pinout (RST/GND/PBRST/ST/VCC) and core supervision functions with MAX823. However, MAX823 is 5 V-only (4.50–4.75 V trip), while DS1819AR-20/T&R is optimized for 3.0 V systems. Board-level substitution requires verifying voltage compatibility and confirming the target MAX823 variant supports PBRST and ST on same pins.

What is the maximum allowed slew rate for VCC during power-up to ensure reliable reset timing?

The DS1819AR-20/T&R specifies a minimum VCC slew rate of 12.5 V/s during rising edge to guarantee proper reset assertion timing. If VCC rises slower than this, the internal power-on reset circuit may not meet the guaranteed 140 ms minimum RST active time after VCC exceeds the trip threshold. This requirement ensures the comparator and timing circuitry stabilize before releasing reset. The value is measured from VCC = 0 V to trip voltage and is validated across temperature and process corners per the AC Electrical Characteristics table.