Analog Devices Inc./Maxim Integrated DS1819CR-5-U+

Overview

DS1819CR-5-U+ from Maxim Integrated is a 3.3V microprocessor supervisory circuit with watchdog timer, pushbutton reset control, and precision power supply monitoring. It provides active-low and active-high reset outputs, 140ms minimum reset pulse width, 1.12s watchdog timeout, and 5% VCC trip accuracy at 3.00V–3.15V for use in embedded microcontroller systems requiring reliable power-up/power-down sequencing.

For engineers reviewing the DS1819CR-5-U+ datasheet, DS1819CR-5-U+ pinout, DS1819CR-5-U+ application, or DS1819CR-5-U+ equivalent, key selection criteria include its SOT-23-5 package, dual-reset output capability, 3V-specific voltage threshold, watchdog strobe timing, and industrial temperature operation from –40°C to +85°C.

Technical Context

The DS1819CR-5-U+ implements a precision bandgap reference and comparator for VCC monitoring with 5mV hysteresis, ensuring stable reset assertion during brownout conditions. Its internal watchdog timer triggers reset if the ST input fails to toggle within 1.12 seconds, and it supports pushbutton debouncing via PBRST with ≥140ms active reset pulse generation upon button release.

This 'C' variant integrates both RST (active-low) and RST (active-high) outputs, uses a push-pull RST driver valid down to 1.0V VCC, and features an internally pulled-up PBRST input (50kΩ typical). The ST input requires ≥200µA drive capability and accepts TTL/CMOS-compatible logic levels referenced to VCC.

Key Specifications

Pinout & Package

SOT-23-5 surface-mount package with 1.6mm × 2.9mm footprint, 0.95mm height, and gull-wing leads compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX823SEUK+T and TPS3808G12DBVR, the DS1819CR-5-U+ uniquely combines 3.3V-specific monitoring, dual-reset outputs, integrated watchdog, and pushbutton support in a single SOT-23-5 device-reducing BOM count and eliminating design compromises in space-constrained embedded systems.

Availability

DS1819CR-5-U+ is available at Aetrix Electronics and suitable for industrial automation, medical handhelds, smart metering, and automotive body electronics requiring stable component supply across extended production lifecycles.

Supply support for DS1819CR-5-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

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The DS1819CR-5-U+ belongs to the MicroMonitor™ family, engineered specifically for robust microprocessor supervision in 3.3V embedded systems where reliability under voltage transients, software faults, and user intervention is critical.

FAQ

What is the exact VCC trip voltage range for DS1819CR-5-U+?

The DS1819CR-5-U+ has a specified VCC trip point of 3.00V to 3.15V, reflecting its 5% tolerance rating for 3.3V systems. This range is guaranteed over the full industrial temperature range (–40°C to +85°C) and includes 5mV hysteresis to prevent oscillation near the threshold. The trip point is set by an internal precision bandgap reference and comparator, not adjustable externally.

Does DS1819CR-5-U+ support both active-low and active-high reset outputs simultaneously?

Yes, DS1819CR-5-U+ provides both RST (pin 1, active-low) and RST (pin 3, active-high) outputs concurrently. This 'C' variant is specifically designed to drive mixed-logic microcontrollers or interface with peripherals requiring complementary reset signals-eliminating the need for external inverters or level shifters in dual-signaling architectures.

How does the watchdog function behave if the ST input is left unconnected?

If the ST input (pin 4) is left floating or tri-stated, the watchdog timer in DS1819CR-5-U+ is automatically disabled. No reset will be generated due to watchdog timeout, and the device operates solely as a power monitor and pushbutton supervisor. This behavior is intentional and documented in the datasheet as a hardware-based disable method.

Can DS1819CR-5-U+ generate a valid reset signal when VCC drops below 1.0V?

The RST output of DS1819CR-5-U+ remains valid down to 1.0V VCC in push-pull mode. To extend validity to 0V, a 100kΩ pull-down resistor from RST to GND is recommended per the datasheet (Figure 9). With this configuration, DS1819CR-5-U+ maintains a defined logic-low reset state throughout full power collapse, enabling controlled shutdown sequencing.

Is DS1819CR-5-U+ pin-compatible with MAX823-series devices?

Yes, DS1819CR-5-U+ is pin- and function-compatible with the MAX823/24/25 family in SOT-23-5 packages. However, functional equivalence depends on variant: DS1819CR-5-U+ matches MAX823's dual-output 'C' configuration but differs in voltage range (3.3V vs. 5V), trip accuracy (5% vs. 10%), and internal hysteresis (5mV vs. 10mV), requiring verification for drop-in replacement.