Analog Devices Inc./Maxim Integrated DS1232LPS+

Overview

DS1232LPS+ from Maxim Integrated (formerly Dallas Semiconductor) is a low-power microprocessor supervisory IC that monitors VCC, implements watchdog timer functionality, and provides pushbutton reset control. It delivers 50 µA quiescent current, supports 5% or 10% VCC threshold detection (4.5 V or 4.75 V trip points), and guarantees ≥250 ms active reset pulse width. It is used in embedded systems requiring reliable power-up sequencing and software fault recovery.

For engineers reviewing the DS1232LPS+ datasheet, DS1232LPS+ pinout, DS1232LPS+ application, or DS1232LPS+ equivalent, key selection considerations include its dual RST/RST outputs (active-high and open-drain active-low), programmable watchdog timeout (150 ms / 600 ms / 1.2 s), TOL-selectable voltage tolerance, industrial temperature range (–40°C to +85°C), and 16-pin SOIC package compatibility.

Technical Context

The DS1232LPS+ integrates three independent monitoring functions: precision VCC supervision using a temperature-compensated bandgap reference and comparator, debounced pushbutton reset with guaranteed 250 ms minimum pulse width, and a non-disableable watchdog timer with TD-selectable timeouts (150 ms, 600 ms, or 1.2 s). Its dual-reset outputs support both CMOS- and TTL-compatible reset assertion.

It operates across 4.5 V to 5.5 V supply, features internal pull-up on PBRST (40 kΩ typical), and maintains valid RST logic levels down to VCC = 2.0 V. The device asserts reset during power-down when VCC falls below the selected threshold and holds reset active for ≥250 ms after power-up recovery.

Key Specifications

Pinout & Package

DS1232LPS+ is supplied in a 16-pin SOIC (300-mil) package with two NC (no-connect) pins per side. Pin 1 is top-left corner, pin 16 is bottom-right corner. Dual RST outputs provide flexibility for mixed-logic-level system interfacing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326US29D3+ and TPS3808G33DBVR, DS1232LPS+ uniquely combines 5 V supervision, user-programmable watchdog timing, hardware-debounced pushbutton reset, and dual-output reset signaling-all in one industrial-temperature 16-pin SOIC package.

Availability

DS1232LPS+ is available at Aetrix Electronics and suitable for industrial automation, medical handheld devices, telecom remote terminals, and smart energy metering applications requiring stable component supply and long-term lifecycle support.

Supply support for DS1232LPS+ 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 (acquired by Analog Devices in 2021) designs precision analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.

The DS1232LPS+ belongs to Maxim's MicroMonitor™ family of supervisory circuits, engineered specifically for robust microprocessor reset and watchdog control in harsh, unattended embedded environments.

FAQ

What is the function of the TOL pin on the DS1232LPS+?

The TOL pin on the DS1232LPS+ selects the VCC detection tolerance: when tied to GND, it configures a 5% trip point (~4.5 V); when tied to VCC, it configures a 10% trip point (~4.25 V). This allows system designers to match the DS1232LPS+ threshold to their microcontroller's minimum operating voltage or supply regulation margin without external resistors.

Does the DS1232LPS+ support disabling the watchdog timer?

No-the DS1232LPS+ watchdog timer cannot be disabled. As stated in the datasheet, "Watchdog can not be disabled. It must be strobed to avoid resets." The ST input must receive a high-to-low transition at least once per selected timeout interval (150 ms / 600 ms / 1.2 s) to prevent automatic reset assertion. This ensures fail-safe behavior in locked-up firmware scenarios.

How does the DS1232LPS+ handle power-up reset timing?

Upon power-up, the DS1232LPS+ holds both RST outputs active for a minimum of 250 ms after VCC rises above the selected trip threshold. This ensures the microprocessor and its clock circuitry fully stabilize before release. The timing is internally generated and independent of external capacitors, guaranteeing consistent reset duration across temperature and supply variations.

What is the purpose of having two RST pins on the DS1232LPS+?

The DS1232LPS+ provides two RST outputs: one active-high push-pull (RST) and one active-low open-drain (RST). This dual-output architecture supports mixed-logic systems-e.g., the push-pull RST drives CMOS inputs directly, while the open-drain RST enables wired-OR reset busing with other supervisors or processors. Both outputs are asserted simultaneously during any fault condition.

Is the DS1232LPS+ pin-compatible with earlier DS1232 variants?

No-DS1232LPS+ uses a 16-pin SOIC package with multiple NC pins, whereas standard DS1232 variants use 8-pin DIP, SOIC, or µ-SOP packages. The pin count, layout, and pin functions differ significantly; therefore, DS1232LPS+ is not a drop-in replacement for 8-pin DS1232 versions. Board redesign is required for migration.