Analog Devices Inc./Maxim Integrated DS1232LP

Overview

DS1232LP from Maxim Integrated (formerly Dallas Semiconductor) is a low-power microprocessor supervisory IC that monitors VCC supply voltage, implements a watchdog timer, and debounces pushbutton reset inputs. It delivers 50 µA quiescent current, 250 ms minimum reset pulse width, and selectable 5% or 10% VCC trip thresholds (4.75 V or 4.5 V), used in embedded microcontroller systems requiring reliable power-up/power-down sequencing and fault recovery.

For engineers reviewing the DS1232LP datasheet, DS1232LP pinout, DS1232LP application, or DS1232LP equivalent, key selection considerations include its dual active-high/active-low RST outputs, 8-pin SOIC (150-mil) package, industrial temperature support (-40°C to +85°C), and fixed watchdog timeout options (150 ms / 600 ms / 1.2 s) set via TD pin configuration.

Technical Context

The DS1232LP integrates three independent monitoring functions: precision VCC detection using a temperature-compensated bandgap reference and comparator, a hardware-debounced pushbutton reset input (PBRST) with guaranteed 250 ms active reset pulse, and a non-disableable watchdog timer triggered by ST strobe transitions. All reset outputs remain active for ≥250 ms after power-up or power-fail events.

Its dual RST outputs (one active-high CMOS, one active-low open-drain) enable direct interfacing with both standard and legacy microcontrollers. The TOL pin selects between 4.75 V (TOL = GND) and 4.5 V (TOL = VCC) VCC trip points, while TD configures watchdog timeout without external components.

Key Specifications

Pinout & Package

DS1232LP is supplied in an 8-pin SOIC package (150-mil width), with lead finish SnPb and RoHS-compliant variants available per ordering suffix. Pinout is identical across DS1232LP/LPS 8-pin variants.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692CPA+ and TPS3823-50DBVR, the DS1232LP uniquely integrates power monitoring, debounced pushbutton reset, and configurable hardware watchdog in one 8-pin SOIC - eliminating three discrete functions and reducing BOM count without sacrificing industrial temperature range or reset timing guarantees.

Availability

DS1232LP is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, point-of-sale terminals, and smart energy meters requiring stable component supply and long-term lifecycle support.

Supply support for DS1232LP 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 applications.

The DS1232LP belongs to Maxim's MicroMonitor™ family of supervisory circuits, engineered specifically for robust, low-power microprocessor reset and watchdog functionality in harsh or battery-constrained environments.

FAQ

What is the function of the TOL pin on the DS1232LP?

The TOL pin on the DS1232LP selects the VCC trip threshold: connecting TOL to GND sets a 4.75 V threshold (±5%), while connecting it to VCC sets a 4.5 V threshold (±10%). This allows designers to match the DS1232LP's power-fail detection to their system's 5 V supply tolerance. The DS1232LP uses this setting to determine when to assert RST and RST̅ during brownout conditions.

Does the DS1232LP require external components to operate its watchdog timer?

No, the DS1232LP watchdog timer requires no external capacitors or resistors. Timeout duration is selected solely by the TD pin state: grounded for ~150 ms, floating for ~600 ms, or tied to VCC for ~1.2 s. The DS1232LP initiates timing on RST deactivation and resets the timer on each ST high-to-low transition - making the DS1232LP fully self-contained for watchdog supervision.

Can the DS1232LP replace the DS1232L in existing designs?

Yes, the DS1232LP is a drop-in replacement for the DS1232L in 8-pin packages, sharing identical pinout, electrical characteristics, and functional behavior - except for reduced quiescent current (50 µA vs. 200–500 µA). The DS1232LP maintains full compatibility with legacy DS1232L layouts and firmware, delivering enhanced battery life without design changes.

What is the purpose of having both RST and RST̅ outputs on the DS1232LP?

The DS1232LP provides RST (active-high CMOS) and RST̅ (active-low open-drain) to support diverse microcontroller reset architectures. RST interfaces directly with MCUs requiring active-high reset, while RST̅ accommodates those needing active-low with configurable pull-up voltage. This dual-output design eliminates external inverters or level translators, and the DS1232LP asserts both simultaneously during all reset events.

Is the DS1232LP watchdog timer disableable?

No, the DS1232LP watchdog timer cannot be disabled - it is inherently active once power is applied. The DS1232LP requires periodic ST strobing to prevent timeout; failure to do so forces RST/RST̅ active for ≥250 ms. This design ensures continuous runtime integrity and prevents accidental or malicious watchdog deactivation, a critical requirement for safety-critical applications using the DS1232LP.