Analog Devices Inc./Maxim Integrated DS1232LPSN

Overview

DS1232LPSN from Maxim Integrated (formerly Dallas Semiconductor) is a low-power microprocessor supervisory IC that monitors VCC supply voltage, implements a watchdog timer, and manages pushbutton reset - with 50 µA quiescent current, 4.5–5.5 V operation, and dual active-high/active-low RST outputs. It is used in embedded systems requiring reliable power-up sequencing and fault recovery, such as industrial controllers and legacy microcontroller-based instrumentation.

For engineers reviewing the DS1232LPSN datasheet, DS1232LPSN pinout, DS1232LPSN application, or DS1232LPSN equivalent, key selection criteria include its 250 ms minimum reset pulse width, selectable 5% or 10% VCC trip tolerance via TOL pin, watchdog timeout options (150 ms / 600 ms / 1.2 s), industrial temperature range (−40°C to +85°C), and dual RST output configuration for compatibility with both active-high and open-drain reset logic.

Technical Context

The DS1232LPSN integrates three independent monitoring functions: precision VCC detection using a temperature-compensated bandgap reference and comparator, debounced pushbutton reset with guaranteed 250 ms minimum active pulse, and a non-disableable watchdog timer with timeout set by TD pin state (GND/float/VCC). All functions drive two complementary reset outputs: RST (active-high push-pull) and RST̅ (active-low open-drain).

Its power-fail detection triggers reset when VCC drops below 4.50 V (TOL = VCC) or 4.62 V (TOL = GND), and holds reset active for ≥250 ms after VCC recovery. The watchdog requires periodic ST strobe transitions; failure to strobe within the selected timeout causes automatic 250 ms reset assertion.

Key Specifications

Pinout & Package

DS1232LPSN is supplied in an 8-pin SOIC (150-mil) package, with pin 1 marked by a notch or dot. Pin assignments are identical to DS1232LPS-2 variant per manufacturer mechanical drawings.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1232LPSN, MAX692AESA+ offers lower power and smaller size but sacrifices dual-reset outputs and pushbutton debounce; TPS3823-50DBVR simplifies design with fixed threshold and minimal features but omits watchdog and manual reset entirely - making DS1232LPSN uniquely suited for legacy systems needing full-featured supervision in industrial temperature range.

Availability

DS1232LPSN is available at Aetrix Electronics and suitable for industrial PLC controllers, legacy medical instrumentation, point-of-sale terminals, and telecom line cards requiring stable component supply and long-lifecycle support.

Supply support for DS1232LPSN 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 DS1232LPSN belongs to Maxim's MicroMonitor™ supervisory IC family, engineered specifically for robust microprocessor reset and watchdog functionality in harsh industrial environments with wide temperature and supply voltage variation.

FAQ

What is the function of the TOL pin on the DS1232LPSN?

The TOL pin on the DS1232LPSN selects the VCC trip point tolerance: connecting TOL to GND sets a 5% threshold (~4.62 V), while connecting it to VCC sets a 10% threshold (~4.37 V). This allows system designers to match the DS1232LPSN's brown-out detection to the specific voltage margin requirements of their microprocessor or power supply, without modifying firmware or adding external components.

Does the DS1232LPSN support both active-high and active-low reset signaling?

Yes, the DS1232LPSN provides two independent reset outputs: RST (active-high push-pull) and RST̅ (active-low open-drain). This dual-output architecture enables direct connection to microcontrollers requiring either reset polarity - eliminating the need for external inverters or pull-up resistors in mixed-logic designs. The DS1232LPSN maintains both outputs synchronized during all reset events including power-up, power-down, watchdog timeout, and pushbutton assertion.

Can the watchdog timer in the DS1232LPSN be disabled?

No, the watchdog timer in the DS1232LPSN cannot be disabled. It is a hardwired, non-disableable function requiring periodic ST input strobing to prevent timeout. This design ensures continuous software supervision even if firmware inadvertently disables watchdog control registers - a critical safety feature for industrial and medical applications where unmonitored processor lockup could lead to hazardous conditions. The DS1232LPSN watchdog must be strobed at intervals less than the selected timeout (150 ms / 600 ms / 1.2 s).

What is the minimum reset pulse width guaranteed by the DS1232LPSN?

The DS1232LPSN guarantees a minimum reset pulse width of 250 ms for both RST and RST̅ outputs across all trigger sources - power-up, power-fail, pushbutton release, and watchdog timeout. This duration exceeds the reset hold time requirements of most 8-bit and 16-bit microcontrollers (e.g., Intel 80Cxx, Motorola 68HCxx), ensuring reliable initialization of internal registers, clocks, and memory subsystems before program execution resumes.

How does the DS1232LPSN handle pushbutton reset input debouncing?

The DS1232LPSN internally debounces the PBRST input using hardware timing logic, eliminating the need for external RC filters or firmware polling. When the pushbutton is released (transitioning PBRST from low to high), the DS1232LPSN initiates a precisely timed ≥250 ms reset pulse on both RST and RST̅ outputs. This behavior ensures clean, bounce-free reset assertion regardless of mechanical switch quality or environmental vibration - a key reliability feature for field-deployed equipment using the DS1232LPSN.