Analog Devices Inc./Maxim Integrated DS1232LPU+T&R

Overview

DS1232LPU+T&R from Maxim Integrated (acquired by Analog Devices) is a low-power microprocessor supervisory IC that monitors VCC supply voltage, detects software lockups via watchdog timer, and accepts pushbutton reset inputs. It delivers active-high and open-drain active-low reset outputs, supports 5% or 10% VCC tolerance selection, and operates across -40°C to +85°C in 8-pin SOIC package - used in embedded controllers requiring reliable power-up/power-down sequencing and fail-safe restart.

For engineers reviewing the DS1232LPU+T&R datasheet, DS1232LPU+T&R pinout, DS1232LPU+T&R application, or DS1232LPU+T&R equivalent, key selection criteria include dual-reset output polarity, 250 ms minimum reset pulse width, selectable watchdog timeout (150/600/1200 ms), 50 µA quiescent current, and industrial-temperature operation with VCC trip points of 4.62 V (5%) or 4.37 V (10%).

Technical Context

The DS1232LPU+T&R integrates three independent monitoring functions: precision VCC comparator with temperature-compensated reference, debounced pushbutton reset input with 250 ms guaranteed pulse width, and programmable watchdog timer with three timeout options set via TD pin logic state. All functions drive dual RST outputs - one CMOS active-high, one open-drain active-low - enabling direct interface to diverse microprocessor reset inputs.

Its power-fail detection asserts reset when VCC drops below 4.62 V (TOL = GND) or 4.37 V (TOL = VCC), and holds reset active for ≥250 ms after VCC recovery. The watchdog requires periodic ST strobe transitions; failure to strobe within selected timeout triggers identical reset assertion with same timing behavior.

Key Specifications

Pinout & Package

DS1232LPU+T&R is housed in an 8-pin SOIC (150-mil width) package, pin-compatible with DS1232LPS-2 variant. Pin assignments are electrically identical to the 8-pin DIP version, with no NC pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326US29D3+ and TPS3808G33DBVR, DS1232LPU+T&R uniquely integrates power monitoring, pushbutton reset, and programmable watchdog in one 8-pin SOIC - eliminating discrete components and PCB area while supporting full fail-safe supervision without firmware overhead.

Availability

DS1232LPU+T&R is available at Aetrix Electronics and suitable for industrial control systems, medical devices, automotive body electronics, and point-of-sale terminals requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for DS1232LPU+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, communications, and computing applications.

The DS1232LPU+T&R belongs to Maxim's MicroMonitor™ family of supervisory circuits, engineered specifically to ensure robust microprocessor startup, runtime integrity, and safe recovery in mission-critical embedded systems.

FAQ

What is the function of the TOL pin on DS1232LPU+T&R?

The TOL pin on DS1232LPU+T&R selects the VCC monitoring tolerance: when tied to GND, DS1232LPU+T&R triggers reset at 4.62 V (5% of 5 V); when tied to VCC, it triggers at 4.37 V (10%). This allows designers to balance noise immunity against early fault detection based on their system's power rail stability and layout constraints.

Does DS1232LPU+T&R support watchdog timer disable?

No, DS1232LPU+T&R does not support watchdog disable. The watchdog timer is always active and must be periodically strobed via the ST pin to prevent reset assertion. As stated in the datasheet note "Watchdog can not be disabled. It must be strobed to avoid resets." This ensures continuous runtime supervision in safety-critical applications using DS1232LPU+T&R.

What are the electrical characteristics of the RST and RST outputs on DS1232LPU+T&R?

DS1232LPU+T&R provides two reset outputs: RST is a CMOS active-high output capable of sourcing ≥8 mA at 2.4 V, while RST is an open-drain active-low output requiring an external pull-up and capable of sinking ≥10 mA at 0.4 V. Both outputs remain asserted for ≥250 ms during power-up, power-down, or watchdog timeout events.

Can DS1232LPU+T&R operate with a 3.3 V supply?

No, DS1232LPU+T&R is specified only for 4.5 V to 5.5 V operation per its Recommended DC Operating Conditions. Its VCC trip points (4.37 V / 4.62 V), internal reference, and output drive levels are optimized for 5 V systems. Using DS1232LPU+T&R with 3.3 V violates absolute maximum and operating specifications and will result in unreliable reset behavior.

How is the pushbutton reset input debounced in DS1232LPU+T&R?

The PBRST input on DS1232LPU+T&R is internally debounced and timed to guarantee a minimum 250 ms active reset pulse upon button release. The datasheet specifies tPB = 20 ms minimum debounce delay before recognition, and tRST ≥ 250 ms pulse width. No external RC network is required - DS1232LPU+T&R handles debouncing and timing autonomously.