Analog Devices Inc./Maxim Integrated DS1239-10+

Overview

DS1239-10+ from Maxim Integrated (now Analog Devices) is a microprocessor supervisory IC that provides power-up/down sequencing, reset generation, nonvolatile SRAM backup control, and power-fail warning in embedded systems. It features 10% VCC monitoring accuracy, active-low RST output, dual PF outputs (active-high and active-low), and supports battery-backed memory write-protection at VCC out-of-tolerance. Used in industrial controllers requiring orderly shutdown during brownout.

For engineers reviewing the DS1239-10+ datasheet, DS1239-10+ pinout, DS1239-10+ application, or DS1239-10+ equivalent, key selection criteria include its PSI/PSO power-control interface, dual PF signaling, VBAT-powered NMI assertion during power failure, WC/SC sleep/wake capability, and compatibility with DS1236-based designs requiring NMOS-mode timing and pin mapping.

Technical Context

The DS1239-10+ implements a dedicated power-supply control architecture using PSI (input) and PSO (output) to initiate AC-to-DC power-up via opto-SCR triggering, with tPSI = 200 ms minimum turn-on response and tPSP = 200–500 ms pulse width. It retains full functional equivalence to the DS1236 in NMOS mode except for RC→PSI and RST→PSO pin reassignments.

It monitors +5V supply (VCC) with ±10% threshold accuracy, asserts active-low RST during power transients, generates early-warning IN signal before PF, and unconditionally write-protects SRAM when VCC falls outside tolerance - all while consuming <100 nA from VBAT. The dual PF pins support both active-high and active-low interrupt logic for host microprocessor interfacing.

Key Specifications

Pinout & Package

DS1239-10+ is available in 16-pin plastic DIP (300-mil) and 16-pin SOIC (300-mil) packages. Both share identical pin mapping and thermal characteristics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1239-5+, the DS1239-10+ trades tighter voltage monitoring for lower cost and broader noise margin; compared with MAX690TSA+, it offers unique PSI/PSO sequencing but lacks watchdog functionality - making DS1239-10+ optimal for keyboard-initiated power management in legacy NMOS-mode systems.

Availability

DS1239-10+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, point-of-sale terminals, and energy meter data loggers requiring stable component supply and long-term obsolescence support.

Supply support for DS1239-10+ 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

Analog Devices (via acquisition of Maxim Integrated) designs precision analog, mixed-signal, and power management ICs for industrial, automotive, and communications infrastructure.

The DS1239-10+ belongs to Maxim's MicroManager family - engineered specifically for robust power sequencing, nonvolatile memory backup, and fail-safe reset control in microprocessor systems operating from AC/DC or battery hybrid supplies.

FAQ

What is the primary function of the DS1239-10+ in a microprocessor system?

The DS1239-10+ serves as a dedicated supervisory IC that manages power-up/down sequencing, generates reset signals, protects battery-backed SRAM during power loss, and warns the microprocessor of impending power failure. Its PSI/PSO interface enables keyboard-initiated AC power control, and its dual PF outputs support both active-high and active-low interrupt logic - all critical functions implemented within the DS1239-10+ without external components.

How does the DS1239-10+ differ from the DS1236?

The DS1239-10+ is functionally identical to the DS1236 in NMOS mode except for two pin replacements: RC is renamed PSI, and RST is replaced by PSO. All other pins, timing, and electrical behavior match the DS1236. This change enables direct integration into power-control architectures requiring active switching of external AC power supplies - a capability not supported by the original DS1236's RC/RST configuration.

What is the purpose of the WC/SC pin on the DS1239-10+?

The WC/SC (Wake-Up Control/Sleep Control) pin on the DS1239-10+ enables low-power "stop mode" operation in battery-powered handheld devices. When asserted, it halts the microprocessor clock while maintaining VCCO to preserve SRAM contents. Upon wake-up signal, the DS1239-10+ restores full operation - allowing systems like portable medical instruments to achieve µA-level standby current without losing volatile context.

Does the DS1239-10+ support industrial temperature range?

The DS1239-10+ is specified for 0°C to +70°C operation. An industrial-grade variant designated DS1239-10IND+ supports –40°C to +85°C, but the DS1239-10+ itself is not rated for extended temperature. Designs requiring industrial operation must verify thermal derating or select the IND version - the DS1239-10+ datasheet explicitly limits ambient operating range to commercial grade.

Can the DS1239-10+ be used to convert standard SRAM into nonvolatile memory?

Yes - the DS1239-10+ converts CMOS SRAM into nonvolatile memory by controlling VCCO (switched SRAM supply) and asserting unconditional write-protection when VCC falls out of tolerance. During power loss, it disconnects VCCO and disables write enables, preserving SRAM data powered solely by VBAT. This architecture is validated in DS1239-10+ applications including energy meters and medical loggers where data retention exceeds 10 years on a single CR2032 cell.