Analog Devices Inc./Maxim Integrated DS1239S-10+

Overview

DS1239S-10+ from Maxim Integrated (now Analog Devices) is a power supply supervisor and memory backup controller for microprocessor systems, featuring 10% VCC monitoring threshold, active-low reset output (RST), power fail detection (PF), and dual PF outputs (active-high and active-low), used in battery-backed SRAM systems requiring orderly shutdown and nonvolatile memory protection.

For engineers reviewing the DS1239S-10+ datasheet, DS1239S-10+ pinout, DS1239S-10+ application, or DS1239S-10+ equivalent, key selection considerations include its VCC=+5V operation, VBAT=+3V battery input, PSI/PSO power sequencing control, NMI interrupt generation, and support for industrial temperature range (-40°C to +85°C) in SOIC package.

Technical Context

The DS1239S-10+ integrates power-on reset generation, power-fail warning with dual PF outputs, wake-up control (WC/SC), and external AC power switching via PSI/PSO interface - enabling keyboard-initiated startup/shutdown without AC switch. It replaces RC/RST pins of DS1236 with PSI/PSO while retaining NMOS-mode compatibility.

It provides unconditional write-protection of SRAM when VCC falls outside tolerance, converts CMOS SRAM to nonvolatile memory using VBAT, and delivers 10 µA PSI sink current for pushbutton debounce with 0.1 µF capacitor - supporting robust, low-power system-level power management in handheld and embedded applications.

Key Specifications

Pinout & Package

DS1239S-10+ is housed in a 16-pin SOIC (300-mil) package, pin-compatible with the 16-pin DIP variant. The device supports surface-mount assembly and occupies minimal PCB area while maintaining full functional equivalence to through-hole versions.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power supervision and memory backup applications.

Compared with DS1239S-5+, DS1239S-10+ offers greater noise margin for noisy 5V rails; compared with MAX690TSA+, it provides unique PSI/PSO-controlled AC power gating but omits watchdog functionality - making it optimal for keyboard-initiated power management in SRAM-based systems.

Availability

DS1239S-10+ is available at Aetrix Electronics and suitable for handheld medical devices, industrial PLC controllers, point-of-sale terminals, and smart energy meters requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.

Supply support for DS1239S-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 applications.

The DS1239S-10+ belongs to Maxim's MicroManager family - engineered specifically for microprocessor-based systems needing coordinated power sequencing, nonvolatile memory backup, and deterministic reset behavior under dynamic supply conditions.

FAQ

What is the primary function of the DS1239S-10+ in a microprocessor system?

The DS1239S-10+ serves as an integrated power supervisor and memory backup controller. It monitors the +5V VCC supply for 10% tolerance violations, generates a reliable active-low reset signal (RST), provides dual power-fail indicators (PF), and manages VBAT-backed SRAM integrity. In the DS1239S-10+, these functions coordinate to ensure deterministic startup, orderly shutdown, and nonvolatile data retention - critical for embedded systems where power reliability is essential.

How does the PSI/PSO interface on the DS1239S-10+ enable keyboard-controlled power sequencing?

The PSI (Power Supply Control Input) accepts a low-going signal from a keypad or pushbutton, causing the DS1239S-10+ to assert PSO (Power Supply Control Output) high for up to 500 ms - sufficient to trigger an opto-SCR and turn on the AC-to-DC power supply. Once VCC stabilizes, a subsequent PSI low pulse tristates PSO to shut down power. This eliminates the need for mechanical switches and enables soft power control - a core capability of the DS1239S-10+.

Does the DS1239S-10+ support industrial temperature operation?

Yes, the DS1239S-10+ is specified for operation from -40°C to +85°C, meeting industrial temperature requirements. This rating is explicitly confirmed in the Absolute Maximum Ratings table and applies to both SOIC and DIP packages. The DS1239S-10+ maintains full electrical performance - including 10% VCC monitoring accuracy, RST timing, and PF response - across this full range, making it suitable for deployment in harsh environments where the DS1239S-10+ is the designated industrial-grade variant.

What is the role of the dual PF pins on the DS1239S-10+?

The DS1239S-10+ provides two physically separate PF pins: one active-high and one active-low. This dual-output design allows direct connection to MCUs with either interrupt polarity preference - eliminating external inverters or level-shifting logic. Both PF signals assert simultaneously upon VCC dropping below 4.5V, giving firmware time to execute critical save routines before RST activates. This redundancy and flexibility are intrinsic to the DS1239S-10+ architecture.

Can the DS1239S-10+ be used to convert standard CMOS SRAM into nonvolatile memory?

Yes, the DS1239S-10+ enables nonvolatile operation of CMOS SRAM by controlling VCCO (Switched SRAM Supply Output) and asserting write-protection when VCC is out of tolerance. When main power fails, VCCO is disabled and SRAM is isolated, while VBAT maintains data retention. The DS1239S-10+ also unconditionally blocks write access to SRAM during brownout - ensuring data integrity. This complete memory backup functionality is a defining feature of the DS1239S-10+.