Analog Devices Inc./Maxim Integrated DS1210S+

Overview

DS1210S+ from Maxim Integrated is a nonvolatile RAM controller IC that converts standard CMOS SRAM into battery-backed nonvolatile memory. It provides automatic power-fail detection (4.5V–4.74V trip range), unconditional write protection, seamless VCCI-to-battery switchover, <100nA battery current draw, and dual-battery redundancy support. It is used in real-time clock backup, industrial data loggers, and embedded systems requiring persistent RAM during AC loss.

For engineers reviewing the DS1210S+ datasheet, DS1210S+ pinout, DS1210S+ application, or DS1210S+ equivalent, key selection criteria include its 16-pin SO package, TOL-pin configurable power-fail threshold (4.25V or 4.5V), CEO-controlled RAM write-enable gating, battery status warning at <2.0V, and industrial-grade (-40°C to +85°C) variants (DS1210SN+).

Technical Context

The DS1210S+ implements five tightly integrated functions: (1) low-drop (<0.3V) bidirectional power switch between VCCI and VBAT1/2; (2) precision comparator-based power-fail detection with TOL-pin selectable trip points (4.25V/4.5V); (3) CEO output that holds RAM write-enable state during power transition to prevent partial writes; (4) automatic battery voltage check at power-up, inhibiting second memory cycle if VBAT <2.0V; and (5) internal isolation switch enabling transparent dual-battery redundancy with automatic highest-voltage selection.

It operates across 0°C to +70°C (standard) or -40°C to +85°C (N variant), supports 2.0V–4.0V battery inputs, delivers up to 80mA ICCO1 to SRAM, and maintains CEO propagation delay ≤20ns under nominal VCCI. The device is UL-recognized (E99151) and RoHS-compliant.

Key Specifications

Pinout & Package

DS1210S+ is housed in a 16-pin small-outline (SO) package, 300 mils wide, with gull-wing leads and RoHS-compliant finish (+ suffix). Thermal resistance is θJA = 70°C/W per JEDEC JESD51-7 (four-layer board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nonvolatile RAM controller applications.

Compared with DS1210S+, DS1216H+ trades external flexibility for integration density and simplified BOM, while MAX6900 replaces parallel control with serial interface and adds RTC functionality - neither offers identical CEO-gated, TOL-configurable, dual-battery SRAM supervision.

Availability

DS1210S+ is available at Aetrix Electronics and suitable for industrial data loggers, real-time clock backup systems, and POS terminal memory retention requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.

Supply support for DS1210S+ 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) is a U.S.-based semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, computing, and communications markets.

The DS1210S+ belongs to Maxim's nonvolatile memory controller product line, designed specifically to enable reliable, low-power, hardware-gated SRAM backup in mission-critical embedded systems without software intervention.

FAQ

What is the function of the TOL pin on the DS1210S+?

The TOL pin on the DS1210S+ selects the power-fail detection threshold: when grounded, it sets VCCTP to 4.50–4.74V; when tied to VCCO, it lowers VCCTP to 4.25–4.49V. This allows designers to match the DS1210S+ trip point precisely to their system's 5V rail tolerance specification without external components. The DS1210S+ uses this signal to trigger CEO-driven write protection and battery switchover.

How does the DS1210S+ handle dual-battery redundancy?

The DS1210S+ supports dual-battery redundancy via dedicated VBAT1 and VBAT2 pins and an internal isolation switch. During battery backup, it automatically selects the higher-voltage battery; if that battery drops below 2.0V, the DS1210S+ issues a status warning and seamlessly transfers load to the secondary battery. No firmware or external logic is needed - the failover is fully transparent and hardware-managed.

Can the DS1210S+ be used with a single battery?

Yes - the DS1210S+ fully supports single-battery operation. Connect the battery to VBAT1 and ground VBAT2. The DS1210S+ disables the redundant path and operates identically to dual-battery mode, including battery voltage checking and write protection. Grounding VBAT2 prevents false battery-fail warnings and ensures optimal current efficiency in the single-source configuration.

What is the maximum SRAM load current the DS1210S+ can drive on VCCO?

The DS1210S+ guarantees up to 80mA average load current on VCCO (ICCO1) under nominal VCCI conditions, sufficient to power typical 32k×8 or 64k×8 CMOS SRAMs. In battery backup mode, it delivers up to 50µA (ICCO2) at VCCO = VBAT – 0.3V. Exceeding these limits risks undervoltage or premature battery depletion - always verify SRAM ICC02 and total system leakage against DS1210S+ specifications.

Does the DS1210S+ require external components for basic operation?

No - the DS1210S+ requires no external resistors, capacitors, or diodes for core functionality. Its precision voltage detection, low-leakage switching, and battery monitoring are fully integrated. Only the SRAM, batteries, and optional pull-up on CE (if open-drain host) are needed. This minimizes BOM count, PCB area, and qualification effort - a key advantage over discrete supervisor + switch solutions.