Analog Devices Inc./Maxim Integrated DS1632

Overview

DS1632 from Maxim Integrated is a PC power-fail and reset controller IC with integrated 32.768 kHz crystal oscillator, ±2 min/month RTC accuracy, 5% or 10% VCC monitoring tolerance, 95 ms/190 ms selectable reset pulse width, and battery-backed VCCO switching for real-time clock support in laptop/notebook chipsets.

For engineers reviewing the DS1632 datasheet, DS1632 pinout, DS1632 application, or DS1632 equivalent, key selection considerations include VCC trip point selectability (4.50–4.75 V or 4.25–4.50 V), dual reset timing modes, low-battery warning outputs, pushbutton reset debouncing, and CMOS-compatible open-drain PF/LB/RST signaling.

Technical Context

The DS1632 integrates three functional blocks: a battery-backed 32.768 kHz crystal oscillator (CL = 6 pF, VBAT > 2.3 V required), a precision VCC comparator with TOL-pin-selectable trip thresholds, and a VCC/VBAT priority switch delivering regulated VCCO output with <0.3 V drop.

Its reset logic combines power-up, power-down, and pushbutton-triggered events with RD-pin-configurable delays (9/18 ms activation, 95/190 ms hold), while LB, PF, and RST outputs are open-drain with guaranteed VOL ≤ 0.4 V and VOH ≥ VCC−0.5 V under load.

Key Specifications

Pinout & Package

Available in 16-pin DIP (300-mil) and 16-pin SOIC (300-mil) packages. Pin functions validated per Maxim DS1632 datasheet Rev. 0.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power-fail and reset controller applications.

Compared with MAX690 and DS1233M, the DS1632 uniquely integrates oscillator, selectable VCC trip, battery monitoring, and VCCO switching-enabling full RTC power management in a single 16-pin package without external components.

Availability

DS1632 is available at Aetrix Electronics and suitable for laptop RTC support, notebook power monitoring, desktop power-fail signaling, industrial control panel battery backup, and embedded system reset management requiring stable component supply across production lifecycles.

Supply support for DS1632 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 semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, computing, and communications systems.

The DS1632 belongs to Maxim's PC peripheral controller product line, designed specifically to consolidate power monitoring, reset generation, and RTC support into a single IC for space-constrained laptop and desktop motherboard designs.

FAQ

What is the function of the RD pin on the DS1632?

The RD pin on the DS1632 selects reset pulse duration: tied to GND it configures a 95 ms active reset hold time after power recovery, and tied to VCC it sets 190 ms. This timing ensures microprocessor clocks and power supplies stabilize before reset deassertion. The DS1632 uses this pin to guarantee reliable boot sequencing without external timing components.

Does the DS1632 require an external crystal?

Yes, the DS1632 requires an external 32.768 kHz tuning-fork crystal connected to X1 and X2 pins. It supports crystals with 6 pF load capacitance (e.g., Daiwa DT26S or Seiko DS-VT-200) and delivers ±2 minutes/month RTC accuracy. The DS1632 itself contains the oscillator circuitry but not the resonator.

How does the DS1632 handle power switchover between VCC and VBAT?

The DS1632 automatically routes power to VCCO from VCC when present, or from VBAT when VCC falls below VBAT and VBAT > 2.3 V. Its internal switch exhibits <0.3 V dropout, ensuring stable RTC supply during transitions. The DS1632 maintains OSCOUT and VCCO operation while driving other outputs to safe states to minimize battery drain.

What are the voltage thresholds for power-fail detection on the DS1632?

The DS1632 offers two VCC trip windows: 4.50–4.75 V (5% tolerance, TOL = GND) or 4.25–4.50 V (10% tolerance, TOL = VCC). These thresholds are precision-comparator based and factory-trimmed. The DS1632 asserts PF outputs immediately upon crossing either threshold and holds RST active for configurable duration post-recovery.

Are the RST, PF, and LB outputs of the DS1632 compatible with standard logic inputs?

Yes - RST, PF, and LB are open-drain outputs rated for 4 mA sink current at 0.4 V, compatible with TTL and CMOS interrupt or enable inputs. External pull-ups are required. The DS1632 guarantees VOL ≤ 0.4 V and VOH ≥ VCC−0.5 V, ensuring noise margin and direct interfacing with common microcontrollers without level shifters.