Analog Devices Inc. ADM692SQ

Overview

ADM692SQ from Analog Devices is a precision microprocessor supervisory circuit with 4.40 V reset threshold, 200 ms reset timeout, 1.6 s watchdog timer, and automatic battery switchover for CMOS RAM backup. It operates over –40°C to +85°C and asserts RESET down to 1 V VCC, enabling reliable system reset during brownout in industrial controllers and embedded instrumentation.

For engineers reviewing the ADM692SQ datasheet, ADM692SQ pinout, ADM692SQ application, or ADM692SQ equivalent, key selection considerations include its 4.40 V reset threshold (vs. 4.65 V on ADM690A), battery switchover hysteresis of 40 mV, PFI comparator reference at 1.25 V, and compatibility with SO-8 and DIP-8 packages for legacy board reuse.

Technical Context

The ADM692SQ integrates four core functions in a single 8-pin IC: a precision voltage monitor with 4.40 V threshold and 40 mV hysteresis, a 1.6 s watchdog timer triggered by WDI transitions, a battery switchover circuit with <1 Ω on-resistance and 0.05 µA standby current, and a 1.25 V referenced power fail comparator with ±2% accuracy on PFI input.

Its RESET output remains functional down to 1 V VCC, ensuring deterministic microprocessor hold during deep brownout. The internal PMOS switch connects VBATT to VOUT only when VCC falls below VBATT by 20 mV (power-down) or rises above VBATT by 20 mV (power-up), providing clean, glitch-free backup switching without external components.

Key Specifications

Pinout & Package

ADM692SQ is available in 8-pin SOIC (SO-8) and plastic DIP (N-8) packages. Pinout is identical across both packages and matches MAX692A pin compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692A and TPS3823-44, the ADM692SQ uniquely combines guaranteed 1 V RESET operation, sub-µA battery backup current, and integrated watchdog/battery switchover-making it irreplaceable in systems requiring deterministic brownout behavior and long-term memory retention without external support circuitry.

Availability

ADM692SQ is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostic equipment, telecom line cards, and automotive infotainment head units requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADM692SQ 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 is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The ADM692SQ belongs to Analog Devices' microprocessor supervisory circuit family, designed specifically to consolidate reset generation, battery backup management, watchdog supervision, and power-fail warning into a single robust IC for mission-critical embedded systems.

FAQ

What is the guaranteed reset voltage threshold for ADM692SQ?

The ADM692SQ has a guaranteed reset voltage threshold of 4.25 V minimum to 4.50 V maximum, with a typical value of 4.40 V. This specification is tested across the full –40°C to +85°C operating temperature range and ensures reliable reset activation before the 5 V supply falls outside microprocessor operational limits. The ADM692SQ's 4.40 V threshold distinguishes it from the 4.65 V ADM690A variant and aligns with tighter industrial 5 V rail tolerances.

Does ADM692SQ support battery backup for CMOS RAM, and how does switchover work?

Yes, ADM692SQ supports automatic battery backup for CMOS RAM via its integrated VBATT-to-VOUT switchover circuit. When VCC falls below the reset threshold and drops 20 mV below VBATT, the internal PMOS switch connects VBATT to VOUT. On power-up, VOUT reverts to VCC when VCC rises 20 mV above VBATT. The ADM692SQ draws only 0.05 µA in battery backup mode, enabling multi-year retention with standard 3 V coin cells or supercapacitors.

Can the watchdog timer in ADM692SQ be disabled, and how?

Yes, the watchdog timer in ADM692SQ can be disabled by leaving the WDI pin floating or connecting it to a high-impedance (three-state) logic output. The WDI input is a three-level interface: high, low, or floating. When floating, the internal watchdog transition detector is inactive, and no RESET pulses are generated due to timeout. This hardware-based disable method requires no firmware intervention and avoids external pull resistors.

What is the function of the PFI and PFO pins on ADM692SQ?

The PFI (Power Fail Input) pin on ADM692SQ connects to a resistor divider monitoring an external power rail; it compares that voltage against an internal 1.25 V reference. When the divided voltage falls below 1.25 V, the PFO (Power Fail Output) pin goes low to signal impending power loss. This allows the microprocessor to execute an orderly shutdown. The ADM692SQ guarantees ±2% PFI accuracy on ADM802L/M variants, though ADM692SQ inherits the same 1.25 V reference architecture.

Is ADM692SQ pin-compatible with other devices in its family, and which packages are offered?

Yes, ADM692SQ is pin-compatible with ADM690A, ADM802M, and MAX692A across all 8-pin configurations. It is offered in both 8-pin SOIC (SO-8) and plastic DIP (N-8) packages, with identical pinout and electrical behavior. The SO-8 package measures 4.90 mm × 3.91 mm with 1.27 mm pitch, while the N-8 DIP is 9.27 mm × 6.35 mm. No microSOIC (RM-8) variant exists for ADM692SQ-only ADM690A carries that option.