Analog Devices Inc. ADM690AAN

Overview

ADM690AAN from Analog Devices is a precision microprocessor supervisory circuit in an 8-pin microSOIC package, providing active-low reset (RESET), watchdog timer (1.6 s timeout), battery switchover, and power-fail detection (1.25 V threshold). It asserts reset down to 1 V VCC and supports CMOS RAM backup with <0.05 µA battery standby current. Used in industrial controllers and embedded systems requiring reliable power-up sequencing and brownout protection.

For engineers reviewing the ADM690AAN datasheet, ADM690AAN pinout, ADM690AAN application, or ADM690AAN equivalent, key selection criteria include its 4.65 V reset threshold, guaranteed reset assertion at VCC ≥ 1 V, integrated battery switchover with 20 mV hysteresis, and compatibility with 5 V microprocessor systems requiring fail-safe startup and runtime monitoring.

Technical Context

The ADM690AAN integrates four core functions on a single die: a precision voltage monitor with 4.65 V ±150 mV threshold, a monostable watchdog timer triggered by WDI transitions (1.6 s timeout), a PMOS-based battery switchover switch with <1 Ω on-resistance, and a dedicated 1.25 V reference comparator for PFI/PFO power-fail signaling. All functions operate independently and remain functional across the full –40°C to +85°C industrial temperature range.

Its RESET output is actively driven low during VCC undervoltage or watchdog timeout, with a guaranteed 200 ms minimum pulse width and logic-level compatibility down to 1 V VCC. The internal battery switchover path ensures seamless VOUT sourcing from VBATT when VCC drops below VBATT − 20 mV, enabling uninterrupted CMOS RAM retention without external circuitry.

Key Specifications

Pinout & Package

ADM690AAN is housed in an 8-lead microSOIC (RM-8) package, measuring 3.10 mm × 3.05 mm × 0.80 mm, optimized for space-constrained industrial PCBs. Its pinout matches the industry-standard SO-8 and DIP-8 footprints electrically but occupies ~40% less board area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690A and TPS3808G33, the ADM690AAN uniquely combines 5 V system compatibility, sub-1 V reset hold, integrated battery switchover, and independent power-fail detection in a space-saving microSOIC package-making it irreplaceable for industrial 5 V microcontroller systems requiring full-feature supervision.

Availability

ADM690AAN is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and telecom infrastructure requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for ADM690AAN 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.

The ADM690AAN belongs to Analog Devices' microprocessor supervisory IC product line, engineered specifically for robust power monitoring, fail-safe reset generation, and battery-backed memory retention in harsh-environment embedded systems.

FAQ

What is the reset voltage threshold for ADM690AAN?

The ADM690AAN has a nominal reset voltage threshold of 4.65 V, with a guaranteed range of 4.5 V to 4.75 V over temperature. This threshold is factory-trimmed and applies specifically to the ADM690AAN variant within the ADM690A/ADM692A family. The ADM690AAN maintains valid RESET assertion even when VCC drops as low as 1 V, ensuring reliable microprocessor hold-down during deep brownout conditions.

Does ADM690AAN support battery backup switching?

Yes, the ADM690AAN provides fully integrated automatic battery backup switching. When VCC falls below VBATT minus 20 mV, the internal PMOS switch connects VBATT to VOUT, sustaining power to external CMOS RAM or low-power peripherals. The switchover hysteresis is 40 mV, and battery standby current is as low as 0.05 µA, enabling multi-year operation on standard coin cells. No external diodes or control logic are required.

Can ADM690AAN be used with 3.3 V microprocessors?

No, the ADM690AAN is designed exclusively for 5 V systems. Its reset threshold is fixed at 4.65 V, and its internal circuitry operates within a VCC range of 1.0 V to 5.5 V - but the reset function is specified only for detecting undervoltage relative to +5 V rails. For 3.3 V applications, Analog Devices offers the ADM809/ADM810 series, which feature 3.08 V or 2.93 V thresholds and are not pin-compatible with ADM690AAN.

How does the watchdog timer on ADM690AAN work?

The ADM690AAN watchdog timer monitors the WDI pin for transitions (high-to-low or low-to-high) and resets if none occur within 1.6 seconds. Each transition restarts the timer; holding WDI static for >1.6 s forces RESET low for 200 ms. The timer is disabled when WDI is left floating or connected to a high-impedance node. This behavior is confirmed in the functional block diagram and timing specifications of the ADM690AAN datasheet.

What package type is used for ADM690AAN?

The ADM690AAN uses the 8-lead microSOIC (RM-8) package, measuring 3.10 mm × 3.05 mm × 0.80 mm. This package is distinct from the SO-8 and DIP-8 variants offered for other members of the same family (e.g., ADM690AARN, ADM690AAN). The RM-8 footprint is not mechanically compatible with SO-8 but shares identical pin numbering and electrical functionality, enabling layout optimization in space-constrained designs.