Analog Devices Inc. ADM699AN

Overview

ADM699AN from Analog Devices is a microprocessor supervisory circuit with precision 4.65 V voltage monitoring, 1.6 s typical watchdog timeout, and guaranteed RESET assertion down to VCC = 1 V. It provides power-up/power-down reset generation and watchdog input (WDI) supervision for embedded microprocessor systems requiring reliable startup and runtime fault detection.

For engineers reviewing the ADM699AN datasheet, ADM699AN pinout, ADM699AN application, or ADM699AN equivalent, this device supports critical power monitoring in industrial controllers, automotive ECUs, and intelligent instrumentation where brown-out resilience and software hang detection are essential design requirements.

Technical Context

The ADM699AN integrates a precision bandgap-based voltage detector with 40 mV hysteresis and an internal monostable that guarantees ≥140 ms RESET active time after VCC rises above 4.73 V. Its WDI input accepts three-level logic (low/high/midsupply) and resets the 1.6 s watchdog timer on each transition.

Unlike the ADM698, the ADM699AN includes dedicated WDI functionality and asserts RESET low if WDI remains static beyond timeout. The RESET output remains functional down to 1 V supply, enabling robust shutdown sequencing even during deep undervoltage conditions.

Key Specifications

Pinout & Package

ADM699AN is housed in an 8-pin plastic DIP (N-8) package with 0.3-inch body width and through-hole mounting. Pin 1 is marked by a notch or dot; pins are numbered counterclockwise from top-left when viewed from top.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX699CPA+ and TPS3823-46DBVR, the ADM699AN uniquely combines guaranteed 1 V reset operation, integrated watchdog timing, and low 0.6 mA quiescent current - making it the only option among the three suitable for safety-critical, low-power, and brown-out-resilient microprocessor supervision.

Availability

ADM699AN is available at Aetrix Electronics and suitable for automotive engine control units, industrial programmable logic controllers, and medical infusion pump controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADM699AN 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 ADM699AN belongs to Analog Devices' microprocessor supervisory product line, engineered specifically for robust power sequencing and runtime fault detection in mission-critical embedded systems operating under harsh electrical conditions.

FAQ

What is the guaranteed minimum VCC level at which ADM699AN asserts RESET?

The ADM699AN guarantees RESET assertion down to VCC = 1 V, ensuring the microprocessor remains held in reset even during severe undervoltage conditions. This capability is verified across the full –40°C to +85°C operating range and is critical for safe shutdown in battery-backed or brown-out-prone systems. The ADM699AN maintains functional RESET output drive strength (≤200 mV at 10 µA sink) at this voltage, unlike many competitors that cease operation above 2.5 V.

Does ADM699AN require external components to operate as a basic supervisor?

No, the ADM699AN operates autonomously with only a 0.1 µF ceramic bypass capacitor on the VCC pin - no external resistors, capacitors, or diodes are needed for core voltage monitoring or watchdog functionality. The WDI input is three-level sensitive, allowing direct connection to any microprocessor I/O pin without pull-up/down resistors. This minimal BOM requirement reduces board area and improves reliability compared to discrete supervisor implementations.

How does the ADM699AN watchdog timer respond to a stuck WDI signal?

If the WDI input remains static (high or low) beyond the 1.0–2.25 s timeout window, the ADM699AN forces RESET low for ≥140 ms. The timer resets on each WDI transition - rising or falling edge - and begins a new timeout period. If WDI is left floating or driven to midsupply (~2.5 V), the watchdog is automatically disabled and RESET remains controlled solely by VCC monitoring. This behavior is intrinsic to the ADM699AN's internal circuitry and requires no configuration.

Can ADM699AN be used in place of ADM698AN in existing designs?

Yes, the ADM699AN is pin-compatible and functionally supersets the ADM698AN in the same N-8 package - both share identical VCC, GND, RESET, and power pinouts. The ADM699AN adds WDI on Pin 3, which is NC on ADM698AN; leaving Pin 3 unconnected preserves ADM698AN functionality while enabling future watchdog upgrades. No PCB changes are required to migrate from ADM698AN to ADM699AN.

What is the thermal performance limit of ADM699AN in its N-8 package?

The ADM699AN in the 8-pin plastic DIP (N-8) package has a maximum power dissipation of 500 mW and a junction-to-ambient thermal impedance (θJA) of 120°C/W. At maximum rated supply current (1.95 mA) and 5.5 V VCC, power dissipation remains below 11 mW - well within safe limits. This allows uninterrupted operation up to +85°C ambient without heatsinking, supporting deployment in enclosed industrial enclosures or under-hood automotive locations.