Analog Devices Inc. ADM695AQ

Overview

ADM695AQ from Analog Devices is a 16-pin quad-function microprocessor supervisory circuit with adjustable reset timeout (200 ms typ.), 4.65 V precision reset threshold, 100 ms/1.6 s selectable watchdog timer, automatic battery backup switchover (2.0–4.25 V VBATT), and CE gating with 5 ns propagation delay. It ensures reliable power-up/down sequencing and data integrity in industrial embedded controllers requiring stable 5 V system monitoring.

For engineers reviewing the ADM695AQ datasheet, ADM695AQ pinout, ADM695AQ application, or ADM695AQ equivalent, key selection criteria include its dual watchdog timeout modes, battery switchover hysteresis (20 mV), VOUT drive capability (100 mA), low 600 nA standby current in backup mode, and compatibility with CMOS RAM write protection via CEIN/CEOUT.

Technical Context

The ADM695AQ integrates four core supervisory functions: a precision 4.65 V reset comparator with 40 mV hysteresis and guaranteed operation down to VCC = 1 V; a configurable watchdog timer supporting internal (100 ms/1.6 s) or external (capacitor- or clock-driven) timeout periods; bidirectional battery switchover logic with 50/70 mV power-down/power-up thresholds; and a 5 ns CE gating path that forces CEOUT high during brownout to prevent spurious writes to backed-up memory.

Its OSC SEL and OSC IN pins enable flexible timing configuration: OSC SEL floating/high selects internal oscillator mode (fixed 200 ms reset pulse, selectable watchdog period), while OSC SEL low enables external timing control. The device operates across –40°C to +85°C and uses an epitaxial CMOS process to achieve 5 mW typical active power dissipation and <1 µs reset comparator response time.

Key Specifications

Pinout & Package

ADM695AQ is housed in a 16-pin plastic DIP (Q-16) package with 0.3-inch body width and standard through-hole mounting. Pin spacing follows JEDEC MS-001AC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX695CPE+ and TPS3823MPW, the ADM695AQ delivers a complete, single-chip solution for complex embedded systems - integrating reset, watchdog, battery management, and memory protection with field-configurable timing, whereas alternatives require multiple discrete ICs or sacrifice critical functionality like CE gating or adjustable timeouts.

Availability

ADM695AQ is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive telematics modules, medical handheld diagnostics, and smart energy meters requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for ADM695AQ 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, founded in 1965 and headquartered in Wilmington, MA.

The ADM690–ADM695 family was designed specifically for robust, low-power microprocessor supervision in harsh industrial and automotive environments - emphasizing precision voltage monitoring, fail-safe memory protection, and seamless battery backup integration.

FAQ

What is the guaranteed reset voltage threshold range for ADM695AQ?

The ADM695AQ has a guaranteed reset voltage threshold range of 4.5 V to 4.73 V at +25°C, with typical value 4.65 V. This specification ensures reliable operation with standard 5 V ±5% power supplies and maintains reset assertion even as VCC decays to 1 V, providing fail-safe microprocessor hold-down during brownout conditions. The ADM695AQ datasheet confirms this range across the full –40°C to +85°C operating temperature.

Does ADM695AQ support adjustable reset timeout, and how is it configured?

Yes, ADM695AQ supports adjustable reset timeout via its OSC SEL and OSC IN pins. With OSC SEL low, connecting a capacitor (e.g., 47 pF) to OSC IN yields ~200 ms nominal reset pulse; scaling the capacitor adjusts timing linearly. With OSC SEL high or floating, reset timeout is fixed at 200 ms. This configurability is documented in Table I of the ADM695AQ datasheet and enables tuning for specific processor startup requirements.

Can ADM695AQ drive external circuitry beyond its 100 mA VOUT rating?

Yes - the ADM695AQ's BATT ON output can directly drive the base of an external PNP transistor to extend VOUT current capability beyond 100 mA. In battery backup mode, BATT ON sinks up to 35 mA and pulls low when VCC is active, enabling high-side switching. This capability is explicitly described in the ADM695AQ functional description and application figure 17 for increasing drive current.

How does ADM695AQ handle power-fail warning and what is the PFI threshold?

The ADM695AQ features a dedicated power-fail comparator with PFI input referenced to an internal 1.3 V bandgap. When PFI falls below 1.3 V (guaranteed 1.25–1.35 V range), PFO asserts low to signal impending supply collapse. This allows the host microprocessor to execute emergency data save routines before VCC drops below the 4.65 V reset threshold. The PFI input draws only ±0.01 nA, minimizing loading on external voltage dividers.

Is ADM695AQ compatible with CMOS RAM write protection, and how is it implemented?

Yes - ADM695AQ implements hardware write protection via CEIN and CEOUT pins. When VCC is valid, CEOUT replicates CEIN with 5 ns delay; when VCC drops below reset threshold, CEOUT is forced high regardless of CEIN state. This prevents spurious writes to battery-backed CMOS RAM during power transients. The ADM695AQ datasheet details this behavior in the CE Gating section and Figure 5.