Analog Devices Inc. ADM690AQ

Overview

ADM690AQ from Analog Devices is an industrial-grade microprocessor supervisory circuit in 8-pin plastic DIP (Q-8) package, providing power-on reset, battery backup switchover, watchdog timer (1.6 s fixed), 4.65 V reset threshold, and power-fail warning. It asserts RESET down to 1 V VCC and delivers up to 100 mA from VOUT to CMOS RAM in systems requiring reliable brownout protection and nonvolatile memory retention.

For engineers reviewing the ADM690AQ datasheet, ADM690AQ pinout, ADM690AQ application, or ADM690AQ equivalent, this device serves as a precision voltage monitor and system health controller for embedded microprocessor platforms where deterministic reset timing, low-power battery backup, and fast CE gating (5 ns) are critical design requirements.

Technical Context

The ADM690AQ integrates a precision 4.65 V reset comparator with 40 mV hysteresis, a fixed 1.6 s watchdog timeout (non-adjustable), and a dedicated battery switchover circuit that transitions between VCC and VBATT with 70 mV rise and 50 mV fall thresholds. Its internal PMOS switch delivers VOUT with ≤0.05 V dropout at 1 mA and supports 100 mA continuous output.

It features a 1.3 V power-fail comparator (PFI/PFO), active-low RESET with 50 ms pulse width, and CEIN/CEOUT gating with 5 ns propagation delay - all operating across –40°C to +85°C while consuming only 1.95 mA typical supply current and 0.6 µA in battery-backup mode.

Key Specifications

Pinout & Package

ADM690AQ is housed in an 8-pin plastic dual in-line package (Q-8), compliant with JEDEC MS-001, with 0.3 inch body width and 0.1 inch lead pitch. Pin 1 is marked by notch or dot; pins are numbered counterclockwise from top-left corner when viewed from top.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690CPA+ and TPS3823MPW, the ADM690AQ uniquely combines industrial temperature range, sub-1 V reset assertion, 100 mA VOUT drive, and integrated 1.6 s watchdog in a single 8-pin DIP - making it irreplaceable for systems requiring coordinated power monitoring, memory backup, and processor health enforcement.

Availability

ADM690AQ is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive body modules, medical infusion pumps, and network router management processors requiring stable component supply with long-term lifecycle support.

Supply support for ADM690AQ 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 ADM690AQ belongs to the ADM690–ADM695 supervisory family, designed specifically for robust power monitoring and battery-backed memory management in mission-critical microprocessor systems operating across extended industrial temperatures.

FAQ

What is the guaranteed minimum operating VCC voltage for ADM690AQ reset assertion?

The ADM690AQ guarantees RESET assertion down to 1 V VCC, ensuring the microprocessor remains held in reset during severe brownout conditions where other supervisors may release prematurely. This behavior is explicitly tested and specified in the Absolute Maximum Ratings and Functional Description sections of the ADM690AQ datasheet, and applies across the full –40°C to +85°C industrial temperature range.

Does ADM690AQ support adjustable watchdog timeout periods?

No, the ADM690AQ provides only a fixed 1.6 s watchdog timeout period. Unlike the ADM691/ADM693/ADM695 variants, ADM690AQ lacks OSC SEL and OSC IN pins for external timing control. Its watchdog timer is internally configured and non-adjustable - a deliberate design choice to simplify implementation in cost-sensitive, fixed-timing applications.

Can ADM690AQ drive a 100 mA CMOS RAM bank directly from VOUT without external components?

Yes, ADM690AQ's VOUT pin is rated for 100 mA continuous output with ≤0.05 V dropout at 1 mA and ≤0.5 V dropout at full 100 mA load. It uses an internal PMOS switch with 1.5 Ω on-resistance, enabling direct connection to CMOS RAM VDD without external pass transistors or diodes - confirmed in the "Battery Switchover Section" and "VOUT vs. IOUT Normal Operation" performance curves.

What is the function of the BATT ON pin on ADM690AQ?

The ADM690AQ does not include a BATT ON pin. That functionality is exclusive to the 16-pin variants (ADM691/ADM693/ADM695). ADM690AQ has only 8 pins: VCC, VBATT, VOUT, GND, RESET, WDI, PFI, and PFO. The absence of BATT ON reflects its simplified feature set focused on core reset, backup switchover, and watchdog - without external PNP base drive capability.

How does ADM690AQ handle power-fail detection and what voltage triggers PFO?

ADM690AQ uses an internal 1.3 V reference to compare against the PFI input voltage; PFO goes low when PFI falls below 1.3 V (guaranteed 1.25–1.35 V range). This allows early warning of power degradation - typically configured via external resistor divider to trigger PFO 5–10 ms before RESET activates - giving the microprocessor time to execute emergency data save routines before shutdown.