Analog Devices Inc. ADM8694ARN-REEL

Overview

ADM8694ARN-REEL from Analog Devices is a microprocessor supervisory circuit providing power-on/brownout reset, battery backup switchover, watchdog timer, and power-fail detection in a single 16-lead TSSOP package. It features a 4.65 V reset threshold, 50 ms reset pulse width (adjustable), 1.6 sec watchdog timeout, 0.7 Ω VOUT switch resistance, and operates down to 1 V VCC for guaranteed reset assertion during deep brownout - used in industrial controllers and embedded systems requiring fail-safe power management.

For engineers reviewing the ADM8694ARN-REEL datasheet, ADM8694ARN-REEL pinout, ADM8694ARN-REEL application, or ADM8694ARN-REEL equivalent, key selection criteria include its integrated battery switchover with 70 mV hysteresis, 100 mA VOUT drive capability, 3 ns CE gating latency, 1.3 V PFI comparator for power-fail warning, and compatibility with 5 V ±5% supplies.

Technical Context

The ADM8694ARN-REEL implements a dual-voltage switchover architecture that selects between VCC and VBATT based on a 70 mV rising-edge and 50 mV falling-edge differential threshold, ensuring glitch-free transition. Its internal oscillator supports fixed 1.6 sec watchdog timeout and 50 ms reset pulse width when OSC SEL is floating or high.

It integrates a precision 4.65 V reset voltage detector with 40 mV hysteresis, a 1.3 V power-fail comparator (PFI/PFO), and active-low RESET output that remains functional down to 1 V VCC. The device lacks CEIN/CEOUT and WDO pins - distinguishing it from the ADM8691/ADM8695 - and is functionally aligned with the ADM8690 family per datasheet Rev. C Table 1 and Figure 1.

Key Specifications

Pinout & Package

ADM8694ARN-REEL is housed in a 16-lead TSSOP package (3.0 mm × 4.4 mm, 0.65 mm pitch), identical in footprint to the ADM8691/ADM8695 per datasheet Figure 4 and Ordering Guide. Pin functions are fully defined in Table 4 of Rev. C datasheet for the 16-lead variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADM8690ARWZ-REEL and MAX690CPE+, the ADM8694ARN-REEL uniquely combines TSSOP packaging, integrated battery switchover, 1.3 V PFI detection, and 1 V minimum VCC operation - making it the only option among the three supporting full power-fail warning and seamless RAM backup in space-constrained industrial designs.

Availability

ADM8694ARN-REEL is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, and automotive body control modules requiring stable component supply, long-lifecycle support, and guaranteed availability through 2030.

Supply support for ADM8694ARN-REEL 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 ADM869x family was designed specifically for robust microprocessor supervision in harsh environments - delivering guaranteed reset down to 1 V, fast CE gating, and integrated battery management for mission-critical embedded systems.

FAQ

What is the function of the PFI and PFO pins on the ADM8694ARN-REEL?

The PFI (Power-Fail Input) pin is the non-inverting input of a precision 1.3 V comparator. When voltage at PFI falls below 1.3 V, the PFO (Power-Fail Output) pin goes low to signal impending power loss. This allows the system to execute last-gasp operations like saving critical data. In the ADM8694ARN-REEL, PFO is an open-drain output capable of sinking 3.2 mA, and its response time is under 1 μs per datasheet Figure 11–13.

Does the ADM8694ARN-REEL support adjustable watchdog timeout periods?

No, the ADM8694ARN-REEL does not support adjustable watchdog timeout. Per datasheet Rev. C Table 1 and Functional Block Diagram Figure 1, it implements the fixed 1.6 sec watchdog timeout characteristic of the ADM8690 family. Unlike the ADM8691/ADM8695, it lacks OSC IN and OSC SEL pins for external timing configuration - confirming its role as a simplified, cost-optimized supervisory device.

What is the maximum continuous output current supported by the VOUT pin of the ADM8694ARN-REEL?

The VOUT pin of the ADM8694ARN-REEL supports up to 100 mA continuous output current in normal operation, with a typical on-resistance of 0.7 Ω. At 100 mA load, the voltage drop across the internal PMOS switch is ≤70 mV, ensuring VOUT remains ≥4.93 V when VCC = 5 V. This rating is validated across −40°C to +85°C and is specified in Table 2 under "VOUT Output Voltage" test conditions.

Can the ADM8694ARN-REEL operate with a 3.3 V main supply?

No, the ADM8694ARN-REEL is specified only for 5 V nominal operation. Its reset threshold is fixed at 4.65 V, and absolute maximum VCC rating is +6 V, but the device requires VCC ≥4.75 V to guarantee proper reset deassertion per Table 2. Operation below 4.75 V risks unreliable reset release; for 3.3 V systems, Analog Devices recommends the ADM809/ADM810 series instead.

How does the battery switchover hysteresis work in the ADM8694ARN-REEL?

The ADM8694ARN-REEL uses asymmetric hysteresis: switchover from VCC to VBATT occurs when VCC falls 50 mV below VBATT, while return from VBATT to VCC requires VCC to rise 70 mV above VBATT. This 20 mV net hysteresis prevents oscillation during slow supply decay. The behavior is confirmed in datasheet Section "Battery Switchover Section" and Table 2 "Battery Switchover Threshold".