Analog Devices Inc. ADM693AARNZ

Overview

ADM693AARNZ from Analog Devices is a microprocessor supervisory circuit integrating power-on reset, battery backup switchover, watchdog timer, chip enable gating, and power-fail detection. It features a 4.4 V ±3% reset threshold, 200 ms fixed or adjustable reset timeout, 100 ms/1.6 s selectable watchdog timeout, and supports VCC down to 1 V operation. It is used in embedded controllers requiring reliable brownout protection and nonvolatile memory retention during main supply loss.

For engineers reviewing the ADM693AARNZ datasheet, ADM693AARNZ pinout, ADM693AARNZ application, or ADM693AARNZ equivalent, key selection criteria include its 4.4 V reset threshold compatibility with ±10% 5 V supplies, dual-mode watchdog (internal oscillator or external clock/capacitor), battery switchover with <1 µA standby current, and integrated CE gating for RAM write protection.

Technical Context

The ADM693AARNZ implements a precision bandgap-based voltage detector with 15 mV hysteresis and an internal RC oscillator for timing functions. Its reset generator holds RESET low for ≥200 ms after VCC exceeds 4.4 V, and remains functional down to VCC = 1 V - enabling robust brownout recovery in industrial systems.

The device integrates three independent functional blocks: (1) a battery switchover circuit with PMOS/VBATT MOSFET paths delivering ≤0.75 Ω VCC-to-VOUT and ≤25 Ω VBATT-to-VOUT on-resistance; (2) a transition-sensitive watchdog with WDI input accepting high/low/mid-supply states; and (3) a 1.25 V reference comparator for PFI/PFO power-fail warning with 25 µs response delay.

Key Specifications

Pinout & Package

ADM693AARNZ is housed in a 16-pin narrow SOIC (R-16N) package with 1.27 mm pitch, JEDEC MS-012AC compliant, and rated for –40°C to +85°C industrial operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX693AESA+, ADM693AARNZ delivers 3,000× lower battery standby current and integrated PFI comparator; compared with TPS3823-44DBVR, it provides complete supervisory integration (switchover, watchdog, CE gating) in one 16-pin SOIC, eliminating four discrete components and PCB area.

Availability

ADM693AARNZ is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive telematics modules, medical infusion pumps, and smart energy meters requiring stable component supply with guaranteed long-term availability.

Supply support for ADM693AARNZ 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 ADM69x family was designed specifically for microprocessor-based systems needing integrated power monitoring, battery backup, and fault-detection capabilities - targeting reliability-critical embedded applications where single-chip supervision reduces BOM count and improves MTBF.

FAQ

What is the reset threshold voltage of the ADM693AARNZ and how does it differ from the ADM691A?

The ADM693AARNZ has a guaranteed reset threshold of 4.4 V ±3%, optimized for 5 V ±10% power supplies. In contrast, the ADM691A specifies 4.65 V ±3%, making it suitable for +5 V supplies with +10%/–5% tolerance. This difference ensures correct reset assertion timing across varying input rail specifications - the ADM693AARNZ triggers earlier during voltage droop, improving responsiveness in wide-tolerance environments.

Can the ADM693AARNZ operate with VCC below 4.5 V, and what happens to its functions?

Yes, the ADM693AARNZ operates with VCC as low as 1 V. Below 4.5 V, the reset output remains asserted (low), the watchdog timer disables, WDI enters high-impedance, and CEOUT is forced high to protect memory. The device continues monitoring VCC and will release RESET only after VCC rises above 4.4 V and remains stable for ≥200 ms - ensuring safe microprocessor initialization even after deep brownouts.

How does the battery switchover function work in the ADM693AARNZ, and what is its maximum supported load current?

The ADM693AARNZ automatically switches VOUT between VCC and VBATT based on relative voltage and validity. When VCC > VBATT + 0.03 V and >4.4 V, VCC powers VOUT via a 0.75 Ω PMOS switch (250 mA max). When VCC falls below VBATT − 0.03 V and <4.4 V, VBATT powers VOUT via a 7 Ω MOSFET (5–20 mA typical). For >250 mA loads, the BATT ON output can drive an external PNP transistor - extending current capability beyond the internal switch limits.

What are the watchdog timeout options for the ADM693AARNZ, and how are they configured?

The ADM693AARNZ supports three watchdog timeout modes: (1) 100 ms short period (OSC IN grounded), (2) 1.6 s long period (OSC IN floating), or (3) adjustable period using external capacitor or clock. With OSC SEL low, connecting COSC = 47 pF to OSC IN yields 1.6 s timeout; scaling C adjusts linearly (Twd = 600 × C/47 pF). External clock input enables precise timing: Twd = 1024/fCLK. Note: first timeout after reset is always 1.6 s regardless of setting.

Does the ADM693AARNZ provide both active-low and active-high reset outputs, and how are they electrically implemented?

Yes, the ADM693AARNZ provides two reset outputs: pin 15 (RESET) is open-drain active-low, and pin 16 (RESET) is active-high complementary output. RESET sinks up to 3.2 mA at 0.4 V, while RESET sources up to 1.6 mA at 3.5 V. Both outputs share the same timing - asserted simultaneously during power-up, brownout, or watchdog timeout - enabling direct interface with µPs requiring either polarity without external inverters.