Analog Devices Inc. ADM691AANZ

Overview

ADM691AANZ from Analog Devices is a microprocessor supervisory circuit providing precision 4.65 V ±3% reset threshold, 200 ms or adjustable reset timeout, 1.6 s/100 ms selectable watchdog timer, automatic battery backup switchover (VCC/VBATT), and chip-enable gating - used in industrial controllers and embedded systems requiring reliable power-up sequencing and brownout protection.

For engineers reviewing the ADM691AANZ datasheet, ADM691AANZ pinout, ADM691AANZ application, or ADM691AANZ equivalent, this page delivers verified functional specifications, validated package mapping (16-pin SOIC-N), confirmed battery switchover behavior, and real-world timing constraints for reset assertion, watchdog timeout, and CEOUT propagation - all critical for fail-safe µP system design.

Technical Context

The ADM691AANZ integrates a precision bandgap-based voltage detector (4.65 V threshold with 15 mV hysteresis), an internal oscillator with dual-mode selection (fixed 200 ms reset / 1.6 s watchdog or external capacitor/clock-adjustable timing), and a PMOS/NMOS hybrid switchover switch enabling seamless transition between VCC and VBATT at sub-1 V operation. Its reset generator remains active down to VCC = 1 V, ensuring deterministic shutdown even during deep brownouts.

It implements three independent protection functions: (1) RESET/RESET outputs with complementary logic and open-drain capability; (2) BATT ON and LOW LINE status signals with defined sink/source drive strength; and (3) CEIN-to-CEOUT gating with 6–10 ns propagation delay and 40–150 Ω on-resistance - all synchronized to the same reset timebase and immune to VCC dropout below 1 V.

Key Specifications

Pinout & Package

ADM691AANZ is packaged in a 16-pin narrow-body SOIC (R-16N, also designated as SOIC-16W per Analog Devices ordering guide). Pin numbering follows standard SOIC top-view convention with Pin 1 at bottom-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX691ACPE+ and TPS3823MPW, the ADM691AANZ uniquely combines reset, watchdog, battery switchover, CE gating, and PFI/PFO in one SOIC-16 package - reducing BOM count by 4 discrete ICs while enabling deterministic fail-safe behavior across power domains.

Availability

ADM691AANZ 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 and traceable sourcing.

Supply support for ADM691AANZ 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 ADM691AANZ belongs to Analog Devices' microprocessor supervisory product line, designed specifically to consolidate power monitoring, reset generation, battery backup, and memory protection into single-chip solutions for mission-critical embedded systems.

FAQ

What is the exact reset voltage threshold and tolerance for ADM691AANZ?

The ADM691AANZ has a guaranteed reset voltage threshold of 4.65 V with ±3% tolerance (4.50 V to 4.75 V) over temperature and supply variation. This is explicitly specified in the datasheet's "Reset Voltage Threshold" table for ADM691A/ADM800L variants and confirmed in Table I's product selection matrix. The threshold is implemented using a precision bandgap reference and remains stable across –40°C to +85°C.

Does ADM691AANZ support battery backup switching, and what are the key electrical limits?

Yes, ADM691AANZ supports automatic battery backup switching between VCC and VBATT. In VCC mode, it delivers up to 250 mA with 0.8–1.2 Ω on-resistance; in VBATT mode, it supplies up to 10 mA with 12–25 Ω on-resistance and draws only 0.04–1 µA quiescent current. Switchover occurs at VBATT + 0.03 V (power-up) and VBATT – 0.03 V (power-down), with 60 mV hysteresis to prevent chatter.

How is the watchdog timeout configured on ADM691AANZ, and what are the available periods?

The ADM691AANZ watchdog timeout is configured via OSC SEL and OSC IN pins. With both floating, it defaults to 1.6 s (long period). Grounding OSC IN selects 100 ms (short period), except immediately after reset when it remains 1.6 s. With OSC SEL grounded, external capacitor or clock sets custom periods: Twd = 600 × (C/47 pF) ms or Twd = 1024 × (1/fCLK) seconds. All configurations are validated in Table II of the datasheet.

Can ADM691AANZ drive CMOS RAM chip-enable lines, and what is its CE gating behavior during reset?

Yes, ADM691AANZ provides dedicated CEIN and CEOUT pins for RAM write protection. CEOUT replicates CEIN with 6–10 ns propagation delay when VCC > reset threshold. During reset (VCC < 4.65 V), CEOUT is forced high regardless of CEIN state - preventing erroneous writes to battery-backed RAM. This behavior is confirmed in the "CE Gating and RAM Write Protection" section and Figure 17 timing diagram.

What is the function of the PFI and PFO pins on ADM691AANZ, and how is the trip point set?

PFI is the non-inverting input of a comparator referenced to an internal 1.25 V bandgap voltage; PFO is its open-drain output. When PFI voltage falls below 1.25 V (guaranteed 1.2–1.3 V range), PFO asserts low. The trip point is set externally using a resistor divider from system input rail to PFI - e.g., a 10 kΩ/2.2 kΩ divider on a 12 V rail yields ~2.2 V at PFI, triggering PFO when input drops to ~7 V. This is detailed in Figure 20 and "Power Fail Warning Comparator" section.