Analog Devices Inc. ADM800MARNZ

Overview

ADM800MARNZ 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 4.4 V ±2% reset threshold, 200 ms fixed reset timeout, 100 ms/1.6 s selectable watchdog periods, and supports VCC down to 1 V operation. It is used in industrial controllers and automotive ECUs for reliable power monitoring and RAM write protection.

For engineers reviewing the ADM800MARNZ datasheet, ADM800MARNZ pinout, ADM800MARNZ application, or ADM800MARNZ equivalent, key selection criteria include its 4.4 V reset threshold tolerance, battery switchover hysteresis (60 mV), VCC-to-VOUT on-resistance (0.8–1.2 Ω), low 100 µA standby current, and compatibility with 5 V ±10% supplies.

Technical Context

The ADM800MARNZ implements a dual-threshold voltage detector (4.4 V nominal, ±2% tolerance) with 15 mV hysteresis and internal 200 ms reset timeout generator. Its battery switchover uses PMOS (VCC→VOUT) and NMOS (VBATT→VOUT) switches with validated 250 mA VCC-source and 10 mA VBATT-source capability.

Watchdog functionality relies on WDI transition detection with configurable timeout via OSC SEL/OSC IN: internal 100 ms or 1.6 s modes, or external clock/capacitor programming. CEIN-to-CEOUT gating provides 6–10 ns propagation delay and 40–150 Ω on-resistance, enabling direct CMOS RAM write protection.

Key Specifications

Pinout & Package

ADM800MARNZ is housed in a 16-pin narrow SOIC (R-16N) package with 1.27 mm pitch, 10.2 mm × 6.2 mm body, and JEDEC MS-012AC compliant footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADM693AARNZ, ADM800MARNZ offers identical supervision specs but benefits from updated manufacturing and longer-term availability; versus MAX809TRD2+T, it delivers integrated multi-function supervision essential for complex embedded systems-eliminating need for 3–4 discrete ICs.

Availability

ADM800MARNZ is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive body control modules, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADM800MARNZ 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 ADM691A/ADM693A/ADM800L/M family was designed specifically for microprocessor-based systems needing integrated power monitoring, battery backup, and system-level fault recovery-targeting reliability-critical embedded applications.

FAQ

What is the reset threshold voltage of the ADM800MARNZ and how tightly is it specified?

The ADM800MARNZ has a nominal reset threshold of 4.4 V with a guaranteed tolerance of ±2%, meaning the actual threshold falls between 4.312 V and 4.488 V across temperature and supply variations. This specification ensures robust reset assertion for 5 V ±10% power supplies while avoiding false triggering during normal ripple or transient conditions. The ADM800MARNZ datasheet confirms this value applies across the full –40°C to +85°C operating range.

Does the ADM800MARNZ support battery backup switchover, and what are the key electrical characteristics?

Yes, the ADM800MARNZ supports automatic battery backup switchover between VCC and VBATT. Key characteristics include a 60 mV switchover hysteresis to prevent oscillation, VCC-to-VOUT on-resistance of 0.8–1.2 Ω (supporting up to 250 mA), and VBATT-to-VOUT resistance of 12–25 Ω (supporting up to 10 mA). In battery-backup mode, supply current drops to 0.04–1 µA, enabling multi-year operation on small coin cells. These values are measured per the ADM800MARNZ datasheet specifications table.

How does the watchdog timer function in the ADM800MARNZ, and can its timeout be adjusted?

The ADM800MARNZ watchdog timer monitors transitions on the WDI pin and asserts RESET and WDO if no transition occurs within the selected timeout period. Timeout is selectable between 100 ms (short) and 1.6 s (long) by grounding or floating OSC IN, respectively-both modes require OSC SEL high. The first timeout after reset is always 1.6 s to allow safe boot recovery. External clock or capacitor programming is also supported when OSC SEL is low. All timing modes are fully documented in the ADM800MARNZ functional description and Table II.

What is the purpose of the CEIN and CEOUT pins on the ADM800MARNZ, and how do they behave during reset?

The CEIN and CEOUT pins implement chip-enable gating for CMOS RAM write protection. CEOUT replicates CEIN with 6–10 ns delay when VCC is valid, but is forced high during reset-regardless of CEIN state-to prevent erroneous writes during power-up, brownout, or shutdown. This behavior is hardwired in the ADM800MARNZ's internal logic and verified in Figure 17 timing diagrams and the "CE Gating and RAM Write Protection" section of the ADM800MARNZ datasheet.

Can the ADM800MARNZ monitor a power supply other than +5 V, and how is that implemented?

Yes, the ADM800MARNZ can monitor auxiliary supplies via the PFI (Power Fail Input) pin, which compares an external voltage against an internal 1.25 V reference. By connecting a resistor divider from the target supply to PFI, users set a custom trip point-for example, detecting 7 V collapse on a 12 V rail. PFO asserts low within 25–60 µs of threshold crossing. This capability is explicitly defined in the ADM800MARNZ "Power Fail Detector" specifications and Figure 20 application schematic.