Analog Devices Inc. ADM1185ARMZ-1

Overview

ADM1185ARMZ-1 from Analog Devices is a quad voltage monitor and sequencer IC designed for precise power supply supervision in multi-rail systems. It features four 0.6 V reference comparators with ±0.8% threshold accuracy, three open-drain enable outputs (OUT1–OUT3), one open-drain power-good output (PWRGD), and operates from 2.7 V to 5.5 V on VCC. It is used in server motherboard power sequencing to ensure safe startup of 3.3 V, 2.5 V, 1.8 V, and 1.2 V rails.

For engineers reviewing the ADM1185ARMZ-1 datasheet, ADM1185ARMZ-1 pinout, ADM1185ARMZ-1 application, or ADM1185ARMZ-1 equivalent, this device delivers deterministic timing-controlled sequencing, fault-latched monitoring, and robust undervoltage detection across four independent rails - critical for telecom equipment, industrial controllers, and high-reliability embedded platforms.

Technical Context

The ADM1185ARMZ-1 implements a state-machine-based digital core that interprets comparator outputs to enforce strict power-on order: VIN1 must assert before OUT1 enables Regulator 1 (190 ms typical delay), followed by VIN2→OUT2, VIN3→OUT3, and finally VIN4→PWRGD assertion after another 190 ms delay. All inputs share a common 0.6 V internal reference with worst-case 0.8% accuracy over −40°C to +85°C.

During normal operation (STATE5), PWRGD remains asserted only when all four VINx inputs exceed 0.6 V; a drop below threshold on VIN1 disables all outputs immediately, while faults on VIN2–VIN4 deassert PWRGD but retain OUT1–OUT3 states. Propagation delays for VIN2/VIN3 transitions are 30 μs (typ), supporting fast fault response without false triggering.

Key Specifications

Pinout & Package

ADM1185ARMZ-1 is housed in a 10-lead MSOP (RM-10) package per JEDEC MO-187-BA, with 0.5 mm pitch and 3.0 mm × 3.0 mm footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad voltage monitoring and sequencing applications.

Compared with TPS3808G33 and MAX6816, the ADM1185ARMZ-1 uniquely integrates four precision 0.6 V comparators, deterministic state-machine sequencing, and a dedicated PWRGD output - eliminating external logic and reducing BOM count in complex multi-rail designs.

Availability

ADM1185ARMZ-1 is available at Aetrix Electronics and suitable for server motherboard design, telecom line card development, and industrial PLC power management requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADM1185ARMZ-1 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.

The ADM1185ARMZ-1 belongs to Analog Devices' power supervision product line, engineered specifically for deterministic, autonomous power sequencing and fault management in multi-voltage electronic systems.

FAQ

What is the reference voltage accuracy of the ADM1185ARMZ-1 over temperature?

The ADM1185ARMZ-1 uses an internal 0.6 V reference with worst-case accuracy of ±0.8% across −40°C to +85°C. This corresponds to a trip threshold range of 0.5952 V to 0.6048 V at TA = 25°C, and the datasheet confirms stability within this band over full operating temperature. The ADM1185ARMZ-1 maintains this specification without external calibration or trimming.

Can the ADM1185ARMZ-1 monitor a 1.2 V rail directly without external resistors?

No, the ADM1185ARMZ-1 cannot monitor a 1.2 V rail directly because its internal comparators are fixed at 0.6 V. To monitor 1.2 V, a resistor divider must scale the rail to 0.6 V at the VINx pin - for example, equal 10 kΩ resistors yield 0.6 V at VINx when VIN = 1.2 V. The ADM1185ARMZ-1 relies entirely on external dividers for threshold programming.

How does the ADM1185ARMZ-1 respond when VIN1 drops below threshold after reaching STATE5?

When VIN1 falls below 0.6 V after the ADM1185ARMZ-1 reaches STATE5 (PWRGD asserted), the device immediately deasserts PWRGD and forces all three enable outputs (OUT1, OUT2, OUT3) low - disabling all downstream regulators. This hard reset behavior protects downstream circuitry from operating with an unstable primary rail, and is distinct from faults on VIN2–VIN4, which only affect PWRGD.

What is the maximum sink current supported by the ADM1185ARMZ-1's open-drain outputs?

The ADM1185ARMZ-1's OUT1–OUT3 and PWRGD outputs support up to 2 mA sink current while maintaining V_OUTL ≤ 0.4 V at VCC = 2.7 V. At lower VCC (e.g., 1 V), the outputs guarantee valid logic levels with 100 μA sink. This rating allows direct interfacing with most regulator enable pins without additional buffering.

Does the ADM1185ARMZ-1 support cascading with other ADM1185ARMZ-1 devices?

Yes, the ADM1185ARMZ-1 supports cascading: its PWRGD output can drive the VIN1 input of a second ADM1185ARMZ-1 to extend sequencing beyond four rails. Figure 23 and Figure 24 in the datasheet show validated configurations for daisy-chaining multiple units, preserving timing integrity and fault isolation across the chain. Each ADM1185ARMZ-1 retains independent monitoring of its four inputs.