Analog Devices Inc. ADM705ARZ

Overview

ADM705ARZ from Analog Devices is a low-cost microprocessor supervisory circuit with precision 4.65 V supply voltage monitoring, 200 ms reset pulse width, and integrated watchdog timer (1.60 s timeout). It guarantees valid RESET output down to VCC = 1 V and features debounced TTL/CMOS manual reset input (MR), making it suitable for reliable power-up sequencing and brownout protection in 5 V embedded systems.

For engineers reviewing the ADM705ARZ datasheet, ADM705ARZ pinout, ADM705ARZ application, or ADM705ARZ equivalent, key selection criteria include reset threshold accuracy (4.65 V ±150 mV), guaranteed operation below 1 V VCC, watchdog timeout tolerance (±0.6 s), and SOIC-8 package compatibility with industrial temperature range (−40°C to +85°C).

Technical Context

The ADM705ARZ implements a dual-function supervisory architecture: a precision bandgap-based voltage monitor triggers active-low RESET during power-up, power-down, or brownout when VCC falls below 4.65 V, and an independent watchdog timer monitors WDI transitions with 1.60 s timeout. Both functions operate with VCC as low as 1 V, ensuring deterministic behavior across full supply collapse.

It integrates a 1.25 V power-fail comparator (PFI/PFO) for secondary supply monitoring and includes internal 250 µA MR pull-up current with 150 ns minimum MR pulse width. The device uses no external components for basic reset generation and supports bidirectional reset line interfacing via series current-limiting resistor.

Key Specifications

Pinout & Package

ADM705ARZ is housed in an 8-lead standard small outline IC (SOIC_N) package per JEDEC MS-012-AA, with 1.27 mm pitch, 4.90 mm × 3.90 mm body, and 1.75 mm height. Pin 1 is marked with a notch or dot; device orientation follows standard SOIC top-view convention.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX705CSA+ and TPS3808G18DBVR, the ADM705ARZ uniquely combines 4.65 V precision reset, integrated watchdog, power-fail comparator, and manual reset in a single SOIC-8 package-enabling full supervisory functionality without external components in 5 V systems.

Availability

ADM705ARZ is available at Aetrix Electronics and suitable for microprocessor power-up sequencing, embedded system brownout recovery, watchdog-based firmware fault detection, and secondary supply monitoring requiring stable component supply across industrial temperature range and long-term production cycles.

Supply support for ADM705ARZ 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The ADM705/ADM706 family was designed specifically for cost-sensitive 5 V microprocessor supervisory applications requiring guaranteed reset validity down to 1 V, integrated watchdog, and power-fail warning capability in compact SOIC or PDIP packages.

FAQ

What is the reset threshold voltage for ADM705ARZ and how tightly is it specified?

The ADM705ARZ has a nominal reset threshold of 4.65 V, with a guaranteed range of 4.50 V to 4.75 V over full temperature and supply conditions. This tight specification ensures consistent reset assertion timing across 5 V systems, preventing premature release or delayed activation that could cause boot failures. The ADM705ARZ maintains this threshold accuracy without requiring external calibration or trimming components.

Does ADM705ARZ support operation below 5 V, and what is the minimum functional VCC?

Yes, ADM705ARZ operates from VCC = 1.0 V to 5.5 V and guarantees valid RESET output down to 1.0 V. At 1.0 V, the RESET output remains functional (low) with sink capability of 50 µA, enabling safe microprocessor hold during deep brownout. This capability is intrinsic to the ADM705ARZ design and does not require external pull-down resistors for basic operation.

How does the watchdog timer in ADM705ARZ function, and what is its timeout period?

ADM705ARZ incorporates an independent watchdog timer with a nominal timeout of 1.60 seconds. It resets on any transition (high-to-low or low-to-high) at the WDI pin and asserts WDO low if no transition occurs within the timeout window. The timer also clears automatically when RESET is asserted. This allows firmware to maintain system liveness by toggling WDI periodically, with ADM705ARZ providing hardware-enforced recovery if software stalls.

Can ADM705ARZ monitor a second power supply, and how is that implemented?

Yes, ADM705ARZ includes a dedicated power-fail comparator with PFI and PFO pins. By connecting a resistive divider from a secondary supply (e.g., 12 V) to PFI, the internal 1.25 V reference detects when the divided voltage falls below threshold, causing PFO to go low. This enables early warning of supply degradation or battery depletion without additional ICs. The ADM705ARZ datasheet provides design equations for hysteresis and noise immunity in this configuration.

What package type and RoHS status does ADM705ARZ have?

ADM705ARZ is supplied in an 8-lead standard small outline package (SOIC_N, JEDEC MS-012-AA), with lead pitch of 1.27 mm and body dimensions of 4.90 mm × 3.90 mm. The "Z" suffix confirms full RoHS compliance per EU Directive 2011/65/EU, including exemption 7a for lead in high-melting-temperature solder. This package is compatible with standard surface-mount assembly processes and reflow profiles.