Analog Devices Inc. ADM705AR

Overview

ADM705AR from Analog Devices is a low-cost microprocessor supervisory circuit with precision 4.65 V supply voltage monitoring, 200 ms reset pulse width, and guaranteed RESET validity down to 1 V VCC - used for power-on reset, brownout protection, and watchdog supervision in 5 V embedded systems.

For engineers reviewing the ADM705AR datasheet, ADM705AR pinout, ADM705AR application, or ADM705AR equivalent, key selection criteria include reset threshold accuracy (4.65 V), watchdog timeout (1.60 sec), manual reset debouncing, power-fail warning capability via PFI/PFO, and SOIC-8 compatibility for industrial-grade 5 V microcontroller systems.

Technical Context

The ADM705AR integrates a precision bandgap reference (4.65 V), a 1.60 sec watchdog timer cleared by WDI transitions, and a 1.25 V power-fail comparator with PFI input and open-drain PFO output. Its RESET output remains valid below 1 V VCC, enabling robust shutdown sequencing.

It features TTL/CMOS-compatible MR input with internal 250 µA pull-up, active-low RESET with 200 ms minimum assertion time, and independent WDO output that asserts low on timeout or VCC brownout - all operating across −40°C to +85°C.

Key Specifications

Pinout & Package

ADM705AR is housed in an 8-lead SOIC_N (R-8) package per JEDEC MS-012-AA, with 1.27 mm lead pitch, 5.00 mm × 3.96 mm body, and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX705CSA+ and TPS3808G33DBVR, the ADM705AR uniquely combines 5 V supply supervision, 1.60 sec watchdog, and 1.25 V PFI comparator in a single SOIC-8 device - making it optimal for cost-sensitive industrial 5 V systems requiring full-feature supervision without design compromises.

Availability

ADM705AR is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, telecom base station management units, and automotive infotainment head units requiring stable component supply across extended temperature ranges.

Supply support for ADM705AR 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 ADM705AR belongs to the ADM705/ADM706 family of microprocessor supervisory circuits engineered specifically for robust 5 V power monitoring, watchdog supervision, and power-fail warning in mission-critical embedded systems.

FAQ

What is the reset threshold voltage for ADM705AR and how tightly is it specified?

The ADM705AR has a nominal reset threshold of 4.65 V, with a guaranteed range of 4.50 V to 4.75 V over temperature and supply variations. This precision ensures consistent brownout detection across −40°C to +85°C without calibration, directly supporting reliable power-on reset behavior in 5 V systems where marginal supply dips must trigger reset before microprocessor malfunction occurs. The ADM705AR maintains this specification under 190 µA quiescent current.

Does ADM705AR support watchdog functionality, and what is its timeout period?

Yes, the ADM705AR includes a fully integrated watchdog timer with a nominal timeout period of 1.60 seconds. It is triggered by lack of transition on the WDI pin and asserts the WDO output low upon timeout. The timer resets on any WDI edge (high-to-low or low-to-high) and is also cleared during RESET assertion. This makes the ADM705AR suitable for detecting firmware lockups in real-time embedded applications where deterministic recovery is required.

Can ADM705AR monitor a second power supply or battery voltage?

Yes, the ADM705AR supports auxiliary supply monitoring via its dedicated PFI (Power-Fail Input) pin, which connects to the noninverting input of an internal 1.25 V comparator. By using an external resistive divider, users can scale a second supply (e.g., 12 V battery or 3.3 V rail) to trip at 1.25 V at the PFI pin, causing PFO to assert low for interrupt or reset generation. This dual-monitoring capability is confirmed in the ADM705AR datasheet Figure 20 and Applications Information section.

What package type and footprint does ADM705AR use, and is it RoHS-compliant?

The ADM705AR is supplied in an 8-lead Standard Small Outline Package (SOIC_N), designated R-8 per JEDEC MS-012-AA, with 1.27 mm lead pitch and 5.00 mm × 3.96 mm body dimensions. Per the Analog Devices ordering guide, the ADM705AR–REEL7 variant is RoHS-compliant (lead-free and halogen-free), indicated by the "Z" suffix in related part numbers like ADM705ARZ–REEL7. The device uses standard SOIC assembly processes compatible with automated SMT lines.

How does ADM705AR ensure reset validity during severe brownout conditions?

The ADM705AR guarantees functional RESET output down to VCC = 1.0 V - verified across temperature and process corners - using internal charge-pump-assisted output drivers. This ensures the microprocessor remains held in reset even during deep supply sags where conventional supervisors lose output drive. The ADM705AR achieves this while maintaining 190 µA quiescent current, enabling safe, predictable shutdown without external pull-down resistors or auxiliary circuitry.