Analog Devices Inc. ADM708ARM

Overview

ADM708ARM from Analog Devices is a low-cost microprocessor supervisory circuit designed for 5 V supply monitoring in embedded systems. It provides active-high and active-low reset outputs, a 4.40 V precision voltage threshold, 200 ms reset pulse width, and power-fail detection via PFI/PFO. It operates down to 1 V VCC and targets critical supply monitoring in industrial controllers and intelligent instruments.

For engineers reviewing the ADM708ARM datasheet, ADM708ARM pinout, ADM708ARM application, or ADM708ARM equivalent, key selection criteria include its dual-reset output capability, guaranteed reset validity below 1 V, 4.40 V trip point for brownout detection, PFI-based low-battery warning, and MSOP-8 package suitability for space-constrained PCB layouts.

Technical Context

The ADM708ARM implements a precision bandgap reference (1.25 V) for the PFI comparator and a separate 4.40 V reset threshold detector with 40 mV hysteresis. Its internal reset generator holds RESET and RESET low/high for 200 ms after VCC recovery or MR deassertion, ensuring reliable microprocessor initialization.

No watchdog timer is integrated - unlike ADM705/ADM706 - making it functionally aligned with ADM707/ADM708 family members. The device supports TTL/CMOS-compatible manual reset input (MR) with internal 250 µA pull-up and debounced response, and features guaranteed operation across −40°C to +85°C.

Key Specifications

Pinout & Package

ADM708ARM is housed in an 8-lead Mini Small Outline Package (MSOP, RM-8), measuring 3.0 mm × 3.0 mm × 0.85 mm, with gull-wing leads and 0.65 mm pitch. It is RoHS-compliant (Z suffix) and optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADM708ARZ and MAX708CSA+, the ADM708ARM offers identical supervision functionality in a 30% smaller footprint with integrated PFI/PFO - enabling enhanced system-level power monitoring without adding discrete comparators or increasing PCB area.

Availability

ADM708ARM is available at Aetrix Electronics and suitable for industrial PLC controllers, smart energy meters, medical handheld diagnostics, and point-of-sale terminals requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for ADM708ARM 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–ADM708 family was engineered specifically for cost-sensitive, space-constrained microprocessor systems needing reliable power-on reset, brownout protection, and auxiliary supply monitoring - with emphasis on industrial and instrumentation applications.

FAQ

What is the reset threshold voltage for ADM708ARM?

The ADM708ARM has a nominal reset threshold of 4.40 V, with a tolerance of ±0.15 V over temperature and supply variations. This value is factory-trimmed and specified in Table 1 of the Rev. H datasheet. The threshold applies to both RESET and RESET outputs and determines the VCC level at which the device asserts reset during power-down or brownout conditions. The ADM708ARM uses this fixed threshold - distinct from the 4.65 V variant used in ADM707 - to provide earlier intervention for systems sensitive to marginal 5 V rail operation.

Does ADM708ARM include a watchdog timer?

No, the ADM708ARM does not include a watchdog timer. It belongs to the ADM707/ADM708 subgroup, which omits the WDI/WDO circuitry present in ADM705/ADM706. The ADM708ARM provides only voltage supervision, manual reset, and power-fail monitoring via PFI/PFO. If watchdog functionality is required, engineers must select ADM706ARMZ (if available in MSOP) or use an external timer circuit - the ADM708ARM pinout excludes WDI and WDO terminals entirely, as confirmed in Figure 5 and Table 3 of the datasheet.

What is the purpose of the PFI and PFO pins on ADM708ARM?

The PFI (Power-Fail Input) and PFO (Power-Fail Output) pins on ADM708ARM enable auxiliary supply monitoring using an internal 1.25 V reference comparator. PFI accepts a scaled-down voltage from an external resistor divider; when that voltage falls below 1.25 V, PFO asserts low. This allows early detection of battery depletion or preregulator failure before the main 5 V rail collapses. In ADM708ARM, PFI and PFO operate independently of the reset function - they do not affect RESET timing or threshold - and are fully functional in the MSOP-8 package as documented in Figure 5 and Table 3.

Can ADM708ARM drive a microprocessor reset pin directly?

Yes, ADM708ARM can drive a microprocessor reset pin directly, but design attention is required for polarity and loading. Its active-low RESET output sinks up to 3.2 mA at 0.4 V (VCC = 5 V), while the active-high RESET output sources up to 800 µA at VCC − 1.5 V. For bidirectional reset lines or high-capacitance buses, a 4.7 kΩ current-limiting resistor is recommended between ADM708ARM's RESET and the MCU pin, as specified in Figure 21 of the datasheet. No external pull-up or pull-down is needed due to the device's rail-to-rail output drive capability.

What package type is used for ADM708ARM?

The ADM708ARM is packaged in an 8-lead Mini Small Outline Package (MSOP), also designated RM-8 per JEDEC MO-187-AA. Its dimensions are 3.0 mm × 3.0 mm × 0.85 mm with 0.65 mm lead pitch and gull-wing terminations. This package is RoHS-compliant (indicated by the "Z" in ADM708ARMZ) and optimized for automated SMT assembly. Unlike the PDIP (N-8) and SOIC (R-8) variants, the RM-8 variant places NC on Pin 8 and swaps RESET/RESET positions - details confirmed in Figure 5 and the Ordering Guide on page 12 of Rev. H.