Analog Devices Inc. ADM708ARMZ

Overview

ADM708ARMZ 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 monitor threshold, 200 ms reset pulse width, and power-fail detection via PFI/PFO. It is used in industrial controllers and intelligent instruments requiring reliable power-on reset and brownout protection.

For engineers reviewing the ADM708ARMZ datasheet, ADM708ARMZ pinout, ADM708ARMZ application, or ADM708ARMZ equivalent, key selection considerations include its 4.40 V reset threshold, dual-reset output polarity, MSOP-8 package footprint, and absence of watchdog timer - distinguishing it from ADM706/ADM705 variants.

Technical Context

The ADM708ARMZ implements a precision bandgap-based voltage reference (1.25 V) to compare VCC against a fixed 4.40 V threshold, generating reset signals during power-up, brownout, or power-down. Its dual-reset architecture delivers both active-low RESET and active-high RESET outputs simultaneously, enabling compatibility with processors requiring either logic polarity.

It integrates a dedicated power-fail comparator with PFI input (1.25 V threshold) and open-drain PFO output, allowing early warning of supply degradation or battery depletion. Unlike ADM705/ADM706, it omits watchdog timer circuitry entirely - confirmed by pinout (no WDI/WDO pins) and functional block diagram Figure 2.

Key Specifications

Pinout & Package

ADM708ARMZ is housed in an 8-lead Mini Small Outline Package (MSOP, RM-8), measuring 3.0 mm × 3.0 mm × 0.85 mm, with 0.65 mm lead pitch and gull-wing leads. 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 ADM706ARZ, ADM708ARMZ trades watchdog capability for dual-reset polarity and smaller MSOP-8 footprint; compared with TPS3808G33DBVR, it offers full 5 V supervision with PFI monitoring and complementary outputs - making it uniquely suited for industrial 5 V microprocessor reset coordination.

Availability

ADM708ARMZ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, network edge routers, and smart energy meters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ADM708ARMZ 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 semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The ADM705–ADM708 family was designed specifically for cost-sensitive, space-constrained microprocessor supervision in industrial and instrumentation applications - emphasizing reliability, low IQ, and dual-output flexibility without watchdog overhead.

FAQ

What is the reset threshold voltage of the ADM708ARMZ?

The ADM708ARMZ has a precision reset threshold of 4.40 V, with a tolerance of ±0.15 V over temperature and supply variations. This value is fixed and matches the ADM706/ADM708 family specification. The ADM708ARMZ uses an internal bandgap reference to maintain accuracy, and the threshold is not adjustable. It triggers reset assertion when VCC falls below this level and holds reset active for 200 ms after VCC rises above it.

Does the ADM708ARMZ include a watchdog timer function?

No, the ADM708ARMZ does not include a watchdog timer. Unlike the ADM705/ADM706 variants, it omits WDI and WDO pins entirely - confirmed by its MSOP-8 pinout (Figure 5) and functional block diagram (Figure 2). The absence of watchdog circuitry is a deliberate design distinction: ADM707/ADM708 variants prioritize dual-reset polarity and power-fail monitoring over software supervision. Therefore, ADM708ARMZ cannot monitor processor activity or generate timeout interrupts.

What are the key differences between ADM708ARMZ and ADM706ARZ?

The ADM708ARMZ and ADM706ARZ share the same 4.40 V reset threshold but differ critically in functionality and package. ADM706ARZ is SOIC-8 packaged and includes a 1.60 sec watchdog timer (WDI/WDO pins), but only provides active-low RESET. ADM708ARMZ is MSOP-8 packaged, offers both active-high and active-low RESET outputs, and excludes the watchdog entirely. Their pinouts are incompatible: ADM706ARZ has WDI/WDO; ADM708ARMZ has dual RESET and NC. They are not pin-compatible or functionally interchangeable.

Can ADM708ARMZ operate with VCC below 4.40 V and still assert RESET?

Yes - the ADM708ARMZ guarantees valid RESET assertion down to VCC = 1.0 V, as specified in the datasheet Absolute Maximum Ratings and Typical Performance Characteristics (Figure 7). When VCC drops below 4.40 V, RESET (active low) goes low and remains low until VCC rises above 4.40 V and stays there for 200 ms. Even at 1.0 V, the output maintains logic-low state with ≤0.3 V sink voltage at 50 µA load, ensuring robust microprocessor hold during deep brownout.

How is the PFI input used in ADM708ARMZ applications?

The PFI input on ADM708ARMZ is a dedicated 1.25 V threshold comparator input used to monitor auxiliary voltages - such as battery levels or secondary power rails - via an external resistor divider. When the voltage at PFI falls below 1.25 V, the open-drain PFO output pulls low, signaling a power-fail condition. PFI must never exceed VCC + 0.3 V; unused PFI should be tied to GND. In smart meter designs, PFI enables pre-reset warning logging, satisfying IEC 62053-21 requirements for supply anomaly tracking.