Analog Devices Inc. ADM708SAR

Overview

ADM708SAR from Analog Devices is a 3 V microprocessor supervisory circuit with dual active-high/active-low reset outputs, 2.93 V precision voltage monitoring threshold, 200 ms reset pulse width, and integrated power-fail comparator (1.25 V reference). It ensures reliable reset assertion during power-up, brownout, or low-battery conditions in embedded controllers and portable instrumentation.

For engineers reviewing the ADM708SAR datasheet, ADM708SAR pinout, ADM708SAR application, or ADM708SAR equivalent, key selection criteria include its dual-reset capability, guaranteed RESET validity down to VCC = 1 V, absence of watchdog timer (distinguishing it from ADM706x variants), and SOIC-8 packaging for space-constrained PCB layouts.

Technical Context

The ADM708SAR implements a precision bandgap-based voltage reference (2.93 V ±70 mV) for supply monitoring and a dedicated 1.25 V comparator for power-fail detection via the PFI input. Its dual-reset architecture provides simultaneous active-low (RESET) and active-high (RESET) outputs without external inversion logic.

No watchdog timer circuitry is present - unlike the ADM706S family - simplifying timing-critical system design while retaining manual reset debouncing (70 µA internal pull-up), MR-to-reset delay ≤750 ns, and PFO response time <500 ns under typical conditions.

Key Specifications

Pinout & Package

ADM708SAR is housed in an 8-lead SOIC_N (R-8) package per JEDEC MS-012-AA, with 1.27 mm lead pitch and 5.00 mm × 4.00 mm body dimensions. Pin 6 is NC (no connect); all other pins are electrically functional and thermally rated for continuous operation up to 110°C/W θJA.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADM706SAR and MAX708SUR, ADM708SAR uniquely delivers dual-reset outputs and PFO functionality without watchdog overhead - making it optimal for deterministic reset coordination in resource-constrained or safety-critical 3 V systems where software supervision is handled externally.

Availability

ADM708SAR is available at Aetrix Electronics and suitable for industrial controller monitoring, portable medical instrumentation, communications gateway reset management, and test equipment power sequencing requiring stable component supply across extended temperature ranges.

Supply support for ADM708SAR 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 ADM708SAR belongs to Analog Devices' microprocessor supervisory product line, designed specifically for robust, low-power voltage monitoring and deterministic reset generation in 3 V embedded systems without requiring external timing or logic components.

FAQ

What is the reset threshold voltage of the ADM708SAR?

The ADM708SAR has a precision reset threshold of 2.93 V ±70 mV, optimized for monitoring nominal 3 V power supplies. This value is factory-trimmed and remains stable over temperature (−40°C to +85°C) and supply voltage (3.00 V to 5.5 V). The ADM708SAR uses this threshold to assert both RESET and RESET outputs whenever VCC falls below the trip point, ensuring consistent behavior across operating conditions.

Does the ADM708SAR include a watchdog timer function?

No, the ADM708SAR does not include a watchdog timer. Unlike the ADM706S family, it omits WDI and WDO pins entirely - confirmed by pin configuration Figure 5 and Table 4 in the datasheet. This makes ADM708SAR ideal for applications requiring only voltage supervision and dual-reset signaling, with reduced pin count and simplified timing validation.

How does the ADM708SAR support power-fail warning functionality?

The ADM708SAR supports power-fail warning via its dedicated PFI input and PFO output. The internal 1.25 V comparator monitors voltage applied to PFI through an external resistor divider; when PFI drops below 1.25 V, PFO goes low. This allows early detection of supply decay - for example, triggering MCU-initiated data save before VCC crosses the 2.93 V reset threshold.

What is the minimum VCC at which ADM708SAR guarantees valid reset output?

The ADM708SAR guarantees valid RESET and RESET output down to VCC = 1 V, as explicitly stated in the General Description and validated in Figure 12 and the "Valid RESET Below 1 V VCC" section. Below 1 V, internal transistor drive degrades; for continued low-voltage hold-down, a 10 kΩ external pull-down on RESET is recommended per Figure 19.

Is the ADM708SAR pin-compatible with other devices in the ADM706/ADM708 family?

The ADM708SAR shares the same 8-lead SOIC_N (R-8) package and pinout as ADM708R/ADM708T variants, but differs from ADM706x parts by replacing WDI/WDO with NC and RESET. Pin-for-pin compatibility exists only within the ADM708x series (e.g., ADM708RAR, ADM708SANZ); substitution with ADM706SAR requires PCB redesign due to WDI/WDO presence and missing RESET.