Analog Devices Inc. ADM706SAR

Overview

ADM706SAR from Analog Devices is a 3 V microprocessor supervisory circuit with active-low reset output, 2.93 V precision voltage monitoring threshold, 200 ms reset pulse width, 100 µA quiescent current, and integrated watchdog timer with 1.6 s timeout-used for reliable power-on reset and brownout protection in embedded microcontroller systems.

For engineers reviewing the ADM706SAR datasheet, ADM706SAR pinout, ADM706SAR application, or ADM706SAR equivalent, key selection criteria include reset threshold accuracy (2.93 V ±40 mV), guaranteed RESET validity down to VCC = 1 V, debounced manual reset input (MR), independent watchdog input (WDI) and output (WDO), and compatibility with 3.3 V supply rails in industrial temperature range (−40°C to +85°C).

Technical Context

The ADM706SAR implements a precision bandgap-based voltage reference (2.93 V nominal) for supply monitoring, paired with a monostable reset generator that holds RESET low for 200 ms after VCC rises above threshold or MR deasserts. Its internal 70 µA pull-up on MR enables direct switch interfacing without external components.

It integrates three independent functional blocks: (1) a power-fail comparator with 1.25 V internal reference and PFI/PFO pins for auxiliary supply monitoring; (2) a transition-detecting watchdog timer cleared by WDI edges; and (3) a reset generator with hysteresis and sub-1 V operation guarantee-ensuring deterministic behavior during power ramp-up and brownout recovery.

Key Specifications

Pinout & Package

ADM706SAR is housed in an 8-lead SOIC_N (R-8) package per JEDEC MS-012-AA, with 1.27 mm pitch, 5.00 mm × 4.00 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 MAX706SASA+, ADM706SAR delivers lower quiescent current and configurable PFI hysteresis; compared with TPS3808G33DBVR, it adds critical watchdog and dual-supply monitoring capabilities essential for robust embedded control.

Availability

ADM706SAR is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical devices, network router boot integrity, and smart meter firmware protection requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for ADM706SAR 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The ADM706x family was designed specifically for microprocessor system supervision-delivering precision voltage monitoring, reliable reset generation, watchdog safety, and auxiliary supply alerting in compact SOIC and PDIP packages.

FAQ

What is the exact reset threshold voltage of the ADM706SAR?

The ADM706SAR has a nominal reset threshold of 2.93 V, with a guaranteed range of 2.85 V to 3.00 V over temperature and supply variations. This value is laser-trimmed at wafer test and applies specifically to the ADM706S variant-distinct from the 2.63 V (R) or 3.08 V (T) versions. The ADM706SAR maintains this specification in its R-8 SOIC package across −40°C to +85°C.

Does the ADM706SAR support both active-high and active-low reset outputs?

No, the ADM706SAR provides only an active-low RESET output (pin 7). It does not include the complementary active-high RESET output found in the ADM708S series. For dual-output capability, the ADM708SAR would be required-but it lacks the watchdog timer present in the ADM706SAR. The ADM706SAR's WDO (pin 8) is a separate active-low watchdog output, not a reset complement.

Can the ADM706SAR operate with a 3.0 V supply, and what is its minimum functional VCC?

Yes, the ADM706SAR operates with VCC as low as 3.00 V (per datasheet Table 1), and its RESET output remains fully valid down to VCC = 1 V. This means the device continues asserting RESET even during deep brownout conditions-critical for holding microprocessors in reset until power is fully restored. Below 1 V, external pull-down may be needed per Figure 19.

How is the watchdog timer in the ADM706SAR cleared, and what is its timeout accuracy?

The ADM706SAR watchdog timer is cleared by any logic transition (rising or falling edge) on the WDI pin (pin 6). Its nominal timeout is 1.6 s, with a guaranteed range of 1.00 s to 2.25 s under specified conditions (VCC = 3.3 V, VIH/VIL thresholds met). The timer also resets automatically when RESET is asserted, ensuring synchronization with power-on or manual reset events.

What is the function of the PFI and PFO pins on the ADM706SAR, and how are they typically used?

The PFI (pin 4) is the noninverting input to a dedicated 1.25 V comparator; the PFO (pin 5) is its active-low open-drain output. Users connect PFI to a resistive divider from an auxiliary supply (e.g., battery or preregulator) so that PFO asserts when that supply falls below the trip point. PFO can drive an interrupt or be wired to MR for automatic system reset on secondary supply failure.