Analog Devices Inc. ADM706AN

Overview

ADM706AN from Analog Devices is a low-cost microprocessor supervisory circuit designed for 5 V supply monitoring and system reset generation in embedded controllers and instrumentation. It features a 4.40 V reset threshold, 200 ms reset pulse width, guaranteed RESET validity down to 1 V VCC, 190 μA quiescent current, and integrated watchdog timer with 1.60 sec timeout - enabling reliable power-on, brownout, and software stall detection in industrial microprocessor systems.

For engineers reviewing the ADM706AN datasheet, ADM706AN pinout, ADM706AN application, or ADM706AN equivalent, key selection criteria include its precise 4.40 V supply monitor level, independent watchdog input (WDI) and output (WDO), debounced manual reset (MR), power-fail comparator interface (PFI/PFO), and compatibility with TTL/CMOS logic levels across −40°C to +85°C operation.

Technical Context

The ADM706AN implements a precision voltage monitor with 40 mV hysteresis and internal 1.25 V reference for PFI-based power-fail detection. Its reset generator remains functional down to 1 V VCC, ensuring deterministic microprocessor hold during undervoltage ramp-up or decay.

It integrates a transition-sensitive watchdog timer cleared by either high-to-low or low-to-high edges on WDI, with timeout disabled when WDI is floating. The MR input includes internal 250 μA pull-up and 250 ns debounce delay, while RESET and WDO outputs drive 800 μA source / 3.2 mA sink loads with rail-to-rail compatible logic thresholds.

Key Specifications

Pinout & Package

ADM706AN is housed in an 8-lead narrow-body plastic dual-in-line package (PDIP, N-8), compliant with JEDEC MS-001-BA, with 0.300-inch body width and 0.100-inch lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX706CSA+ and TPS3808G33DBVR, the ADM706AN uniquely combines 4.40 V supply supervision, integrated watchdog timer, and dedicated power-fail comparator (PFI/PFO) in a through-hole PDIP package - making it suitable for legacy industrial designs requiring full-feature supervision without layout redesign.

Availability

ADM706AN is available at Aetrix Electronics and suitable for industrial PLCs, medical instrumentation, point-of-sale terminals, and embedded data acquisition systems requiring stable component supply and long-term obsolescence management.

Supply support for ADM706AN 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/ADM706 family was engineered specifically for cost-sensitive microprocessor supervision in industrial and instrumentation applications, emphasizing reliability under brownout, low-VCC, and software fault conditions.

FAQ

What is the reset threshold voltage for ADM706AN?

The ADM706AN has a nominal reset threshold of 4.40 V, with a tolerance of ±0.15 V (4.25 V to 4.50 V). This value is factory-trimmed and specified over the full industrial temperature range (−40°C to +85°C). The threshold is used to detect brownout conditions on the 5 V supply, asserting the active-low RESET output whenever VCC falls below this level. The ADM706AN's 4.40 V threshold distinguishes it from the ADM705AN (4.65 V) and ensures compatibility with systems requiring earlier reset assertion during supply decay.

Does ADM706AN include a watchdog timer function?

Yes, the ADM706AN includes a fully integrated watchdog timer with a nominal timeout period of 1.60 seconds. The timer is cleared by any transition (high-to-low or low-to-high) on the WDI pin. If no transition occurs within the timeout window, the WDO output goes low. The watchdog is automatically disabled when WDI is left floating or connected to a high-impedance state. This feature enables autonomous detection of software lockups in microprocessor-based systems without requiring additional external components.

Can ADM706AN monitor a secondary power supply?

Yes, the ADM706AN can monitor a secondary supply using its PFI (Power-Fail Input) and PFO (Power-Fail Output) pins. The internal 1.25 V reference connects to the inverting input of a comparator, while PFI serves as the noninverting input. By applying a scaled version of the secondary supply to PFI via a resistor divider, the device asserts PFO low when the monitored voltage falls below 1.25 V. This allows early warning of battery depletion or auxiliary rail failure - a capability not present in simpler reset-only supervisors like the MAX706 series.

What package type is used for ADM706AN?

The ADM706AN is supplied in an 8-lead narrow-body plastic dual-in-line package (PDIP), designated N-8 per JEDEC MS-001-BA. It features a 0.300-inch body width, 0.100-inch lead pitch, and through-hole mounting. This package provides mechanical robustness and ease of prototyping or repair in industrial PCB assemblies. Unlike the SOIC (R-8) or MSOP (RM-8) variants, the ADM706AN does not use surface-mount packaging, making it suitable for legacy designs or environments where thermal cycling reliability favors through-hole construction.

How does ADM706AN ensure valid reset operation at low supply voltages?

The ADM706AN guarantees valid RESET output down to VCC = 1.0 V, meaning the RESET pin remains actively driven low even as the supply collapses. This is achieved through specialized low-voltage biasing and output stage design, ensuring the microprocessor stays held in reset throughout the entire undervoltage event - unlike many supervisors that release reset prematurely below ~2.5 V. This behavior is confirmed in Figure 6 of the datasheet and is critical for preventing undefined CPU states during power ramp-down or brownout recovery sequences.