Analog Devices Inc. ADM709TAR

Overview

ADM709TAR from Analog Devices is a precision power supply monitor IC with active-low reset output, 3.08 V threshold, 140 ms minimum power-on reset pulse, and operation down to 1 V supply voltage-designed for reliable reset assertion in +3 V microprocessor systems during power-up, brownout, and power-down events.

For engineers reviewing the ADM709TAR datasheet, ADM709TAR pinout, ADM709TAR application, or ADM709TAR equivalent, key selection considerations include reset threshold accuracy (±0.08 V), guaranteed RESET functionality at VCC ≥ 1 V, SO-8 package compatibility, and direct upgrade path from MAX709 for 3.08 V monitoring.

Technical Context

The ADM709TAR integrates a precision voltage comparator and internal timer to generate a clean, glitch-immune active-low RESET signal. It asserts RESET when VCC falls below 3.08 V and holds it low for ≥140 ms after VCC rises above threshold-ensuring stable microprocessor initialization.

VCC-to-RESET delay is ≤20 µs, and RESET remains functional down to 1.0 V supply, enabling robust shutdown sequencing. The device features no-connect pins (1, 4, 5, 6, 8) and requires no external components for basic operation, though optional 0.1 µF bypass capacitor improves noise immunity.

Key Specifications

Pinout & Package

ADM709TAR is housed in an 8-pin SOIC (SO-8) package with standard JEDEC MS-012AC dimensions (3.90 mm × 4.90 mm, 1.27 mm pitch). Pin 1 is marked by a beveled corner or dot; pins 1, 4, 5, 6, and 8 are internally unconnected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power supply monitor applications.

Compared with MAX709TSA+ and TPS3808G30DBVR, the ADM709TAR uniquely guarantees RESET functionality down to 1.0 V VCC while maintaining tight 3.08 V threshold accuracy-making it optimal for systems demanding fail-safe reset hold during deep brownout and cold-start conditions.

Availability

ADM709TAR is available at Aetrix Electronics and suitable for industrial PLC controllers, medical handheld diagnostics, automotive body control modules, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADM709TAR 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 ADM709 belongs to Analog Devices' precision power monitoring product line, engineered specifically for deterministic reset generation in microprocessor-based systems subject to voltage transients, brownouts, and unregulated supply conditions.

FAQ

What is the exact reset threshold voltage of the ADM709TAR?

The ADM709TAR has a nominal reset threshold of 3.08 V, with a guaranteed range of 3.00 V to 3.15 V over the full –40°C to +85°C temperature range. This value is factory-trimmed and does not require external calibration. The ADM709TAR's 3.08 V threshold is specifically optimized for reliable monitoring of +3 V supply rails in microcontroller and embedded applications.

Does the ADM709TAR support operation below 2.0 V VCC?

Yes-the ADM709TAR is fully specified to operate with VCC as low as 1.0 V, and its RESET output remains functional and asserted low throughout that range. This capability ensures robust reset hold during deep brownout or controlled power-down sequences where other supervisors may release prematurely. The ADM709TAR's 1 V operation is explicitly tested and guaranteed per datasheet Section "RESET at Voltages < 1 V".

What is the minimum power-on reset pulse width for the ADM709TAR?

The ADM709TAR guarantees a minimum RESET active time-out period of 140 ms after VCC rises above the 3.08 V threshold. Typical duration is 280 ms, and maximum is 380 ms. This fixed internal timer eliminates reliance on external RC networks and ensures consistent microprocessor initialization timing across temperature and unit variation-critical for reliable boot in the ADM709TAR's target applications.

Which pins are unused on the ADM709TAR SO-8 package?

Pins 1, 4, 5, 6, and 8 of the ADM709TAR are designated NC (No Connect) and are not bonded internally. They serve no electrical function and may be left floating or tied to GND for mechanical reinforcement-no routing or termination is required. Only Pins 2 (VCC), 3 (GND), and 7 (RESET) are active terminals in the ADM709TAR's functional implementation.

Is the ADM709TAR a direct replacement for the MAX709T?

The ADM709TAR is positioned as an upgrade for the MAX709 family, sharing identical 3.08 V threshold, SO-8 footprint, and functional behavior-but with enhanced specifications including guaranteed 1 V operation and improved glitch immunity. While not formally certified as pin-compatible, the ADM709TAR's pinout matches MAX709T (VCC=2, GND=3, RESET=7), and no PCB changes are needed for drop-in replacement in most designs using the ADM709TAR.