Analog Devices Inc. ADM708ANZ

Overview

ADM708ANZ 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 to ensure reliable boot-up and brownout recovery.

For engineers reviewing the ADM708ANZ datasheet, ADM708ANZ pinout, ADM708ANZ application, or ADM708ANZ equivalent, key selection criteria include reset threshold accuracy (4.40 V), dual-reset output polarity support, guaranteed RESET validity down to 1 V VCC, quiescent current (190 µA), and compatibility with TTL/CMOS manual reset inputs.

Technical Context

The ADM708ANZ implements a precision bandgap-based voltage reference (1.25 V) for power-fail comparison and a separate 4.40 V reset threshold comparator. Its dual-reset architecture delivers both active-low (RESET) and active-high (RESET) outputs simultaneously, eliminating need for external inverters in mixed-logic systems.

No watchdog timer is integrated - unlike ADM705/ADM706 - making it suitable for applications requiring only supply supervision and power-fail warning. The PFI input accepts external resistive dividers to monitor auxiliary supplies, and PFO asserts low when PFI falls below 1.25 V.

Key Specifications

Pinout & Package

ADM708ANZ is supplied in an 8-lead narrow-body plastic dual-in-line package (PDIP, N-8), compliant with JEDEC MS-001-BA. Pin spacing is 0.100 inch (2.54 mm), with 0.300 inch body width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADM708ARZ, ADM708ANZ offers identical supervision functionality in a through-hole PDIP package ideal for lab validation and legacy designs; versus MAX708CSA+, ADM708ANZ trades watchdog capability for lower quiescent current and simpler timing behavior, better suited for static supply monitoring.

Availability

ADM708ANZ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, and telecom remote terminal units requiring stable component supply across extended temperature ranges (−40°C to +85°C).

Supply support for ADM708ANZ 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 systems needing reliable power-on reset, brownout protection, and auxiliary supply monitoring - with variants optimized for reset threshold, output polarity, and feature set.

FAQ

What is the reset threshold voltage of the ADM708ANZ?

The ADM708ANZ has a nominal reset threshold voltage 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 VCC supply and assert both RESET and RESET outputs accordingly. This exact 4.40 V setting distinguishes ADM708ANZ from ADM707ANZ (4.65 V) and aligns it with the ADM706 series.

Does the ADM708ANZ include a watchdog timer?

No, the ADM708ANZ does not include a watchdog timer. It belongs to the ADM707/ADM708 variant group, which omits the watchdog circuitry found in ADM705/ADM706. Instead, ADM708ANZ provides dual-reset outputs (active-low RESET and active-high RESET) and a dedicated power-fail comparator (PFI/PFO). If watchdog functionality is required, ADM706ANZ or ADM705ANZ should be considered - but those lack the active-high RESET output present in ADM708ANZ.

What is the purpose of the NC pin on the ADM708ANZ?

Pin 6 on the ADM708ANZ is marked NC (No Connect) and is internally unconnected. It must remain floating or be tied to GND - it serves no electrical function. This pin corresponds to the WDI (Watchdog Input) pin on the ADM705/ADM706 variants, which are excluded in ADM708ANZ due to absence of watchdog circuitry. PCB layouts must avoid routing signals to this pin, and soldering it to ground is acceptable but unnecessary.

Can the ADM708ANZ monitor a 3.3 V supply?

Yes, the ADM708ANZ can monitor a 3.3 V supply using its PFI input and 1.25 V internal reference. A resistive divider (e.g., R1 = 16.2 kΩ, R2 = 10 kΩ) scales the 3.3 V supply to ~1.25 V at PFI. When the 3.3 V rail drops below ~3.15 V, PFI falls below 1.25 V and PFO asserts low - signaling a fault. This technique is documented in the ADM705/ADM706/ADM707/ADM708 datasheet Figure 20 and Application Information section "Monitoring Additional Supply Levels".

What is the minimum VCC voltage at which ADM708ANZ guarantees valid RESET output?

The ADM708ANZ guarantees valid RESET output down to VCC = 1.0 V, as confirmed in the Absolute Maximum Ratings table and Typical Performance Characteristics (Figure 6 and Figure 7). At 1.0 V, RESET remains low with a maximum VOL of 0.3 V (ISINK = 50 µA), ensuring compatible logic-level hold for microprocessors with low-threshold inputs. This specification enables safe system shutdown during deep undervoltage events, a key reliability feature distinguishing ADM708ANZ from many competing supervisors.