Analog Devices Inc. ADM695ARZ

Overview

ADM695ARZ from Analog Devices is a 16-pin SOIC microprocessor supervisory circuit with adjustable reset timeout (200 ms or user-configurable), 4.65 V precision reset threshold, 100 ms/1.6 s selectable watchdog timer, automatic battery backup switchover (2.0–4.25 V VBATT), and CE gating with 5 ns propagation delay. It ensures reliable power-up/down sequencing and RAM write protection in industrial embedded controllers.

For engineers reviewing the ADM695ARZ datasheet, ADM695ARZ pinout, ADM695ARZ application, or ADM695ARZ equivalent, key selection criteria include its adjustable reset/watchdog timing, dual-mode oscillator (internal/external), BATT ON base-drive capability for external PNP transistors, and guaranteed RESET assertion down to 1 V VCC - critical for brownout resilience in automotive and industrial microprocessor systems.

Technical Context

The ADM695ARZ integrates a precision 4.65 V reset comparator with 40 mV hysteresis, a three-level WDI input supporting watchdog disable via mid-supply bias, and independent PFO/PFI circuitry for early power-fail warning using a 1.3 V internal reference. Its battery switchover uses 70 mV turn-on / 50 mV turn-off thresholds with 20 mV hysteresis to prevent oscillation during slow VCC decay.

It features dual-mode timing control: OSC SEL high/floating enables internal oscillator (fixed 200 ms reset, 100 ms/1.6 s watchdog); OSC SEL low enables external clock or capacitor-based adjustment per Table I. CEOUT is actively gated - forced high when VCC < reset threshold - ensuring fail-safe RAM write blocking.

Key Specifications

Pinout & Package

ADM695ARZ is housed in a 16-lead SOIC (R-16) package with 1.27 mm pitch, RoHS-compliant, and rated for –40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX695CSA+ and TPS3823MPW, the ADM695ARZ uniquely combines adjustable timing, integrated CE gating, BATT ON drive, and full battery switchover - making it the only option among the three that satisfies simultaneous requirements for RAM write protection, extended backup runtime, and programmable supervision in industrial edge devices.

Availability

ADM695ARZ is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive telematics units, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADM695ARZ 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 ADM690–ADM695 family was designed specifically for robust microprocessor system supervision - integrating reset, watchdog, battery switchover, power-fail warning, and memory protection into a single IC to reduce board space and improve system reliability.

FAQ

What is the guaranteed minimum operating VCC for ADM695ARZ reset functionality?

The ADM695ARZ guarantees RESET assertion down to 1 V VCC, ensuring the microprocessor remains held in reset during severe brownout conditions. This specification is validated across the full –40°C to +85°C temperature range and is critical for maintaining deterministic behavior in automotive and industrial power environments where supply collapse may be gradual. The ADM695ARZ achieves this via specialized low-voltage comparator circuitry not found in standard reset ICs.

How does ADM695ARZ implement adjustable reset timeout, and what components are required?

The ADM695ARZ implements adjustable reset timeout by configuring OSC SEL and OSC IN pins: with OSC SEL low, an external capacitor (e.g., 47 pF) between OSC IN and GND sets reset pulse width to 130 ms × C/47 pF (ADM695). Alternatively, an external clock (0–250 kHz) applied to OSC IN yields precise cycle-based timing (e.g., 2048 cycles). No additional resistors or op-amps are needed - the oscillator circuitry is fully integrated within the ADM695ARZ die.

Can ADM695ARZ drive external circuitry beyond its 100 mA VOUT limit, and how?

Yes - the ADM695ARZ's BATT ON output is designed to directly drive the base of an external PNP transistor (e.g., MMBT3906), enabling VOUT currents exceeding 500 mA while maintaining low dropout. During battery backup, BATT ON goes high and sources ~35 mA, providing sufficient base current for common PNP pass devices. This capability is documented in Figure 17 of the ADM695ARZ datasheet and requires no additional driver ICs.

What is the function of the LOW LINE output on ADM695ARZ, and how does it differ from RESET?

The LOW LINE output on ADM695ARZ is an active-low signal that asserts immediately when VCC falls below the 4.65 V reset threshold and de-asserts immediately upon recovery - unlike RESET, which holds for 200 ms post-recovery. This makes LOW LINE ideal for real-time status indication (e.g., LED drivers or interrupt flags), while RESET serves as the timed system reset signal. Both outputs are electrically isolated and can be used concurrently in the same design.

Does ADM695ARZ support write protection for EEPROM, and how is it implemented?

Yes - ADM695ARZ supports EEPROM write protection via its CEOUT pin, which is a gated replica of CEIN. When VCC drops below the reset threshold, CEOUT is forced high regardless of CEIN state, preventing write commands from reaching the EEPROM. This is explicitly validated in battery backup mode (Table II) and applies to all supported EEPROM types, including serial (I²C/SPI) and parallel variants, as confirmed in the "CE Gating and RAM Write Protection" section of the ADM695ARZ datasheet.