Analog Devices Inc. ADM6321BZ25ARJZ-R7

Overview

ADM6321BZ25ARJZ-R7 from Analog Devices is a supervisory circuit with watchdog timer and open-drain active-low reset output, designed for microprocessor supply voltage monitoring. It features a 2.5 V reset threshold (±2.5% over −40°C to +85°C), 20 ms minimum reset timeout, 25.6 sec typical watchdog timeout, manual reset disable, and consumes ≤12 µA at 3.6 V. It ensures reliable system reset during power-up, brownout, or code execution failure in portable embedded controllers.

For engineers reviewing the ADM6321BZ25ARJZ-R7 datasheet, ADM6321BZ25ARJZ-R7 pinout, ADM6321BZ25ARJZ-R7 application, or ADM6321BZ25ARJZ-R7 equivalent, key selection criteria include its open-drain RESET configuration (requiring external pull-up), absence of manual reset input, dual-reset-output architecture (RESET and RESET), and compatibility with low-voltage 2.5 V systems requiring long watchdog supervision.

Technical Context

The ADM6321BZ25ARJZ-R7 implements a precision bandgap-based voltage reference and comparator to monitor VCC against a factory-trimmed 2.5 V threshold with ±2.5% tolerance across −40°C to +85°C. Its watchdog timer clears on any WDI logic transition and times out after 25.6 sec (typical), asserting reset if firmware fails to service it.

This device uses an open-drain active-low RESET output and a push-pull active-high RESET output - enabling flexible reset signaling to multiple downstream logic families. It guarantees valid reset assertion down to VCC = 1 V and provides glitch immunity against fast VCC transients up to 100 ns.

Key Specifications

Pinout & Package

ADM6321BZ25ARJZ-R7 is housed in a 5-lead SOT-23 package (JEDEC MO-178-AA compliant), with 1.3 mm × 2.9 mm footprint and 1.15 mm height - optimized for space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6321XR25-T and TPS3808G33DBVR, ADM6321BZ25ARJZ-R7 uniquely delivers dual-polarity reset outputs and integrated 25.6 sec watchdog in a single 5-pin SOT-23 - eliminating external components and enabling robust, self-contained system supervision for space- and reliability-critical designs.

Availability

ADM6321BZ25ARJZ-R7 is available at Aetrix Electronics and suitable for industrial PLCs, portable medical devices, smart energy meters, and automotive body control modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ADM6321BZ25ARJZ-R7 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 ADM63xx family was engineered specifically for microprocessor-based systems needing guaranteed power-on reset, brownout protection, and firmware-execution supervision - with emphasis on low power, small footprint, and industrial temperature resilience.

FAQ

What is the reset threshold voltage and tolerance for ADM6321BZ25ARJZ-R7?

The ADM6321BZ25ARJZ-R7 has a nominal reset threshold of 2.5 V, with ±2.5% tolerance over the full industrial temperature range (−40°C to +85°C). This specification ensures accurate brownout detection in 2.5 V supply domains without false triggering due to temperature drift or process variation. The threshold is factory-trimmed and does not require external resistors.

Does ADM6321BZ25ARJZ-R7 include a manual reset input?

No, ADM6321BZ25ARJZ-R7 does not feature a manual reset (MR) input. Per Table 1 in the datasheet, the ADM6321 variant is defined as having watchdog enabled and manual reset disabled. Reset assertion occurs only via VCC undervoltage, watchdog timeout, or externally driven WDI transitions - making it suitable for fully autonomous supervision without user intervention.

What are the electrical characteristics of the RESET and RESET outputs on ADM6321BZ25ARJZ-R7?

ADM6321BZ25ARJZ-R7 provides two independent reset outputs: pin 1 (RESET) is open-drain active-low, requiring an external pull-up; pin 3 (RESET) is push-pull active-high, capable of sourcing up to 800 µA and sinking 1.2 mA. Both outputs remain valid down to VCC = 1 V, and RESET logic high is guaranteed to reach ≥0.8 × VCC at 150 µA source current.

How does the watchdog timer on ADM6321BZ25ARJZ-R7 operate, and what is its timeout value?

The watchdog timer in ADM6321BZ25ARJZ-R7 clears on every logic transition (low-to-high or high-to-low) at the WDI pin and times out after 25.6 sec (typical), with min/max of 17.9 sec / 38.4 sec. If the firmware fails to toggle WDI within this period, the device asserts both RESET and RESET. The timer also resets automatically during VCC undervoltage or MR-induced reset - though ADM6321 has no MR pin.

Is ADM6321BZ25ARJZ-R7 compatible with 1.8 V or 3.3 V microcontrollers?

Yes, ADM6321BZ25ARJZ-R7 operates from VCC = 1 V to 5.5 V and guarantees valid reset output states across that range. Its RESET output (push-pull) meets 1.8 V logic high/low thresholds when VCC ≥ 1.8 V, and RESET (open-drain) can be pulled up to any compatible rail ≤6 V - enabling direct interfacing with 1.8 V, 2.5 V, 3.3 V, or 5 V MCUs without level translation.