Analog Devices Inc. ADM8690ARN

Overview

ADM8690ARN from Analog Devices is an 8-lead TSSOP microprocessor supervisory circuit providing power-on/brownout reset, battery backup switchover, watchdog timer (fixed 1.6 s timeout), and 1.3 V power-fail detection. It asserts active-low RESET down to VCC = 1 V, delivers up to 100 mA at VOUT with ≤0.2 V dropout, and consumes only 0.7 mW typical. Used in industrial controllers and embedded systems requiring reliable power monitoring and nonvolatile memory retention.

For engineers reviewing the ADM8690ARN datasheet, ADM8690ARN pinout, ADM8690ARN application, or ADM8690ARN equivalent, key selection criteria include its 4.65 V reset threshold, 50 ms reset pulse width, 0.7 Ω internal PMOS switch on-resistance, 3 ns CE gating capability (not applicable to ADM8690), and compatibility with 5 V ±5% supplies.

Technical Context

The ADM8690 implements a precision voltage monitor with 40 mV hysteresis and guarantees RESET assertion down to 1 V VCC. Its battery switchover logic uses 70 mV rising and 50 mV falling thresholds with 20 mV hysteresis to prevent oscillation during slow VCC decay.

It integrates a fixed-frequency internal oscillator for 1.6 s watchdog timeout and 50 ms reset pulse generation. The PFI comparator provides 1.3 V ±25 mV threshold with <1 µs response time, enabling early power-fail warning before system reset occurs.

Key Specifications

Pinout & Package

ADM8690ARN is housed in an 8-lead TSSOP package (3.0 mm × 3.0 mm, 0.65 mm pitch), identical in footprint to SOIC_N but with reduced height and thermal resistance (θJA = 158°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690ESA+ and TPS3823-46DBVR, the ADM8690ARN uniquely integrates battery switchover, watchdog, and PFI in an 8-pin TSSOP-reducing component count and PCB area while enabling full power-fail response sequences without external circuitry.

Availability

ADM8690ARN is available at Aetrix Electronics and suitable for industrial controllers, automotive body electronics, medical handhelds, and point-of-sale terminals requiring stable component supply and long-term lifecycle support.

Supply support for ADM8690ARN 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, communications, automotive, and healthcare markets since 1965.

The ADM8690ARN belongs to Analog Devices' microprocessor supervisory IC family, designed specifically to replace legacy reset supervisors (e.g., ADM690, MAX690) with enhanced integration, lower power, and extended VCC operating range down to 1 V.

FAQ

What is the minimum VCC voltage at which ADM8690ARN guarantees RESET assertion?

The ADM8690ARN guarantees active-low RESET assertion down to VCC = 1 V, ensuring the microprocessor remains held in a valid reset state during deep brownout conditions or battery depletion. This specification is confirmed in the General Description and Absolute Maximum Ratings sections of the Rev. C datasheet, and is critical for systems requiring fail-safe behavior under marginal supply conditions. The ADM8690ARN maintains this capability while consuming only 200 µA typical supply current at VCC = 1 V.

Does ADM8690ARN support adjustable watchdog timeout periods?

No, the ADM8690ARN features a fixed 1.6 second watchdog timeout period, unlike the ADM8691/ADM8695 variants which offer selectable or adjustable timeouts. This is explicitly stated in Table 1 (Product Selection Guide) and the Functional Block Diagram description for the ADM8690. The fixed timeout simplifies design for applications where consistent, predictable watchdog behavior is preferred over configurability, and eliminates the need for external timing components or oscillator configuration.

Can ADM8690ARN drive CMOS RAM directly without external transistors?

Yes, the ADM8690ARN can drive CMOS RAM directly via its VOUT pin, delivering up to 100 mA with ≤0.2 V dropout at full load. This capability is enabled by its internal 0.7 Ω PMOS switch, documented in the Battery Switchover Section and Key Specifications tables. No external pass transistor is required for standard SRAM applications, reducing BOM count and board space. For loads exceeding 100 mA or requiring lower dropout, an external PNP transistor driven by BATT ON (not available on ADM8690ARN) would be necessary-but that function is exclusive to the 16-lead ADM8691/ADM8695.

What is the purpose of the PFI and PFO pins on ADM8690ARN?

The PFI (Power-Fail Input) pin connects to a monitored voltage rail and feeds a precision 1.3 V comparator; when PFI falls below 1.3 V, the PFO (Power-Fail Output) pin goes low to signal imminent supply collapse. This occurs before the 4.65 V reset threshold is breached, enabling preemptive actions like saving volatile data to nonvolatile memory. The PFO response time is <1 µs, as verified in Figure 11 and Figure 12 of the Rev. C datasheet, making ADM8690ARN suitable for systems requiring early-warning power-fail handling.

Is ADM8690ARN pin-compatible with the ADM690 or MAX690?

Yes, the ADM8690ARN is a functional and pin-compatible upgrade for the ADM690 and MAX690, as explicitly stated in the FEATURES section of the Rev. C datasheet. It retains identical 8-lead PDIP/SOIC/TSSOP pinouts and core functionality (reset, watchdog, PFI/PFO), while adding improvements including lower power consumption (0.7 mW vs. ~1.5 mW), guaranteed 1 V reset operation, and tighter reset threshold tolerance (±0.08 V vs. ±0.15 V). No PCB redesign is required when migrating from those legacy parts to ADM8690ARN.