Analog Devices Inc. ADM690AN

Overview

ADM690AN from Analog Devices is an 8-pin DIP microprocessor supervisory circuit providing power-on reset, battery backup switchover, watchdog timer (1.6 s fixed), and power-fail warning for +5 V systems. It asserts RESET down to VCC = 1 V, delivers up to 100 mA at VOUT with ≤0.5 V dropout, and features a 1.3 V PFI comparator for early power failure detection - used in industrial controllers and embedded instrumentation requiring reliable brownout recovery.

For engineers reviewing the ADM690AN datasheet, ADM690AN pinout, ADM690AN application, or ADM690AN equivalent, key selection criteria include its fixed 4.65 V reset threshold, 50 ms reset pulse width, battery switchover hysteresis (20 mV), CE gating disable status, and absence of adjustable timeout or RAM write protection - distinguishing it from ADM691/ADM695 variants.

Technical Context

The ADM690AN integrates a precision 4.65 V reset comparator with 40 mV hysteresis, a fixed-frequency internal oscillator setting both reset timing (50 ms) and watchdog timeout (1.6 s), and a dual-path PMOS/NMOS battery switchover circuit that transitions at VCC–VBATT = 70 mV (rise) and 50 mV (fall). Its RESET output remains functional below 1 V VCC, and VOUT sustains 100 mA load with <0.25 V drop at full current.

No external capacitor or clock input is required: OSC SEL is internally pulled up, disabling external timing configuration. The device lacks CEIN/CEOUT and BATT ON pins - confirming absence of chip-enable gating and external PNP base drive - and operates exclusively in the 8-pin N-8 DIP package across –40°C to +85°C.

Key Specifications

Pinout & Package

ADM690AN is housed in an 8-pin plastic DIP (N-8) package with 0.3-inch width and through-hole mounting. Pin functions are validated per Analog Devices REV. A datasheet Figure 5 and Pin Function Description table.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690CPA+, ADM690AN offers identical supervision functionality with Analog Devices' qualification and support ecosystem; versus TPS3823-46DBVR, ADM690AN provides complete system-level supervision (reset, watchdog, battery switchover, PFI) in one 8-pin DIP, eliminating need for multiple discrete supervisors.

Availability

ADM690AN is available at Aetrix Electronics and suitable for industrial controllers, medical instrumentation, automotive body modules, and test equipment requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for ADM690AN 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 semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control systems.

The ADM690AN belongs to the ADM690–ADM695 supervisory family, designed specifically for robust power monitoring and fail-safe operation in 5 V microprocessor systems operating across industrial temperature ranges.

FAQ

What is the guaranteed reset voltage threshold for ADM690AN?

The ADM690AN has a guaranteed reset voltage threshold of 4.5 V minimum to 4.73 V maximum, with a typical value of 4.65 V. This specification ensures reliable reset assertion for +5 V systems with ±5% supply tolerance. The ADM690AN uses this fixed threshold without adjustment capability, and it remains valid over the full –40°C to +85°C operating temperature range as specified in the official Analog Devices datasheet.

Does ADM690AN support adjustable watchdog timeout or reset pulse width?

No, ADM690AN does not support adjustable watchdog timeout or reset pulse width. It features a fixed 1.6 s watchdog timeout and fixed 50 ms reset pulse width, both generated by its internal oscillator. Unlike ADM691/ADM695 variants, ADM690AN lacks OSC IN and OSC SEL pins for external timing configuration - confirmed by its 8-pin N-8 DIP pinout and functional block diagram in the datasheet.

Can ADM690AN drive CMOS RAM directly without external components?

Yes, ADM690AN can drive CMOS RAM directly: its VOUT pin delivers up to 100 mA with ≤0.25 V dropout at full load, sufficient for typical SRAM banks. No external pass transistor or regulator is needed. The device also provides automatic switchover to VBATT (2.0–4.25 V) during main supply failure, preserving RAM data integrity without additional circuitry.

What is the purpose of the PFI and PFO pins on ADM690AN?

The PFI (Power Fail Input) pin connects to a resistor divider monitoring a DC rail, comparing it to an internal 1.3 V reference. When PFI falls below 1.3 V, the PFO (Power Fail Output) pin goes low - providing an early warning interrupt before VCC crosses the 4.65 V reset threshold. This enables the host microprocessor to execute emergency save routines, making ADM690AN suitable for systems requiring graceful shutdown on power degradation.

Is ADM690AN pin-compatible with other devices in the ADM690–ADM695 family?

ADM690AN shares the same 8-pin N-8 DIP footprint with ADM692AN and ADM694AN, but is not functionally pin-compatible with 16-pin variants (e.g., ADM691AN) or packages with CEIN/CEOUT/BATT ON pins. Its pinout omits CEIN, CEOUT, BATT ON, LOW LINE, RESET (active-high), and OSC IN - confirming hardware-level differentiation from feature-rich siblings. Always verify pin mapping against the specific variant's datasheet.