Analog Devices Inc. LTC699IS8#TRPBF

Overview

LTC699IS8#TRPBF from Analog Devices (formerly Linear Technology) is a microprocessor supervisory circuit with integrated watchdog timer and precision 4.65V reset threshold. It provides guaranteed reset assertion down to VCC = 1V, 200ms reset active time, 1.6s watchdog timeout, open-drain RESET output, and operates from 3.0V to 5.5V supply - used for reliable power-on reset and runtime fault detection in embedded controllers.

For engineers reviewing the LTC699IS8#TRPBF datasheet, LTC699IS8#TRPBF pinout, LTC699IS8#TRPBF application, or LTC699IS8#TRPBF equivalent, key selection criteria include guaranteed low-VCC reset behavior, temperature-stable reset threshold hysteresis (40mV), SO-8 package compatibility, and watchdog input transition sensitivity - critical for automotive and industrial microcontroller systems requiring fail-safe startup and runtime supervision.

Technical Context

The LTC699IS8#TRPBF integrates a bandgap-referenced voltage comparator monitoring VCC against a precise 4.65V threshold with 40mV hysteresis, ensuring immunity to supply transients. Its open-drain RESET output remains valid down to VCC = 1V, enabling robust system hold-in-reset during brownout conditions.

A dedicated three-level WDI input supports watchdog enable/disable via logic high/low hold or floating state. The internal 1.6s watchdog timeout resets on every WDI transition and forces a minimum 140ms active-low RESET pulse upon timeout - independent of power-up reset timing.

Key Specifications

Pinout & Package

Package: 8-lead plastic SOIC (S8), 3.9mm × 4.9mm body, gull-wing leads, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX699CSA+ and TPS3808G18DBVR, the LTC699IS8#TRPBF uniquely combines precision reset supervision with an integrated, transition-triggered watchdog in a single SO-8 package - eliminating external timing components and simplifying firmware integration while maintaining guaranteed low-VCC reset behavior essential for mission-critical systems.

Availability

LTC699IS8#TRPBF is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC controllers, and medical diagnostic instruments requiring stable component supply, long-term lifecycle support, and guaranteed reset performance across temperature extremes.

Supply support for LTC699IS8#TRPBF 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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.

The LTC699 series was designed specifically for microprocessor-based systems needing simultaneous power monitoring and watchdog supervision in a single IC - targeting automotive, industrial, and medical applications demanding reliability under voltage stress and temperature variation.

FAQ

What is the guaranteed minimum VCC level at which LTC699IS8#TRPBF asserts RESET?

The LTC699IS8#TRPBF guarantees RESET assertion even when VCC drops as low as 1V - a critical feature for holding microprocessors in a known safe state during severe brownout conditions. This behavior is verified across temperature and process corners, and is enabled by internal charge-pump circuitry that sustains comparator operation below normal logic thresholds. Unlike many supervisors, the LTC699IS8#TRPBF maintains this guarantee without external components.

Does LTC699IS8#TRPBF support adjustable reset threshold voltage?

No, the LTC699IS8#TRPBF features a factory-trimmed fixed reset threshold of 4.65V ±50mV, optimized for 5V systems. It does not support external resistor programming or voltage adjustment. For designs requiring user-configurable thresholds, consider alternatives like the TPS3808 series. The fixed threshold ensures predictable, repeatable reset timing without calibration overhead - ideal for high-volume automotive and industrial applications where consistency is mandatory.

How does the watchdog function behave when the WDI pin is left floating on LTC699IS8#TRPBF?

When the WDI pin is left floating, the watchdog timer in the LTC699IS8#TRPBF is automatically disabled - no RESET pulses will be generated due to watchdog timeout. This behavior is intentional and documented in the Linear Technology datasheet. Floating WDI serves as a hardware disable mechanism, allowing designers to retain the IC's reset functionality while omitting watchdog supervision in specific configurations without modifying firmware or adding pull resistors.

What is the maximum sink current capability of the RESET output on LTC699IS8#TRPBF?

The RESET output of the LTC699IS8#TRPBF is an open-drain NMOS device rated for up to 25mA sink current at VCC = 4.25V and TA = 25°C. At lower VCC (e.g., 1V), sink capability reduces to 10µA minimum, consistent with its guaranteed low-VCC operation. This allows direct interfacing with most µP reset inputs and supports wired-OR configurations with multiple supervisors - provided total sink current remains within spec and external pull-up value is selected accordingly.

Is LTC699IS8#TRPBF pin-compatible with the MAX699 family?

The LTC699IS8#TRPBF shares identical SO-8 pinout and core functionality with the MAX699CSA+, including VCC, GND, WDI, and RESET assignments. However, it adds internal watchdog logic not present in the MAX699, and its WDI pin implements three-level detection (high/low/floating). While PCB layout is compatible, firmware must account for enhanced WDI behavior - making it a functional upgrade rather than a drop-in replacement unless watchdog use is explicitly validated.