Texas Instruments TPS3851H18EDRBR

Overview

TPS3851H18EDRBR from Texas Instruments is a precision voltage supervisor IC with integrated watchdog timer, designed for reliable power-up and fault monitoring in microcontroller-based systems. It delivers 0.8% undervoltage threshold accuracy (–40°C to +125°C), 200 ms reset timeout (±15%), and user-programmable watchdog timing via external capacitor or factory-set delays. It supports 1.8 V supply rails and operates across 1.6 V to 6.5 V input range.

For engineers reviewing the TPS3851H18EDRBR datasheet, TPS3851H18EDRBR pinout, TPS3851H18EDRBR application, or TPS3851H18EDRBR equivalent, this device serves as a high-accuracy supervisory solution where tight tolerance reset behavior, independent watchdog fault signaling, and low-quiescent-current operation are critical - especially in safety-aware embedded systems requiring deterministic reset sequencing and watchdog event isolation.

Technical Context

The TPS3851H18EDRBR implements a precision comparator with 0.5% hysteresis and 0.8% VITN accuracy over full temperature range, enabling robust undervoltage detection on 1.8 V rails without external calibration. Its dual-output architecture separates RESET (system reset) and WDO (watchdog fault flag), allowing independent handling of power faults versus software hangs.

Watchdog timing is configurable via CWD pin: open or 10 kΩ pullup enables factory-programmed delays (1600 ms standard, 200 ms extended), while a capacitor (0.1–1000 nF) provides continuous programmability. SET1 disables watchdog entirely; MR enables manual reset assertion; WDI accepts falling-edge-triggered watchdog refresh signals.

Key Specifications

Pinout & Package

TPS3851H18EDRBR uses an 8-pin VSON package (DRB), 3.00 mm × 3.00 mm body size, with exposed thermal pad connected internally to GND. The package supports high-density PCB layouts and efficient heat dissipation via thermal pad soldering to ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor with watchdog applications.

Compared with TPS3851G18EDRBR and TPS3823-18DBVR, the TPS3851H18EDRBR uniquely combines 0.8% threshold accuracy, 0.5% hysteresis, and dual open-drain outputs - enabling both precise power-fault response and non-disruptive software hang detection in space-constrained industrial designs.

Availability

TPS3851H18EDRBR is available at Aetrix Electronics and suitable for WLAN access points, wireless security cameras, IP network cameras, electricity meters, and string inverters requiring stable component supply across extended temperature and long product lifecycles.

Supply support for TPS3851H18EDRBR 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

Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in precision power management and real-time signal monitoring solutions.

The TPS3851 family is engineered for high-reliability embedded supervision - delivering factory-trimmed accuracy, dual-output fault isolation, and flexible watchdog configuration to meet stringent requirements in industrial automation, energy infrastructure, and connected edge devices.

FAQ

What is the exact undervoltage threshold voltage for TPS3851H18EDRBR?

The TPS3851H18EDRBR has a nominal undervoltage threshold (VITN) of 1.728 V, with guaranteed accuracy of ±0.8% over –40°C to +125°C. This value is factory-trimmed and specifically optimized for 1.8 V supply rails, ensuring reliable reset assertion before the microcontroller's minimum operating voltage is violated.

How does the watchdog timeout work on TPS3851H18EDRBR when CWD is left unconnected?

When CWD is left unconnected (high-impedance) and SET1 is high, the TPS3851H18EDRBR uses its factory-programmed watchdog timeout of 1600 ms (typical). This mode provides ±15% timing accuracy and eliminates external components, simplifying layout while maintaining high precision for firmware hang detection.

Can TPS3851H18EDRBR monitor a 1.8 V rail while powered from a higher voltage like 3.3 V?

Yes - the TPS3851H18EDRBR monitors VDD directly, so it must be powered from the same 1.8 V rail it supervises. Its 1.6 V to 6.5 V supply range allows operation on that rail; however, connecting it to 3.3 V would shift the effective VITN to 3.3 V × (1.728/1.8) ≈ 3.17 V, invalidating its 1.8 V rail supervision function.

What is the role of the SET1 pin on TPS3851H18EDRBR?

The SET1 pin on TPS3851H18EDRBR controls watchdog enable/disable functionality: grounding SET1 disables the watchdog timer entirely, causing WDI to be ignored and WDO to remain high-impedance. This allows safe development and debugging without unintended timeouts, while preserving RESET functionality for power supervision.

Does TPS3851H18EDRBR require an external capacitor on the CWD pin to operate?

No - the TPS3851H18EDRBR operates fully without an external capacitor on CWD. Leaving CWD unconnected or pulling it up to VDD via 10 kΩ enables factory-programmed watchdog delays. A capacitor is optional and used only when user-defined timing (e.g., 100 ms or 5 s) is required via the 375 nA constant-current charge circuit.