Texas Instruments TPS3851G50SDRBR

Overview

TPS3851G50SDRBR 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 features a 4.8 V undervoltage threshold (VITN = 4.8 V), 0.8% accuracy over –40°C to +125°C, 200 ms reset timeout (tRST), open-drain RESET and WDO outputs, and operates from 1.6 V to 6.5 V supply. It serves as a system-level safety monitor in industrial and connected-device power rails.

For engineers reviewing the TPS3851G50SDRBR datasheet, TPS3851G50SDRBR pinout, TPS3851G50SDRBR application, or TPS3851G50SDRBR equivalent, this page delivers verified functional roles, factory-programmed timing values, thermal pad handling guidance, watchdog disable logic via SET1, and precise hysteresis behavior critical for tight-tolerance 5 V rail supervision.

Technical Context

The TPS3851G50SDRBR implements a high-accuracy comparator with 0.5% hysteresis and 0.8% VITN accuracy across temperature, enabling robust undervoltage detection on 5 V rails without external calibration. Its dual-output architecture separates RESET (system reset) and WDO (watchdog fault flag), allowing independent fault diagnosis without full system reset.

Watchdog timing is determined by CWD pin configuration: unconnected or pulled up with 10 kΩ enables factory-programmed 1600 ms (typical) timeout; capacitor-based timing supports adjustable delays. SET1 pin disables watchdog entirely, and MR provides manual reset initiation with internal pullup - all operating within the same 1.6–6.5 V VDD range.

Key Specifications

Pinout & Package

TPS3851G50SDRBR is housed in a 3.00 mm × 3.00 mm, 8-pin VSON package with exposed thermal pad internally connected to GND. The package supports high-density PCB layouts and requires thermal pad soldering to a large-area ground plane for optimal thermal performance (RθJB = 25.8 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3851G50SDRBR, TPS3851G18SDRBR serves a different voltage rail and cannot replace it without circuit redesign, while MAX6369KA29+T trades precision and integration for lower cost and higher threshold tolerance - making both alternatives non-interchangeable without functional and layout validation.

Availability

TPS3851G50SDRBR is available at Aetrix Electronics and suitable for WLAN access points, IP network cameras, string inverters, and medical monitors requiring stable component supply with guaranteed long-term manufacturability and automotive-grade temperature support.

Supply support for TPS3851G50SDRBR 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 power management, signal chain, and real-time control ICs.

The TPS3851 product line delivers high-accuracy, integrated supervisors for mission-critical embedded systems - designed specifically to replace discrete reset ICs and external watchdog circuits in space-constrained, thermally demanding applications.

FAQ

What is the exact undervoltage threshold voltage of the TPS3851G50SDRBR?

The TPS3851G50SDRBR has a factory-set undervoltage threshold (VITN) of 4.8 V with ±0.8% accuracy over –40°C to +125°C. This value is laser-trimmed during production and confirmed in the device's characterization data (Figure 5-9). The 4.8 V threshold is optimized for supervision of standard 5 V power rails in industrial and networking equipment, ensuring reset assertion before the microcontroller's minimum operating voltage is violated. The TPS3851G50SDRBR does not support field adjustment of VITN.

How does the watchdog timeout work on the TPS3851G50SDRBR when CWD is left unconnected?

When the CWD pin of the TPS3851G50SDRBR is left unconnected (high-impedance), the device selects the factory-programmed standard timing mode with a typical watchdog timeout of 1600 ms (min 1360 ms, max 1840 ms). This value is stored in nonvolatile memory and requires no external components. The internal state machine evaluates CWD at power-up (tINIT = 381 µs) and locks the timing mode until next power cycle. Leaving CWD unconnected is a valid, production-ready configuration explicitly supported in TI's datasheet Table 7-1.

Can the TPS3851G50SDRBR be used to supervise a 3.3 V rail?

No - the TPS3851G50SDRBR is specifically trimmed for a 4.8 V threshold and is not suitable for direct 3.3 V rail supervision. For 3.3 V applications, Texas Instruments offers the TPS3851G33 variant (VITN = 3.072 V). Using the TPS3851G50SDRBR on a 3.3 V rail would result in permanent RESET assertion since VDD (3.3 V) remains below the 4.8 V VITN threshold. The device family supports multiple fixed thresholds, but each part number is calibrated for one nominal voltage; cross-voltage use violates datasheet operating conditions.

What is the role of the SET1 pin on the TPS3851G50SDRBR, and how should it be configured?

The SET1 pin on the TPS3851G50SDRBR controls watchdog enable/disable: grounding SET1 disables the watchdog timer entirely, causing WDI to be ignored and WDO to remain high-impedance (pulled up externally). When SET1 is high (>0.8 × VDD), the watchdog operates normally. This pin supports dynamic toggling, but requires a 150 µs setup time after enabling before WDI is recognized. For most applications, SET1 is tied to VDD or controlled by a GPIO to allow safe-mode entry or development-stage watchdog suspension.

Does the TPS3851G50SDRBR require an external capacitor on the CWD pin to function?

No - the TPS3851G50SDRBR functions fully without any external capacitor on the CWD pin. Leaving CWD unconnected or pulling it up to VDD via a 10 kΩ resistor activates the factory-programmed 1600 ms watchdog timeout. A capacitor is only required if user-adjustable timing is needed (e.g., using Equation 1: tWD = 3.23 × CCWD + 0.381). The device's default operational mode assumes CWD is unconnected, and this configuration is validated across temperature and process corners in TI's production test flow.