Texas Instruments TPS3851G50SDRBT

Overview

TPS3851G50SDRBT from Texas Instruments is a precision voltage supervisor IC with integrated watchdog timer, designed for system-level power integrity monitoring in microcontroller-based applications. It delivers 0.8% undervoltage threshold accuracy (–40°C to +125°C), 200 ms reset timeout with 15% accuracy, and factory-programmed 1.6 s watchdog timeout (standard timing) - all operating across 1.6 V to 6.5 V supply range. It serves as the primary reset and fault-detection controller in safety-critical embedded systems such as IP network cameras and electricity meters.

For engineers reviewing the TPS3851G50SDRBT datasheet, TPS3851G50SDRBT pinout, TPS3851G50SDRBT application, or TPS3851G50SDRBT equivalent, this page provides verified functional context, validated pin roles, confirmed timing behavior under temperature stress, and real-world implementation constraints - including open-drain output drive capability, CWD capacitor programming limits, and SET1-controlled watchdog disable functionality.

Technical Context

The TPS3851G50SDRBT implements dual independent timing paths: a high-accuracy comparator-based undervoltage detection circuit with 0.5% hysteresis and a state-machine-driven watchdog timer supporting both factory-programmed (1.6 s typical) and user-adjustable (via CWD capacitor) timeouts. Its RESET output asserts when VDD falls below 4.8 V ± 0.8%, remains low for 200 ms ± 15%, then transitions to high-impedance; WDO asserts independently on watchdog timeout only when RESET is deasserted.

Functional mode selection is determined by logic states on SET1 (watchdog enable/disable) and CWD (capacitor vs resistor vs floating configuration), with internal evaluation completed within 381 µs after VDD enters valid operating range. The device uses a 375 nA constant-current source to charge the external CWD capacitor, enabling precise timeout calculation per TI's standard timing equation: t_WD = 3.23 × C_CWD(nF) + 0.381 ms.

Key Specifications

Pinout & Package

TPS3851G50SDRBT is housed in a 3.00 mm × 3.00 mm, 8-pin VSON package (DRB) with exposed thermal pad connected internally to GND. The package supports reflow soldering and requires connection of the thermal pad to a large-area ground plane for thermal reliability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3851G18SDRBT and MAX6369KA29+T, the TPS3851G50SDRBT uniquely combines 4.8 V precision threshold, factory-programmed 1.6 s watchdog, and full CWD/SET1 configurability in a 3 mm × 3 mm VSON package - making it optimal for 5 V-powered IoT edge devices requiring both accuracy and design adaptability.

Availability

TPS3851G50SDRBT is available at Aetrix Electronics and suitable for IP network cameras, electricity meters, WLAN access points, and portable medical devices requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for TPS3851G50SDRBT 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 high-reliability industrial ICs.

The TPS3851 family is designed for precision power-supply monitoring in mission-critical embedded systems - delivering ultra-stable reset timing, factory-trimmed thresholds, and configurable watchdog functionality for automotive, industrial, and medical applications.

FAQ

What is the exact undervoltage threshold voltage for TPS3851G50SDRBT?

The TPS3851G50SDRBT has a nominal undervoltage threshold (VITN) of 4.8 V, with guaranteed accuracy of ±0.8% over the full operating temperature range (–40°C to +125°C). This value is factory-trimmed and specified in the device ordering suffix 'G50', confirming its targeting for 5 V rail supervision. The hysteresis is 0.5%, resulting in a release point of approximately 4.824 V.

How does the watchdog timeout behave when SET1 is grounded on TPS3851G50SDRBT?

When SET1 is grounded (logic low), the watchdog timer in TPS3851G50SDRBT is fully disabled - WDI input is ignored, and WDO remains in high-impedance state regardless of WDI activity. This mode is intended for development or systems where watchdog functionality is not required. Note that WDI must still be driven to VDD or GND (not left floating) to prevent increased IDD.

Can TPS3851G50SDRBT monitor a 3.3 V supply rail?

No - the TPS3851G50SDRBT is specifically configured for 4.8 V threshold and is not suitable for direct 3.3 V rail monitoring. For 3.3 V systems, TI offers the TPS3851G33 variant. Using TPS3851G50SDRBT on a 3.3 V rail would result in continuous RESET assertion, as VDD would remain below the 4.8 V threshold under all normal operating conditions.

What is the maximum allowable CWD capacitor value for adjustable timing on TPS3851G50SDRBT?

The maximum recommended CWD capacitor value for TPS3851G50SDRBT is 1000 nF, which yields a watchdog timeout of 3.23 seconds (standard timing) or 77.45 seconds (extended timing). Exceeding this value may cause timing inaccuracies due to leakage current effects and reduced signal-to-noise ratio in the internal 375 nA charging circuit.

Does TPS3851G50SDRBT require an external pullup resistor on the RESET pin?

Yes - TPS3851G50SDRBT features open-drain RESET and WDO outputs, requiring external pullup resistors (1 kΩ to 100 kΩ) to the appropriate voltage rail (VPU). The pullup voltage may differ from VDD (e.g., 3.3 V pullup while monitoring 5 V VDD), enabling level-shifting and wired-OR reset bus configurations commonly used in multi-rail systems.