Texas Instruments TPS3851G18SDRBR

Overview

TPS3851G18SDRBR from Texas Instruments is a precision voltage supervisor IC with integrated watchdog timer, designed for microcontroller and SoC power-rail monitoring in industrial and embedded systems. It delivers 0.8% undervoltage threshold accuracy (–40°C to +125°C), 200 ms reset timeout with 15% accuracy, and supports 1.8 V supply rails with 0.5% hysteresis. Its open-drain RESET and WDO outputs interface directly with logic-level systems requiring fail-safe startup and runtime fault detection.

For engineers reviewing the TPS3851G18SDRBR datasheet, TPS3851G18SDRBR pinout, TPS3851G18SDRBR application, or TPS3851G18SDRBR equivalent, this device is selected when high-accuracy undervoltage supervision (±0.8%), programmable watchdog timing (standard/extended modes), manual reset input, and operation across –40°C to +125°C are required - especially in space-constrained designs needing the 3 mm × 3 mm VSON-8 package.

Technical Context

The TPS3851G18SDRBR implements a precision bandgap-based comparator for undervoltage detection on the VDD rail, with factory-trimmed threshold (VITN = 1.728 V for G18 variant) and built-in 0.5% hysteresis. Its reset delay circuit uses an internal RC oscillator with 15% timing accuracy over temperature, independent of external components.

Watchdog functionality operates via dual-mode timing: factory-programmed fixed delays (e.g., 1600 ms standard mode) or user-adjustable capacitor-based timing (0.1–1000 nF). The CWD pin evaluates configuration at power-up (381 µs initialization), while SET1 enables dynamic watchdog disable and WDI accepts falling-edge-triggered pulses with 50 ns minimum width.

Key Specifications

Pinout & Package

TPS3851G18SDRBR is housed in a thermally enhanced 3.00 mm × 3.00 mm, 8-pin VSON package (DRB) with exposed thermal pad connected internally to GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3851G18SDRBR, the G33 variant shifts threshold for 3.3 V systems without altering timing or package, while the G18-compatible TPS3852 adds debug-oriented watchdog control at the cost of 2 µA higher typical supply current.

Availability

TPS3851G18SDRBR is available at Aetrix Electronics and suitable for WLAN access points, wireless security cameras, IP network cameras, and string inverter control units requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TPS3851G18SDRBR 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 voltage supervision and watchdog functionality for mission-critical embedded systems where supply integrity and fault resilience are essential.

FAQ

What is the exact undervoltage threshold voltage for TPS3851G18SDRBR?

The TPS3851G18SDRBR has a factory-trimmed undervoltage threshold (VITN) of 1.728 V, corresponding to a 4% undervoltage margin below a nominal 1.8 V supply rail. This value is guaranteed within ±0.8% across –40°C to +125°C operating temperature, as verified in TI's production test data and electrical characteristics table.

How does the watchdog timeout get configured on TPS3851G18SDRBR?

The TPS3851G18SDRBR supports two watchdog timeout modes: factory-programmed (1600 ms typical) when CWD is left unconnected or pulled up to VDD via 10 kΩ, or user-adjustable via capacitor (0.1–1000 nF) connected between CWD and GND. The mode is auto-detected during power-up initialization (381 µs).

Can TPS3851G18SDRBR supervise multiple voltage rails simultaneously?

No - the TPS3851G18SDRBR monitors only the VDD pin, which serves as both its supply and the monitored rail. It cannot independently supervise multiple rails; each instance supervises one rail. For multi-rail systems, multiple TPS3851G18SDRBR devices or a multi-channel supervisor like TPS386000 would be required.

What is the function of the SET1 pin on TPS3851G18SDRBR?

The SET1 pin on TPS3851G18SDRBR controls watchdog enable/disable: grounding SET1 disables the watchdog timer entirely, causing WDI to be ignored and WDO to remain high-impedance. When SET1 is high, the watchdog operates normally. This allows safe development and debug without unintended timeouts.

Is the thermal pad on TPS3851G18SDRBR electrically connected, and how should it be handled?

Yes - the thermal pad on the TPS3851G18SDRBR VSON-8 package is internally connected to GND. It must be soldered to a large-area PCB ground plane to achieve specified RθJB = 25.8 °C/W and ensure reliable operation at 125°C junction temperature. Leaving it unconnected degrades thermal performance and risks premature failure.