Texas Instruments TPS3305-18DGNR

Overview

TPS3305-18DGNR from Texas Instruments is a dual-voltage supervisor IC for DSP and processor-based systems, monitoring 3.3 V (SENSE1) and 1.8 V (SENSE2) rails with factory-programmed 200 ms reset delay, watchdog timeout of 1.6 s typ, and operation from 2.7 V to 6 V supply. It delivers micropower performance (40 µA max IDD) in an 8-pin HVSSOP package and is used in notebook computers and industrial equipment for reliable power sequencing and fault detection.

For engineers reviewing the TPS3305-18DGNR datasheet, TPS3305-18DGNR pinout, TPS3305-18DGNR application, or TPS3305-18DGNR equivalent, key selection criteria include dual-rail threshold accuracy (2.93 V / 1.68 V typ), active-low and active-high RESET outputs, MR and WDI control interface timing, and HVSSOP thermal pad layout compatibility.

Technical Context

The TPS3305-18DGNR implements two independent voltage sensing channels with temperature-compensated 1.25 V reference and hysteresis (30 mV typ at 2.93 V threshold), enabling robust immunity to supply noise. Its internal oscillator drives both a power-on reset generator and a watchdog timer, with separate assertion logic for SENSEn undervoltage, manual reset (MR), and watchdog timeout events.

RESET assertion is synchronized across all triggers-SENSE1/SENSE2 falling below VIT–, MR low, or WDI stall >1.6 s-and held active for the fixed 200 ms delay before release. The dual-output architecture (RESET and RESET) supports direct interfacing to processors requiring either polarity without external inversion.

Key Specifications

Pinout & Package

HVSSOP-8 (DGN) package: 3 mm × 3 mm, 0.65 mm pitch, 1.1 mm max height, with exposed thermal pad (Pin 9) for enhanced thermal dissipation and PCB grounding. RoHS-compliant, NIPDAU lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-voltage supervisor applications.

Compared with TPS3305-18DR, the TPS3305-18DGNR offers 43% smaller footprint and superior thermal performance; compared with MAX6816EUT+T, it provides essential dual-rail supervision, integrated watchdog, and dual-polarity reset-making it irreplaceable in DSP/processor sequencing where both rails and firmware integrity must be verified.

Availability

TPS3305-18DGNR is available at Aetrix Electronics and suitable for industrial control units, automotive infotainment systems, and notebook computer baseboards requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for TPS3305-18DGNR 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 leader specializing in analog, embedded processing, and digital signal technologies, with decades of expertise in power management and system supervision ICs.

The TPS3305 family was designed specifically for dual-rail DSP and microprocessor systems requiring coordinated power-up, undervoltage detection, and software watchdog functionality-targeting industrial, computing, and automotive applications demanding high reliability and low quiescent current.

FAQ

What is the exact reset threshold voltage for SENSE1 and SENSE2 on the TPS3305-18DGNR?

The TPS3305-18DGNR has a nominal SENSE1 threshold of 2.93 V (typ) for monitoring a 3.3 V rail and a SENSE2 threshold of 1.68 V (typ) for a 1.8 V rail. These values are factory-trimmed and specified over –40°C to +85°C with ±3% tolerance. Hysteresis is 30 mV at SENSE1 and 20 mV at SENSE2, ensuring noise immunity during rail transitions. These thresholds are fixed per device variant and do not require external resistor programming.

Does the TPS3305-18DGNR require an external capacitor for its reset delay function?

No, the TPS3305-18DGNR does not require an external capacitor for its reset delay function. Its 200 ms power-on reset delay is factory-programmed and internally generated using a precision oscillator and timer circuit. This eliminates timing capacitor placement, reduces bill-of-materials count, avoids capacitor aging effects, and ensures consistent delay timing across production lots and temperature ranges-key for high-reliability applications.

How does the watchdog timer in the TPS3305-18DGNR operate, and what is its timeout period?

The watchdog timer in the TPS3305-18DGNR monitors the WDI (Watchdog Input) pin and asserts RESET if the input remains static for longer than 1.6 s (typical). The timer resets on each rising or falling edge of WDI, requiring regular toggling-typically implemented via a GPIO bit flip in firmware. This provides autonomous detection of software hangs without CPU involvement, and the timeout is fixed, not adjustable externally.

Can the TPS3305-18DGNR monitor voltages other than 3.3 V and 1.8 V?

The TPS3305-18DGNR is factory-configured to monitor 3.3 V (SENSE1) and 1.8 V (SENSE2) rails with fixed thresholds of 2.93 V and 1.68 V respectively. It cannot be reconfigured for other voltages. For different combinations, TI offers variants such as TPS3305-25 (3.3 V / 2.5 V) and TPS3305-33 (5.0 V / 3.3 V). Selecting the correct variant ensures accurate supervision without external resistor dividers or calibration.

What is the purpose of having both RESET and RESET outputs on the TPS3305-18DGNR?

The TPS3305-18DGNR provides both active-low RESET (open-drain) and active-high RESET (push-pull) outputs to interface natively with diverse processor and logic families. RESET supports systems requiring open-drain reset with external pull-up (e.g., older microcontrollers), while RESET drives high directly for modern SoCs or FPGAs with active-high reset inputs-eliminating external inverters, saving board space, and reducing signal integrity risk from added components.