Texas Instruments TPS3305-18DGNRG4

Overview

TPS3305-18DGNRG4 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 supply current of 40 µA. It asserts active-low and active-high RESET outputs when either sensed voltage falls below its threshold (2.93 V / 1.68 V typ) or WDI stalls - used in industrial embedded controllers requiring reliable power sequencing.

For engineers reviewing the TPS3305-18DGNRG4 datasheet, TPS3305-18DGNRG4 pinout, TPS3305-18DGNRG4 application, or TPS3305-18DGNRG4 equivalent, key selection criteria include dual-rail threshold accuracy (±30 mV hysteresis), MSOP-8 package thermal performance, MR input compatibility with 0.3×/0.7×VDD logic levels, and guaranteed RESET assertion down to VDD ≥1.1 V.

Technical Context

The TPS3305-18DGNRG4 integrates two independent voltage comparators with temperature-compensated 1.25 V reference, each feeding a latch-and-timer circuit that drives complementary RESET outputs. Its watchdog timer uses an internal oscillator to detect WDI inactivity exceeding 1.6 s (typ), triggering reset independently of supply rail status.

Reset assertion is synchronized across both SENSE inputs and MR/WDI events via internal logic that holds RESET low for the full 200 ms (typ) delay after all monitored conditions return to valid state - ensuring deterministic deassertion timing critical for FPGA configuration and DSP boot sequences.

Key Specifications

Pinout & Package

HVSSOP-8 (DGN) package: 3.0 mm × 3.0 mm, 0.65 mm pitch, 1.1 mm max height, exposed thermal pad (Pin 9) - optimized for space-constrained PCB layouts and thermal dissipation in high-density digital systems.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-supply monitoring applications.

Compared with TPS3305-18DGNRG4, the TPS3305-18DGN offers identical supervision functionality in the same HVSSOP-8 package but lacks the G4 moisture-sensitive labeling; MAX6816EUT+T provides lower quiescent current but omits dual-rail monitoring and watchdog - making it unsuitable for applications requiring coordinated 3.3 V/1.8 V reset sequencing.

Availability

TPS3305-18DGNRG4 is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive ADAS ECUs, notebook embedded controllers, and wireless baseband processors requiring stable component supply with guaranteed long-term manufacturability.

Supply support for TPS3305-18DGNRG4 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 and embedded processing technologies, with decades of expertise in power management and system supervision ICs.

The TPS3305 family was designed specifically for dual-rail power sequencing in DSP and microprocessor systems - addressing the need for precise, capacitor-free reset timing and independent watchdog supervision in space-constrained industrial and automotive applications.

FAQ

What is the function of the dual RESET outputs on the TPS3305-18DGNRG4?

The TPS3305-18DGNRG4 provides both active-low (Pin 5, open-drain) and active-high (Pin 6, push-pull) RESET outputs to interface with diverse downstream logic families. The active-low output requires an external pull-up resistor for voltage-level translation, while the active-high output drives directly to VDD or GND - enabling flexible integration with FPGAs, ASICs, and microcontrollers that accept either reset polarity without additional components. This dual-output architecture eliminates level-shifter requirements in mixed-voltage systems.

Does the TPS3305-18DGNRG4 require an external capacitor for reset timing?

No, the TPS3305-18DGNRG4 does not require an external capacitor for reset timing. Its 200 ms (typ) power-on reset delay is factory-programmed and implemented using internal precision timing circuitry. This eliminates timing capacitor variability, board space, and long-term drift concerns - simplifying design validation and improving reliability across temperature and lifetime. The absence of external timing components also reduces BOM cost and assembly steps.

How does the watchdog timer in the TPS3305-18DGNRG4 operate independently of supply voltage monitoring?

The watchdog timer in the TPS3305-18DGNRG4 operates from an internal oscillator and monitors the WDI (Pin 3) input independently of SENSE1/SENSE2 voltage levels. If WDI is not toggled within 1.6 s (typ), RESET is asserted regardless of whether both monitored rails remain above their thresholds. This allows detection of firmware hangs or software lockups even when power supplies are stable - providing robust system-level fault coverage beyond basic power-rail supervision.

What is the minimum VDD voltage at which the TPS3305-18DGNRG4 guarantees RESET assertion?

The TPS3305-18DGNRG4 guarantees RESET assertion down to VDD ≥1.1 V, as specified in the Electrical Characteristics table. This ensures reliable reset generation during brownout conditions or slow power-down sequences where VDD decays below nominal operating range but remains sufficient to power internal comparators and logic. The device maintains defined output states and threshold accuracy throughout this extended low-voltage range - critical for orderly system shutdown in industrial equipment.

Can the TPS3305-18DGNRG4 monitor voltages other than 3.3 V and 1.8 V?

The TPS3305-18DGNRG4 is factory-configured to monitor 3.3 V (SENSE1) and 1.8 V (SENSE2) rails with fixed thresholds of 2.93 V (typ) and 1.68 V (typ), respectively. It cannot be reprogrammed or externally adjusted to monitor different voltages. For alternative voltage combinations, Texas Instruments offers the TPS3305-25 (3.3 V / 2.5 V) and TPS3305-33 (5.0 V / 3.3 V) variants - all sharing identical timing, watchdog, and package characteristics but differing only in threshold values.