Texas Instruments TPS3306-18DG4

Overview

TPS3306-18DG4 from Texas Instruments is a dual-voltage supervisory IC designed for DSP and processor-based systems requiring independent monitoring of 3.3 V and 1.8 V rails. It integrates power-on reset (100 ms delay), watchdog timer (0.8 s timeout), open-drain RESET and PFO outputs, and a dedicated PFI comparator - enabling robust system initialization and fail-safe operation in embedded control and portable battery-powered equipment.

For engineers reviewing the TPS3306-18DG4 datasheet, TPS3306-18DG4 pinout, TPS3306-18DG4 application, or TPS3306-18DG4 equivalent, key selection criteria include dual-threshold voltage supervision (2.93 V / 1.68 V), low quiescent current (15 µA typ.), defined RESET assertion down to VDD ≥ 1.1 V, and compatibility with SOIC-8 and VSSOP-8 packages for space-constrained designs.

Technical Context

The TPS3306-18DG4 implements two independent voltage comparators with fixed thresholds (2.93 V for SENSE1, 1.68 V for SENSE2) referenced to an internal 1.25 V bandgap, each with ~15 mV hysteresis. Its RESET logic asserts low when either SENSE input falls below its threshold or during power-up until VDD ≥ 1.1 V, then holds active for 100 ms after both inputs exceed thresholds.

It includes a transition-triggered watchdog circuit (0.8 s timeout) accepting WDI edge transitions, a separate PFI comparator comparing external voltages against 1.25 V reference (with 10 mV hysteresis), and open-drain outputs (RESET, PFO) compatible with 3.3 V/5 V logic families - all operating across –40°C to +85°C with supply range 2.7–6 V.

Key Specifications

Pinout & Package

VSSOP-8 (DGK) package: 3.0 mm × 3.0 mm body, 0.65 mm pitch, 1.1 mm max height, exposed pad not electrically connected - suitable for high-density PCB layouts with thermal relief via optional bottom-side copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3306-18D, the TPS3306-18DG4 offers identical functionality in a 40% smaller footprint ideal for compact designs, while TPS3808G18 trades dual supervision and watchdog for extreme low-power operation - making it unsuitable as a drop-in alternative but viable for simplified single-rail use cases.

Availability

TPS3306-18DG4 is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical monitors, automotive infotainment head units, DSP-based audio processors, and battery-powered instrumentation requiring stable component supply and long-term manufacturability.

Supply support for TPS3306-18DG4 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and consumer markets.

The TPS3306 family was engineered specifically for dual-voltage supervision in DSP and microprocessor systems - addressing the need for coordinated reset generation, watchdog safety, and auxiliary supply monitoring in mixed-rail architectures.

FAQ

What are the exact voltage thresholds monitored by the TPS3306-18DG4?

The TPS3306-18DG4 monitors SENSE1 at a typical threshold of 2.93 V (for 3.3 V nominal rail) and SENSE2 at 1.68 V (for 1.8 V nominal rail), with ±1.5% tolerance over temperature. These fixed thresholds are internally trimmed and do not require external resistors - ensuring consistent trip points across production lots and operating conditions for the TPS3306-18DG4.

Can the watchdog timer in the TPS3306-18DG4 be disabled, and how?

Yes, the watchdog timer in the TPS3306-18DG4 is disabled by leaving the WDI pin unconnected (high-impedance). No pull-up or pull-down is required. When WDI is floating, the internal watchdog circuit remains inactive and does not affect RESET behavior - allowing full use of the supervisory functions without watchdog overhead for the TPS3306-18DG4.

What is the minimum VDD required for the TPS3306-18DG4 to assert a valid RESET signal?

The TPS3306-18DG4 asserts RESET as soon as VDD reaches ≥1.1 V, and maintains a defined logic state throughout operation. This ultra-low activation voltage ensures reliable reset generation even during slow or noisy power ramps - a critical feature confirmed in the TPS3306-18DG4 datasheet and validated across –40°C to +85°C.

How does the PFI input function in the TPS3306-18DG4, and what voltage can it monitor?

The PFI input in the TPS3306-18DG4 compares an external voltage against an internal 1.25 V reference. Using a two-resistor divider (e.g., R1 = 100 kΩ, R2 = 100 kΩ), it can monitor any voltage >1.25 V - such as battery levels or auxiliary supplies. The PFO output goes low when PFI falls below 1.25 V (±30 mV), providing programmable power-fail detection independent of the main SENSE rails for the TPS3306-18DG4.

Is the TPS3306-18DG4 pin-compatible with other members of the TPS3306 family?

Yes, all TPS3306-x variants (e.g., TPS3306-15DG4, TPS3306-25DG4) share identical pinout, package dimensions, and interface logic - differing only in factory-trimmed SENSE1/SENSE2 thresholds. This allows direct substitution within the same VSSOP-8 footprint when adjusting for different nominal supply voltages, simplifying design reuse for the TPS3306-18DG4.