Texas Instruments TPS3306-18D

Overview

TPS3306-18D 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 operates from 2.7 V to 6 V supply with 15 µA typical quiescent current. Used in embedded control systems where reliable dual-rail power sequencing and fail-safe restart are critical.

For engineers reviewing the TPS3306-18D datasheet, TPS3306-18D pinout, TPS3306-18D application, or TPS3306-18D equivalent, key selection considerations include its dual SENSE threshold accuracy (2.93 V / 1.68 V), –40°C to +85°C industrial temperature range, SOIC-8 package compatibility, and integrated power-fail comparator with external resistor programmability.

Technical Context

The TPS3306-18D implements two independent voltage comparators with fixed thresholds (2.93 V on SENSE1, 1.68 V on SENSE2) referenced to an internal 1.25 V bandgap, each with ~20 mV hysteresis. Its RESET output asserts low when either sensed voltage falls below its threshold or during power-up until VDD ≥1.1 V, then remains active for 100 ms after both inputs exceed their thresholds.

A dedicated PFI input compares against the same 1.25 V reference, enabling user-configurable power-fail detection via external resistor divider; WDI accepts edge-triggered watchdog resets with 0.8 s timeout, disabling automatically if left floating. All logic is fully specified across the full –40°C to +85°C operating range.

Key Specifications

Pinout & Package

TPS3306-18D is housed in an 8-pin SOIC (D) package, 3.9 mm × 4.9 mm, 1.75 mm max height, RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3306-18DGK and TPS3823-18, the TPS3306-18D uniquely delivers dual-rail supervision in a standard SOIC footprint with full watchdog and power-fail functionality-making it irreplaceable in multi-voltage DSP or FPGA platforms requiring coordinated reset and fault signaling.

Availability

TPS3306-18D is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical monitors, DSP-based audio processors, and automotive infotainment modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TPS3306-18D 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 personal electronics markets.

The TPS3306 family was engineered specifically for dual-supply initialization and fault recovery in DSP and microprocessor systems-addressing the need for precise, low-power, and temperature-stable supervision of heterogeneous voltage domains.

FAQ

What is the exact SENSE1 and SENSE2 threshold voltage for TPS3306-18D?

The TPS3306-18D has a nominal SENSE1 threshold of 2.93 V and SENSE2 threshold of 1.68 V, both specified at TA = 25°C with ±3% tolerance over temperature. These values are factory-trimmed and documented in Table 1 of the SLVS290C datasheet. The TPS3306-18D uses these fixed thresholds to supervise 3.3 V and 1.8 V rails respectively, with built-in hysteresis (~20 mV) to prevent chatter near trip points.

Can TPS3306-18D monitor voltages other than 3.3 V and 1.8 V?

Yes - while SENSE1 and SENSE2 are fixed at 2.93 V and 1.68 V, the PFI input accepts an externally configured voltage divider to monitor any supply above 1.25 V. By selecting precision 1% resistors (e.g., R1 = 180 kΩ, R2 = 100 kΩ), users can set VPFI to 3.5 V or other values. The TPS3306-18D's PFO output then signals when that custom voltage drops below threshold, extending its utility beyond the nominal dual-rail use case.

Does TPS3306-18D require external components to operate?

The TPS3306-18D operates autonomously with only a 0.1 µF ceramic bypass capacitor on VDD (recommended per datasheet Section 2). No external timing components are needed for RESET delay or watchdog timeout - both are fully internal. Pull-up resistors on RESET and PFO are required for open-drain operation, and optional resistors on PFI enable custom power-fail detection. The TPS3306-18D thus minimizes BOM count while retaining full configurability.

What is the watchdog timeout behavior of TPS3306-18D?

The TPS3306-18D watchdog has a nominal timeout of 0.8 s. A rising or falling edge on WDI resets the timer; failure to retrigger within that window forces RESET active for 100 ms. If WDI is left unconnected, the watchdog is disabled and RESET remains controlled solely by SENSE1/SENSE2 and power-up conditions. This behavior is confirmed in the "DETAILED DESCRIPTION" section of the TPS3306-18D datasheet and applies identically across all TPS3306-xx variants.

Is TPS3306-18D compatible with lead-free PCB assembly processes?

Yes - the TPS3306-18D is RoHS-compliant with NiPdAu lead finish and rated for MSL Level-1 (unlimited floor life) at 260°C peak reflow per JEDEC J-STD-020. Its SOIC-8 package is qualified for standard lead-free reflow profiles, including ramp-to-spike and soak profiles. The TPS3306-18D's absolute maximum VDD rating of 7 V (with derating above 25°C) also accommodates transient overshoot common in high-speed reflow ovens.