Texas Instruments TPS3305-33D

Overview

TPS3305-33D from Texas Instruments is a dual-voltage supervisor IC for DSP- and processor-based systems, monitoring 5.0 V (SENSE1) and 3.3 V (SENSE2) rails with factory-programmed 200 ms reset delay, watchdog timeout of 1.6 s typ, and supply current ≤40 µA. It provides active-low and active-high RESET outputs and operates across –40°C to +85°C in SOIC-8 package.

For engineers reviewing the TPS3305-33D datasheet, TPS3305-33D pinout, TPS3305-33D application, or TPS3305-33D equivalent, key selection factors include dual-rail threshold accuracy (4.55 V / 2.93 V typ), watchdog input timing, MR assertion behavior, and SOIC-8 thermal/power dissipation limits at 725 mW.

Technical Context

The TPS3305-33D implements two independent voltage-sense comparators with temperature-compensated 1.25 V reference, hysteresis (40 mV at 4.55 V threshold), and internal power-on reset generator. Its watchdog timer asserts RESET if WDI remains static >1.6 s, and manual reset (MR) forces immediate low-going RESET pulse.

RESET assertion occurs when either SENSE1 < 4.55 V or SENSE2 < 2.93 V (typ), with defined output down to VDD ≥1.1 V. The device supports simultaneous core/I/O rail supervision in embedded processors, with propagation delays <5 µs from sense input to RESET and <500 ns from MR to RESET.

Key Specifications

Pinout & Package

TPS3305-33D is housed in an 8-pin SOIC (D) package, 3.9 mm × 4.9 mm, 1.75 mm max height, RoHS-compliant NIPDAU lead finish, MSL Level-1, rated for 725 mW total power dissipation at TA ≤ +25°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3305-33DGN, the TPS3305-33D offers higher power dissipation margin in SOIC packaging but occupies more PCB area; versus MAX6816EPA+, it delivers full dual-rail supervision and watchdog functionality essential for processor-based systems.

Availability

TPS3305-33D is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive infotainment head units, and notebook system management requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TPS3305-33D 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 voltage monitoring in DSP- and microprocessor-based systems, addressing the need for coordinated reset generation, watchdog safety, and low-power operation in space- and energy-constrained applications.

FAQ

What is the exact threshold voltage for SENSE1 on the TPS3305-33D?

The TPS3305-33D has a nominal SENSE1 threshold of 4.55 V (typical), with guaranteed range of 4.46 V to 4.67 V across –40°C to +85°C. This threshold monitors a 5.0 V supply rail and includes 40 mV hysteresis to prevent chatter during slow voltage transitions. The value is factory-programmed and does not require external resistor networks - the TPS3305-33D uses an internal temperature-compensated reference to maintain accuracy.

Does the TPS3305-33D support both active-high and active-low reset outputs simultaneously?

Yes, the TPS3305-33D provides two independent reset outputs: pin 5 (RESET) is active-low open-drain, and pin 6 (RESET) is active-high push-pull. Both assert synchronously when either SENSE input falls below its threshold or WDI times out. The TPS3305-33D allows direct interfacing with legacy chipsets requiring active-low reset and modern SoCs expecting active-high assertion - no level-shifting circuitry needed.

Can the watchdog timeout period of the TPS3305-33D be adjusted externally?

No, the watchdog timeout period of the TPS3305-33D is fixed at 1.6 s (typical), with a guaranteed range of 1.1 s to 2.3 s. It is implemented using an internal oscillator and cannot be modified with external components. For adjustable watchdog timing, consider TI's TPS386000 family or discrete timer + supervisor combinations - the TPS3305-33D prioritizes simplicity and reliability over configurability.

What is the minimum VDD required for the TPS3305-33D to assert a valid RESET signal?

The TPS3305-33D guarantees defined RESET output behavior down to VDD ≥1.1 V, per its electrical characteristics table. Below this, the internal reference and comparators may not operate reliably. This feature ensures fail-safe reset assertion during deep brownout conditions - critical for preserving memory state and preventing undefined MCU behavior. The TPS3305-33D continues to monitor SENSE inputs and assert RESET as long as VDD remains above 1.1 V.

Is the TPS3305-33D pin-compatible with other members of the TPS3305 family?

Yes, all TPS3305-x variants - including TPS3305-18D, TPS3305-25D, and TPS3305-33D - share identical SOIC-8 (D) and HVSSOP-8 (DGN) packages and pinouts. Only the internal voltage thresholds differ: SENSE1/SENSE2 thresholds are factory-set per variant (e.g., 4.55 V / 2.93 V for TPS3305-33D). This allows drop-in replacement when rail voltages change, provided the new thresholds match the target system's monitored supplies.