Texas Instruments TPS3305-33DGNR

Overview

TPS3305-33DGNR 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 of 40 µA. It delivers active-low and active-high RESET outputs in an 8-pin HVSSOP package for embedded power sequencing in industrial and portable equipment.

For engineers reviewing the TPS3305-33DGNR datasheet, TPS3305-33DGNR pinout, TPS3305-33DGNR application, or TPS3305-33DGNR equivalent, key selection criteria include dual-rail threshold accuracy (4.55 V / 2.93 V typ), temperature-compensated reference, MR/WDI control flexibility, and MSOP-8 footprint compatibility with thermal pad layout requirements.

Technical Context

The TPS3305-33DGNR implements two independent voltage sense comparators with hysteresis (30–40 mV) referenced to a stable 1.25 V internal bandgap, enabling reliable detection of undervoltage on both SENSE1 (5.0 V nominal) and SENSE2 (3.3 V nominal) inputs. Its integrated oscillator drives a watchdog timer that asserts RESET if WDI remains static beyond 1.6 s.

Reset assertion occurs when either SENSEn falls below its VIT− threshold or MR is pulled low; RESET remains asserted for the full 200 ms delay after both SENSEn return above VIT+ and MR is released. The device operates across 2.7 V to 6.0 V supply range and supports defined RESET output down to VDD ≥ 1.1 V.

Key Specifications

Pinout & Package

HVSSOP-8 (DGN) package, 3.0 mm × 3.0 mm, 0.65 mm pitch, 1.1 mm max height, with exposed thermal pad (Pin 9) for enhanced thermal dissipation. RoHS-compliant, NIPDAU lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3305-33DR and MAX6816EUT+T, the TPS3305-33DGNR uniquely combines dual-rail supervision, integrated watchdog, and HVSSOP thermal performance in a single 3×3 mm footprint-making it optimal for space-constrained, thermally demanding embedded systems requiring robust power sequencing.

Availability

TPS3305-33DGNR is available at Aetrix Electronics and suitable for industrial PLC control units, portable medical monitors, automotive infotainment head units, and notebook embedded controllers requiring stable component supply and long-term production continuity.

Supply support for TPS3305-33DGNR 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 power management technologies, with decades of expertise in high-reliability supervisory circuits.

The TPS3305 family was designed specifically for dual-rail power monitoring in DSP and processor-based systems-addressing the need for accurate, low-power, and thermally robust reset generation in industrial, automotive, and portable applications.

FAQ

What is the exact threshold voltage for SENSE1 and SENSE2 on the TPS3305-33DGNR?

The TPS3305-33DGNR has factory-trimmed threshold voltages of 4.55 V (typ, VIT+) and 2.93 V (typ, VIT+) for SENSE1 and SENSE2 respectively, with ±3% tolerance over temperature. These values correspond to nominal supervised rails of 5.0 V and 3.3 V, and are temperature-compensated using an internal 1.25 V reference. The TPS3305-33DGNR datasheet specifies minimum/maximum limits across –40°C to +85°C, ensuring consistent behavior in industrial environments.

Does the TPS3305-33DGNR require external components to set the reset delay time?

No, the TPS3305-33DGNR features a factory-programmed 200 ms reset delay with no external capacitor or resistor required. This fixed timing is implemented internally using precision RC elements and is guaranteed across temperature and supply voltage. Unlike adjustable supervisors, the TPS3305-33DGNR eliminates BOM items and layout sensitivity associated with external timing networks-reducing design risk and improving repeatability in high-volume manufacturing.

Can the TPS3305-33DGNR monitor voltages other than 5.0 V and 3.3 V?

The TPS3305-33DGNR is specifically trimmed for 5.0 V (SENSE1) and 3.3 V (SENSE2) nominal rails, with corresponding VIT+ thresholds of 4.55 V and 2.93 V. While it can technically detect any voltage within its input range (0 V to VDD), accurate supervision outside these targets requires external resistor dividers-which void the guaranteed threshold accuracy and add error sources. For non-standard rails, TI recommends the TPS3839 family or programmable supervisors instead of repurposing the TPS3305-33DGNR.

How does the watchdog timer on the TPS3305-33DGNR interact with the voltage supervision function?

The watchdog timer and voltage supervision operate independently but share the same RESET outputs. A watchdog timeout (WDI inactive >1.6 s) asserts RESET regardless of SENSE1/SENSE2 status; similarly, undervoltage on either sense input asserts RESET regardless of WDI activity. Both conditions hold RESET active for the full 200 ms delay after recovery. The TPS3305-33DGNR truth table confirms RESET is low whenever MR is low, SENSEn < VIT−, or WDI timeout occurs-enabling comprehensive fault coverage in safety-critical systems.

Is the exposed thermal pad on the TPS3305-33DGNR's HVSSOP package electrically connected?

No, the exposed thermal pad (Pin 9) on the TPS3305-33DGNR HVSSOP package is not electrically connected to any internal circuit node-it serves solely for thermal conduction to the PCB. TI's datasheet and package drawings explicitly designate it as a thermal pad with no electrical function. For optimal thermal performance, it must be soldered to a large copper pour tied to GND (mechanically, not electrically required), and stencil design should ensure ≥100% solder paste coverage per TI's recommended land pattern.