Texas Instruments TPS3306-33DGK

Overview

TPS3306-33DGK from Texas Instruments is a dual-voltage supervisory IC designed for monitoring 5 V and 3.3 V supply rails in DSP and processor-based systems. It provides power-on reset with 100 ms delay, watchdog timer (0.8 s timeout), open-drain RESET and PFO outputs, and operates from –40°C to +85°C in VSSOP-8 package.

For engineers reviewing the TPS3306-33DGK datasheet, TPS3306-33DGK pinout, TPS3306-33DGK application, or TPS3306-33DGK equivalent, key selection criteria include dual-threshold voltage supervision (4.55 V / 2.93 V), low 15 µA supply current, defined RESET assertion down to VDD ≥ 1.1 V, and compatibility with battery-powered and automotive-grade embedded control designs.

Technical Context

The TPS3306-33DGK integrates two independent voltage comparators with fixed thresholds (4.55 V for SENSE1, 2.93 V for SENSE2), a power-fail comparator referenced to 1.25 V, and a watchdog timer retriggered by WDI transitions. Its RESET output remains active until both sensed voltages exceed their respective thresholds and sustain for ≥100 ms.

It features open-drain outputs (RESET and PFO) supporting wired-OR configurations, internal hysteresis (30–40 mV depending on threshold), and operates across VDD = 2.7–6 V. The device disables watchdog functionality when WDI is left unconnected or held at high impedance.

Key Specifications

Pinout & Package

VSSOP-8 (DGK) package: 3.0 mm × 3.0 mm body, 0.65 mm lead pitch, 1.1 mm max height, exposed thermal pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3306-33DR and TPS3823-33DBVR, the TPS3306-33DGK uniquely delivers integrated dual-rail supervision, watchdog, and power-fail detection in the smallest footprint-making it optimal for space-constrained, function-rich embedded systems requiring high reliability.

Availability

TPS3306-33DGK is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive infotainment systems, portable medical monitors, and network edge router control cards requiring stable component supply and long-term manufacturability.

Supply support for TPS3306-33DGK 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 and embedded processing solutions for industrial, automotive, and communications markets.

The TPS3306 family was engineered specifically for dual-supply initialization and fault monitoring in DSP and processor-based systems-addressing the need for coordinated reset timing, power-fail warning, and watchdog protection in resource-constrained embedded platforms.

FAQ

What is the exact voltage threshold monitored by SENSE1 on the TPS3306-33DGK?

The TPS3306-33DGK monitors SENSE1 at a nominal threshold of 4.55 V, corresponding to supervision of a 5 V supply rail. This value is specified at 25°C with ±3% variation over the full –40°C to +85°C operating range and is factory-trimmed for accuracy. The threshold exhibits typical temperature coefficient of ±100 ppm/°C, ensuring stable trip points across environmental conditions. This precise setting allows reliable detection of 5 V rail undervoltage without false triggering during normal ripple or transient events.

Does the TPS3306-33DGK require external components to operate as a basic dual-supply supervisor?

No, the TPS3306-33DGK functions as a complete dual-supply supervisor with only two external pull-up resistors (for RESET and PFO open-drain outputs) and bypass capacitor (0.1 µF ceramic near VDD/GND). SENSE1 and SENSE2 connect directly to the 5 V and 3.3 V rails respectively. The watchdog timer is disabled by default (WDI left floating or high-impedance), and the PFI input can be grounded if unused. No external timing resistors or capacitors are needed for reset delay or watchdog operation.

Can the TPS3306-33DGK supervise voltages other than 5 V and 3.3 V?

Yes-the PFI input accepts an external resistor divider to monitor any voltage above 1.25 V, enabling supervision of battery, backup, or auxiliary supplies. For example, connecting a 1 MΩ total divider (R1 + R2) with R2 = 390 kΩ sets VPFI ≈ 3.2 V. SENSE1 and SENSE2 thresholds are fixed per variant (4.55 V / 2.93 V for TPS3306-33DGK) and cannot be adjusted; alternate variants like TPS3306-25DGK (4.55 V / 2.25 V) or TPS3306-18DGK (2.93 V / 1.68 V) support different rail combinations.

What is the maximum recommended VDD voltage for continuous operation of the TPS3306-33DGK?

The absolute maximum VDD rating is 7 V, but TI specifies a continuous operational limit of 6 V per the Recommended Operating Conditions table. Operation at 7 V is permitted only for ≤1000 hours lifetime and is not recommended for production designs. At 6 V, the device maintains full parametric performance including 15 µA supply current, 4.55 V/2.93 V thresholds, and 100 ms reset delay. Exceeding 6 V risks accelerated parametric drift and reduced long-term reliability.

How does the watchdog timer on the TPS3306-33DGK interact with the RESET output during a timeout event?

When the watchdog timer times out (after ~0.8 s without WDI transition), the TPS3306-33DGK asserts RESET low for the full 100 ms delay period-identical to power-on or supply-fault reset behavior. During this time, the watchdog counter resets and begins a new timeout cycle. If WDI remains inactive, RESET will pulse low every 0.8 s. The RESET pulse ensures full system restart, while the watchdog's periodic assertion provides fail-safe recovery even if firmware fails to service interrupts or execute main loop.