Texas Instruments TPS2379DDA

Overview

TPS2379DDA from Texas Instruments is an IEEE 802.3at Type-2 Powered Device (PD) interface IC with integrated 0.5-Ω hot-swap MOSFET, 140 mA inrush current limit, 1 A operating current limit, and auxiliary gate driver for external high-power pass transistor control. It enables PoE-powered security cameras, multiband access points, and VoIP telephones requiring robust 100-V input tolerance and hardware-based Type-2 classification.

For engineers reviewing the TPS2379DDA datasheet, TPS2379DDA pinout, TPS2379DDA application, or TPS2379DDA equivalent, key selection criteria include its 0.5-Ω internal switch R_DS(ON), 140 mA inrush limiting, 1 A continuous current capability, 15 kV/8 kV system-level ESD rating, and support for external gate-driven high-power expansion beyond IEEE 802.3at's 30 W limit.

Technical Context

The TPS2379DDA implements full IEEE 802.3at Type-2 PD functionality-including detection (via 24.9 kΩ RDEN), hardware classification (via RCLS resistor), and dual-stage current limiting-with integrated 0.5-Ω pass FET and independent auxiliary GATE output. Its UVLO thresholds (38.1 V rising / 32 V falling) and thermal shutdown (145 °C) ensure safe operation across 40–57 V PoE input ranges.

It features three critical open-drain outputs: CDB (converter disable bar, active-low, referenced to RTN), T2P (Type-2 PSE indicator, active-low, latched after 2-event classification), and CLS (classification current sink). All operate with precise voltage thresholds-e.g., CLS upper threshold at 22 V ±0.78 V-and are validated over –40 °C to +125 °C junction temperature.

Key Specifications

Pinout & Package

TPS2379DDA uses the HSOP-8 (DDA) package with exposed PowerPAD thermally connected to VSS. The 4.89 mm × 3.90 mm body requires large VSS copper area for heat dissipation and ≥0.025″ clearance from high-voltage traces (e.g., VDD).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PoE PD interface applications.

Compared with LT4275AIMSE#PBF and MAX5974DETE+T, the TPS2379DDA uniquely combines Type-2 classification latching (T2P), auxiliary gate drive (GATE), and 1 A current limit in a single HSOP-8 package-making it the only option for scalable, standards-compliant >25 W PoE endpoints requiring explicit PSE type awareness and external FET coordination.

Availability

TPS2379DDA is available at Aetrix Electronics and suitable for security cameras, multiband access points, and VoIP telephones requiring stable component supply, long-term lifecycle assurance, and full IEEE 802.3at Type-2 compliance.

Supply support for TPS2379DDA 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 connectivity technologies, with decades of leadership in power management and industrial communications ICs.

The TPS2379DDA belongs to TI's Power over Ethernet (PoE) PD interface product line, engineered specifically for high-reliability, standards-compliant powered devices that demand hardware-based Type-2 classification, robust inrush control, and scalable power delivery beyond 30 W.

FAQ

What is the maximum continuous current supported by the TPS2379DDA's internal pass FET?

The TPS2379DDA's internal MOSFET supports up to 0.85 A continuous current under typical thermal conditions (R_θJA = 45.9 °C/W, T_A = 25 °C). This is enabled by its low 0.42 Ω (typical) R_DS(ON) and PowerPAD-enhanced thermal dissipation. For currents exceeding 0.85 A, the TPS2379DDA's GATE pin must drive an external MOSFET in parallel with the internal FET.

How does the TPS2379DDA indicate detection of an IEEE 802.3at Type-2 PSE?

The TPS2379DDA asserts the T2P pin low (active-low, open-drain) after completing two successful hardware classification events and exiting inrush limiting. This latched signal remains low until thermal shutdown, inrush reactivation, or VDD falling below the mark reset threshold (~3.9 V). T2P is referenced to RTN and requires an external pullup to indicate Type-2 PSE presence to downstream logic.

Can the TPS2379DDA be used in non-IEEE-compliant high-power PoE systems?

Yes-the TPS2379DDA's GATE pin and robust 100-V input rating allow implementation of proprietary high-power PoE systems (e.g., 4-pair, 60 W+). Its detection and classification circuits can be disabled via DEN grounding, and the internal FET remains functional for current limiting and protection. However, such use voids IEEE 802.3at compliance and requires full system-level SOA validation of external MOSFETs and ballast resistors.

What is the purpose of the CDB pin on the TPS2379DDA, and how is it typically interfaced?

The CDB pin is an open-drain, active-low output that pulls to RTN during inrush limiting and goes high-impedance once the bulk capacitor is charged and the external FET is fully enhanced. It is commonly connected to the SS (soft-start) pin of a downstream DC/DC controller (e.g., UCC2897A) to delay converter startup until stable input is established-preventing inrush-related overcurrent faults. A pullup resistor to VDD or bias rail is required for active-high enable interfaces.

Does the TPS2379DDA require external components for IEEE 802.3at detection and classification?

Yes-detection requires a 24.9 kΩ ±1% resistor (RDEN) between VDD and DEN; classification requires an external resistor (RCLS) between CLS and VSS, selected per Table 1 in the datasheet (e.g., 137 Ω for Class 2, 90.9 Ω for Class 3). No external capacitors are required for basic operation, though 0.1 µF bypass at VDD and bulk capacitance (CBULK) at RTN are mandatory for stability and inrush control.