Texas Instruments TPS23785BPWP

Overview

TPS23785BPWP from Texas Instruments is a dual-function IEEE 802.3at Type 2 Power over Ethernet (PoE) powered device (PD) interface and non-isolated DC-to-DC controller IC. It integrates a 100-V, 0.5-Ω hot-swap MOSFET, supports up to 30-W input power, delivers 5.1-V regulated VB rail, features two complementary gate drivers with programmable dead time, and operates across –40°C to 125°C junction temperature for surveillance camera and VoIP telephone PD designs.

For engineers reviewing the TPS23785BPWP datasheet, TPS23785BPWP pinout, TPS23785BPWP application, or TPS23785BPWP equivalent, key selection criteria include PoE classification compliance (Class 0–4), converter UVLO thresholds (35 V / 4.5 V hysteresis), duty cycle range (0–78%), TSSOP-24 PowerPAD™ package thermal performance (θJCbot = 1.8°C/W), and dual-gate driver timing control via DT and FRS pins.

Technical Context

The TPS23785BPWP implements a two-event physical-layer classification engine compliant with IEEE 802.3at for Type 2 PSE detection, with programmable CLS current (0.44–25.5 W) via external resistor. Its DC-to-DC controller uses current-mode control with internal slope compensation (155 mV typical), 78% max duty cycle, and softstart (3.9 ms typical).

It features dual gate drivers (GATE and GAT2) with independently programmable dead time (via DT pin, 40–188 ns), oscillator synchronization capability (FRS pin), and adaptive blanking (BLNK pin). The integrated hotswap MOSFET supports inrush limiting (140 mA typical) and foldback protection (12.3 V threshold), while VC bias startup is managed by a dedicated current source (4.8 mA typical at VDD1 = 48 V).

Key Specifications

Pinout & Package

TSSOP-24 PowerPAD™ package with exposed thermal pad (connected to VSS); 0.65-mm pitch, 7.8-mm × 4.4-mm body; RoHS-compliant, moisture-sensitive level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS23785BPWP, TPS23753APWP offers lower cost but no Type 2 support or dual-gate capability, while LT4275AIMSE#PBF provides greater flexibility in power stage design at the expense of integration and component count.

Availability

TPS23785BPWP is available at Aetrix Electronics and suitable for surveillance camera deployments, VoIP telephone manufacturing, and wireless access point production requiring stable component supply and long-term industrial lifecycle support.

Supply support for TPS23785BPWP 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 broad industrial and communications portfolio coverage.

The TPS23785B product line delivers integrated PoE PD and DC-to-DC control for high-power IEEE 802.3at applications, targeting space-constrained, thermally demanding endpoints such as IP cameras and enterprise telephony.

FAQ

What is the purpose of the APD pin on the TPS23785BPWP?

The APD pin on the TPS23785BPWP enables adapter priority mode: when voltage exceeds 1.5 V relative to ARTN, it disables the internal hotswap MOSFET, turns off classification, and asserts T2P to signal external power use. This allows seamless fallback to an external VDD1–RTN adapter without firmware involvement. The TPS23785BPWP uses APD to manage power-source arbitration in hybrid-powered devices like dual-input security cameras.

How does the TPS23785BPWP implement IEEE 802.3at Type 2 classification?

The TPS23785BPWP performs two-event hardware classification per IEEE 802.3at by applying 2.5 V across the CLS resistor during both detection and classification cycles, measuring resulting current to determine Class 0–4. It signals Type 2 readiness via the T2P pin, which goes active low after tT2P delay (5–15 ms) once classification completes. The TPS23785BPWP supports Class 4 (63.4 Ω) for up to 25.5 W input power, enabling compatibility with high-power midspan PSEs.

Can the TPS23785BPWP operate without the GAT2 driver enabled?

Yes, the TPS23785BPWP can operate with GAT2 disabled by connecting the DT pin directly to VB, placing GAT2 in high-impedance state. This configuration supports single-MOSFET topologies like forward or basic flyback converters. The TPS23785BPWP retains full functionality of GATE, CS sensing, CTL loop control, and PoE interface when GAT2 is disabled, making it adaptable to simpler power architectures without sacrificing PD compliance.

What thermal considerations apply to the TPS23785BPWP PowerPAD™ package?

The TPS23785BPWP's PowerPAD™ must be soldered to a large VSS copper area for effective heat dissipation, given its θJCbot of 1.8°C/W. Layout requires minimum 0.025" clearance between VSS/RTN and high-voltage nodes (VDD/VDD1) to prevent arcing. The TPS23785BPWP's thermal shutdown activates at 145°C with 20°C hysteresis, so PCB copper area, airflow, and ambient temperature must be validated to maintain TJ ≤125°C under 30-W load conditions.

How is the switching frequency programmed on the TPS23785BPWP?

The TPS23785BPWP switching frequency is set by connecting a resistor from the FRS pin to ARTN, with value determined by RFRS (kΩ) = 17250 / fSW (kHz). For example, 68.1 kΩ yields 253 kHz typical. The FRS pin also accepts external synchronization pulses above the free-running frequency. The TPS23785BPWP supports 50–937 kHz range, allowing optimization for efficiency (lower fSW) or size (higher fSW) in final designs.