Texas Instruments TPS23756PWP

Overview

TPS23756PWP from Texas Instruments is an IEEE 802.3at Type 2 Powered Device (PD) interface and current-mode DC-DC controller optimized for isolated converters. It integrates a 100-V, 0.5-Ω hotswap MOSFET, supports up to 30-W input power, and features dual gate drivers with programmable dead time. It enables PoE-powered security cameras and multiband access points with 9-V converter start-up.

For engineers reviewing the TPS23756PWP datasheet, TPS23756PWP pinout, TPS23756PWP application, or TPS23756PWP equivalent, key selection criteria include PoE classification compliance (IEEE 802.3at), dual-gate drive capability for active-clamp forward topologies, 9-V UVLO threshold, thermal shutdown at 145°C, and HTSSOP-20 package compatibility with PowerPAD™ thermal enhancement.

Technical Context

The TPS23756PWP implements a combined PoE interface and current-mode DC-DC controller. Its PoE section delivers IEEE 802.3at-compliant detection, classification (programmable via CLS resistor), and Type 2 hardware classification flag (T2P output), while its DC-DC controller provides two complementary gate drivers (GATE and GAT2) with adjustable dead time (via DT pin) and 78% max duty cycle.

It supports adapter ORing logic with APD and PPD pins, enabling priority-based power sourcing between PoE and external VDD1 adapters. The controller includes internal soft-start, bootstrap start-up source, slope compensation (155 mV typical), and programmable switching frequency (227–278 kHz with RFRS = 68.1 kΩ).

Key Specifications

Pinout & Package

TPS23756PWP is housed in a 20-pin HTSSOP (PWP) package with exposed PowerPAD™ thermal pad (connected to VSS). The package measures 6.50 mm × 4.40 mm and supports high-power dissipation via bottom-side thermal vias.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PoE PD interface and DC-DC controller applications.

Compared with TPS23754PWP, the TPS23756PWP enables earlier start-up from low-voltage PoE sources but offers identical protection and classification features; versus LT4275AIMSE#PBF, it reduces component count and layout complexity by integrating dual gate drivers and current-mode control, at the cost of topology flexibility.

Availability

TPS23756PWP is available at Aetrix Electronics and suitable for security cameras, VoIP telephones, and multiband access points requiring stable component supply, long-term lifecycle assurance, and full IEEE 802.3at compliance.

Supply support for TPS23756PWP 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 company specializing in analog and embedded processing technologies, with leadership in power management, signal chain, and connectivity solutions.

The TPS23756PWP belongs to TI's Power over Ethernet (PoE) PD controller product line, designed specifically to integrate IEEE 802.3at-compliant interface functionality with high-efficiency isolated DC-DC control for space-constrained, thermally demanding powered devices.

FAQ

What is the minimum PoE input voltage required for TPS23756PWP to initiate converter operation?

The TPS23756PWP features a 9.0-V (typical) UVLO threshold on the VC pin, meaning converter operation begins once the internal bias rail reaches this level. This allows reliable start-up from PoE sources as low as ~37 V after diode bridge drop, unlike the 15-V threshold of the TPS23754PWP. The actual minimum input depends on VDD1 coupling and CVC sizing, but 37–40 V is typically sufficient for robust turn-on.

How does the TPS23756PWP handle power source arbitration between PoE and an external adapter?

The TPS23756PWP uses dedicated APD and PPD pins to implement deterministic power-source arbitration. Raising APD above 1.5 V disables the internal hotswap MOSFET and forces power from VDD1–RTN, while pulling PPD above 1.55 V enables the MOSFET and activates classification. These pins allow firmware-independent, hardware-level selection without external logic or microcontroller intervention.

Can the TPS23756PWP drive synchronous rectifiers in an isolated forward converter?

Yes - the TPS23756PWP's GAT2 output is fully functional and complementary to GATE, with programmable dead time via the DT pin. When configured for synchronous rectification, GAT2 drives the secondary-side MOSFET with precise timing relative to GATE, reducing conduction losses and improving efficiency in forward or active-clamp topologies. No external driver IC is needed.

What is the purpose of the T2P pin on the TPS23756PWP, and how is it used in system design?

The T2P pin is an active-low, open-drain output that signals successful IEEE 802.3at Type 2 hardware classification, or activation of APD/PPD. System designers use T2P to enable downstream circuitry (e.g., MCU boot, display backlight) only after valid PoE+ power is confirmed, preventing premature initialization. It also serves as a status flag for field diagnostics and PSE compatibility verification.

Does the TPS23756PWP support programmable current limiting during inrush, and what is its value?

Yes - the TPS23756PWP incorporates a 140-mA (typical) inrush current limit during startup, enforced by internal circuitry before full current regulation engages. This prevents tripping of upstream PSE current limits during initial capacitor charging. The limit is fixed and not user-programmable, but works in conjunction with the 850-mA continuous RTN current limit and thermal shutdown for comprehensive fault protection.