Texas Instruments TPS23755RJJR

Overview

TPS23755RJJR from Texas Instruments is an IEEE 802.3at Type-1 Power over Ethernet (PoE) powered device (PD) interface IC with integrated 150-V, 0.77-Ω flyback DC-DC controller and robust 100-V, 0.36-Ω hotswap MOSFET. It delivers up to 13 W at 12 V output with ±3% load regulation (5–100% load), supports primary-side regulation (PSR), and operates across –40°C to 125°C junction temperature in a 6 mm × 4 mm VSON-24 package. It enables compact, optocoupler-free PoE PD designs for security cameras and IP phones.

For engineers reviewing the TPS23755RJJR datasheet, TPS23755RJJR pinout, TPS23755RJJR application, or TPS23755RJJR equivalent, key selection criteria include its integrated PoE detection/classification compliance, PSR-based flyback control without secondary-side feedback components, programmable switching frequency (223–273 kHz), spread-spectrum dithering for EMI reduction, and auxiliary power priority management with smooth PoE/adapter transition.

Technical Context

The TPS23755RJJR integrates dual functional blocks: an IEEE 802.3at-compliant PD front-end (detection, classification, hotswap control) and a current-mode flyback DC-DC controller with internal 150-V power FET. Its PSR architecture uses CP and FB pins to sample auxiliary winding voltage, eliminating optocouplers and shunt regulators. The controller supports continuous conduction mode (CCM) operation at 250 kHz nominal switching frequency with adjustable frequency via FRS pin and spread-spectrum dithering via DTHR pin.

Secondary-side auxiliary power detection (AUX_D) triggers dynamic output voltage reconfiguration via AUX_V, enabling seamless switchover between PoE and external adapter inputs without efficiency loss or thermal penalty. Advanced startup reduces bias capacitor requirements, while slope compensation, blanking, and soft-start ensure stable transient response and reliable inrush management.

Key Specifications

Pinout & Package

TPS23755RJJR is housed in a thermally enhanced 24-pin VSON package (6.00 mm × 4.00 mm body size) with exposed thermal pad connected to VSS. The package supports high-power density layouts and requires PCB copper fill under the pad for optimal thermal dissipation (R_θJB = 14.5°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS23755RJJR, TPS23753ARJBR offers lower integration but broader 802.3af compatibility, while LT4275AIMSE#PBF provides superior PD feature set (e.g., multi-event classification) at the cost of requiring full external DC-DC implementation-making TPS23755RJJR optimal for space-constrained, single-output 12-V PoE endpoints.

Availability

TPS23755RJJR is available at Aetrix Electronics and suitable for security cameras, IP phones, and wireless access points requiring stable component supply, long-term lifecycle support, and guaranteed authenticity for production ramp.

Supply support for TPS23755RJJR 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 leadership in Power over Ethernet solutions.

The TPS23755RJJR belongs to TI's PoE PD controller product line, engineered specifically for compact, cost-sensitive IEEE 802.3at Type-1 endpoints that require integrated power conversion and robust thermal performance in minimal footprint.

FAQ

What is the maximum output power supported by the TPS23755RJJR in a typical 12-V flyback design?

The TPS23755RJJR is specified as an IEEE 802.3at Type-1 PD, supporting up to 13 W delivered to the load. In a typical 12-V output flyback configuration with secondary-side diode rectification and CCM operation, it achieves >80% efficiency across 0.1–1.0 A load range, enabling reliable 12-V/1.08-A operation. Actual output power depends on transformer design, layout, and thermal management-TI's TPS23755EVM-894 reference design validates this capability.

Does the TPS23755RJJR require an optocoupler for output voltage regulation?

No, the TPS23755RJJR does not require an optocoupler. It implements primary-side regulation (PSR) using feedback from the transformer's auxiliary winding via the CP and FB pins. This architecture eliminates the need for secondary-side shunt regulators and optocouplers, reducing component count, board space, and cost while maintaining ±3% load regulation at 12 V.

How does the TPS23755RJJR manage seamless switchover between PoE and auxiliary power sources?

The TPS23755RJJR uses the AUX_D pin to detect presence of a secondary-side adapter and the AUX_V pin to dynamically adjust the FB reference voltage, lowering the output setting during adapter use. This coordination ensures zero-output-dip transition with no efficiency or thermal penalty-verified in TI's application notes and the TPS23755EVM-894 evaluation module behavior.

What is the purpose of the DTHR and FRS pins on the TPS23755RJJR?

The FRS pin sets the nominal switching frequency (223–273 kHz) via an external resistor to RTN. The DTHR pin enables spread-spectrum frequency dithering: connecting a capacitor to RTN and resistor to FRS generates a triangular dither waveform (1.005–1.046 V pk-pk), reducing peak EMI and allowing smaller, lower-cost input filters-critical for meeting FCC Class B limits in compact PoE devices.

Can the TPS23755RJJR be used in buck topology applications?

Yes, the TPS23755RJJR supports non-isolated buck topology in addition to flyback. Its DC-DC controller section includes internal slope compensation, soft-start, and current-mode control compatible with low-side switch configurations. When configured for buck, the internal 150-V FET serves as the high-side switch, and external components define output voltage and current capability per TI's application guidelines.