Texas Instruments TPS23755RJJT

Overview

TPS23755RJJT 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 ±3% load regulation at 12-V output, operates from –40°C to 125°C, and supports primary-side regulation (PSR) for optocoupler-free flyback designs in security cameras and IP phones.

For engineers reviewing the TPS23755RJJT datasheet, TPS23755RJJT pinout, TPS23755RJJT application, or TPS23755RJJT equivalent, this device enables compact, EMI-optimized PoE PD designs with secondary-side adapter priority, spread-spectrum dithering, and programmable classification-critical for space-constrained 13-W Type-1 applications requiring stable 12-V output and seamless power-source handover.

Technical Context

The TPS23755RJJT integrates a current-mode flyback DC-DC controller with PSR feedback via auxiliary winding, eliminating external shunt regulators and optocouplers. Its 250-kHz nominal switching frequency operates in continuous conduction mode (CCM) with secondary-side diode rectification and supports low-side buck topology for non-isolated use.

It implements advanced startup with minimal bias capacitance, slope compensation, blanking, and soft-start/cool-down timing. Secondary auxiliary power detection (AUX_D/AUX_V) enables smooth transition between PoE and adapter input without efficiency or thermal penalty, while SRR/SRF pins allow programmable V_DS slew rate control for EMI reduction.

Key Specifications

Pinout & Package

TPS23755RJJT uses a 24-pin VSON package (6.0 mm × 4.0 mm) with exposed thermal pad soldered to VSS for thermal management. Anchor pins A1–A4 are mechanical-only and unconnected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS23755RJJT, TPS23753ARJBR offers lower integration and no PSR, increasing solution size and cost; LT4275AIMSE#PBF provides greater flexibility but requires full external power stage design-making TPS23755RJJT optimal for compact, cost-sensitive 12-V PoE PDs needing seamless dual-input operation.

Availability

TPS23755RJJT 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 traceable sourcing for industrial deployments.

Supply support for TPS23755RJJT 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 and embedded processing technologies, with decades of expertise in power management and connectivity solutions.

The TPS23755RJJT belongs to TI's Power over Ethernet product line, engineered specifically for compact, high-efficiency Type-1 PD implementations where integration, thermal resilience, and seamless dual-power operation are critical.

FAQ

What is the maximum PoE input voltage supported by the TPS23755RJJT?

The TPS23755RJJT supports a PoE input voltage range of 34.7 V to 57 V under recommended operating conditions, with an absolute maximum rating of 100 V on VPD and VSS pins. This ensures compatibility with standard IEEE 802.3at midspan and endspan PSEs while providing margin against transients and cable drop. The device incorporates UVLO thresholds and foldback protection to maintain safe operation across this range.

Does the TPS23755RJJT require an optocoupler for feedback in flyback designs?

No, the TPS23755RJJT does not require an optocoupler. It implements primary-side regulation (PSR) using feedback from the transformer's auxiliary winding connected to the CP and FB pins. This 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 output across 5–100% load range.

How does the TPS23755RJJT handle power source handover between PoE and a wall adapter?

The TPS23755RJJT uses dedicated AUX_D and AUX_V pins to detect secondary-side auxiliary power and adjust the output voltage setpoint smoothly. When AUX_D is pulled low (e.g., via optocoupler), AUX_V modifies the FB node to reduce output voltage-enabling zero-droop, glitch-free transition between PoE and adapter without efficiency or thermal trade-offs. This behavior is confirmed in the device's functional description and typical application schematics.

What is the purpose of the SRR and SRF pins on the TPS23755RJJT?

The SRR (source sinking) and SRF (source sourcing) pins on the TPS23755RJJT control the V_DS slew rate of the internal 150-V switching MOSFET. Connecting resistors from SRR to GND and SRF to VB sets the turn-on and turn-off rates, respectively. This programmable slew rate reduces EMI emissions and relaxes filtering requirements-confirmed by electrical characteristics showing controlled dV/dt behavior and referenced in the "EMI reduction" feature description.

Can the TPS23755RJJT be used in non-isolated buck topologies?

Yes, the TPS23755RJJT supports non-isolated buck topology in addition to flyback. Section 3 of the datasheet explicitly states buck support, and the DC-DC controller section confirms operation with low-side switch configuration. The device's current-mode control, soft-start, and slope compensation functions remain fully applicable-making TPS23755RJJT suitable for simpler, lower-cost 12-V PoE-derived rails where isolation is not required.