Product details


Vin (Min) (V) 10.2 Vin (Max) (V) 60 PoE current limit (Min) (mA) 750 PoE inrush limit (Typ) (mA) 140 rDS(on) per FET (Typ) (mOhms) 300 PoE standards supported 802.3at Type 1 (802.3af), 802.3at Type 2, 802.3bt Type 3 PD power level 13W, 25W DC/DC control PD and DC/DC Fault response Auto Retry Features Adapter priority, Advanced startup, Automatic MPS, Error Amplifier, Inrush delay, Primary Side Adapter Priority, Primary-Side Regulation, Spread Spectrum Frequency Dithering, Thermal Shutdown Switching frequency Programmable, Synchronizable open-in-new Find other Powered devices

Package | Pins | Size

VQFN (RMT) 45 35 mm² 7 x 5 open-in-new Find other Powered devices


  • Complete IEEE 802.3bt Type 3 (Class 1-4) and 802.3at PoE PD Solution
    • EA Gen 2 logo-ready (PoE 2 PD Controller)
    • Robust 100-V, 0.3-Ω (typ) Hotswap MOSFET
    • Supports power levels for up to 30-W operation
  • Integrated PWM controller for flyback configuration
    • Flyback control with primary-side regulation
      • Supports CCM operation
      • ±1.5% (typ, 5-V output) load regulation (0-100% load range) — with Sync FET
      • ±3% (typ, 12-V output) load regulation (5-100% load range) — diode rectified
    • Also supports secondary-side regulation
    • Soft-start control with advanced startup and hiccup mode overload protection
    • Soft-stop shutdown
    • Adjustable frequency with synchronization
    • Programmable frequency dithering for EMI
  • Automatic Maintain Power Signature (MPS)
    • Auto-adjust to PSE type and load current with auto-stretch
  • Primary adapter priority input
  • –40°C to 125°C junction temperature range

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The TPS23731 device combines a Power over Ethernet (PoE) powered device (PD) interface, and a current-mode DC-DC controller optimized for flyback switching regulator designs where the use of primary-side regulation (PSR) is supported. The PoE interface supports the IEEE 802.3bt and IEEE 802.3at standards for applications needing up to 25.5 W or less at PD input.

Programmable spread spectrum frequency dithering (SSFD) is provided to minimize the size and cost of EMI filter. Advanced Startup with adjustable soft-start helps to use minimal bias capacitor while simplifying converter startup and hiccup design, also ensuring that IEEE 802.3bt/at startup requirements are met.

The soft-stop feature minimizes stress on switching sync FET(s), allowing FET BOM cost reduction.

The PSR feature of the DC-DC controller uses feedback from an auxiliary winding for control of the output voltage, eliminating the need for external shunt regulator and optocoupler. It is optimized for continuous conduction mode (CCM), and can work with secondary side synchronous rectification, resulting in optimum efficiency, regulation accuracy and step load response over multiple outputs.

The DC-DC controller features slope compensation and blanking. Typical switching frequency is 250 kHz.

The automatic MPS enables applications with low power modes or multiple power feeds. It automatically adjusts its pulsed current amplitude and duration according to PSE Type and system conditions, to maintain power while minimizing consumption.

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Technical documentation

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Type Title Date
* Data sheet TPS23731 IEEE 802.3bt Type 3 Class 1-4 PoE PD with No-Opto Flyback DC-DC Control datasheet Oct. 02, 2020
User guide TPS23731EVM-095 Evaluation Module Nov. 19, 2020
Certificate TPS23731EVM-095 EU RoHs Declaration of Conformity (DoC) Nov. 13, 2020
Application note Soft-Stop: TPS2373X Feature Explanation Oct. 27, 2020

Design & development

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Hardware development

document-generic User guide

The TPS23731 evaluation module (TPS23731EVM-095) contains evaluation and reference circuitry for the TPS23731, which is a IEEE802.3bt Type 3 Class 4 PoE PD controller suitable for Class 4 (25.5W) PoE PD applications.

  • IEEE802.3bt type 3 Class 4 compliant PoE PD
  • Integrated PWM controller for flyback congifuration
  • Frequency dithering for EMI reduction
  • Soft-start control with advanced startup and hiccup mode overload protection
  • Soft-stop shutdown

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VQFN (RMT) 45 View options

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