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TPS23731

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IEEE 802.3bt type 3 class 1-4 PoE PD with no-opto flyback DC-DC controller

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Data sheet

TPS23731

ACTIVE
Data sheet Order now

Product details

Vin (min) (V) 10.2 Vin (max) (V) 60 PoE current limit (min) (mA) 750 PoE inrush limit (mA) (typ) 140 rDS(on) per FET (typ) (mΩ) 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 Operating temperature range (°C) -40 to 125 Rating Catalog
Vin (min) (V) 10.2 Vin (max) (V) 60 PoE current limit (min) (mA) 750 PoE inrush limit (mA) (typ) 140 rDS(on) per FET (typ) (mΩ) 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 Operating temperature range (°C) -40 to 125 Rating Catalog
VQFN (RMT) 45 35 mm² 7 x 5
  • 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
  • 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

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 standard s 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.

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 standard s 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 Controller datasheet PDF | HTML 02 Oct 2020
Application note PoE Powered Devices Debug Guidelines PDF | HTML 19 Jul 2021
Application note PoE PD Schematic Review Guidelines PDF | HTML 29 Apr 2021
EVM User's guide TPS23731EVM-095 Evaluation Module PDF | HTML 19 Nov 2020
Certificate TPS23731EVM-095 EU RoHs Declaration of Conformity (DoC) 13 Nov 2020
Application note Soft-Stop: TPS2373X Feature Explanation PDF | HTML 27 Oct 2020

Design & development

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Evaluation board

TPS23731EVM-095 — TPS23731 IEEE802.3bt type 3 Class 4 PoE PD applications evaluation module

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.

User guide: PDF | HTML
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PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
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Reference designs

PMP22806 — Class 4 PoE PD isolated-flyback converter (12 V, 2.1 A) primary side regulation reference design

This reference design implements a Power over Ethernet (PoE) Power Device (PD) flyback converter with 12-V and 2.1-A output. TPS23731 PD and PWM controller provides all necessary functions to implement the PoE PD control and PWM control for the flyback converter. TPS23731 uses primary side (...)
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VQFN (RMT) 45 View options
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