1 Features

• Complete IEEE 802.3bt Type 3 (Class 1-6) 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 60-W operation

– Allocated power indicator outputs - parallel or

serial encoding selectable

• Integrated PWM controller for flyback or Active

Clamp Forward 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

– 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

2 Applications

• Video and VoIP Telephones

• Access Points

• Pass-through System

• Security Cameras

• Redundant Power Feeds or Power Sharing

3 Description

The TPS23730 device combines a Power over

Ethernet (PoE) powered device (PD) interface, and a

current-mode DC-DC controller optimized for flyback

and active clamp forward (ACF) switching regulator

designs . In the case of flyback configuration, the use

of primary-side regulation (PSR) is supported. The

PoE interface supports the IEEE 802.3bt standard for

applications needing up to 51 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 startup requirements are met.

The soft-stop feature minimizes stress on switching

power FETs , 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.