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.