LTC4278 - IEEE 802.3at PD with Synchronous No-Opto Flyback Controller and 12V Aux Support
Features
- 25.5W IEEE 802.3at Compliant (Type 2) PD
- 10V to 57V Auxiliary Power Input
- Shutdown Pin for Flexible Auxiliary Power Support
- Integrated State-of-the-Art No-Opto Synchronous Flyback Controller – Isolated Power Supply Efficiency >92%
- Superior EMI Performance
- Robust 100V 0.7Ω (Typ) Integrated Hot Swap MOSFET
- IEEE 802.3at High Power Available Indicator
- Integrated Signature Resistor and Programmable Class Current
- Undervoltage, Overvoltage and Thermal Protection
- Short-Circuit Protection with Auto-Restart
- Programmable Soft-Start and Switching Frequency
- Complementary Power Good Indicators
- Thermally Enhanced 7mm × 4mm DFN Package
– 88% Efficiency Including Diode Bridge and Hot Swap™ FET
Typical Application
Description
The LTC4278 is an integrated Powered Device (PD) controller and switching regulator intended for high power IEEE 802.3at and 802.3af applications. With a wide input voltage range, the LTC4278 is specifically designed to support PD applications that include a low-voltage auxiliary power input such as a 12V wall adaptor. The inclusion of a shutdown pin provides simple implementation of both PoE and auxiliary dominate applications. In addition, the LTC4278 supports both 1-event and 2-event classifications as defined by the IEEE, thereby allowing the use in a wide range of product configurations.The LTC4278 synchronous, current mode, flyback controller generates multiple supply rails in a single conversion step providing for the highest system efficiency while maintaining tight regulation across all outputs. The LTC4278 includes Linear Technology’s patented No-Opto feedback topology to provide full IEEE 802.3 isolation without the need of an opto-isolator circuit. A true soft-start function allows graceful ramp-up of all output voltages.
The LTC4278 is available in a space saving 32-pin DFN package.
Packaging
CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.
For complete and up to date package information and drawings, please refer to our packaging page
| Part Number | Package | Code | Temp | Package Drawing |
RoHS |
|---|---|---|---|---|---|
| LTC4278CDKD#PBF | 7x4 DFN-32 | DKD | C | 05-08-1734 | Yes |
| LTC4278CDKD#TRPBF | 7x4 DFN-32 | DKD | C | 05-08-1734 | Yes |
| LTC4278IDKD#PBF | 7x4 DFN-32 | DKD | I | 05-08-1734 | Yes |
| LTC4278IDKD#TRPBF | 7x4 DFN-32 | DKD | I | 05-08-1734 | Yes |
Order Info
- Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
- Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
- Please refer to our general ordering information or the product datasheet for more details
Package Variations and Pricing
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LTC4278CDKD#PBF | 7x4 DFN-32 | C | $3.71 | $2.60 | Yes | |
| LTC4278CDKD#TRPBF | 7x4 DFN-32 | C | $2.66 | Yes | ||
| LTC4278IDKD#PBF | 7x4 DFN-32 | I | $4.46 | $3.12 | Yes | |
| LTC4278IDKD#TRPBF | 7x4 DFN-32 | I | $3.18 | Yes | ||
| Buy Now • Request Samples | ||||||
Demo Boards
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC1561B | LTC4278 IEEE802.3at PD Controller with 12V Aux, Vout = 5V, Iout = 4.5A | $75.00 | |
| Buy Now | |||
Applications
- VoIP Phones with Advanced Display Options
- Dual-Radio Wireless Access Points
- PTZ Security Cameras
- RFID Readers
- Industrial Controls
People Who Viewed This Product Also Viewed
- LT4275 - LTPoE++/PoE+/PoE PD Controller
- LTC4269-1 - IEEE 802.3at High Power PD and No-Opto Flyback Controller with AUX Support
- LTC4267 - Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator
- LTC4265 - IEEE 802.3 at High Power PD Interface Controller with 2-Event Classification Recognition
- LT4321 - PoE Ideal Diode Bridge Controller
- LTC4364 - Surge Stopper with Ideal Diode
- LT4320/LT4320-1 - Ideal Diode Bridge Controller
- LT3748 - 100V Isolated Flyback Controller
- LTC4269-2 - IEEE 802.3at High Power PD and Synchronous Forward Controller with AUX Support
- LT8705 - 80V VIN and VOUT Synchronous 4-Switch Buck- Boost DC/DC Controller
Product Notifications
Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.
Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.
Design Tools
LTspice
LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice
Models for the following parts are available in LTspice:
LTC4278
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
