LTC4257 - IEEE 802.3af PD Power over Ethernet Interface Controller
The LTC4257 provides complete signature and power interface functions for a device operating in an IEEE 802.3af Power over Ethernet (PoE) system. The LTC4257 simplifies Powered Device (PD) design by incorporating the 25k signature resistor, the classification current source, input current limit with thermal foldback, undervoltage lockout and power good signaling, all in a single 8-pin package. By incorporating a high voltage power MOSFET onboard, the LTC4257 provides the system designer with reduced cost while also saving board space.
The LTC4257 can interface directly with a variety of Linear Technology DC/DC converter products to provide a cost effective power solution for IP phones, wireless access points and other PDs. Linear Technology also provides solutions for Power Sourcing Equipment (PSE) applications with quad network power controllers.
The LTC4257 is available in the 8-pin SO and low profile (3mm x 3mm) DFN packages.
Features
Typical Application  | Applications
Packaging  |
Order Information
| Part Number | Package | Temp | Price(1-99) | Price (1k)* |
|---|---|---|---|---|
| LTC4257CDD#PBF | 3x3 DFN-8 | C | $2.41 | $1.70 |
| LTC4257CDD#TRPBF | 3x3 DFN-8 | C | $1.76 | |
| LTC4257CS8#PBF | SO-8 | C | $2.32 | $1.65 |
| LTC4257CS8#TRPBF | SO-8 | C | $1.71 | |
| LTC4257IDD#PBF | 3x3 DFN-8 | I | $2.77 | $1.95 |
| LTC4257IDD#TRPBF | 3x3 DFN-8 | I | $2.01 | |
| LTC4257IS8#PBF | SO-8 | I | $2.68 | $1.90 |
| LTC4257IS8#TRPBF | SO-8 | I | $1.96 |
Demo Boards
| Part Number | Description | Price |
|---|---|---|
| DC959A | LTC4257-1 High-Power PD Demo Bd | $50.00 |
- LTC4257 Package Drawing LTC4257
- DN338 - Power over Ethernet Isolated Power Supply Delivers 11.5W at 90% Efficiency
- PoE Consortium Clause # 33 Parametric Report
- PoE Consortium Interoperability Report
- R413 Reliability Data
- PoE PD Controllers
- PoE+ for the Power Hungry
- Power over Ethernet Solutions
- LTC4257 Footprints and Symbols
