LTC4257
PRODUCTIONIEEE 802.3af PD Power over Ethernet Interface Controller
- Part Models
- 8
- 1ku List Price
- Starting From $1.19
Overview
- Complete Power Interface Port for IEEE 802.3af® Powered Devices (PDs)
- Onboard 100V, 400mA Power MOSFET
- Precision Input Current Limit
- Onboard 25k Signature Resistor
- Programmable Classification Current (Class 0-4)
- Undervoltage Lockout
- Smart Thermal Protection
- Power Good Signal
- Available in 8-Pin SO and Low Profile (3mm × 3mm) DFN Packages
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 ADI's DC/DC converter products to provide a cost effective power solution for IP phones, wireless access points and other PDs. Analog Devices 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 × 3mm) DFN packages.
Applications
- IP Phone Power Management
- Wireless Access Points
- Telecom Power Control
Documentation
Data Sheet 1
Reliability Data 3
Design Note 1
Technical Articles 1
Video 1
Product Selector Card 3
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.
| Part Model | Pin/Package Drawing | Documentation | CAD Symbols, Footprints, and 3D Models |
|---|---|---|---|
| LTC4257CDD#PBF | 8-Lead DFN (3mm x 3mm x 0.75mm w/ EP) | ||
| LTC4257CDD#TRPBF | 8-Lead DFN (3mm x 3mm x 0.75mm w/ EP) | ||
| LTC4257CS8#PBF | 8-Lead SOIC (Narrow 0.15 Inch) | ||
| LTC4257CS8#TRPBF | 8-Lead SOIC (Narrow 0.15 Inch) | ||
| LTC4257IDD#PBF | 8-Lead DFN (3mm x 3mm x 0.75mm w/ EP) | ||
| LTC4257IDD#TRPBF | 8-Lead DFN (3mm x 3mm x 0.75mm w/ EP) | ||
| LTC4257IS8#PBF | 8-Lead SOIC (Narrow 0.15 Inch) | ||
| LTC4257IS8#TRPBF | 8-Lead SOIC (Narrow 0.15 Inch) |
| Part Models | Product Lifecycle | PCN |
|---|---|---|
|
Dec 14, 2023 - 22_0255 Epoxy Change from Henkel 8290 to 8290A for 8-Lead SOIC Package (PCN part 2 of 2) |
||
| LTC4257CS8#PBF | PRODUCTION | |
| LTC4257CS8#TRPBF | PRODUCTION | |
| LTC4257IS8#PBF | PRODUCTION | |
| LTC4257IS8#TRPBF | PRODUCTION | |
|
Jun 16, 2021 - 21_0026 Laser Top Mark for 8SOICN Assembled in ADPG, UTL and CRM |
||
| LTC4257CS8#PBF | PRODUCTION | |
| LTC4257CS8#TRPBF | PRODUCTION | |
| LTC4257IS8#PBF | PRODUCTION | |
| LTC4257IS8#TRPBF | PRODUCTION | |
This is the most up-to-date revision of the Data Sheet.
Software Resources
Can't find the software or driver you need?
Request a Driver/SoftwareHardware Ecosystem
| Parts | Product Life Cycle | Description |
|---|---|---|
| Circuit Monitors 1 | ||
| LT2940 | PRODUCTION | Power and Current Monitor |
| Power-over-Ethernet (PoE) Controllers 1 | ||
| LT4275 | PRODUCTION | LTPoE++/PoE+/PoE PD Controller |
| Parts | Product Life Cycle | Description |
|---|---|---|
| LTC4257-1 | PRODUCTION | IEEE 802.3af PD Power over Ethernet Interface Controller with Dual Current Limit |
Tools & Simulations
LTspice
Models for the following parts are available in LTspice:
- LTC4257
- LTC4257-1
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.