SD4957 is an Ethernet powered device and DC/DC controller IC compatible with IEEE 802.3af/at standard. The DC-DC controller supports 7.5-70V wide-range input, and the PD controller part provides functions such as detection, grading and inrush current limiting for the receiving equipment in the power over Ethernet power supply system (PoE). SD4957 integrates a 100V power MOSFET with on-resistance of 0.55Ω, and features built-in current limit, undervoltage protection and over temperature protection.
The DC/DC controller supports SSR flyback, active clamp forward topology, and PSR flyback. It provides accurate constant voltage control loop with high system efficiency and good EMI characteristics.
PD controller
Complete power interface based on IEEE 802.3af/at powered devices
100V,0.22Ω On-chip MOSFET
Undervoltage lockout
Over temperature protection
120mA inrush current limit
Fault automatic retry
Support for auxiliary power supply
Delay output of PG signal after inrush current limitation has ceased
T2P function
DC/DC controller
Support for active clamped forward topology
Support for SSR flyback synchronous rectification
Support for PSR flyback
Built-in high voltage start-up
Integrated error amplifier
Maximum duty cycle limitation
Soft startup
FB over voltage protection
VCC undervoltage protection
Over temperature protection (external NTC resistor)
Over load protection
Cycle-by-cycle current limit
Feedback loop open-circuit protection
External input undervoltage protection
Maintenance Performance System (MPS functionality), supporting ultra-low power standby mode
| Product Name | Package form | Marking | Hazardous Substance Control | Packing Type | Remarks |
|---|---|---|---|---|---|
| SD4957TR | QFN-28-4×5×0.75-0.5 | SD4957 | Halogen free | Tape&Reel | |
| SD4957 | QFN-28-4×5×0.75-0.5 | SD4957 | Halogen free | Tray |
| title | Types of | Size (KB) | date | Download the latest English version |
|---|---|---|---|---|
| SD4957 | 0 | 2025-11-20 | SD4957 Brief Datasheet |