The SSL5257TE is a highly integrated, high-precision buck-boost controller with an internal MOSFET. It is intended to drive low-cost compact dimmable LED lamps up to 10 W. The SSL5257TE is designed to achieve high power factor, phase-dimmable applications.
The SSL5257TE operates in Boundary Conduction Mode (BCM) with on-time control. It regulates a constant output current over line and load variations. The wide switching frequency range makes it possible to choose an inductor, which enables the optimization of inductor size, efficiency and EMI.
The SSL5257TE can start up and operate in switching mode directly from the rectified mains. To provide a low-cost driver design, an off-the-shelf inductor can be used, which provides flexibility in application design.
Integrated MOSFET (10 /700 V)
Supports most available dimming solutions
Deep dimming level
Low component count ensuring a compact solution and small, single layer
Printed-Circuit Board (PCB) footprint
Excellent line regulation and load regulation and good LED output current accuracy
Hotaru current control
Internal thermal foldback
Efficient BCM operation with:
Minimal recovery losses in freewheel diode
Zero Current Switching (ZCS) and Valley switching for turn-on of switch
Minimal inductance value and size required
High efficiency (up to 90 %)
Ultra low IC current during operation (< 200 uA)
Cycle-by-cycle OverCurrent Protection (OCP)
Internal OverTemperature Protection (OTP)
Output OverVoltage Protection (OVP)
Output Short Protection (OSP)
The SSL5257TE is intended for low-cost, non-isolated dimmable lighting applications that work from single mains voltage.
The SSL5257DB1291 demo board incorporates a form factor that is compatible with the base of an A19 LED lamp fitting, used in Solid State Lighting (SSL) applications. The SSL5257DB1291 demo board is designed to deliver an output power of 11.5 W at 72 V and 140 mA with an efficiency > 87 %. It complies with EMI and safety regulations. The design uses components that allow enough headroom for the board to fit in an A19 lamp base.
The SSL5257DB1291 demo board input is connected to the 230 V mains. Avoid touching the board while it is connected to the mains voltage and when it is in operation. An isolated housing is obligatory when used in uncontrolled, non-laboratory environments. Galvanic isolation from the mains phase using a fixed or variable transformer is always recommended.