SSL5251T - Mains dimmable buck-boost LED driver IC


This device is no longer available.  Please see the EOL notice.

  • Supports most available dimming solutions
  • Deep dimming level
  • Flicker-free dimming
  • 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
  • Efficient BCM operation with:
    • Minimal reverse recovery losses in freewheel diode
    • Zero Current Switching (ZCS) and Valley switching for turn-on of switch
    • Minimum inductance value and size required
    • High efficiency (up to 88 %)
    • Ultra low IC current during operation (< 200 μA)
  • Many auto-recovery protections:
    • UnderVoltage LockOut (UVLO)
    • Cycle-by-cycle OverCurrent Protection (OCP)
    • Internal OverTemperature Protection (OTP)
    • Output OverVoltage Protection (OVP)
    • Output Short Protection (OSP)
  • Extended IC lifetime

Typical Application


The SSL5251T is a highly integrated, high-precision dimmable controller with an external MOSFET. It is intended to drive LED lamps in dimmable lighting applications up to 25 W. The SSL5251T is designed for high power factor, phase-dimmable applications.

The SSL5251T operates in Boundary Conduction Mode (BCM) with on-time control. It provides a constant output current control with good LED output current accuracy. Adaptive switching frequency gives freedom to choose the inductor, which enables the optimization of inductor size, efficiency and EMI.

The SSL5251T can start up and operate in switching mode directly from an external resistor without capacitor charge pump supply or auxiliary supply. This feature simplifies the VCC supply. So, a low-cost off-the-shelf inductor can be used, which provides flexibility in application design.


The SSL5251T is intended for low-cost, non-isolated dimmable lighting applications that work from single mains voltage.