SSL5021BTS/1 - Compact low-ripple buck LED driver IC


  • Driving LED strings from a rectified mains supply, low-ripple (< ±5 %)
  • Small electronic Bill of Materials (BOM) enabling a compact solution and a small, single layer Printed-Circuit Board (PCB) footprint
  • Excellent line and load regulation and LED output current accuracy
  • Efficient BCM operation with:

Minimal reverse recovery losses in freewheel diode

Zero Current Switching (ZCS) and valley switching for switch turn-on

Minimal inductance value and size required

High efficiency (up to 91 %)

Ultra low IC current during operation (< 150 mA)

  • Auto-recovery protections:

Under Voltage Lock Out (UVLO)

Cycle-by-cycle Over Current Protection (OCP)

Internal Over Temperature Protection (OTP)

Output Over Voltage Protection (OVP)

Output Short Protection (OSP)

Thermal foldback protection via a single PTC or NTC resistor

  • Compatible with wall switches with built-in standby indicator lights (Hotaru switch)
  • Extended IC lifetime

Typical Application


The SSL5021BTS is a highly integrated, high-precision, non-isolated MOSFET/bipolar buck controller. It is intended to drive LED lamps in universal mains non-dimmable lighting applications up to 25 W. The SSL5021BTS is designed for low-ripple applications.

The SSL5021BTS operates in Boundary Conduction Mode (BCM) with on-time regulation. Operating in BCM provides a constant output current control with high accuracy. Adaptive switching frequency gives freedom to choose the inductor, which enables the optimization of inductor size, efficiency and EMI.

The SSL5021BTS starts up and operates in switching mode directly from an external resistor without dV/dt supply or auxiliary supply. This feature simplifies the VCC supply. It allows a low-cost off-the-shelf inductor to be used, providing flexibility in application design.

The SSL5021BTS comes in a compact SOT23-6 package.

The SSL5031BTS is suitable for high power factor/Low-THD applications with a high-temperature foldback function. The SSL5031CTS is best for high power factor/low-THD applications without a high-temperature foldback function.


The SSL5021BTS is intended for low-cost, non-isolated LED lighting applications with accurate fixed current output up to 25 W for single mains or universal mains voltage (90 V (AC) to 277 V (AC)).