Energy-Efficient, Accurate Primary-Side Regulation CC Switcher LED Lighting Applications

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Figure 1. Typical Flyback Implementation – Not a Simplified Circuit.

Data Sheets

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LYTSwitch-2 ECAD Models

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Product Details


LYTSwitch-2 dramatically simplifies low power CC LED drivers by eliminating the optocoupler and secondary control circuitry. The family introduces a revolutionary control technique to provide very tight output current regulation, compensating for transformer and external component variations, and device parameter tolerances as well as input voltage variations.

The device incorporates a 725 V power MOSFET, a novel ON/OFF control state machine, a high-voltage switched current source for self-biasing, frequency jitter to reduce EMI, cycle-by-cycle current limit and hysteretic thermal shutdown circuitry into a monolithic IC.

Product Highlights

Accurate CC Regulation (< ±3% typical)

  • Transformer inductance variation
  • External component changes with temperature
  • Input line voltage variations – this ensures accurate regulation in production

Highly Reliable, Small Size Designs

  • Eliminates the optocoupler and secondary CC control circuitry
  • Eliminates control loop compensation circuitry
  • Frequency jittering greatly reduces EMI filter cost
  • Programmable switching frequency reduces transformer size
  • 725 V Switching MOSFET enables clampless flyback designs

Advanced Protection/Safety Features

  • Auto-restart protection reduces power delivered by >90% for output short-circuit and control loop faults (open and short-circuit components)
  • Hysteretic thermal shutdown – with automatic recovery
  • Reduced field returns
  • Meets high-voltage creepage requirements between DRAIN and all other pins both on the PCB and at the package

EcoSmart™ – Energy Efficient

  • No-load consumption <30 mW1
  • No current sense resistors – maximizes efficiency

Green Package

  • Halogen free and RoHS compliant package


  • LED bulbs, downlights, luminaires, ballasts and T8 tubes


Power Table

Output Power Table2
Product5 90-308 VAC
Enclosed Bulb3 Ballast Driver4
LYT2002D 5 W 6 W
LYT2003D 6 W 7 W
LYT2004D 7 W 8 W
LYT2004K/E 9 W 10 W
LYT2005K/E 10 W 12 W


  1. Nominal input and bias supply applied to BYPASS pin.
  2. Performance for typical design.
  3. Maximum continuous power in a typical non-ventilated bulb measured at ±50 °C ambient, device TJ ≤ 100 °C.
  4. Maximum practical continuous power in an open frame design with adequate heat sinking, measured at +50 °C.
  5. Packages: D: SO-8C, E: eSIP-7C, K: eSOP-12B.

Product Documents

Design Examples

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