Energy-Efficient, Accurate Primary-Side Regulation CV/CC Switcher for Adapters and Chargers
Figure 1. Typical Application – Not a Simplified Circuit.

The LinkSwitch-3 family of ICs dramatically simplifies low power CV/CC charger designs by eliminating an optocoupler and secondary control circuitry. The device introduces a revolutionary control technique to provide very accurate output voltage and current regulation, compensating for transformer and internal parameter tolerances along with 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 jittering, cycle-by-cycle current limit and hysteretic thermal shutdown circuitry onto a monolithic IC.

Product Highlights

Dramatically Simplifies CV/CC Converters

  • Eliminates optocoupler and all secondary CV/CC control circuitry
  • Eliminates all control loop compensation circuitry

Advanced Performance Features

  • Compensates for transformer inductance tolerances, input line voltage variations, and cable voltage drop
  • Very tight IC parameter tolerances using proprietary trimming technology
  • Frequency jittering greatly reduces EMI filter cost
  • Programmable switching frequency up to 85 kHz to reduce transformer size
  • Minimum operation frequency fixed to improve transient load response

Advanced Protection/Safety Features

  • Hysteretic thermal shutdown – automatic recovery reduces power supply returns from the field
  • Meets high-voltage creepage requirements between DRAIN and all other pins both on the PCB and at the package

EcoSmart™– Energy Efficient

  • Easily meets all global energy efficiency regulations with no added components
  • No-load consumption at 230 VAC input with bias winding <30 mW

Green Package

  • Halogen free and RoHS compliant package


  • Chargers for cell/cordless phones
  • PDAs
  • Adapters
  • MP3/portable audio devices

Output Power (Watts)1,2,3,4
Product590-264 VAC
D (SO-8) Package
AdapterOpen Frame
7.5 W7.5 W
Product5K (eSOP) and E (eSIP) Packages
AdapterOpen Frame
8.5 W 9 W
10 W 10 W
10 W 10 W


  1. Assumes minimum input DC voltage >90 VDC, KP ≥1 (Recommend KP ≥1.15 for accurate CC regulation), η >78%, DMAX <55%.
  2. Output power capability is reduced if a lower input voltage is used.
  3. Minimum continuous power with adequate heat sink measured at 50 °C ambient with device junction below 110 °C.
  4. Assumes bias winding is used to supply BYPASS pin.
  5. Package: D: SO-8C, E: eSIP-7C, K: eSOP-12B

Product Documents
Package Informationpackageinfo.pdf
Data Sheetlinkswitch-3_family_datasheet.pdf