(19)
(11) EP 2 683 068 A8

(12) CORRECTED EUROPEAN PATENT APPLICATION
Note: Bibliography reflects the latest situation

(15) Correction information:
Corrected version no 1 (W1 A1)

(48) Corrigendum issued on:
12.02.2014 Bulletin 2014/07

(43) Date of publication:
08.01.2014 Bulletin 2014/02

(21) Application number: 12175428.7

(22) Date of filing: 06.07.2012
(51) International Patent Classification (IPC): 
H02M 3/335(2006.01)
(84) Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME

(71) Applicant: NXP B.V.
5656 AG Eindhoven (NL)

(72) Inventors:
  • Zhang, Cheng
    Redhill, Surrey RH1 1NY (GB)
  • Strijker, Joan Wichard
    Redhill, Surrey RH1 1NY (GB)
  • Halberstadt, Hans
    Redhill, Surrey RH1 1NY (GB)

(74) Representative: Hardingham, Christopher Mark 
NXP B.V. Intellectuel Property & Licensing Red Central 60 High Street
Redhill, Surrey RH1 1SH
Redhill, Surrey RH1 1SH (GB)

   


(54) Control circuit for a switched-mode power supply


(57) A control circuit for a switched-mode power supply having an input side (101) connectable to an electrical power source and an output side (102) connectable to a load. The control circuit comprises: a primary control circuit (140) adapted to generate a driving signal for a switching element (110) at the input side of the power supply; a secondary control circuit (150) adapted to monitor an output signal at the output side (102) of the power supply; and an opto-coupler (300, 400), wherein the opto-coupler is arranged to receive its input from the secondary control circuit and to provide a control signal to the primary control circuit, and the primary control circuit comprises a compensation circuit (900, 1000, 1100, 1400, 2010, 2610) adapted to process the control signal to generate a compensation signal for reducing power consumption in the opto-coupler, wherein the compensation circuit is adapted to generate the compensation signal such that a current in the opto-coupler tends to return to a desired minimum value.