US 6,982,548 B2
Switched mode power supply with delay-compensated current mode control
Jan Reinder De Boer, Drachten (Netherlands)
Assigned to Koninklijke Philips Electronics N.V., Eindhoven (Netherlands)
Appl. No. 10/497,434
PCT Filed Nov. 20, 2002, PCT No. PCT/IB02/04968
§ 371(c)(1), (2), (4) Date Jun. 02, 2004,
PCT Pub. No. WO03/049265, PCT Pub. Date Jun. 12, 2003.
Claims priority of application No. 01204751 (EP), filed on Dec. 07, 2001.
Prior Publication US 2005/0017698 A1, Jan. 27, 2005
Int. Cl. G05F 1/44 (2006.01)
U.S. Cl. 323—282 5 Claims
OG exemplary drawing
 
1. A switched mode power supply comprising:
a controllable switch (9) for connecting and disconnecting an inductive element (7) to a power source (5) in response to a control signal;
a current sensor (10) for sensing a current through the inductive element (7) and generating a sensing signal corresponding to the current;
a reference generator (11) for generating a reference signal;
a comparator (12) for comparing the sensing signal with the reference signal and generating the control signal; and
a compensation circuit (14) operative on the reference generator (11) or the current sensor (10) for adjusting the reference signal or the sensing signal to compensate for delayed disconnecting of the inductive element (7) by the controllable switch (9) due to circuitry delay times,
wherein the compensation circuit comprises means (14) for correcting the reference signal or the sensing signal by means of a correction signal proportional to the gradient of the current through the inductive element (7).
wherein the current sensor comprises a sensing resistor (17) connected in series with the inductive element (7), the sensing signal being a voltage across the sensing resistor (17), wherein the reference generator comprises a reference voltage source (18), the voltage of the reference voltage source being the reference signal, and wherein the compensation circuit comprises;
a current mirror (19) having a current input terminal (20) and a current output terminal (21),
a capacitor (16) coupling the voltage across the sensing resistor (17) to the current input terminal (20),
a compensation resistor (15) in series with the reference voltage source (18),
the current output terminal (21) being coupled to the compensation resistor (15) for causing a current flow through the compensation resistor (15) so as to form the correction signal.