US 6,982,889 B2
DC/AC converter and its controller IC
Kenichi Fukumoto, Kyoto (Japan)
Assigned to Rohm Co., LTD, Kyoto (Japan)
Appl. No. 10/501,795
PCT Filed Aug. 29, 2003, PCT No. PCT/JP03/11032
§ 371(c)(1), (2), (4) Date Jul. 16, 2004,
PCT Pub. No. WO2004/051835, PCT Pub. Date Jun. 17, 2004.
Claims priority of application No. 2002-346855 (JP), filed on Nov. 29, 2002.
Prior Publication US 2005/0073859 A1, Apr. 07, 2005
Int. Cl. H02M 5/42 (2006.01); H02M 3/335 (2006.01); H02M 7/122 (2006.01); H02M 7/5387 (2006.01)
U.S. Cl. 363—98 10 Claims
OG exemplary drawing
 
1. A dc-ac converter, comprising:
a dc power supply;
a transformer having a primary winding and at least one secondary winding;
a semiconductor switch circuit for alternately flowing current from said dc power supply to said primary winding in a first and a second directions;
a load connected to said secondary winding;
a current detection circuit for detecting the magnitude of said current flowing through said load to generate a current detection signal;
a triangular wave signal generation circuit for generating a triangular wave signal;
a PWM control signal generation circuit, receiving said triangular wave signal and said current detection signal, for generating a PWM control signal by comparing said triangular wave signal with an error signal that is formed based on said current detection signal; and
a switch driving circuit receiving said PWM control signal and a run-stop signal, said switch driving circuit adapted to provide said semiconductor switch circuit with switch drive signals in accord with said PWM control signal when said run-stop signal has a logical run-state, but, when said run-stop signal has a logical stop-state (instructing standby), provide said semiconductor switch circuit with switch drive signals instructing not to flow current to said primary winding, wherein when said run-stop signal gains the stop-state,
the power from said power supply to said PWM control signal generating circuit and switch driving circuit is cut off; and
said switch driving circuit controls at least one of the switch drive signals enabling the switches of said semiconductor switch circuit so as to turn off said at least one switch.