| 摘要 |
PROBLEM TO BE SOLVED: To provide a PWM comparator dispensing with a differential amplifier for detecting a current, in a control circuit constituting a DC-DC converter of a current mode control method. SOLUTION: The PWM comparator includes: a differential input stage having two sets of input differential transistor pairs of which the sources are connected in common; two constant current sources each connected to the common source of the two sets of input differential transistor pairs; a common load transistor connected to the drain side of the two sets of input differential transistor pairs for performing current-voltage conversion; and an output stage connected to the connection point between the differential input stage and the load transistor. The feedback voltage of the output voltage and a slope compensating waveform signal are input into the input terminal of one input differential transistor pair of the two sets of input differential transistor pairs, while the voltages at both ends of the current detecting resistors connected in series with the inductor are input into the input terminal of the other input differential transistor pair. COPYRIGHT: (C)2011,JPO&INPIT |
