| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a switching power supply that implements a stable switching frequency in a light load state. <P>SOLUTION: An error amplifier 10 generates an error signal V<SB POS="POST">ERR</SB>depending on an error between a feedback signal V<SB POS="POST">FB</SB>and a predetermined reference voltage V<SB POS="POST">REF</SB>. A first oscillator 12 generates a first periodic signal V<SB POS="POST">OSC1</SB>of a first frequency f<SB POS="POST">1</SB>having a slope segment. A second oscillator 14 generates a second periodic signal V<SB POS="POST">OSC2</SB>of a second frequency f<SB POS="POST">2</SB>lower than the first frequency f<SB POS="POST">1</SB>having a slope segment. A first pulse modulator 16 generates a first pulse signal S1 having a pulse width depending on the error signal V<SB POS="POST">ERR</SB>, and clamps the pulse width to a first minimum pulse widthτ<SB POS="POST">MIN1</SB>. A second pulse modulator 24 generates a second pulse signal S2 having a pulse width depending on the error signal V<SB POS="POST">ERR</SB>. A combination section 30 combines the first pulse signal S1 and the second pulse signal S2 to generate a driving pulse signal S5. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
