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Single chip switching power supply design
Switching power supply has the outstanding advantages of high efficiency, light weight, small size, wide range of voltage regulation. Since it came out in the middle of the 20th century, it has developed extremely rapidly and has been widely used in computer, communication, aerospace, office and household appliances, etc., and has the potential to replace linear voltage regulation power supply.
Improving the integration of circuit is one of the pursuits of switching power supply, which is to realize the integration of single chip.
Switching integrated voltage regulator refers to the control circuit, power switch tube and protection circuit integrated in a chip, and the switching power supply composed of the integrated voltage regulator is called a single chip switching power supply.
American PI company's monolithic switching power supply series is its remarkable representative.
The 250W switching power supply circuit designed by TOPSwitch-GX is shown in Figure 1.
The DC voltage is added to the drain terminal D of TOPSwitch-GX through the primary side of the transformer;
If the frequency selector terminal F and the limit current setting terminal X are connected to the source pole S, the functions of the two ends are useless, that is, the limit current is not set from the outside, and the self-protection current Ilimit is automatically set from the inside, and the switching operating frequency is 132K.
The control pole is connected to the optocoupler LTV817, and the feedback signal is received to realize the duty cycle control of the internal integrated high-voltage power MOS tube.
Line detection side through a 2 L m Ω resistance and dc input connected to the positive side of high in order to realize the over-voltage, owe line-to-line voltage feedforward line detection.
Capacitor C1 is the high-frequency filter capacitor;
Transient voltage suppressor P6KE200 BYV26C constitute and super fast recovery diode clamping circuit, and the RC absorption circuit in series with the (R2, R3 and C6), so in addition to being able to absorb the energy in the leakage inductance of the part, also can be in 200 v voltage clamp, can make the switch power supply in the case of a start or overload TOPSwitch - GX internal integration MOS tube drain voltage not over 700 v.
The secondary output of the high-frequency transformer T1 is filtered by Murl640CT rectification and C9, C10 and C11, and then filtered by magnetic beads L1 and C12 to filter out the switching noise, and the output voltage is obtained.
VD4 and C14 constitute the soft start circuit.
The monolithic switching power supply has the obvious advantages of monolithic integration, the simplest peripheral circuit, the best performance index, and the complete isolation can be achieved by the non-power frequency transformer, which is the ideal choice for us to design the switching power supply below 290W.
Single chip switching power supply design
Switching power supply has the outstanding advantages of high efficiency, light weight, small size, wide range of voltage regulation. Since it came out in the middle of the 20th century, it has developed extremely rapidly and has been widely used in computer, communication, aerospace, office and household appliances, etc., and has the potential to replace linear voltage regulation power supply.
Improving the integration of circuit is one of the pursuits of switching power supply, which is to realize the integration of single chip.
Switching integrated voltage regulator refers to the control circuit, power switch tube and protection circuit integrated in a chip, and the switching power supply composed of the integrated voltage regulator is called a single chip switching power supply.
American PI company's monolithic switching power supply series is its remarkable representative.
The 250W switching power supply circuit designed by TOPSwitch-GX is shown in Figure 1.
The DC voltage is added to the drain terminal D of TOPSwitch-GX through the primary side of the transformer;
If the frequency selector terminal F and the limit current setting terminal X are connected to the source pole S, the functions of the two ends are useless, that is, the limit current is not set from the outside, and the self-protection current Ilimit is automatically set from the inside, and the switching operating frequency is 132K.
The control pole is connected to the optocoupler LTV817, and the feedback signal is received to realize the duty cycle control of the internal integrated high-voltage power MOS tube.
Line detection side through a 2 L m Ω resistance and dc input connected to the positive side of high in order to realize the over-voltage, owe line-to-line voltage feedforward line detection.
Capacitor C1 is the high-frequency filter capacitor;
Transient voltage suppressor P6KE200 BYV26C constitute and super fast recovery diode clamping circuit, and the RC absorption circuit in series with the (R2, R3 and C6), so in addition to being able to absorb the energy in the leakage inductance of the part, also can be in 200 v voltage clamp, can make the switch power supply in the case of a start or overload TOPSwitch - GX internal integration MOS tube drain voltage not over 700 v.
The secondary output of the high-frequency transformer T1 is filtered by Murl640CT rectification and C9, C10 and C11, and then filtered by magnetic beads L1 and C12 to filter out the switching noise, and the output voltage is obtained.
VD4 and C14 constitute the soft start circuit.
The monolithic switching power supply has the obvious advantages of monolithic integration, the simplest peripheral circuit, the best performance index, and the complete isolation can be achieved by the non-power frequency transformer, which is the ideal choice for us to design the switching power supply below 290W.