Transformer less switch mode power supplies have turned out to be extremely prevalent nowadays. The circuit appeared underneath is of a 12V/120mA yield, 85 to 230V AC data transformerless switch mode power supply utilizing LNK304 IC. Uses of a force supply taking into account this IC incorporates hand held gadgets, clocks, little machines, LED drivers, modern devices and so forth.
LNK304 is a low part tally, proficient logged off switcher IC that can bolster buck, buck-help and flyback topologies. The IC has an implicit auto begin circuit for short out and open circle shortcoming assurance. Different elements of LNK304 incorporates low temperature variety, warm close down,high separate voltage, great line and load regulation, high band width , wide data voltage range (85 to 230V AC) and so forth. As a rule the LNK304 has a superior execution when contrasted with the numerous other discrete buck controllers.
The pin arrangement and the run of the mill application graph of LNK304 are appeared previously. Channel (D) stick the channel association of the inherent force MOSFET. The outside by pass capacitor (0.1uF) is joined with the BYPASS (BP) terminal. Input (FB) pin controls the exchanging of the implicit force MOSFET. A current above than 49uA conveyed to this pin will hinder the exchanging. The interior force MOSFETs source is associated with the SOURCE (S) pin.
LNK304 is a low part tally, proficient logged off switcher IC that can bolster buck, buck-help and flyback topologies. The IC has an implicit auto begin circuit for short out and open circle shortcoming assurance. Different elements of LNK304 incorporates low temperature variety, warm close down,high separate voltage, great line and load regulation, high band width , wide data voltage range (85 to 230V AC) and so forth. As a rule the LNK304 has a superior execution when contrasted with the numerous other discrete buck controllers.
The pin arrangement and the run of the mill application graph of LNK304 are appeared previously. Channel (D) stick the channel association of the inherent force MOSFET. The outside by pass capacitor (0.1uF) is joined with the BYPASS (BP) terminal. Input (FB) pin controls the exchanging of the implicit force MOSFET. A current above than 49uA conveyed to this pin will hinder the exchanging. The interior force MOSFETs source is associated with the SOURCE (S) pin.
LNK304 based switch mode power supply circuit.
The circuit graph of a functional 12V/120mA transformerless switch mode power supply is appeared previously. Resistor R1, capacitors C1 and C2, diodes D1 and D2 and inductor L1 frames the data stage. D1 and D2 frames the rectifier area while C1 and C2 are information channels. Resistor R1 which is a fusible resistor restricts the inrush current, expands differential mode commotion weakening furthermore serves as a data security wire.
The following stage is the controller stage which comprises of IC LNK304, diodes D3 and D4, capacitors C3, C4 and C5, resistors R3, R4 and R5 and inductor L2. D3 is the freewheeling diode while L2 is the yield stifle. C5 is the yield channel capacitor which restrains the yield swell voltage to a worth as low as would be prudent. The IC LNK304 is configured to the point that the force supply worked in the most intermittent mode and that is the reason a quick recuperation diode (UF4005) is utilized as the freewheeling diode (D3). UF4005 has a converse recuperation time of around 75nS and it is all around ok for the given circumstance.
The voltage drop crosswise over diodes D3 and D4 are basically same thus the voltage crosswise over C4 tracks the yield voltage and this voltage is picked by the system including resistors R2, R3 and is bolstered to the criticism pin. R2 and R3 sets the yield voltage and for 12V yield the voltage at the criticism pin must be 1.65V DC. The circuit accomplishes regulation by skirting the exchanging cycles. At the point when the yield voltage rise, the current at the criticism stick additionally rises and when the present ascents over the limit esteem, resulting cycles are skipped until the current at the input pin goes underneath the edge and consequently a consistent yield voltage is kept up.
The IC will auto restart if no cycles are skipped amid a 50mS time period and this limits the most extreme yield energy to 6% of the greatest over burden power. That is the manner by which over burden assurance is accomplished. Resistor R4 serves as a little preload which invalidates the impacts of following mistake.
Notes.
Gather the circuit on a decent quality PCB.
LNK304 is a high effectiveness exchanging controller IC that has a handfull of utilizations.
LNK304 is ordinarily accessible in SMD bundle (DIP is likewise accessible) and consideration must be taken while binding it.
D1 and D2 are standard 1N4007 silicon rectifier diodes.
D3 (UF4005) is a quick recuperation diode.
D4 (1N4005GP) is a glass passivated diode.
C3 can be a clay capacitor.
C1,C2 and C4 are polyester capacitors.
C5 can be electrolytic or polyester capacitor.
Voltage appraisals of the capacitors are appeared in the circuit chart.
R1 is a fusible, flame resistant resistor.
Greatest conceivable yield current is 120mA.
input voltage reach is 85 to 230V AC.
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