LNK362 LNK363 LNK364 is kind of energy efficient feature with low power off-line switch IC.This LNK have 3 effect is optimized for lowest system cost,superior to Linear/RCC and EcoSmart™ to bring many useful for applying in working circuit.Almost LNK is used for chargers/adapters for cell/cordless phones and LNK362 LNK363 LNK364 is similar,beside it usually apply for other circuit such as : PDAs, digital cameras, MP3/portable audio players, and shavers or supplied for appliances, industrial systems, and metering.That explain that this LNK is multiple-function in electronic technology.
2.Type packet and output voltage
About this part,it is simple because LNK362 LNK363 LNK364 is common and easy to practice.Some LNK here have 3 type of packet is P,G and D packet and have the clearly difference.
The output voltage of 3 LNK is not similar,in adapters,LNK362 is 2.8W ,LNK363 is 5W and LNK364 is the highest with 5.5W.So just like other LNK about output voltage,the higher can be replaced for the smaller but in contrast,the smaller is not replaced for the higher.
LNK362 LNK363 LNK364 is similar to almost other LNK Mosfet,it have four core Pin is Drain,Source,Feedback,Bypass.
DRAIN (D) Pin: Power MOSFET drain connection. Provides internal operating current for both start-up and steady-state operation.
BYPASS (BP) Pin: Connection point for a 0.1 µF external bypass capacitor for the internally generated 5.8 V supply. If an external bias winding is used, the current into the BP pin must not exceed 1 mA.
FEEDBACK (FB) Pin: During normal operation, switching of the power MOSFET is controlled by this pin. MOSFET switching is disabled when a current greater than 49 µA is delivered into this pin.
SOURCE (S) Pin: This pin is the power MOSFET source connection. It is also the ground reference for the BYPASS and FEEDBACK pins.
4.Application in circuit
To regconize that LNK362 LNK363 LNK364 is easily understable but in circuit,practical application is not simple.Each LNK have to guarantee output voltage of device as well as processing execution.
In 2 W Universal Input CV Adapter,the input current is AC with high voltage,to acess to the circuit,resistor RF1 is clamped for reduce input voltage and protect 4 diode in behind.The current go through the circiuit will be converted from AC to DC and rectified by D1 to D4 at the same time before filtered by π form C1,C2 and L1,L2 and R1 will decrease noise cause by L1 and L2.Finally,the current will become smooth for transmitting.
The current continuously goes to primary coil T1 but CY1 capacitor is clamped to control voltage current to be suitable for output requirement.
After that,the current will go to Mosfet in LNK from D Pin to S Pin,and the operation in Mosfet will be happened.In here,the Mosfet have a G Pin as a gate,if the Mosfet is working,the G will close and the current can transmit and set a circle.Beside,if the Mosfet is OFF,the G Pin will open and not allow the current go through so the current will be stored in primary coil T1 but the current still go contrariwise to a cycle with down slowly voltage by time.
So with the bumpy form of voltage after high fluctuately frequency,the current certainly transmit to secondary coil by pulse transformer.The current is continuously rectified by diode D5 and filtered by capacitor C4.
The combined current drops across varistor VR1, resistor R2 and the LED of U2 to determine the output voltage.So if the output voltage increases suddenly and flow through the LED.As the LED voltage go-up so the current fed into FB Pin will rise then create a signaling to Mosfet to reduce circle frequency to ensure possible ouput voltage by a formula.Furthermore,resistor R2 and R3 are design to test and allow adjust current as well as voltage to track errors before going to output device.
So,it is a particular example of application but it help see part of function and feature of this LNK.Moreover,LNK362 LNK363 LNK364 can be used in many other circuit but it is very good and possible.That's all and hope bring a brief knowledge for all.Thanks.