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USB Charger for Mobile Phones
 

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    USB Charger for Mobile Phones

    Dileep Chacko


    All of us worry about our mobile phone draining out of charge while travelling. In such a situation, this SMPS-based USB charger powered by just two AA-size batteries will come handy. The advantage of SMPS is high efficiency and low cost. Of course, most mobile phones can also be charged through the standard USB port available in desktop and laptop computers.

    A unit load is 100 mA in USB 2.0, and 150 mA in USB 3.0. An individual device may draw a maximum of 5 units load (500 mA) from USB 2.0 and 6 units (900 mA) from USB 3.0.

    This USB charger for mobile phones operates off a 2.4V or 3V battery. It is designed around an average input-current-controlled buck-boost DC-DC converter LTC3127 (IC1) and some discrete components. The circuit converts 3V or 2.4V input into 5V output.

    Pins SW1 (pin 2) and SW2 (pin 11) are used to connect the inductor. SHDN (pin 4) shuts down the output of LTC3127 when low. Pin 5 is used to change the mode of operation between PWM and burst modes. If Mode pin is low the mode will be PWM; when it is high the  mode will change to burst mode. PROG (pin 6) is used to set the average input current limit threshold. Vc (pin 9) is used to connect the compensation components, which impart stability to this regulator.

    The values of R1 and R2 decide the output voltage level as follows:
    VOUT = 1.195×1 + R2R1

    You can select appropriate values of R1 and R2 to get 5V output (VOUT).

    Most mobile phones have a USB male connector for charging, so a female connector is required for the charger side. Assemble the circuit on a small PCB and enclose in a suitable cabinet. Use a USB female connector and solder the connections as shown in the figure. The table gives the pin details of a USB connector. For powering the circuit, use an AA-size battery pack having either two 1.5V alkaline batteries or two 1.2V (Ni-Cd or Li-ion) batteries.


     

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    Post Comment | 28 Comments



    very Interesting   620 days ago

    i ll try it
    Reply  
    Gaurav Sharma   616 days ago

    Can you please explain the output voltage equation.?R1 R2 gives ohm dimension.....but equation is voltage...can u please enlighten on the same?i guess a current term is missing there among R1R2?
    Reply  
    masood   614 days ago

    can any1 suggest me miniproject based on microcontroller or microprocessor??
    Reply  
    EHSAN HABIB   613 days ago

    IS IT ONLY FOR USB CHARGERED MOBILES? I MEAN NOT FOR NOKIA N70
    Reply  
    Mikku   613 days ago

    This circuit can run for any type of mobile phones just change the connector pin in place of usb according to your mobile phones...thx
    Reply  
    sruthi.chagarlamudi   610 days ago

    i will try it
    Reply  
    Rajendran   608 days ago

    I didnt get the ICLTC3172 in Salem TN &tell me the alternative IC Is it available in kitsnspare store. how can i get it from there.
    Reply   1 Reply
    ramdev   443 days ago

    ICI LTC3127 DETAILS TEL ME PLZ?
    Reply  
    Ravichandran   604 days ago

    i will try it thank you
    Reply  
    Amresh   598 days ago

    it is super good idea.....
    Reply  
    kalyani   597 days ago

    VERY GOOD IDEA
    Reply  
    Rahul   596 days ago

    this circuit is not useful smart phones android etc this type phones need Data & Data -
    Reply  
    vishal   594 days ago

    ic ltc3127 is not available in market tell me comparative ic or the available storeshop in india
    Reply   1 Reply
    P.Rebekah Final year B.E.Electronic and communiction   344 days ago

    IC LTC 3127 is not available in the Madurai Tamilnadu market .please tell me where it is available so that I can get
    Reply  
    Amritpal Singh   588 days ago

    please tell the formula again....I could not get it correctly....early reply solicited
    Reply  
    deepak   584 days ago

    this idea is my final year project iam working on it from one year
    Reply  
    Naveen   579 days ago

    It is nice...I will try it...
    Reply  
    vinod   577 days ago

    sir how to make inductor of 4.7 ???
    Reply  
    msm   576 days ago

    alternative ic ? i couldnot get ltc3127
    Reply  
    K.R.Prabu   570 days ago

    good i will try .
    Reply  
    manjunath a   566 days ago

    it s interesting ..and very useful
    Reply  
    pritesh chorbele   564 days ago

    Basic things are more clear...
    Reply  
    Sijo johnson   563 days ago

    for smartphone PULL UP D & D- otherwise this ckt wont work
    Reply  
    abhishek   560 days ago

    whats would be the approx cost for this project?
    Reply  
    dinesh   560 days ago

    thanks ji... its working..
    Reply  
    ABHIJEET SINGH   556 days ago

    Sircan u please tell me how to PULL UP D & D-??OR how to change the CONNECTOR in place of USB?
    Reply  
    ankyz   553 days ago

    nice
    Reply  
    Jonathan Dacosta   516 days ago

    LTC 3127 available at Component master lamington roadMumbai for 400 rupees.
    Reply  

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