" Help needed- 4.2V@1.5A form 3.7V Li Ion battery "

Discussion in 'The Projects Forum' started by mishra87, Jun 15, 2016.

  1. mishra87

    Thread Starter Member

    Jan 17, 2016
    166
    2
    Could anybody recommend me a device/chip under below specifications-

    Input- 3.7V/1450mAh Li Ion Battery
    Input Voltage range - 3-4.2V
    output- 4.2V @1.5A

    I need a step up (boost) converter under above spec.
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
  3. mishra87

    Thread Starter Member

    Jan 17, 2016
    166
    2
    That does not ship to India.

    With the above supply i want to drive a stepper motor.

    Means if the if input voltage of battery is 3.3V , the output should be 4.2V for stepper motor driver which drives stepper motor .
    Because at lower voltage the the performance of of the motor degrade. and there is some audible sound.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,006
    3,762
    Stepper motors will whine in normal operation (like a transformer) because of the rapid charge and discharge of the coils in the motor. The iron actually changes shape under a magnetic field - google magnetostriction and other resonances of the system. (See "coil noise").

    Here, a very creative person has some fun with the noise made by stepper motors - and controls the noise perfectly.

     
    mcgyvr and bertus like this.
  5. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    Note that your battery current will go up in proportion to the step up voltage divided by the boost converter efficiency.
    Thus for a 90% efficiency boost converter form 3.7V to 4.2V @ 1.5A output, the battery current will be (4.2/3.7) /0.9 * 1.5 = 1.89A.
     
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