LP3201-00

Aug.-2019

www.lowpowersemi.com

Page 7 of 10

Preliminary Datasheet

LP3201

Dropout Operation

When the battery input voltage decreases near the value of

the output voltage, the LP3201 allows the main switch to

remain on for more than one switching cycle and increases

the duty cycle until it reaches 100%. The duty cycle D of a

step-down converter is defined as:

× 100%

frequency. The output voltage then is the input voltage minus

the voltage drop across the main switch and the inductor. At

MOSFET increases, and the efficiency of the converter

decreases. Caution must be exercised to ensure the heat

dissipated does not exceed the maxi-mum junction

temperature of the IC.

Setting the Output Voltage

than 0.6V. To limit the bias current required for the external

feedback resistor string while maintaining good noise

Although a larger value will further reduce quiescent current, it

will also increase the impedance of the feedback node,

making it more sensitive to external noise and interference.

The LP3201 delivers enhanced transient response for

extreme pulsed load applications. The addition of the feed

output voltage according to the following equation:

)

0.6V

Inductor Selection

For most designs, the LP3201 operates with inductor values

of 1μH to 4.7μH. Low inductance values are physically smaller

but require faster switching, which results in some efficiency

loss. The inductor value can be derived from the following

equation:

L =

lower ripple current and small value inductors result in high

ripple currents. Choose inductor ripple current approximately

60% of the maximum load current 1A, or

For output voltages above 2.0V, when light-load efficiency is

important, the minimum recommended inductor is 2.2μH.

Manufacturer’s specifications list both the inductor DC current

rating, which is a thermal limitation, and the peak current

rating, which is determined by the saturation characteristics.

The inductor should not show any appreciable saturation

under normal load conditions. Some inductors may meet the

peak and average current ratings yet result in excessive

losses due to a high DCR.

Always consider the losses associated with the DCR and its

effect on the total converter efficiency when selecting an

inductor. For optimum voltage-positioning load transients,

100mΩ range. For higher efficiency at heavy loads (above

200mA), or minimal load regulation (but some transient

overshoot), the resistance should be kept below 100mΩ. The

DC current rating of the inductor should be at least equal to

the maximum load current plus half the ripple current to

prevent core saturation (1A + 300mA).