Preliminary

Datasheet

LP78086

LP78086 –00 Ver. 1.0 Datasheet

Feb.-2008

Page 7 of 9

efficiency and which change would produce the most

improvement efficiency can be expressed as :

Efficiency= 100%- (L1+L2+L3…)

Where L1、L2, etc. are the individual losses as a percentage of

Input power .although all dissipative elements in the for most

efficiency loss at medium to high load currents. In a typical

efficiency plot, the efficiency curve at very low load currents

can be misleading since the actual power lost is of no

consequence.

1.The VIN quiescent current is due to two components:

the DC Bias current as given in the electrical

characteristics and the Internal main switch and

synchronous switch gate charge currents. the gate

charge current results from switching the gate

capacitance

of

the

internal

power

MOSFET

switches .Each time the gate charge current.results

from switching the gate capacitance of the internal

power MOSFET switches. Each time the gate is

switches from high to low to high again, a packet of

larger than the DC bias current. In continuous mode.

bottom switches. Both the DC bias and gate charge losses are

pronounced at higher supply voltages.

the average output current flowing through inductor L is

“chopped” between the main switch and the synchronous

switch. Thus, the series resistance looking into the LX pin is a

cycle (DC) as follows:

obtained from the typical performance characteristics curves.

the square of the average output current.

losses and inductor core losses generally account for

less than 2% of the total loss.