Datasheets»National Semiconductor (acquired by TI (Texas Instruments))»LM3524D Datasheet

LM3524D Datasheet - Page 14

Download or read online National Semiconductor LM3524D Regulating Pulse Width Modulator pdf datasheet.



Page
14 of 18
prevnext
Typical Applications
(Continued)
THE STEP-UP SWITCHING REGULATOR
Figure 18 shows the basic circuit for a step-up switching
regulator In this circuit Q1 is used as a switch to alternately
apply V
across inductor L1 During the time t
Q1 is ON
IN
ON
and energy is drawn from V
and stored in L1 D1 is re-
IN
verse biased and I
is supplied from the charge stored in C
o
o
When Q1 opens t
voltage V1 will rise positively to the
OFF
point where D1 turns ON The output current is now sup-
plied through L1 D1 to the load and any charge lost from C
o
during t
is replenished Here also as in the step-down
ON
regulator the current through L1 has a DC component plus
some I
I
is again selected to be approximately 40% of
L
L
Figure 19 shows the inductor’s current in relation to Q1’s
I
L
ON and OFF times
TL H 8650 – 23
FIGURE 18 Basic Step-Up Switching Regulator
TL H 8650 – 24
FIGURE 19
14

Comments to this Datasheet