AN938

Typical application

Doc ID 5410 Rev 10

21/33

Co also has to support load transients. An idea of the magnitude of the output voltage drop

during load transients is given below:

Equation 12

where

ΔI

Vo nominal is 5.1 V; and finally L is 68 µH.

input voltage.

These curves are represented for different output capacitors 2x150 µF, 2x220 µF, 2x330 µF

all KY, 35 V.

Figure 29.

Output drop (%) vs minimum input voltage

3.6

Compensation network

The complete control loop block diagram is shown in Figure 30. The error amplifier basic

characteristics are:

●

gm = 2.5 mS

●

Ro = 1.2 M

Ω

●

Avo = 60 dB

●

Isource/sink = 300 µA.

ΔV

O

ΔI

O

()

2

L

O

⋅

2C

O

V

inmin

D

max

V

O

–

⋅

()

⋅⋅

--------------------------------------------------------------------------

=

AM03511v1

10

15

20

25

30

354045

0

1

2

3

4

5

6

7

8

Cout = 2 x 15 0uF

Cout = 2 x 22 0uF

Cout = 2 x 33 0uF

Vin