11

LTC3413

sn3413 3413fs

APPLICATIO S I FOR ATIO

125

°C.

Note that at higher supply voltages, the junction tempera-

Checking Transient Response

The regulator loop response can be checked by looking at

the load transient response. Switching regulators take

several cycles to respond to a step in load current. When

equal to

overshoot or ringing that would indicate a stability prob-

tor shown in Figure 1a will provide adequate compensa-

tion for most applications.

the input voltage to drop if there is insufficient bulk

output voltage during the load step transient is caused by

poor load regulation.

Design Example

As a design example, consider using the LTC3413 in an

First, calculate the timing resistor:

Rk

k

Ω

323 10

110

10

313

11

6

.•

•

–

Use a standard value of 309k. Next, calculate the inductor

value for about 40% ripple current:

L

V

MHz

A

V

V

H

=

















=µ

125

11 2

1

125

25

047

.

•.

–

.

.

.

Using a 0.47

µH inductor results in a maximum ripple

current of:

∆=

µ

















=

I

V

MHz

H

V

V

A

L

125

10 47

1

125

25

133

.

•.

–

.

.

.

satisfy the output voltage ripple requirement and the bulk

capacitance needed for loop stability. For this design, two

100

for a maximum current rating of:

IA

V

V

V

V

A

RMS

RMS

=









=

3

125

25

25

125

11 5

.

.

.

.

–.