LTC3604 Linear Technology, LTC3604 Datasheet - Page 19

• Manufacturer Part Number: LTC3604
• Description: 2.5A 15V Monolithic Synchronous Step-Down Regulator
• Manufacturer: Linear Technology

Design Example
As a design example, consider using the LTC3604 in an
application with the following specifi cations:
V
10mA, f = 1MHz
Because effi ciency is important at both high and low load
currents, Burst Mode operation is selected.
First, the correct R
frequency must be chosen. Based on the equation dis-
cussed earlier, R
Next, determine the inductor value for approximately 40%
ripple current (ΔI
A standard value 1.5μH inductor will work well for this
application.
Next, C
transient performance and the required ESR to satisfy
the output voltage ripple. For this design, a 47μF ceramic
capacitor will be used.
APPLICATIONS INFORMATION
IN
L
= 12V, V
=
⎛
⎝ ⎜
OUT
1
MHz
1 8
.
is selected based on the required output
OUT
V
•
1
RT
A
L(MAX)
= 1.8V, I
⎞
⎠ ⎟
RT
should be 324k.
⎛
⎝ ⎜
1
resistor value for 1MHz switching
12V
V
–
IN
= 1A) using:
1 8
12
2.2μF
OUT(MAX)
.
V
V
C
22μF
⎞
⎠ ⎟
IN
=
1 53
.
= 2.5A, I
100k
324k
μH
V
RUN
MODE/SYNC
INTV
PGOOD
ITH
RT
Figure 8. 1.8V, 2.5A Regulator at 1MHz
IN
SGND
CC
LTC3604
OUT(MIN)
TRACK/SS
PGND
BOOST
V
SW
ON
3604 F08
FB
=
C
C
L1: VISHAY IHLP2525CZER1R5M01
IN
OUT
C
Decoupling the V
should be adequate for most applications. A 0.1μF boost
capacitor should also work for most applications.
To save board space the I
pin to select an internal compensation network.
The PGOOD pin is connected to V
resistor.
C1
0.1μF
: TDK C3225X5R1C226M
IN
: TDK C3225X5R0J476M
I
RMS
1.5μH
should be sized for a maximum current rating of:
L1
=
2 5
.
R3
80k
R4
40k
A
⎛
⎜
⎜
⎝
IN
C
22pF
1 8 12
F
pins with a 22μF ceramic capacitor
.
V
(
TH
12
C
47μF
pin is connected to the INTV
OUT
V
V
– .
V
1.8V
2.5A
OUT
1 8
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V
IN
)
⎞
⎟
⎟
⎠
LTC3604
through a 100k
=
0 89
.
A
19
3604f
CC