LTC3605 LINER [Linear Technology], LTC3605 Datasheet - Page 16

• Manufacturer Part Number: LTC3605
• Description: 20V, 5A Synchronous Step-Down Regulator
• Manufacturer: LINER [Linear Technology]

TYPICAL APPLICATIONS
Design Example
As a design example, consider using the LTC3605A in an
application with the following specifications:
Because efficiency is important at both high and low load
current, discontinuous mode operation will be utilized.
First select from the characteristic curves the correct R
resistor value for 2MHz switching frequency. Based on that
R
about 50% ripple current at maximum V
The nearest standard value inductor would be 0.33µH.
LTC3605A
OPERATION
16
T
V
I
L =
should be 80.6k. Then calculate the inductor value for
OUT(MIN)
IN

 
= 10.8V to 13.2V, V
2MHz • 2.5A
1.8V
= 500mA, f = 2MHz
330pF
12k

 

 
162k
10pF
1–
13.2V
OUT
1.8V
C1: AVX 0805ZD225MAT2A
C
C
IN
OUT
: TDK C4532X5RIC226M
= 1.8V, I
: TDK C3216X5ROJ476M

 
0.1µF
= 0.31µH
1
2
3
4
5
6
IN
CLKIN
RT
PHMODE
MODE
FB
TRACK/SS
ITH
SV
RUN
OUT(MAX)
:
IN
7
C1
2.2µF
24
12V to 1.2V 1MHz Buck Regulator
CLKOUT SGND
PGOOD V
23
8
100k
D1: CENTRAL SEMI CMDSH-3
L1: VISHAY IHLP-2525CZERR68-M01
= 5A,
LTC3605A
ON
9
22
T
INTV
PGND
21
CC
10
D1
C
satisfy the output voltage ripple requirement and the bulk
capacitance needed for loop stability. For this design, two
47µF ceramic capacitors will be used.
C
Decoupling the PV
is adequate for most applications.
BOOST SV
OUT
IN
SW
I
11
20
RMS
should be sized for a maximum current rating of:
will be selected based on the ESR that is required to
PV
PV
SW
SW
SW
SW
SW
IN
IN
IN
= 5A
12
19
10
0.1µF
18
17
16
15
14
13

 
PGND
13.2V
L1 0.68µH
1.8V
IN
C
22µF
×2
pins with two 22µF ceramic capacitors
IN

 

 
SGND
13.2V
C
47µF
×2
1.8V
0.1µF
OUT
V
4V TO 20V
IN
– 1
3605A TA02
47µF

 
1/ 2
= 1.7A
4.99k
4.99k
V
1.2V
5A
OUT
3605af