Datasheet

LTC3883/LTC3883-1
57
3883fa
For more information www.linear.com/LTC3883
GND
0.1µF
1µF
10µF
V
IN
6V TO 20V
5mΩ
10k
2200pF
6.04k
22µF
50V
+
D4
M1
M2 2.2k
V
OUT
3.3V
15A
C
OUT
530µF
6V
3883 F28
10nF
C
OUT
: 330μH SANYO 4TPF330ML, 2× 100µF AVX 12106D107KAT2A
L: COILCRAFT XPL7070 1µH
M1: RENESAS RJK0305DPB
M2: RENESAS RJK0330DPB
1.0µF
1.0µF
0.2µF
1.0µH
TG
BG
PGND
FREQ_CFG
I
IN_SNS
BOOST
V
IN_SNS
PGOOD
V
IN
SW
INTV
CC
LTC3883
10k
GPIO
10k
SYNC
10k
SDA
10k
PMBus
INTERFACE
V
DD33
SCL
V
OUT_CFG
V
TRIM_CFG
ASEL
WP
I
SENSE
+
I
SENSE
–
V
SENSE
+
V
SENSE
–
V
DD25
V
DD33
TSNS
I
TH
10k
ALERT
10k
RUN
5k
SHARE_CLK
MMBT3906
100Ω100Ω
1µF
10nF10nF
10µF
3Ω
Figure 28. High Efficiency 500kHz 3.3V Step-Down Converter
APPLICATIONS INFORMATION
All other user defined parameters must be programmed
into the NVM. The GUI can be utilized to quickly set up
the part with the desired operating parameters.
The inductance values are based on a 35% maximum ripple
current assumption (5.25A). The highest value of ripple
current occurs at the maximum input voltage:
L =
V
OUT
f • ∆I
L(MAX)
1–
V
OUT
V
IN(MAX)
⎡
⎣
⎢
⎢
⎤
⎦
⎥
⎥
The controller will require 1.05µH. The nearest standard
value is 1µH. At the nominal input the ripple will be:
∆I
L(NOM)
=
V
OUT
f •L
1–
V
OUT
V
IN(NOM)
⎡
⎣
⎢
⎢
⎤
⎦
⎥
⎥
The ripple will be 4.79A (32%). The peak inductor current
will be the maximum DC value plus one-half the ripple
current or 17.39A. The minimum on time occurs at the
maximum V
IN
, and should not be less than 90ns:
t
ON(MIN)
=
V
OUT
V
IN(MAX)
• f
=
1.8V
20V 500kHz
( )
= 180n
s
The Vishay IHLP4040DZ-11 1µH (2.3mΩ DCR
TYP
at 25°C)
is the chosen inductor.
Assuming the temperature measurement of the inductor
temperature is accurate and C1 is set to 0.2µF, R
D
is infinite
and removed from the equations.
R1=
L
DCR at 25°C
( )
• C1
=
1µH
2.5mΩ • 0.2µF
= 1.37
k