LTC3832-1ES8#TR Linear Technology, LTC3832-1ES8#TR Datasheet - Page 14

• Manufacturer Part Number: LTC3832-1ES8#TR
• Description: IC CTRLR DC/DC SYNC BUCK 8-SOIC
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC3832-1ES8#TR

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 2.5V
• Current - Output: 20A
• Frequency - Switching: 300kHz
• Voltage - Input: 3 ~ 8 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

Note that the required R
times that of Q1 in this example. Note also that while the
required R
power dissipation numbers are only 0.83W per device or
less; large TO-220 packages and heat sinks are not neces-
sarily required in high efficiency applications. Siliconix
Si4410DY or International Rectifier IRF7413 (both in
SO-8) or Siliconix SUD50N03-10 (TO-252) or ON Semi-
conductor MTD20N03HDL (DPAK) are small footprint
surface mount devices with R
at 5V of V
higher P
decreases the MOSFET cost and the circuit efficiency and
increases the MOSFET heat sink requirements.
Table 1 highlights a variety of power MOSFETs for use in
LTC3832 applications.
Inductor Selection
The inductor is often the largest component in an LTC3832
design and must be chosen carefully. Choose the inductor
value and type based on output slew rate requirements. The
maximum rate of rise of inductor current is set by the
inductor’s value, the input-to-output voltage differential and
Table 1. Recommended MOSFETs for LTC3832 Applications
PARTS
Siliconix SUD50N03-10
TO-252
Siliconix Si4410DY
SO-8
ON Semiconductor MTD20N03HDL
DPAK
Fairchild FDS6670A
S0-8
Fairchild FDS6680
SO-8
ON Semiconductor MTB75N03HDL
DD PAK
IR IRL3103S
DD PAK
IR IRLZ44
TO-220
Fuji 2SK1388
TO-220
Note: Please refer to the manufacturer’s data sheet for testing conditions and detailed information.
LTC3832/LTC3832-1
APPLICATIO S I FOR ATIO
14
MAX
GS
DS(ON)
that work well in LTC3832 circuits. Using a
value in the R
values suggest large MOSFETs, the
U
DS(ON)
U
DS(ON)
DS(ON)
AT 25 C (m )
for Q2 is roughly three
calculations generally
R
W
DS(ON)
values below 0.03
19
20
35
10
19
28
37
8
9
U
RATED CURRENT (A)
11.5 at 25 C
10 at 100 C
16 at 100 C
59 at 100 C
45 at 100 C
36 at 100 C
15 at 25 C
10 at 25 C
20 at 25 C
13 at 25 C
75 at 25 C
64 at 25 C
50 at 25 C
35 at 25 C
8 at 70 C
the LTC3832’s maximum duty cycle. In a typical 3.3V in-
put, 2.5V output application, the maximum rise time will be:
where L
quency compensation, the combination of the inductor
and output capacitor values determine the transient recov-
ery time. In general, a smaller value inductor improves
transient response at the expense of ripple and inductor
core saturation rating. A 1 H inductor has a 0.76A/ s rise
time in this application, resulting in a 6.6 s delay in
responding to a 5A load current step. During this 6.6 s,
the difference between the inductor current and the output
current is made up by the output capacitor. This action
causes a temporary voltage droop at the output. To
minimize this effect, the inductor value should usually be
in the 1 H to 5 H range for most 3.3V input LTC3832
circuits. To optimize performance, different combinations
of input and output voltages and expected loads may
require different inductor values.
Once the required value is known, the inductor core type
can be chosen based on peak current and efficiency
DC
MAX
O
is the inductor value in H. With proper fre-
• (
TYPICAL INPUT
CAPACITANCE
L
V
O
IN
C
ISS
3200
2700
3200
2070
4025
1600
3300
1750
880
–
(pF)
V
OUT
)
. 0 76
L
O
JC
1.67
2.08
( C/W)
1.8
1.4
25
25
1
1
A
s
T
JMAX
sn3832 3832fs
175
150
150
150
150
150
175
175
150
( C)