LTC3417AIFE-1#PBF Linear Technology, LTC3417AIFE-1#PBF Datasheet - Page 10

• Manufacturer Part Number: LTC3417AIFE-1#PBF
• Description: IC BUCK SYNC ADJ 1A/1.5A 20TSSOP
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC3417AIFE-1#PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.8 ~ 5 V
• Current - Output: 1A, 1.5A
• Frequency - Switching: 1.5MHz, 0.6MHz ~ 4MHz
• Voltage - Input: 2.25 ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

APPLICATIONS INFORMATION
LTC3417A-1
A reasonable starting point for setting ripple current is
ΔI
current output. The largest ripple, ΔI
mum input voltage. To guarantee that the ripple current
stays below a specifi ed maximum, the inductor value
should be chosen according to the following equation:
The inductor value will also have an effect on Burst Mode
operation. The transition from low current operation begins
when the peak inductor current falls below a level set by the
burst clamp. Lower inductor values result in higher ripple
current which causes this to occur at lower load currents.
This causes a dip in effi ciency in the upper range of low
current operation. In Burst Mode operation, lower inductor
values will cause the burst frequency to increase.
Inductor Core Selection
Different core materials and shapes will change the size/
current relationship of an inductor. Toroid or shielded
pot cores in ferrite or permalloy materials are small and
don’t radiate much energy, but generally cost more than
powdered iron core inductors with similar electrical
characteristics. The choice of which style inductor to use
often depends more on the price vs size requirements
of any radiated fi eld/EMI requirements than on what the
LTC3417A-1 requires to operate. Table 1 shows some
Table 1
MANUFACTURER
L1 on OT1
Toko
Coilcraft
Sumida
Midcom
L2 on OUT2
Toko
Coilcraft
Sumida
Midcom
10
L
L =
= 0.35I
f
O
V
OUT
• I
LOAD(MAX)
L
1–
PART NUMBER
A920CY-1R5M-D62CB
A918CY-1R5M-D62LCB
D01608C-152ML
CDRH4D22/HP 1R5
DUP-1813-1R4R
A915AY-2ROM-D53LC
D01608C-222ML
CDRH3D16/HP 2R2
DUP-1813-2R2R
V
IN(MAX)
, where I
V
OUT
LOAD(MAX)
L
, occurs at the maxi-
is the maximum
VALUE (μH)
1.5
1.5
1.5
1.5
1.4
2.0
2.2
2.2
2.2
2.2
typical surface mount inductors that work well in
LTC3417A-1 applications.
Input Capacitor (C
In continuous mode, the input current of the converter can
be approximated by the sum of two square waves with
duty cycles of approximately V
prevent large voltage transients, a low equivalent series
resistance (ESR) input capacitor sized for the maximum
RMS current must be used. Some capacitors have a
de-rating spec for maximum RMS current. If the capaci-
tor being used has this requirement, it is necessary to
calculate the maximum RMS current. The RMS current
calculation is different if the part is used in “in phase” or
“out of phase”.
For “in phase”, there are two different equations:
V
V
where:
I
MAX DC CURRENT (A)
I
RMS
RMS
OUT1
OUT2
D1=
= 2 •I
= 2 •I
> V
> V
1.75
2.8
2.9
2.6
3.9
5.5
3.9
2.3
1.6
3.9
V
OUT1
V
OUT2
OUT1
IN
1
1
•I
•I
:
:
2
2
and D2 =
• D1(1– D2) +I
• D2(1– D1) +I
IN
) Selection
0.014
0.018
0.031
0.033
0.027
0.047
0.035
0.047
DCR
0.06
0.07
V
OUT2
V
IN
2
2
2
OUT1
2
(D2 – D2
DIMENSIONS L × W × H (mm)
6 × 6 × 2.5
6 × 6 × 2
6.6 × 4.5 × 2.9
5 × 5 × 2.4
4.3 × 4.8 × 3.5
5 × 5 × 3
6.6 × 4.5 × 2.9
4 × 4 × 1.8
3.2 × 3.2 × 2
4.3 × 4.8 × 3.5
(D2 – D2
/V
IN
2
and V
2
) +I
) +I
1
1
2
2
OUT2
(D1– D1
(D1– D1
/V
3417a1fa
IN
2
2
)
. To
)