LTC3624_15 Datasheet, PDF (13/20 Pages) Linear Technology – 17V, 2A Synchronous Step-Down Regulator with 3.5A Quiescent Current

LTC3624/LTC3624-2
Applications Information
Table 1. Inductor Selection Table
INDUCTOR
INDUCTANCE
(µH)
XAL4020 Series
1.0
1.5
2.2
XAL4030 Series
3.3
4.7
6.8
IHLP-1616BZ-11 Series
1.0
2.2
IHLP-2020BZ-01 Series
1
2.2
3.3
4.7
5.6
6.8
FDV0620 Series
1
2.2
3.3
4.7
MPLC0525L Series
1
1.5
2.2
HCP0703 Series
1
1.5
2.2
3.3
4.7
6.8
8.2
RLF7030 Series
1
1.5
2.2
3.3
4.7
6.8
WE-TPC 4828 Series
1.2
1.8
2.2
2.7
3.3
DCR
(mΩ)
13.25
21.45
35.20
26.0
40.1
67.4
24
61
18.9
45.6
79.2
108
113
139
18
37
51
68
16
24
40
9
14
18
28
37
54
64
8.8
9.6
12
20
31
45
17
20
23
27
30
MAX CURRENT
(A)
8.7
7.1
5.6
5.5
4.5
3.6
4.5
3.25
7
4.2
3.3
2.8
2.5
2.4
5.7
4
3.2
2.8
6.4
5.2
4.1
11
9
8
6
5.5
4.5
4
6.4
6.1
5.4
4.1
3.4
2.8
3.1
2.7
2.5
2.35
2.15
DIMENSIONS
(mm)
4.3 × 4.3
4.3 × 4.3
4.3 × 4.3
4.3 × 4.3
4.3 × 4.3
4.3 × 4.3
4.3 × 4.7
4.3 × 4.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
5.4 × 5.7
6.7 × 7.4
6.7 × 7.4
6.7 × 7.4
6.7 × 7.4
6.2 × 5.4
6.2 × 5.4
6.2 × 5.4
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
7 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
6.9 × 7.3
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
4.8 × 4.8
HEIGHT
(mm)
2.1
2.1
2.1
3.1
3.1
3.1
2
2
2
2
2
2
2
2
2
2
2
2
2.5
2.5
2.5
3
3
3
3
3
3
3
3.2
3.2
3.2
3.2
3.2
3.2
2.8
2.8
2.8
2.8
2.8
MANUFACTURER
Coilcraft
www.coilcraft.com
Vishay
www.vishay.com
Toko
www.toko.com
NEC/Tokin
www.nec-tokin.com
Cooper Bussmann
www.cooperbussmann.com
TDK
www.tdk.com
Würth Elektronik
www.we-online.com
Checking Transient Response
The regular loop response can be checked by looking at the
load transient response. Switching regulators take several
cycles to respond to a step in load current. When a load step
occurs, V_OUT immediately shifts by an amount equal to the
∆I_LOAD • ESR, where ESR is the effective series resistance
of C_OUT. ∆I_LOAD also begins to charge or discharge C_OUT
generating a feedback error signal used by the regulator to
return V_OUT to its steady-state value. During this recovery
time, V_OUT can be monitored for overshoot or ringing that
would indicate a stability problem.
The initial output voltage step may not be within the
bandwidth of the feedback loop, so the standard second
order overshoot/DC ratio cannot be used to determine
phase margin. In addition, a feedforward capacitor can
be added to improve the high frequency response, as
For more information www.linear.com/LTC3624
36242fc
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