LTC3672B-1_15 Datasheet, PDF (9/12 Pages) Linear Technology – Monolithic Fixed-Output 400mA Buck Regulator with Dual

APPLICATIONS INFORMATION
Table 1. Recommended Inductors for the Buck Regulator
INDUCTOR TYPE
L
(μH)
MAX I_DC
(A)
DB318C
4.7
1.07
3.3
1.2
D312C
4.7
0.79
3.3
0.9
DE2812C
4.7
1.15
3.3
1.37
CDRH3D16
4.7
0.9
3.3
1.1
CDRH2D11
4.7
0.5
3.3
0.6
CLS4D09
4.7
0.75
SD3118
4.7
1.3
3.3
1.59
SD3112
4.7
0.8
3.3
0.97
SD12
4.7
1.29
3.3
1.42
SD10
4.7
1.08
3.3
1.31
LPS3015
4.7
1.1
3.3
1.3
* = Typical DCR
LTC3672B-1
MAX DCR
(Ω)
0.1
0.07
0.24
0.2
0.13*
0.105*
0.11
0.085
0.17
0.123
0.19
0.162
0.113
0.246
0.165
0.117*
0.104*
0.153*
0.108*
0.2
0.13
SIZE IN mm
(L × W × H)
3.8 × 3.8 × 1.8
3.8 × 3.8 × 1.8
3.6 × 3.6 × 1.2
3.6 × 3.6 × 1.2
3 × 2.8 × 1.2
3 × 2.8 × 1.2
4 × 4 × 1.8
4 × 4 × 1.8
3.2 × 3.2 × 1.2
3.2 × 3.2 × 1.2
4.9 × 4.9 × 1
3.1 × 3.1 × 1.8
3.1 × 3.1 × 1.8
3.1 × 3.1 × 1.2
3.1 × 3.1 × 1.2
5.2 × 5.2 × 1.2
5.2 × 5.2 × 1.2
5.2 × 5.2 × 1
5.2 × 5.2 × 1
3 × 3 × 1.5
3 × 3 × 1.5
MANUFACTURER
Toko
www.toko.com
Sumida
www.sumida.com
Cooper
www.cooperet.com
Coil Craft
www.coilcraft.com
INPUT/OUTPUT CAPACITOR SELECTION
Low ESR (equivalent series resistance) ceramic capacitors
should be used to bypass the following pins to ground:
V_IN, V_IN1, the buck output, LDO1, and LDO2. Only X5R
or X7R ceramic capacitors should be used because they
retain their capacitance over wider voltage and temperature
ranges than other ceramic types. A 10μF output capaci-
tor is sufficient for the buck regulator output. For good
transient response and stability the output capacitor for
the buck regulator should retain at least 4μF of capaci-
tance over operating temperature and bias voltage. The
V_IN pin should be bypassed with a 2.2μF capacitor. The
LDO1 and LDO2 output pins should be bypassed with a
1μF capacitor or greater. V_IN1 should be bypassed with a
1μF capacitor, which may be omitted if V_IN1 is tied to the
buck regulator’s output capacitor.
Consult with capacitor manufacturers for detailed infor-
mation on their selection and specifications of ceramic
capacitors. Many manufacturers now offer very thin (<1mm
tall) ceramic capacitors ideal for use in height-restricted
designs. Table 2 shows a list of several ceramic capacitor
manufacturers.
Table 2. Ceramic Capacitor Manufacturers
AVX
www.avxcorp.com
Murata
www.murata.com
Taiyo Yuden
www.t-yuden.com
Vishay Siliconix
www.vishay.com
TDK
www.tdk.com
3672B1f
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