LTC3527-1_15 Datasheet, PDF (14/22 Pages) Linear Technology – Dual 800mA/400mA, 1.2MHz/2.2MHz Synchronous Step-Up DC/DC Converters

LTC3527/LTC3527-1
APPLICATIONS INFORMATION
Table 1. Recommended Inductors
VENDOR
Coilcraft
www.coilcraft.com
Coiltronics
www.cooperet.com
FDK
www.fdk.com
Murata
www.murata.com
Sumida
www.sumida.com
TDK
www.global.tdk.co.jp
Taiyo Yuden
www.t-yuden.com
PART/STYLE
MSS5131
MSS4020
ME3220
SD10
SD12
MIP3226D
MIPF2520D
LQH43C
LQH32C
CDRH3D16
CDRH2D14
VLF3010A
VLF5012A
NR3010
NR3015
L
(μH)
2.2-10
3.3-10
1-10
1-10
1.2-10
1.5-6.8
1.5-4.7
1-10
1-4.7
4.7-15
4.7-12
1.5-10
2.2-10
4.7-15
4.7-15
MAXIMUM
CURRENT
(mA)
1900-870
1100-540
3000-780
1930-760
2450-818
1400-1000
1500-1000
1080-650
800-650
900-450
680-420
1200-490
1500-800
750-400
1000-560
DCR
(Ω)
0.023-0.083
0.085-0.210
0.05-0.90
0.045-0.289
0.037-0.284
0.07-0.12
0.07-0.11
0.08-0.24
0.09-0.15
0.11-0.29
0.12-0.32
0.068-0.58
0.090-0.30
0.19-0.74
0.12-0.36
DIMENSIONS
L×W×H
(mm)
5.1 × 5.1 × 1
4×4×2
3.2 × 2.5 × 2
5.2 × 5.2 × 1
5.2 × 5.2 × 1.2
3.2 × 2.6 × 1
2.5 × 2 × 1
4.5 × 3.2 × 2.6
3.2 × 2.5 × 2
3.8 × 3.8 × 1.8
3.2 × 3.2 × 1.5
2.6 × 2.8 × 1
4.5 × 4.7 × 1.2
3×3×1
3 × 3 × 1.5
Output and Input Capacitor Selection
Low ESR (equivalent series resistance) capacitors should
be used to minimize output voltage ripple. Multilayer
ceramic capacitors are an excellent choice as they have
extremely low ESR and are available in small footprints.
A 4.7μF to 10μF output capacitor is sufficient for most
applications. Larger values up to 22μF may be used to
obtain lower output voltage ripple and improve transient
response. X5R and X7R dielectric materials are preferred
for their ability to maintain capacitance over wide voltage
and temperature ranges. Y5V types should not be used.
The internal loop compensation of the LTC3527/
LTC3527-1 is designed to be stable with output capacitor
values of 4.7μF or greater. Although ceramic capacitors
are recommended, low ESR tantalum capacitors may be
used as well.
A small ceramic capacitor in parallel with a larger tantalum
capacitor may be used in demanding applications which
have large load transients. Another method of improv-
ing the transient response is to add a small feedforward
capacitor across the top resistor of the feedback divider
[from V_OUT1 (V_OUT2) to FB1 (FB2)]. A typical value of 15pF
will generally suffice.
Low ESR input capacitors reduce input switching noise and
reduce the peak current drawn from the battery. It follows
that ceramic capacitors are also a good choice for input
decoupling and should be located as close as possible to
the device. A 2.2μF input capacitor is sufficient for most
applications, although larger values may be used without
limitations. Table 2 shows a list of several ceramic capaci-
tor manufacturers. Consult the manufacturers directly for
detailed information on their selection of ceramic parts.
Table 2. Capacitor Vendor Information
SUPPLIER
PHONE
AVX
[phone]
Murata
[phone]
Taiyo-Yuden
[phone]
TDK
[phone]
WEBSITE
www.avxcorp.com
www.murata.com
www.t-yuden.com
www.component.tdk.com
35271fc
14