MAX8640Y 查看數據表（PDF） - Maxim Integrated
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MAX8640Y Datasheet PDF : 13 Pages
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MAX8640Y/MAX8640Z
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
Table 1. Suggested Inductors
MANUFACTURER
FDK
Murata
Sumida
Taiyo Yuden
TDK
TOKO
SERIES
INDUCTANCE
(µH)
MIPFT2520D
2.0
1.5
MIPF2520D
2.2
3.3
1.0
LQM31P
1.5
2.2
1.2
CDRH2D09
1.5
2.2
1.0
CKP3216T
1.5
2.2
1.0
GLF201208T
2.2
1.0
GLF2012T
2.2
1.0
GLF251812T
2.2
1.0
MDT2520-CR
2.2
1.0
D2812C
2.2
DC RESISTANCE
(Ω typ)
0.16
0.07
0.08
0.10
0.12
0.16
0.22
0.08
0.09
0.12
0.11
0.13
0.14
0.15
0.36
0.07
0.10
0.10
0.20
0.05
0.08
0.07
0.14
CURRENT RATING
(mA)
900
1500
1300
1200
1200
1000
900
590
520
440
1100
1000
900
460
300
400
300
800
600
1000
700
1100
770
DIMENSIONS
L x W x H (mm)
2.5 x 2.0 x 0.5
2.5 x 2.0 x 1.0
3.2 x 1.6 x 0.95
3.0 x 3.0 x 1.0
3.2 x 1.6 x 0.9
2.0 x 1.25 x 0.9
2.0 x 1.25 x 1.35
2.5 x 1.8 x 1.35
2.5 x 2.0 x 1.0
2.8 x 2.8 x 1.2
Input Capacitor
The input capacitor, C1, reduces the current peaks
drawn from the battery or input power source and
reduces switching noise in the IC. The impedance of C1
at the switching frequency should be kept very low.
Ceramic capacitors are recommended due to their
small size and low ESR. Make sure the capacitor main-
tains its capacitance over temperature and DC bias.
Capacitors with X5R or X7R temperature characteristics
typically perform well. Due to the MAX8640Y/
MAX8640Z soft-start, the input capacitance can be very
low. For optimum noise immunity and low input ripple,
choose a capacitor value in µF that is equal to or larger
than the inductor’s value in µH.
PCB Layout and Routing
High switching frequencies and large peak currents
make PCB layout a very important part of design. Good
design minimizes excessive EMI on the feedback paths
and voltage gradients in the ground plane, both of
which can result in instability or regulation errors.
Connect the inductor, input capacitor, and output
capacitor as close together as possible, and keep their
traces short, direct, and wide. Connect the two GND
pins under the IC and directly to the grounds of the
input and output capacitors. Keep noisy traces, such
as the LX node, as short as possible. Refer to the
MAX8640Z evaluation kit for an example PCB layout
and routing scheme.
Maxim Integrated
7
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