MP2104 MPS, MP2104 Datasheet - Page 10

• Manufacturer Part Number: MP2104
• Description: 1.7mhz, 600ma Synchronous Step-down Converter
• Manufacturer: MPS

Input Capacitor Selection
The input capacitor reduces the surge current
drawn from the input and switching noise from
the device. The input capacitor impedance at
the switching frequency shall be less than input
source impedance to prevent high frequency
switching current passing to the input. Ceramic
capacitors with X5R or X7R dielectrics are
highly recommended because of their low ESR
and small temperature coefficients. For most
applications, a 4.7µF capacitor is sufficient.
Output Capacitor Selection
The output capacitor keeps output voltage
ripple small and ensures regulation loop stable.
The output capacitor impedance shall be low at
the switching frequency. Ceramic capacitors
with X5R or X7R dielectrics are recommended.
The output ripple ∆V
MP2104 Rev. 1.4
5/28/2008
∆
V
OUT
≤
V
OUT
V
IN
×
×
(
V
f
OSC
IN
−
×
OUT
V
L
OUT
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
is approximately:
)
×
⎛
⎜
⎜
⎝
ESR
MP2104 – 1.7MHz 600mA SYNCHRONOUS STEP-DOWN CONVERTER
+
8
×
f
OSC
© 2008 MPS. All Rights Reserved.
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×
C
3
⎞
⎟
⎟
⎠
PC Board Layout
The high current paths (GND, IN and SW)
should be placed very close to the device with
short, direct and wide traces. Input capacitor C1
needs to be as close as possible to the IN and
GND pins. The external feedback resistors shall
be placed next to the FB pin. Keep the
switching node SW short and away from the
feedback network. Figure 3 illustrates an
example of PCB layout and signal routing.
For the fixed output versions (MP2104DJ-1.5
and MP2104-1.8), R1 is shorted and R2 is open.
Figure 3—MP2104 Suggested Layout
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