MP2104DJ-1.5 MPS [Monolithic Power Systems], MP2104DJ-1.5 Datasheet - Page 9

• Manufacturer Part Number: MP2104DJ-1.5
• Description: 1.7MHz, 600mA Synchronous Step-Down Converter
• Manufacturer: MPS [Monolithic Power Systems]

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
NOTICE: MPS believes the information in this document to be accurate and reliable. However, it is subject to change without
notice. Contact MPS for current specifications. MPS encourages users of its products to ensure that third party Intellectual
Property rights are not infringed upon when integrating MPS products into any application. MPS cannot assume any legal
responsibility for any said applications.
MP2104 Rev. 1.0
10/4/05
© 2004 MPS, Inc.
∆
V
OUT
2.5V - 6V
OFF ON
≤
INPUT
V
OUT
V
IN
TM
×
Figure 4—V
×
(
V
f
OSC
IN
−
×
OUT
V
4
1
L
OUT
Tel: [phone] ♦ Fax: [phone] ♦ www.MonolithicPower.com
IN
EN
is approximately:
)
IN
×
983 University Avenue, Building A, Los Gatos, CA 95032 USA
MP2104
⎛
⎜
⎜
⎝
= 2.5V to 6V, V
GND
ESR
(L = 10µH for Higher Light-Load Efficiency)
MP2104 – 1.7MHz 600mA SYNCHRONOUS STEP-DOWN CONVERTER
2
+
SW
FB
8
×
3
5
Monolithic Power Systems, Inc.
f
OSC
1
×
OUT
C
3
⎞
⎟
⎟
⎠
= 1.8V, I
OUTPUT
1.8V
600mA
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.
LOAD
MP2104_F04
Figure 3—MP2104 Suggested Layout
= 600mA Step-Down Circuit
100
90
80
70
60
50
40
30
20
10
0
10
Efficiency vs
Load Current
V
IN
= 3.3V
LOAD CURRENT (mA)
V
IN
= 4.2V
100
MP2104-EC02
1000
9