TM
MP1411 – 2A, 18V, 380KHz STEP-DOWN CONVERTER
5)
Connect IN, SW, and especially GND
respectively to a large copper area to cool
the chip to improve thermal performance and
long-term reliability. For single layer, do not
solder exposed pad of the IC
R4
C4
R2
C3
C6
R3
R4
R1
R2
SS
10
EN
9
COMP
8
FB
7
GND
6
SGND
SGND
C3
R3
C6
5
SW
1
NC
3
NC
2
BS
4
IN
C4
R1
C5
SS
10
EN
9
COMP
8
FB
7
GND
6
L1
SGND
C1
PGND
D1
C2
5
SW
1
NC
3
NC
2
BS
4
IN
L1
Figure 3—PCB Layout (Single Layer)
External Bootstrap Diode
An external bootstrap diode may enhance the
efficiency of the regulator, the applicable
conditions of external BST diode are:
V
OUT
=5V or 3.3V; and
Duty cycle is high: D=
V
OUT
>65%
V
IN
C5
C1
PGND
D1
C2
Top Layer
In these cases, an external BST diode is
recommended from the output of the voltage
regulator to BST pin, as shown in Fig.4
External BST Diode
IN4148
BST
C
BST
5V or 3.3V
MP1411
SW
L
C
OUT
+
Figure 4—Add Optional External Bootstrap
Diode to Enhance Efficiency
The recommended external BST diode is IN4148,
and the BST cap is 0.1~1µF.
Bottom Layer
Figure 2—PCB Layout (Double Layer)
MP1411 Rev. 1.3
1/22/2010
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