MP2108DQ MPS [Monolithic Power Systems], MP2108DQ Datasheet - Page 10

• Manufacturer Part Number: MP2108DQ
• Description: 2A, 6V, 740KHz Synchronous Buck Converter
• Manufacturer: MPS [Monolithic Power Systems]

Choose the compensation resistor to set the
desired crossover frequency. Determine the
value by the following equation:
Where
(450µA/V) and f
frequency (preferably 33KHz).
Choose the compensation capacitor to set the
zero below one fourth of the crossover
frequency. Determine the value by the following
equation:
Determine
capacitor, C4 is required. It is required if the
ESR zero of the output capacitor happens at
less than half of the switching frequency or:
where R
of the output capacitor.
MP2108 Rev 1.1
10/2/2006
ESR
G
EA
R
is the equivalent series resistance
if
π
3
×
is
=
C
C
2
the
G
3
C
2
π
the
EA
×
>
×
is the desired crossover
R
C
π
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
×
ESR
2
×
second
G
×
R
EA
CS
2
f
3
×
C
×
f
SW
×
f
C
transconductance
V
V
OUT
>
FB
1
compensation
MP2108 – 2A, 6V, 740KHz SYNCHRONOUS BUCK CONVERTER
© 2006 MPS. All Rights Reserved.
www.MonolithicPower.com
The
determined by the equation:
Where R
output capacitor.
External Boost Diode
It is recommended that an external boost diode
be added to help improve the regulator
efficiency. The diode can be a low cost diode
such as an IN4148 or BAT54.
This diode is also recommended for high duty
cycle operation (when
second
Figure 3—External Boost Diode
ESR(MAX)
MP2108
C
4
compensation
is the maximum ESR of the
=
C
BST
LX
2
×
V
V
R
OUT
1
3
R
IN
ESR
3
5V
>65%).
(max)
BOOST
DIODE
10nF
capcacitor
10
is