B340L MPS [Monolithic Power Systems], B340L Datasheet - Page 8

• Manufacturer Part Number: B340L
• Description: 2A, 32V, 330KHz Step-Down Converter
• Manufacturer: MPS [Monolithic Power Systems]

To optimize the compensation components that
are not listed in Table 4, use the following
procedure.
Choose the compensation resistor to set the
desired crossover frequency. Determine the
value by the following equation:
Putting in the know constants and setting the
crossover frequency to the desired 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, C3, is required. It is required if the
ESR zero of the output capacitor occurs at less
than four times the crossover frequency, or
If this is the case, then add the second
compensation resistor. Determine the value by
the equation:
Where R
output capacitor.
MP1591 Rev. 2.3
9/27/2006
ESR(MAX)
C
R
4
R
3
>
if
8
3
≅
C
π
π
=
3
. 6
×
×
the
2
is the maximum ESR of the
C
=
88
G
R
π
5
2
3
C
EA
×
×
×
5
×
C
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
10
R
×
×
f
5
C
second
ESR
G
R
7
×
R
CS
≈
ESR
×
V
3
C
. 1
×
OUT
×
(
5
f
93
MAX
C
V
×
R
REF
×
≥
×
V
)
3
f
10
1
OUT
C
compensation
−
5
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www.MonolithicPower.com
MP1591 – 2A, 32V, 330KHz STEP-DOWN CONVERTER
Example:
Use the nearest standard value of 7.5kΩ.
Use standard value of 2.7nF.
8π x C5 x R
Therefore, no second compensation capacitor
(C3) is required.
External Bootstrap Diode
It is recommended that an external bootstrap
diode be added when the system has a 5V
fixed input or the power supply generates a 5V
output. This helps improve the efficiency of the
regulator. The bootstrap diode can be a low
cost one such as IN4148 or BAT54.
This diode is also recommended for high duty
cycle operation (when
output voltage (V
V
OUT
Figure 2—External Bootstrap Diode
R3 ≈ 6.88x10
= 5V, C5 = 22µF Ceramic (ESR = 10mΩ)
C4 > 1.93x10
ESR
MP1591
x f
OUT
C
7
= 0.22, which is less than 1.
>12V) applications.
(22x10
-5
SW
BS
/ 7.5K = 2.57nF
V
1
3
V
OUT
-6
IN
) (5) = 7568Ω
5V
>65%) and high
10nF
8