MAX15020EVKIT+ Maxim Integrated Products, MAX15020EVKIT+ Datasheet - Page 15

• Manufacturer Part Number: MAX15020EVKIT+
• Description: EVAL KIT FOR MAX15020
• Manufacturer: Maxim Integrated Products

Specifications of MAX15020EVKIT+

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 30V
• Current - Output: 2A
• Voltage - Input: 7.5 ~ 40V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: MAX15020
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

For larger ESR capacitors such as tantalum and alu-
minum electrolytics, f
< f
remain the same as before, however, f
equal to f
quency is higher than f
loop crossover frequency. The equations that define
the error amplifier’s poles and zeros (f
and f
lower than the closed-loop crossover frequency. Figure
4 shows the error-amplifier feedback as well as its gain
response for circuits that use higher-ESR output capac-
itors (tantalum or aluminum electrolytic).
Pick a value for the feedback resistor R9 in Figure 4
(values between 1kΩ and 10kΩ are adequate).
C12 is then calculated as:
The error-amplifier gain between f
mately equal to R9 / R6 (given that R6 << R7). R6 can
then be calculated as:
Figure 3. Error-Amplifier Compensation Circuit (Closed-Loop
and Error-Amplifier Gain Plot) for Ceramic Capacitors
GAIN
(dB)
C
V
, then f
OUT
P3
) are the same as before. However, f
ZESR
C11
C
occurs between f
2A, 40V Step-Down DC-DC Converter with
. The output capacitor’s ESR zero fre-
C
R7
CLOSED-LOOP
GAIN
12
R6
______________________________________________________________________________________
f
Z1
=
R8
ZESR
2
Compensation when f
Dynamic Output-Voltage Programming
π
f
Z2
LC
×
0 8
can occur before f
but lower than the closed-
.
SS
FB
f
C
1
×
P2
f
LC
AMPLIFIER
R9
C13
P2
ERROR
f
P2
and f
×
R
and f
9
f
P3
Z1
C12
P3
P2
, f
P3
. f
Z2
FREQUENCY (Hz)
Z1
is now set
is approxi-
C
C
P2
ERROR-
AMPLIFIER
GAIN
, f
. If f
> f
and f
P1
is now
COMP
ZESR
, f
ZESR
P2
Z2
,
C11 is then calculated as:
Since R7 >> R6, R7 + R6 can be approximated as R7.
R7 is then calculated as:
f
Based on the calculations above, the following com-
pensation values are recommended when the switch-
ing frequency of DC-DC converter ranges from 100kHz
to 500kHz. (Note: The compensation parameters in
Figure 2 are strongly recommended if the switching
frequency is from 300kHz to 500kHz.)
Figure 4. Error-Amplifier Compensation Circuit (Closed-Loop
and Error-Amplifier Gain Plot) for Higher ESR Output Capacitors
P3
GAIN
(dB)
is set at 5 x f
V
OUT
C11
C
13
R7
C
. Therefore, C13 is calculated as:
f
R
R6
Z1
C
=
R
6
11
7
2
R8
=
=
π
f
Z2
=
R
×
2
C
9 10
π
C
CLOSED-LOOP
GAIN
OUT
×
12
×
SS
f
f
C
LC
C
R
×
FB
1
2
12
6
×
×
R
×
f
ESR
9
f
LC
P2
AMPLIFIER
R9
C
×
C13
ERROR
11
2
f
P
3
f
C
−
C12
1
f
P3
FREQUENCY (Hz)
ERROR-
AMPLIFIER
GAIN
COMP
15