MAX15031EVKIT+ Maxim Integrated Products, MAX15031EVKIT+ Datasheet - Page 13

• Manufacturer Part Number: MAX15031EVKIT+
• Description: KIT EVALUATION FOR MAX15031
• Manufacturer: Maxim Integrated Products

Specifications of MAX15031EVKIT+

• Main Purpose: DC/DC, Step Up
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 70V
• Current - Output: 4mA
• Voltage - Input: 2.9 ~ 5.5V
• Regulator Topology: Boost
• Frequency - Switching: 400kHz
• Board Type: Fully Populated
• Utilized Ic / Part: MAX15031
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The MAX15031’s high switching frequency demands a
high-speed rectifier. Schottky diodes are recommend-
ed for most applications because of their fast recovery
time and low forward-voltage drop. Ensure that the
diode’s peak current rating is greater than the peak
inductor current. Also the diode reverse-breakdown
voltage must be greater than V
of the boost converter.
For most applications, use a small output capacitor of
0.1μF or greater. To achieve low output ripple, a capaci-
tor with low ESR, low ESL, and high capacitance value
should be selected. If tantalum or electrolytic capacitors
are used to achieve high capacitance values, always
add a smaller ceramic capacitor in parallel to bypass
the high-frequency components of the diode current.
The higher ESR and ESL of electrolytic capacitors
increase the output ripple and peak-to-peak transient
voltage. Assuming the contribution from the ESR and
capacitor discharge equals 50% (proportions may vary),
calculate the output capacitance and ESR required for a
specified ripple using the following equations:
Figure 2. Typical Operating Circuit with RC Filter
C
OUT
[
V
μF
IN
= 2.7V TO 5.5V
]
=
Output Filter Capacitor Selection
0.5 x
80V, 300mW Boost Converter and Current
ESR m
I
OUT
______________________________________________________________________________________
[
Δ
V
C
Ω
OUT
PWR
]
=
⎡
⎢
⎢
⎣
0.5 x
T
S
I
C
−
O O UT
OUT
CP
ΔV
I
LPEAK
Monitor for APD Bias Applications
(V
OUT
Diode Selection
. The output voltage
OUT
x L
−
PWR
CNTRL
SHDN
CP
CN
PGND
V
OPTIM
IN_MIN
MAX15031
SGND
U U M
IN
)
⎤
⎥
⎥
⎦
L1
C
BIAS
IN
LX
FB
For very low output ripple applications, the output of the
boost converter can be followed by an RC filter to further
reduce the ripple. Figure 2 shows a 100Ω (R
(C
1mV
The output-voltage regulation resistor-divider must remain
connected to the diode and output capacitor node.
Use X7R ceramic capacitors for more stability over the full
temperature range. Use an X5R capacitor for -40°C to
+85°C applications.
Bypass PWR to PGND with a 1μF (min) ceramic capaci-
tor and bypass IN to PGND with a 1μF (min) ceramic
capacitor. Depending on the supply source imped-
ance, higher values may be needed. Make sure that the
input capacitors are close enough to the IC to provide
adequate decoupling at IN and PWR as well. If the lay-
out cannot achieve this, add another 0.1μF ceramic
capacitor between IN and PGND (or PWR and PGND)
in the immediate vicinity of the IC. Bulk aluminum elec-
trolytic capacitors may be needed to avoid chattering
at low input voltage. In case of aluminum electrolytic
capacitors, calculate the capacitor value and ESR of
the input capacitor using the following equations:
C
IN
F
[
) filter used to reduce the switching output ripple to
μ
P-P
F
]
=
D1
with a 0.1mA load or 2mV
η
x V
IN_MIN
V
ESR m
OUT
R
R
2
1
[
x I
x 0.5 x
Ω
OUT
]
=
0.5 x
C
Input Capacitor Selection
100Ω
Δ
OUT1
R
V
F
IN
Δ
V
⎡
⎢
⎢
⎣
V
OUT
T T
IN
S
−
x η
x I
I
LPEAK
OUT
V
x V
IN_MIN OUT
P-P
IN_M
x L
with a 4mA load.
(V
I I N
OPTIMUM
C
0.1μF
F
−
V
V
OUT
I
N N _MIN
F
x V
), 0.1μF
OUT
)
⎤
⎥
⎥
⎦
13