MAX17014EVKIT+ Maxim Integrated Products, MAX17014EVKIT+ Datasheet - Page 29

• Manufacturer Part Number: MAX17014EVKIT+
• Description: KIT EVAL FOR MAX17014
• Manufacturer: Maxim Integrated Products

Specifications of MAX17014EVKIT+

• Main Purpose: Special Purpose DC/DC, LCD Supply
• Outputs And Type: 4, Non-Isolated
• Power - Output: 32.9W
• Voltage - Output: 3.3V, 16V, -6V, 35V
• Current - Output: 2A, 1.5A, 100mA, 50mA
• Voltage - Input: 10.8 ~ 13.2V
• Regulator Topology: Boost, Buck
• Frequency - Switching: 1.2MHz
• Board Type: Fully Populated
• Utilized Ic / Part: MAX17014
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

where I
Inductor Selection section). For ceramic capacitors, the
output voltage ripple is typically dominated by
V
characteristics of the output capacitor must also be
considered. Note that all ceramic capacitors typically
have large temperature coefficient and bias voltage
coefficients. The actual capacitor value in circuit is typi-
cally significantly less than the stated value.
The input capacitor reduces the current peaks drawn
from the input supply and reduces noise injection into
the IC. A 22µF ceramic capacitor is used in the typical
operating circuit (Figure 1) because of the high source
impedance seen in typical lab setups. Actual applica-
tions usually have much lower source impedance since
the step-up regulator often runs directly from the output
of another regulated supply. Typically, the input capaci-
tance can be reduced below the values used in the typi-
cal operating circuit.
The MAX17014’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. In general, a 2A Schottky
diode complements the internal MOSFET well.
The output voltage of the step-up regulator can be
adjusted by connecting a resistive voltage-divider from
the output (V
ed to FB1 (see Figure 1). Select R4 in the 10kΩ to 50kΩ
range. Calculate R3 with the following equation:
where V
is 1.25V. Place R4 and R3 close to the IC.
Choose R
cy integrator gain for fast transient response. Choose
C
maintain loop stability.
For low-ESR output capacitors, use the following equa-
tions to obtain stable performance and good transient
response:
AVDD
COMP
_
AVDD
RIPPLE(C)
FB1
(C17 in Figure 1) to set the integrator zero to
COMP
, the step-up regulator’s feedback set point,
_
AVDD
PEAK
(R5 in Figure 1) to set the high-frequen-
. The voltage rating and temperature
R
) to GND with the center tap connect-
______________________________________________________________________________________
3
is the peak inductor current (see the
=
R
4
×
⎛
⎜
⎝
V
Input Capacitor Selection
Output-Voltage Selection
AVDD
V
FB
1
Loop Compensation
−
1
⎞
⎟
⎠
Rectifier Diode
Power Supply for LCD TVs
Low-Cost Multiple-Output
To further optimize transient response, vary R
20% steps and C
transient response waveforms.
For highest efficiency, always choose the lowest number
of charge-pump stages that meet the output requirement.
The number of positive charge-pump stages is given by:
where n
stages, V
regulator, V
pump regulators, V
charge-pump diode, and V
margin for the regulator. Use V
The number of negative charge-pump stages is given by:
where n
stages and V
pump regulator.
The above equations are derived based on the
assumption that the first stage of the positive charge
pump is connected to V
negative charge pump is connected to ground.
Sometimes fractional stages are more desirable for bet-
ter efficiency. This can be done by connecting the first
stage to V
charge-pump stage is powered from V
above equations become:
Selecting the Number of Charge-Pump Stages
NEG
R
POS
C
GON
n
COMP
n
NEG
OUT
COMP
n
POS
POS
SUP
GOFF
n
is the number of positive charge-pump
is the number of negative charge-pump
is the output of the positive charge-pump
NEG
=
=
or another available supply. If the first
≈
=
≈
is the supply voltage of the charge-
−
V
125
COMP
V
V
GON
1250
=
is the output of the negative charge-
D
GON
GOFF
−
is the forward voltage drop of the
×
L
V
Charge-Pump Regulators
AVDD
GOFF
V
+
×
AVDD
+
V
V
V
VIN
in 50% steps while observing
V
V
V
+
I
AVDD
SUP
SUP
SUP
SUP
AVDD MAX
V
DROPOUT
V
DROPOUT
DROPOUT
×
×
+
DROPOUT
V
− ×
− ×
DROPOUT
− ×
and the first stage of the
− ×
I
V
AVDD MAX
(
AVDD
×
2
2
2
2
DROPOUT
C
AVDD
V
V
V
V
)
D
D
D
(
D
−
×
×
−
V
+
R
C
V
AVDD
V
COMP
OUT
is the dropout
AVDD
= 300mV.
)
OUT
OUT
, then the
COMP
29
in