MAX17014EVKIT+ Maxim Integrated Products, MAX17014EVKIT+ Datasheet - Page 20

• 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

On the rising edge of the internal clock, the controller
sets a flip-flop, turning on the n-channel MOSFET and
applying the input voltage across the inductor. The cur-
rent through the inductor ramps up linearly, storing
energy in its magnetic field. Once the sum of the current-
feedback signal and the slope compensation exceed the
COMP voltage, the controller resets the flip-flop and turns
off the MOSFET. Since the inductor current is continuous,
a transverse potential develops across the inductor that
turns on the diode (D1). The voltage across the inductor
then becomes the difference between the output voltage
and the input voltage. This discharge condition forces
the current through the inductor to ramp back down,
transferring the energy stored in the magnetic field to the
output capacitor and the load. The MOSFET remains off
for the rest of the clock cycle.
The MAX17014 includes an integrated 120mΩ high-
voltage p-channel MOSFET to allow true shutdown of
the step-up converter output (AV
cally connected in series between the step-up regula-
tor’s Schottky catch diode and its output capacitors. In
addition to allowing step-up output to discharge com-
pletely when disabled, this switch also controls the
startup inrush current into the step-up regulator’s out-
put capacitors.
When EN2 is low, SUI is internally pulled up to SWI
through an internal 1kΩ resistor. Once EN2 is high and
the step-down regulator is in regulation, the MAX17014
Low-Cost Multiple-Output
Power Supply for LCD TVs
Figure 3. Positive Charge-Pump Regulator Block Diagram
20
______________________________________________________________________________________
1.25V
REF
AMPLIFIER
ERROR
OSC
POSITIVE CHARGE-PUMP REGULATOR
p-Channel MOSFET Pass Switch
Step-Up Regulator Internal
MAX17014
DD
). This switch is typi-
P1
N1
GNDP
DRVP
SUP
starts pulling down SUI with a 30µA internal current
source. The internal p-channel MOSFET turns on and
connects the cathode of the step-up regulator Schottky
catch diode to the step-up regulator load capacitors,
when V
MOSFET. When V
regulator and the positive charge pump are enabled
and initiate a soft-start routine.
The step-up regulator achieves soft-start by linearly
ramping up its internal current limit. The soft-start termi-
nates when the output reaches regulation or the full
current limit has been reached. The current limit rises
from zero to the full current limit in approximately 3ms.
The soft-start feature effectively limits the inrush current
during startup (see the Step-Up Regulator Soft-Start
(Heavy Load) waveforms in the Typical Operating
Characteristics ).
The positive charge-pump regulator is typically used to
generate the positive supply rail for the TFT LCD gate
driver ICs. The output voltage is set with an external
resistive voltage-divider from its output to GND with the
midpoint connected to FBP. The number of charge-
pump stages and the setting of the feedback divider
determine the output voltage of the positive charge-
pump regulator. The charge pump includes a high-side
p-channel MOSFET (P1) and a low-side n-channel
MOSFET (N1) to control the power transfer as shown in
Figure 3.
FBP
SUI
SUPPLY
INPUT
falls below the turn-on threshold of the
Positive Charge-Pump Regulator
C19
C21
C20
SUI
reaches (V
D5
SWI
- 5V), the step-up
C22
C23
OUTPUT
Soft-Start