MAX17014EVKIT+ Maxim Integrated Products, MAX17014EVKIT+ Datasheet - Page 21

• 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

During the first half-cycle, N1 turns on and charges fly-
ing capacitors C20 and C21 (Figure 3). During the sec-
ond half cycle, N1 turns off and P1 turns on, level
shifting C20 and C21 by V
across C23 plus a diode drop (V
than the level-shifted flying capacitor voltage (V
V
(D5) turns off. The amount of charge transferred to the
output is determined by the error amplifier that controls
N1’s on-resistance.
The positive charge-pump regulator’s startup can be
delayed by connecting an external capacitor from
DEL2 to GND. An internal constant-current source
begins charging the DEL2 capacitor when EN2 is logic-
high, and the step-down regulator reaches regulation.
When the DEL2 voltage exceeds V
charge-pump regulator is enabled. Each time it is
enabled, the positive charge-pump regulator goes
through a soft-start routine by ramping up its internal
reference voltage from 0 to 1.25V in 128 steps. The
soft-start period is 3ms (typ) and FBP fault detection is
disabled during this period. The soft-start feature effec-
tively limits the inrush current during startup.
The negative charge-pump regulator is typically used to
generate the negative supply rail for the TFT LCD gate
driver ICs. The output voltage is set with an external
Figure 4. Negative Charge-Pump Regulator Block Diagram
SUP
), charge flows from C20 to C23 until the diode
Negative Charge-Pump Regulator
0.25V
REF
AMPLIFIER
______________________________________________________________________________________
ERROR
NEGATIVE CHARGE-PUMP REGULATOR
OSC
SUP
OUT
volts. If the voltage
MAX17014
REF
+ V
, the positive
D
) is smaller
C20
Power Supply for LCD TVs
+
Low-Cost Multiple-Output
P2
N2
resistive voltage-divider from its output to REF with the
midpoint connected to FBN. The number of charge-
pump stages and the setting of the feedback divider
determine the output of the negative charge-pump reg-
ulator. The charge-pump controller includes a high-side
p-channel MOSFET (P2) and a low-side n-channel
MOSFET (N2) to control the power transfer as shown in
Figure 4.
During the first half cycle, P2 turns on, and flying
capacitor C13 charges to V
(Figure 4). During the second half cycle, P2 turns off,
and N2 turns on, level shifting C13. This connects C13
in parallel with reservoir capacitor C12. If the voltage
across C12 minus a diode drop is greater than the volt-
age across C13, charge flows from C12 to C13 until the
diode (D3) turns off. The amount of charge transferred
from the output is determined by the error amplifier,
which controls N2’s on-resistance.
The negative charge-pump regulator is enabled when
EN1 is logic-high and the step-down regulator reaches
regulation. Each time it is enabled, the negative
charge-pump regulator goes through a soft-start rou-
tine by ramping down its internal reference voltage
from 1.25V to 250mV in 102 steps. The soft-start period
is 3ms (typ) and FBN fault detection is disabled during
this period. The soft-start feature effectively limits the
inrush current during startup.
DRVN
GND1
FBN
IN
SUPPLY
INPUT
C13
R1
D3
SUP
R2
minus a diode drop
C12
OUTPUT
REF
21