MAX16928CGUP/V+ Maxim Integrated, MAX16928CGUP/V+ Datasheet - Page 9

• Manufacturer Part Number: MAX16928CGUP/V+
• Description: LCD Drivers Automotive TFT Power Supply
• Manufacturer: Maxim Integrated

Specifications of MAX16928CGUP/V+

• Rohs: yes

Figure 1
regulator. An error amplifier compares the signal at
FBP to 1V and changes the COMPV output. The volt-
age at COMPV sets the peak inductor current. As the
load varies, the error amplifier sources or sinks current
to the COMPV output accordingly to produce the peak
inductor current necessary to service the load. To main-
tain stability at high duty cycles, a slope-compensation
signal (set by the capacitor at COMPI) is summed with
the current-sense signal. 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 current through the inductor
ramps up linearly, storing energy in its magnetic field.
Once the sum of the current feedback signal and the
Figure 1. Boost Converter Functional Diagram
Maxim Integrated
shows the functional diagram of the boost
Automotive TFT-LCD Power Supply with Boost
Converter and Gate Voltage Regulators
OSCILLATOR
MAX16928
2.2MHz
TO FAULT LOGIC
CLOCK
COMPARATOR
COMPARATOR
COMPARATOR
FAULT
PWM
I
LIM
LOGIC AND
DRIVER
0.85V
Σ
slope compensation exceeds the COMPV voltage, the
controller turns off the MOSFET. The inductor current
then flows through the diode to the output. The MOSFET
remains off for the rest of the clock cycle.
The external p-channel FET controlled by GATE protects
the output during fault conditions and provides True
Shutdown of the converter. Connect a pullup resistor
between GATE and INA (see the
to select the value for the pullup resistor). Under normal
operation, GATE turns on the p-channel FET, connecting
the supply to the boost input. During a fault condition or
in shutdown, GATE is off and the pullup resistor turns off
the p-channel FET, disconnecting the supply from the
boost input.
SOFT-
START
ERROR
AMP
CURRENT
SENSE
SLOPE
COMP
V
LIMIT
1V
LXP
PGNDP
COMPI
FBP
COMPV
MAX16928
Boost Converter
section
9