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RT9921PQV View Datasheet(PDF) - Richtek Technology

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RT9921PQV Datasheet PDF : 15 Pages
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Preliminary
RT9921
Integrated Multi-Channel DC-DC Converter
for TFT LCD Panels
General Description
The RT9921 includes a high-performance boost regulator,
a low dropout linear regulator (LDO), a gate pulse
modulator (GPM), a voltage detector, a VCOM buffer (unity-
gain OPA), and a VGH charge pump controller for active-
matrix thin-film transistor (TFT) liquid-crystal displays
(LCDs).
The boost converter provides the regulated supply voltage
for the panel source driver ICs. The converter is a high
switching frequency (640kHz or 1.2MHz) current-mode
regulator with an integrated 16V N-Channel 0.2Ω MOSFET
that allows the use of ultra-small inductors and ceramic
capacitors. It provides fast transient response to pulsed
loading while achieving efficiency over 90%. The device
can produce output voltage as high as 15V from an input
as low as 2.5V. Soft-Start is programmed by external
capacitor, which sets the input-current ramp-rate.
The low-dropout (LDO) linear regulator can supply up to
350mA current while input voltage is 3.3V. It uses an
internal PMOS as the pass device. It is suitable for the
supply voltage of the timing controller.
The GPM is controlled by frame signals from timing
controller to modulate the Gate-On voltage, VGHM, which
acts a flicker compensation circuit to reduce the coupling
effect between gate lines and pixels. It also can delay the
Gate-On voltage while power-on for achieving a corrected
power-on sequence for gate driver ICs. Both of power-on
delay time and the falling time of the Gate-On voltage are
programmable by external capacitor and resistor.
The voltage detector monitors the supply voltage to issue
a reset signal while the detected voltage is too low. The
detecting level is decided by an external resistor divider
and the delay time is programmable by an external
capacitor.
The VCOM buffer can drive the LCD VCOM voltage that
features high short-circuit current (140mA), fast slew rate
(12V/μs), wide bandwidth (12MHz) and rail-to-rail inputs
and outputs.
The VGH charge pump controller provides regulated TFT
Gate-On voltage. The regulation of the positive charge
pump is generated by the internal comparator that senses
the output voltage and compares it with an internal
reference.
Features
z 2.5V to 5.5V Input Supply Voltage
z 640kHz/1.2MHz Current-Mode Boost Regulator
`Fast Transient Response to Pulsed Load
`Adjustable Output Voltage (±1%)
`Built-In 16V, 2A, 0.2Ω N-MOSFET
`High Efficiency Up to 90%
`Programmable Soft-Start
`Over-Current Protection
`Output Under-Voltage Protection
z Low Dropout Voltage Linear Regulator
`Adjustable Output Voltage : 1.5V to VIN 0.5V
( ±1.5%)
`Maximum Output Current : 350mA
On-Chip GPM Controller with Adjustable http://www.DataSheet4U.net/
z
`Falling Time and Power-On Delay
`Flicker Compensator
`Power-On Sequence Control
z Low Voltage Detector
`Programmable Detecting Voltage (±2%) and Delay
Time
z Unity-Gain Operation Amplifier for VCOM Buffer
z Charge Pump for VGH regulation
z Over-Temperature Protection
z Thin 24 Lead VQFN Package
z RoHS Compliant and 100% Lead (Pb)-Free
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.
DS9921-00 November 2007
www.richtek.com
1
datasheet pdf - http://www.DataSheet4U.net/
 

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