DS9921-00PT00  April  2007
www.richtek
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 V IN  − 0.5V ( ±1.5%)
`Maximum Output Current : 350mA
z
On-Chip GPM Controller with Adjustable `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
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 voltag
e 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), wid e bandwidth (12MHz) and rail-to-rail inputs and outputs.
Integrated Multi-Channel DC-DC Converter for TFT LCD Panels
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.
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.
Typical Application Circuit Pin Configurations
(TOP VIEW)
VQFN-24L 4x4
Ordering Information
LX
VIN
SS AGND ADJ LDOO
AVDD
DRVP
FBP
VGH
VGHM
RE
C
O
M
P
modulateO
P
A
O
P
G
N
D
F
R
E
Q
F
B
O
P
A
I
V
F
L
K
L
D
O
I
V
D
I
V
R
E
S
E
T
V
D
P
M
C
D
RT9921
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
Note :
RichTek Pb-free and Green products are :
`RoHS compliant and compatible with the current require-  ments of IPC/JEDEC J-STD-020.
`Suitable for use in SnPb or Pb-free soldering processes. `100% matte tin (Sn) plating.
V
DS9921-00PT00  April  2007www.richtek
Function Block Diagram
Absolute Maximum Ratings (Note 1)
z Supply Input Voltage, V IN----------------------------------------------------------------------------------------−0.3 to 6.5V
z L X---------------------------------------------------------------------------------------------------------------------−0.3 to 16V
z VGH, VGHM, RE--------------------------------------------------------------------------------------------------−0.3 to 30V
z A V DD-----------------------------------------------------------------------------------------------------------------−0.3 to 16V
z VGH − AVDD, VGHM − AVDD----------------------------------------------------------------------------------−0.3 to 20V
z OPAI, OPAO, DRVP----------------------------------------------------------------------------------------------−0.3 to
(V AVDD + 0.3V) z VDPM, VFLK, CD, RESET, VDIV, SS, COMP, FB, FBP------------------------------------------------−0.3 to (V IN + 0.3V) z LDOI------------------------------------------------------------------------------------------------------------------−0.3 to 6.5V
z ADJ, LDOO---------------------------------------------------------------------------------------------------------−0.3 to (LDOI+0.3V) z Power Dissipation, P D @ T A = 25°C
VQFN-24L 4x4-----------------------------------------------------------------------------------------------------1.786W
z Package Thermal Resistance  (Note 4)
VQFN-24L 4x4, θJA------------------------------------------------------------------------------------------------56°C/W
z Lead Temperature (Soldering, 10 sec.)-----------------------------------------------------------------------260°C
z Junction T emperature---------------------------------------------------------------------------------------------150°C
z Storage T emperature Range------------------------------------------------------------------------------------−65°C to 150°C
z ESD Susceptibility  (Note 2)
HBM (Human Body Mode)--------------------------------------------------------------------------------------2kV
MM (Machine Mode)----------------------------------------------------------------------------------------------200V Recommended Operating Conditions  (Note 3)
z Maximum Output Voltage Setting, AVDD and VOUT------------------------------------------------------15V
z Maximum (VGH − AVDD)---------------------------------------------------------------------------------------18V
z Junction T emperature Range------------------------------------------------------------------------------------−40°C to 125°C
z Ambient T emperature Range------------------------------------------------------------------------------------−40°C to 85°C Electrical Characteristics
(V IN = 3.3V, V OUT = 8.5V, T A= 25°C, unless otherwise specification)
To be continued DS9921-00PT00  April  2007www.richtek

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