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G5524A Datasheet, PDF (1/2 Pages) Global Mixed-mode Technology Inc – Integrated Power Supply for TFT-LCD Panels with 4-Channel White LED Driver | |||
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Global Mixed-mode Technology Inc.
G5524A
Integrated Power Supply for TFT-LCD Panels with
4-Channel White LED Driver
Features
 2.5V to 5.5V Input Supply Range
 Boost Regulator
 640kHz/1.2MHz Fixed Frequency
 Current-Mode Control
 Fast Transient Response to Pulse Load
 ±1% Accurate Output Voltage
 Built-In 20V/2A, 0.2Ω N-Channel MOSFET
 High Efficiency up to 90%
 Programmable Soft-Start
 Over-Current Protection
 Output Under-Voltage Protection
 White-LED Driver
 Wide 4.2V to 24V Input Supply Range
 Adjustable Switching Frequency
 40V/2A, 0.3Ω n-channel MOSFET
 Input Under-Voltage Protection
 Over Current Protection
 Over Voltage Protection
 Maximum Programmable LED Channel Current
50mA
 Maximum 3% Matching between Channels
 100Hz~20kHz PWM Dimming
 High-Performance Operational Amplifiers
 ±150mA Output Short-Circuit Current
 12V/µs Slew Rate
 12MHz, -3dB Bandwidth
 Rail-to-Rail Input and Output
 Low Dropout Voltage Linear Regulator
 350mA Maximum Output Current
 Adjustable Output Voltage
 On-Chip GPM Controller
 Adjustable Falling Time and Power-On Delay
 Flicker Compensator
 Power-On Sequence Control
 Charge pump for VGH regulation
 Low Voltage Detector
 Programmable Detecting Voltage and Delay Time
 Thermal Protection
 RoHs Compliant
 TQFN5X5-40 and TQFN3.8X6.2-44 Package
Applications
 Notebook Computer Displays
 UMPCs
 LCD Monitor
General Description
The G5524A includes a high-performance boost regulator,
4-channel LED driver, 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 dis-
plays (LCDs).
The boost converter provides the regulated supply volt-
age for the panel source driver ICs. The converter is a
high switching frequency (640kHz or 1.2MHz) cur-
rent-mode regulator with an integrated 20V N-Channel
0.2Ω MOSFET that allows the use of ultra-small inductors
and ceramic capacitors. It provides fast transient re-
sponse to pulsed loading while achieving efficiency over
90%. The device can produce output voltage as high as
18V from an input as low as 2.8V. Soft-Start is pro-
grammed by external capacitor, which sets the in-
put-current ramp-rate.
The LED driver automatically regulated supply voltage for
the LED light bars without the need to calculate the output
for different LED types. A FREQ2 pin is applied to adjust
switching frequency in the range of 640kHz to 2MHz. It
also integrates a 40V n-channel MOSFET that provides
high output power. The 4-channel current driver is ideal
for constant current driving, and, well matched less than
3%. To set the maximum driving current, the ISET pin is
used to determine reference current. Each channel of the
current drivers is set to 1300 times of this reference cur-
rent. A PWM pin can be used to perform PWM dimming
from the range of 100Hz to 20kHz. Open LED-string
automatically disable the channel from entering over
voltage protection.
The low-dropout (LDO) linear regulator can supply up to
350mA current while input voltage is 3.3V. It uses an inter-
nal 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 con-
troller 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 ca-
pacitor.
The VCOM buffer can drive the LCD VCOM voltage that
features high short-circuit current (150mA), fast slew rate
(12V/µs), wide bandwidth (12MHz) and rail-to-rail in-
put/output.
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 refer-
ence.
Ver: 0.2
Feb 16, 2011
TEL: 886-3-5788833
http://www.gmt.com.tw
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