ISL97644 Просмотр технического описания (PDF) - Renesas Electronics
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ISL97644 Datasheet PDF : 15 Pages
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ISL97644
Typical Application Diagram
VIN
C1
22µF
VIN2
C3
2.2nF COMP
R5
C4 10k
10nF SS
L1
10µH
BOOST
AVDD
VCOM
+4.0V
R6
130k
R7
80k
C6
0.1µF
ENABLE
FREQ-
VDPM
VFLK
C5
470P CE
RE
R3
2k POS
C11
1µF
NEG-
OUT
VIN1
AGND
GND
GPM
CIRCUIT
LDO
CONTROLLER
D1
LX
C2
47µF
FB
PGND
AVDD
R1
10k
C9 (OPTIONAL)
R2
1.3k
VGH
VON
VDD_1
VGH_M
VDD2
C10
2.2µF
TO ROW DRIVER
LDO_OUT
ADJ
VLOGIC
C7
4.7µF
FIGURE 14. TYPICAL APPLICATION DIAGRAM
Applications Information
The ISL97644 provides a complete power solution for TFT
LCD applications. The system consists of one boost converter
to generate AVDD voltage for column drivers, one logic LDO
regulator to provide voltage to logic circuit in the LCD panel,
one integrated VCOM buffer which can provide up to 400mA
peak current. This part also integrates Gate Pulse Modulator
circuit that can help to optimize the picture quality.
Enable Control
When enable pin is pulling down, the ISL97644 is shut down
reducing the supply current to <10µA. When the voltage at
enable pin reaches 2.2V, the ISL97644 is on.
Boost Converter
Frequency Selection
The ISL97644 switching frequency can be user selected to
operate at either constant 650kHz or 1.2MHz. Lower switching
frequency can save power dissipation, while higher switching
frequency can allow smaller external components like inductor
and output capacitors, etc. Connecting FREQ pin to ground
sets the PWM switching frequency to 650MHz, or connecting
FREQ pin to VIN for 1.2MHz.
Soft-Start
The soft-start is provided by an internal 2.5µA current source to
charge the external soft start capacitor. The ISL97644 ramps
up current limit from 0A up to full value, as the voltage at SS
pin ramps from 0 to 1.2V. Hence the soft-start time is 4.8ms
when the soft-start capacitor is 10nF, 22.6ms for 47nF and
48ms for 100nF.
FN9228 Rev 1.00
December 14, 2007
Page 9 of 15
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