ISL97645 Intersil Corporation, ISL97645 Datasheet - Page 8

• Manufacturer Part Number: ISL97645
• Description: Boost VON Slice VCOM
• Manufacturer: Intersil Corporation

Typical Application Diagram
Applications Information
The ISL97645 provides a complete power solution for TFT
LCD applications. The system consists of one boost
converter to generate A
integrated V
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 ISL97645 is shut down
reducing the supply current to <10µA. When the voltage at
enable pin reaches 2.2V, the ISL97645 is on.
Boost Converter
Frequency Selection
The ISL97645 switching frequency can be user selected to
operate at either constant 650kHz or 1.2MHz. Lower
+4.0V
V
A
COM
VDD
COM
80k
R6
130k
R7
buffer which can provide up to 400mA peak
22µF
0.1µF
C1
C6
V
IN
VDD
voltage for column drivers, one
S1
S2
S3
R3
2K
8
C3
2.2nF
C4
10nF
C11
1µF
ENABLE
C5
470P
FREQ-
AGND
COMP
VDPM
VFLK
NEG-
GND
POS
OUT
VIN
RE
CE
SS
FIGURE 12. TYPICAL APPLICATION DIAGRAM
CIRCUIT
GPM
ISL97645
BOOST
10µH
L1
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 V
1.2MHz.
Soft-Start
The soft-start is provided by an internal 2.5µA current source
to charge the external soft start capacitor. The ISL97645
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.
Operation
The boost converter is a current mode PWM converter
operating at either a 650kHz or 1.2MHz. It can operate in
both discontinuous conduction mode (DCM) at light load and
NC
LX
FB
PGND
VGH
VDD_1
VGH_M
VDD2
NC
47µF
0.47µF
C2
D1
V ON
TO ROW DRIVER
A
R1
10K
VDD
1.3K
R2
April 11, 2006
IN
FN9263.0
for