isl97645a Intersil Corporation, isl97645a Datasheet - Page 8

• Manufacturer Part Number: isl97645a
• Description: Boost + Von Slice + Vcom
• Manufacturer: Intersil Corporation

Functional Block Diagram
Applications Information
The ISL97645A provides a complete power solution for TFT
LCD applications. The system consists of one boost
converter to generate A
integrated V
current, and one supply monitor to generate the reset signal
when the input voltage is low. 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 ISL97645A is shut
down reducing the supply current to <10µA. When the
voltage at enable pin reaches 2.2V, the ISL97645A is on.
COM
buffer which can provide up to 400mA peak
V
IN
VDD
VIN
voltage for column drivers, one
8
VSHDN
RESET
FREQ-
COMP
AGND
VDPM
VFLK
NEG-
GND
POS
VIN
SS
CE
RE
FIGURE 13. FUNCTIONAL BLOCK DIAGRAM
CIRCUIT
ISL97645A
GPM
BOOST
REF
Boost Converter
Frequency Selection
The ISL97645A 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 the FREQ pin to GND 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 ISL97645A
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.
LX
FB
PGND
VGH
VDD1
VGH_M
VDD2
OUT
CD2
VDIV
V ON
VIN
V
GATE
A
VDD
IN
July 2, 2007
FN6353.0
for