EL7640 INTERSIL [Intersil Corporation], EL7640 Datasheet - Page 11

• Manufacturer Part Number: EL7640
• Description: TFT-LCD DC/DC with Integrated Amplifiers
• Manufacturer: INTERSIL [Intersil Corporation]

The current through MOSFET is limited to 3A peak. This
restricts the maximum output current based on the following
equation:
I
OMAX
=


I
LMT
–
∆I
--------
2
L


FBB
×
V
---------
V
IN
O
I
I
FB
REF
11
FIGURE 18. THE BLOCK DIAGRAM OF THE BOOST CONTROLLER
COMPENSATION
AMPLIFIER
AMPLIFIER
CURRENT
GENERATOR
REFERENCE
GM
SLOPE
EL7640, EL7641, EL7642
COMP
CLOCK
Where ∆I L is peak to peak inductor ripple current, and is set
by:
where f
∆I
AMPLIFIER
VOLTAGE
LOGIC
PWM
L
=
V
---------
S
L
IN
is the switching frequency.
×
---- -
f
D
S
SHUTDOWN
& STARTUP
BUFFER
CONTROL
I
REF
I
FB
PGND
LX
September 26, 2005
FN7415.1