ISL78022 Intersil Corporation, ISL78022 Datasheet - Page 11

• Manufacturer Part Number: ISL78022
• Description: (ISL78020 / ISL78022) Automotive Grade TFT-LCD DC/DC
• Manufacturer: Intersil Corporation

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The current through MOSFET is limited to 3A peak. This
restricts the maximum output current based on Equation 3:
I
OMAX
=
⎛
⎝
I
LMT
–
ΔI
--------
2
L
⎞
⎠
FBB
×
V
---------
V
IN
O
I
I
FB
REF
11
FIGURE 17. THE BLOCK DIAGRAM OF THE BOOST CONTROLLER
COMPENSATION
AMPLIFIER
AMPLIFIER
CURRENT
GENERATOR
REFERENCE
GM
SLOPE
ISL78020, ISL78022
COMP
(EQ. 3)
CLOCK
Where ΔI L is peak to peak inductor ripple current, and is set
by Equation 4:
where f
ΔI
AMPLIFIER
VOLTAGE
LOGIC
PWM
L
=
V
---------
S
L
IN
is the switching frequency.
×
---- -
f
D
S
AND START-UP
SHUTDOWN
BUFFER
CONTROL
I
REF
I
FB
PGND
LX
December 6, 2007
FN6386.2
(EQ. 4)