ISL78020 Datasheet, PDF (11/19 Pages) Intersil Corporation – Automotive Grade TFT-LCD DC/DC with Integrated Amplifiers

ISL78020, ISL78022
The current through MOSFET is limited to 3A peak. This
restricts the maximum output current based on Equation 3:
I_OMAX
=
⎝⎛^ILMT ^{– -Δ--}₂^--I--L-⎠⎞
×
V_-----I--N--
V_O
(EQ. 3)
Where ΔIL is peak to peak inductor ripple current, and is set
by Equation 4:
ΔI_L
=
-^V----^I--^N--
L
×
-^D---
f_S
(EQ. 4)
where f_S is the switching frequency.
SLOPE
COMPENSATION
CLOCK
SHUTDOWN
AND START-UP
CONTROL
I_FB
I_REF
CURRENT
AMPLIFIER
FBB
GM
AMPLIFIER
REFERENCE
GENERATOR
PWM
LX
LOGIC
BUFFER
I_FB
VOLTAGE
AMPLIFIER
I_REF
COMP
PGND
FIGURE 17. THE BLOCK DIAGRAM OF THE BOOST CONTROLLER
11
FN6386.2
December 6, 2007