isl97645a Intersil Corporation, isl97645a Datasheet - Page 13

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

Start-Up Sequence
When V
threshold value, Boost converter starts up, and gate pulse
modulator circuit output holds until VDPM is charged to
1.215V. Note that there is a DC path in the boost converter
from the input to the output through the inductor and diode,
hence the input voltage will be seen at output with a forward
voltage drop of diode before the part is enabled. If this
voltage is not desired, the following circuit can be inserted
between input and inductor to disconnect the DC path when
the part is disabled.
IN
>VLOR
>VLOR
V
exceeds VLOR and ENABLE reaches the VIH
x
x
x
IN
U V LO
T hreshold
V G H _M
R E S E T
V D P M
V G H
V in
V FL K
0
13
<1.215V
<1.215V
>1.215V
VDPM
x
x
FIGURE 17. GATE PULSE MODULATOR TIMING DIAGRAM
V G H
P ow er on dela y tim e is
co ntrolled b y C
V G L
TABLE 6. VGH_M STATUS TABLE
D P M
RESET
High
High
Low
x
x
ISL97645A
S lope is controlled
b y R E
.
FIGURE 18. CIRCUIT TO DISCONNECT THE DC PATH OF
TO INDUCTOR
<2.5V
>2.5V
>2.5V
>2.5V
>2.5V
VGH
D ela y tim e is
controlled b y C E
ENABLE
BOOST CONVERTER
GROUND
GROUND
GROUND
Switching
controlled by
VFLK
VGH
VGH_M
1.215V
V G H _M is forced to
V G H w h en R E S E T
goes to low A N D
V G H >2.5V
Will be grounded if VIN is above
a logic threshold. Could occur at
power up or power down
Startup only condition:If either
V
VDPM < 1.215V, GND VGHM
Power down state. Could occur
at power up if part starts with
VGH > 2.5V
IN
> VLOR or reset is H, but
COMMENT
July 2, 2007
INPUT
FN6353.0