EL7586 INTERSIL [Intersil Corporation], EL7586 Datasheet - Page 14

• Manufacturer Part Number: EL7586
• Description: TFT-LCD Power Supply
• Manufacturer: INTERSIL [Intersil Corporation]

The V
of the row driver in the LCD panel. The DC/DC consists of an
external diode-capacitor charge pump powered from the
inductor (LX) of the boost converter, followed by a low
dropout linear regulator (LDO_ON). The LDO_ON regulator
uses an external PNP transistor as the pass element. The
onboard LDO controller is a wide band (>10MHz)
transconductance amplifier capable of 4mA drive current,
which is sufficient for up to 40mA or more output current
under the low dropout condition (forced beta of 10). Typical
V
from +15V to +36V. A fault comparator is also included for
monitoring the output voltage. The undervoltage threshold is
set at 25% below the 1.2V reference.
The V
supply of the row driver in the LCD panel. The DC/DC
PG_LDON
ON
0.9V
PG_LDOL
0.4V
FIGURE 30. V
voltage supported by EL7586 and EL7586A ranges
FIGURE 29. V
ON
OFF
GMN
+
-
power supply is used to power the positive supply
+
GML
power supply is used to power the negative
-
+
-
+
CLAMP
-
ESD
36V
1 : Nn
1 : N1
LOGIC
LDO_OFF
OFF
LDO_LOG
FUNCTIONAL BLOCK DIAGRAM
FUNCTIONAL BLOCK DIAGRAM
FBN
DRVN
14
R
3kΩ
BN
DRVL
FBL
500Ω
R
BL
20kΩ
R
R
N2
N1
V
V
20kΩ
IN
REF
(3V TO 6V)
R
R
Q2
L1
L2
OR V
Q5
0.1µF
(1.3V TO 3.6V)
PROT
CP (TO -26V)
V
V
OFF
LOGIC
(TO -20V)
EL7586, EL7586A
LX
0.1µF
C
C
10µF
OFF
LOG
consists of an external diode-capacitor charge pump
powered from the inductor (LX) of the boost converter,
followed by a low dropout linear regulator (LDO_OFF). The
LDO_OFF regulator uses an external NPN transistor as the
pass element. The onboard LDO controller is a wide band
(>10MHz) transconductance amplifier capable of 4mA drive
current, which is sufficient for up to 40mA or more output
current under the low dropout condition (forced beta of 10).
Typical V
ranges from -5V to -20V. A fault comparator is also included
for monitoring the output voltage. The undervoltage
threshold is set at 200mV above the 0.2V reference level.
The V
within the LCD panel. The DC/DC may be powered directly
from the low voltage input, 3.3V or 5.0V, or it may be
powered through the fault protection switch. The
LDO_LOGIC regulator uses an external PNP transistor as
the pass element. The onboard LDO controller is a wide
band (>10MHz) transconductance amplifier capable of
16mA drive current, which is sufficient for up to 160mA or
more output current under the low dropout condition (forced
beta of 10). Typical V
and EL7586A ranges from +1.3V to V
comparator is also included for monitoring the output
voltage. The undervoltage threshold is set at 25% below the
1.2V reference.
Set-Up Output Voltage
Refer to the Typical Application Diagram, the output voltages
of V
equations:
V
V
V
Where V
Resistor networks in the order of 250kΩ, 120kΩ and 10kΩ
are recommended for V
Charge Pump
To generate an output voltage higher than V
multiple stages of charge pumps are needed. The number of
stage is determined by the input and output voltage. For
positive charge pump stages:
N
where V
the linear regulator. It ranges from 0.3V to 1V depending on
ON
OFF
LOGIC
POSITIVE
ON
=
LOGIC
=
, V
V
V
CE
=
REF
REF
OFF
OFF
REFN
V
≥
is the dropout voltage of the pass component of
REF
power supply is used to power the logic circuitry
V
------------------------------------------------------------- -
×
= 1.2V, V
, and V
voltage supported by EL7586 and EL7586A
OUT



+
1
V
×
+
R
--------- -
R
INPUT



22
21
+
1
R
--------- -
R
V
12
11
+
LOGIC
LOGIC
×
CE
R
--------- -
R



REFN
(
–
V
42
41
ON
–
2
REFN



V
×
, V
INPUT
are determined by the following
voltage supported by EL7586
V
= 0.2V.
OFF
F
–
V
REF
and V
)
DD
LOGIC
-0.2V. A fault
BOOST
, respectively.
October 7, 2005
, single or
FN9210.1