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EL7586A Schematic ( PDF Datasheet ) - Intersil Corporation

Teilenummer EL7586A
Beschreibung TFT-LCD Power Supply
Hersteller Intersil Corporation
Logo Intersil Corporation Logo 




Gesamt 21 Seiten
EL7586A Datasheet, Funktion
®
Data Sheet
EL7586, EL7586A
January 17, 2006
FN9210.2
TFT-LCD Power Supply
The EL7586 and EL7586A represent multiple output
regulators for use in all large panel, TFT-LCD applications.
Both feature a single boost converter with an integrated 2A
FET, two positive LDOs for VON and VLOGIC generation,
and a single negative LDO for VOFF generation. The boost
converter can be programmed to operate in either P-mode
or PI-mode for improved load regulation.
Both EL7586 and EL7586A also integrate fault protection for
all four channels. Once a fault is detected, the device is
latched off until the input supply or EN is cycled. EL7586
also features an integrated start-up sequence for
VBOOST/VLOGIC, VOFF, then VON or for VLOGIC, VOFF,
VBOOST, and VON. The latter requires a single external
transistor. The timing of the start-up sequence is set using
an external capacitor.
EL7586A features an immediately-enabled VLOGIC output
which is independent of EN input. The VLOGIC output will be
switched off if a fault is detected and the power supply needs
to be recycled to reset this condition.
Both the EL7586 and EL7586A are pin-compatible, come in
the 20 Ld 4x4 QFN package, and are specified for operation
over the -40°C to +85°C temperature range.
Ordering Information
PART TAPE &
PART NUMBER MARKING REEL PACKAGE
PKG.
DWG. #
EL7586ILZ
(Note)
7586ILZ
- 20 Ld 4x4 QFN MDP0046
(Pb-free)
EL7586ILZ-T7 7586ILZ
(Note)
7” 20 Ld 4x4 QFN MDP0046
(Pb-free)
EL7586ILZ-T13 7586ILZ
(Note)
13” 20 Ld 4x4 QFN MDP0046
(Pb-free)
EL7586AILZ
(Note)
7586AIL Z
- 20 Ld 4x4 QFN MDP0046
(Pb-free)
EL7586AILZ-T7 7586AIL Z
(Note)
7” 20 Ld 4x4 QFN MDP0046
(Pb-free)
EL7586AILZ-T13 7586AIL Z
(Note)
13” 20 Ld 4x4 QFN MDP0046
(Pb-free)
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are RoHS compliant and
compatible with both SnPb and Pb-free soldering operations. Intersil
Pb-free products are MSL classified at Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
Features
• 2A current limit FET options
• 3V to 5V input
• Up to 20V boost out
• 1% regulation on all outputs
• VLOGIC-VOFF-VBOOST-VON or
VBOOST/VLOGIC-VOFF-VON sequence control
- VLOGIC is on from start-up for EL7586A
• Programmable sequence delay
• Fully fault protected
• Thermal shutdown
• Internal soft-start
• 20 Ld 4x4 QFN packages
• Pb-free plus anneal available (RoHS compliant)
Applications
• LCD monitors (15”+)
• LCD-TV (up to 40”+)
• Notebook displays (up to 16”)
• Industrial/medical LCD displays
Pinout
EL7586, EL7586A
(20 LD 4X4 QFN)
TOP VIEW
CDLY 1
DELB 2
LX1 3
LX2 4
DRVP 5
THERMAL
PAD
15 CINT
14 VREF
13 PGND
12 PGND
11 FBN
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2005, 2006. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.






EL7586A Datasheet, Funktion
EL7586, EL7586A
Typical Performance Curves (Continued)
0
-0.5
-1.0
-1.5
-2.0
-2.5 AVDD=15V
-3.0
AVDD=9V
-3.5
-4.0
0
AVDD=12V
100 200 300 400 500
IOUT (mA)
FIGURE 7. VBOOST LOAD REGULATION AT VIN = 3V (P MODE)
0
-1
-2
AVDD=9V
-3
-4
AVDD=15V
AVDD=12V
-5 0 200 400 600 800
IOUT (mA)
FIGURE 8. VBOOST LOAD REGULATION AT VIN = 5V (P MODE)
0.05
0.04
0.03
0.02
0.01
0
-0.01
-0.02
3.0 3.5 4.0 4.5 5.0 5.5 6.0
VIN (V)
FIGURE 9. VBOOST LINE REGULATION (PI MODE)
0
-0.5
-1.0
1.5
-2.0
-2.53.0 3.5 4.0 4.5 5.0 5.5 6.0
VIN (V)
FIGURE 10. VBOOST LINE REGULATION (P MODE)
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
0
20 40 60
IOUT (mA)
80
FIGURE 11. VON LOAD REGULATION
0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
0
20 40 60 80 100
IOUT (mA)
FIGURE 12. VOFF LOAD REGULATION
6 FN9210.2
January 17, 2006

6 Page









EL7586A pdf, datenblatt
EL7586, EL7586A
The following table gives typical values (margins are
considered 10%, 3%, 20%, 10%, and 15% on VIN, VO, L, fS,
and IOMAX:
TABLE 2.
VIN (V)
3.3
VO (V)
9
L (µH)
6.8
fS
(MHz)
1
IOMAX
(EL7586, EL7586A)
0.490686
3.3 12 6.8
1
0.307353
3.3 15 6.8
1
0.197353
5 9 6.8 1
0.743464
5
12 6.8
1
0.465686
5
15 6.8
1
0.29902
Input Capacitor
An input capacitor is used to supply the peak charging
current to the converter. It is recommended that CIN be
larger than 10µF. The reflected ripple voltage will be smaller
with larger CIN. The voltage rating of input capacitor should
be larger than maximum input voltage.
Boost Inductor
The boost inductor is a critical part which influences the
output voltage ripple, transient response, and efficiency.
Values of 3.3µH to 10µH are to match the internal slope
compensation. The inductor must be able to handle the
following average and peak current:
ILAVG = 1----I-–-O----D---
ILPK = ILAVG + ---2--I--L-
Rectifier Diode
A high-speed diode is necessary due to the high switching
frequency. Schottky diodes are recommended because of
their fast recovery time and low forward voltage. The rectifier
diode must meet the output current and peak inductor
current requirements.
Output Capacitor
The output capacitor supplies the load directly and reduces
the ripple voltage at the output. Output ripple voltage
consists of two components: the voltage drop due to the
inductor ripple current flowing through the ESR of output
capacitor, and the charging and discharging of the output
capacitor.
VRIPPLE = ILPK × ESR + -V----O---V--–---O--V----I--N-- × C-----O-I--O--U----T- × -f-1S--
For low ESR ceramic capacitors, the output ripple is
dominated by the charging and discharging of the output
capacitor. The voltage rating of the output capacitor should
be greater than the maximum output voltage.
NOTE: Capacitors have a voltage coefficient that makes their
effective capacitance drop as the voltage across them increases.
COUT in the equation above assumes the effective value of the
capacitor at a particular voltage and not the manufacturer’s stated
value, measured at zero volts.
Compensation
The EL7586, and EL7586A can operate in either P mode or
PI mode. Connecting the CINT pin directly to VIN will enable
P mode; For better load regulation, use PI mode with a
4.7nF capacitor in series with a 10K resistor between CINT
and ground. This value may be reduced to improve transient
performance, however, very low values will reduce loop
stability.
Boost Feedback Resistors
As the boost output voltage, AVDD, is reduced below 12V the
effective voltage feedback in the IC increases the ratio of
voltage to current feedback at the summing comparator
because R2 decreases relative to R1. To maintain stable
operation over the complete current range of the IC, the
voltage feedback to the FBB pin should be reduced
proportionally, as AVDD is reduced, by means of a series
resistor-capacitor network (R7 and C7) in parallel with R1,
with a pole frequency (fp) set to approximately 10kHz for C2
effective = 10µF and 4kHz for C2 (effective) = 30µF.
R7 = ((1/0.1 x R2) - 1/R1)^-1
C7 = 1/(2 x 3.142 x fp x R7)
PI Mode CINT (C23) and RINT (R10)
The IC is designed to operate with a minimum C23 capacitor
of 4.7nF and a minimum C2 (effective) = 10µF.
Note that, for high voltage AVDD, the voltage coefficient of
ceramic capacitors (C2) reduces their effective capacitance
greatly; a 16V 10µF ceramic can drop to around 3µF at 15V.
To improve the transient load response of AVDD in PI mode,
a resistor may be added in series with the C23 capacitor. The
larger the resistor the lower the overshoot but at the expense
of stability of the converter loop - especially at high currents.
With L = 10µH, AVDD = 15V, C23 = 4.7nF, C2 (effective)
should have a capacitance of greater than 10µF. RINT (R7)
can have values up to 5kfor C2 (effective) up to 20µF and
up to 10K for C2 (effective) up to 30µF.
Larger values of RINT (R7) may be possible if maximum
AVDD load currents less than the current limit are used. To
ensure AVDD stability, the IC should be operated at the
maximum desired current and then the transient load
response of AVDD should be used to determine the
maximum value of RINT.
12 FN9210.2
January 17, 2006

12 Page





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