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PDF MAX1543ETP Data sheet ( Hoja de datos )
| Número de pieza | MAX1543ETP | |
| Descripción | TFT LCD DC-to-DC Converter with Operational Amplifiers | |
| Fabricantes | Maxim Integrated | |
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19-2741; Rev 0; 4/03
EVAALVUAAILTAIOBNLEKIT
TFT LCD DC-to-DC Converter with
Operational Amplifiers
General Description
The MAX1542/MAX1543 include a high-performance
boost regulator and two high-current operational ampli-
fiers for active matrix, thin-film transistor (TFT), liquid-
crystal displays (LCDs). Also included is a logic-
controlled, high-voltage switch with adjustable delay.
The MAX1543 includes an additional high-voltage load
switch and features pin-selectable boost regulator
switching frequency.
The step-up DC-to-DC converter is a high-frequency
640kHz (MAX1543)/1.2MHz (MAX1542/MAX1543) cur-
rent-mode regulator with a built-in power MOSFET that
allows the use of ultra-small inductors and ceramic
capacitors. It provides fast transient response to pulsed
loads while producing efficiencies over 85%.
The two easy-to-use, high-performance operational
amplifiers can drive the LCD backplane (VCOM) and/or
the gamma correction divider string. The devices fea-
ture high short-circuit current (150mA), fast slew rate
(7.5V/µs), wide bandwidth (12MHz), and Rail-to-Rail®
inputs and outputs.
The MAX1542/MAX1543 are available in 20-pin thin
QFN packages with a maximum thickness of 0.8mm for
ultra-thin LCD panel design.
Applications
Notebook Computer Displays
LCD Monitor Panels
PDAs
Car Navigation Displays
Pin Configurations
TOP VIEW
COM
SRC
I.C.
PGND
AGND
1
2
3
4
5
MAX1543
15 FREQ
14 IN
13 LX
12 SUP
11 POS2
Features
o Ultra-High-Performance Step-Up Regulator
Fast Transient Response to Pulsed Load Using
Current-Mode Control Architecture
High-Accuracy Output Voltage (1.3%)
Built-In 14V, 1.2A, 0.2Ω N-Channel Power
MOSFET with Lossless Current-Sensing
High Efficiency (85%)
8-Step Current-Controlled Digital Soft-Start
o Two High-Performance Operational Amplifiers
150mA Output Short-Circuit Current
7.5V/µs Slew Rate
12MHz -3dB Bandwidth
Rail-to-Rail Inputs/Outputs
Unity Gain Stable
o Logic-Controlled High-Voltage Switch with
Adjustable Delay
o Timer Delay Latch FB Fault Protection
o Thermal Protection
o 2.6V to 5.5V Input Operating Voltage Range
o 3.6mA (Switching), 0.45mA (Not Switching)
Quiescent Current
o Ultra-Thin 20-Pin Thin QFN Package
(5mm x 5mm x 0.8mm)
Ordering Information
PART
MAX1542ETP
MAX1543ETP
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 Thin QFN (5mm x 5mm)
20 Thin QFN (5mm x 5mm)
THIN QFN (5mm x 5mm)
Pin Configurations continued at end of data sheet.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
TFT LCD DC-to-DC Converter with
Operational Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 3V, VSUP = 8V, VSRC = 28V, FREQ = IN (MAX1543), PGND = AGND = 0, TA = -40°C to +85°C, unless otherwise noted.)
PARAMETER
LX Current Limit
Current-Sense Transresistance
OPERATIONAL AMPLIFIERS
SUP Supply Range
SUP Supply Current
Input Offset Voltage
Input Bias Current
Input Common-Mode Voltage
Range
SYMBOL
CONDITIONS
ILIM VFB = 1V, duty cycle = 65%
VSUP
ISUP
VOS
IBIAS
VCM
Buffer configuration, VPOS_ = 4V, no load
VCM = VSUP/2, TA = +25ºC
NEG1, NEG2, POS1, POS2
MIN
1.2
0.30
TYP
MAX
1.8
0.65
UNITS
A
Ω
4.5 13.0 V
2.1 mA
12 mV
±50 nA
0
VSUP
V
Output Voltage Swing High
Output Voltage Swing Low
Short-Circuit Current
VOH
VOL
IOUT_ = 100µA
IOUT_ = 5mA
IOUT_ = -100µA
IOUT_ = -5mA
To VSUP/2
Source
Sink
VSUP -
15
VSUP -
150
50
50
mV
15
mV
150
mA
Output Source-and-Sink Current
Buffer configuration, VPOS_ = 4V,
| ∆VOS | < 10mV
POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES
DEL Capacitor Charge Current
DEL Turn-On Threshold
CTL Input Low Voltage
CTL Input High Voltage
SRC Input Voltage Range
VTH (DEL)
During startup, VDEL = 1.0V
VIN = 2.6V to 5.5V
VIN = 2.6V to 5.5V
SRC Input Current
ISRC
VDRN = 8V, CTL = IN, MAX1542
VDEL = 1.5V
MAX1543
VDRN = 8V, CTL = AGND, VDEL = 1.5V
DRN Input Current
IDRN
VDRN = 8V, CTL = AGND, VDEL = 1.5V,
MAX1543
SRC to COM Switch On-
Resistance
MAX1542
RSRC(ON) VDEL = 1.5V, CTL = IN MAX1543
40
4
1.178
2
mA
6
1.302
0.6
28
130
180
30
150
10
30
µA
V
V
V
V
µA
µA
Ω
DRN to COM Switch On-
Resistance (MAX1543)
RDRN(ON) VDEL = 1.5V, CTL = AGND
60 Ω
COM to PGND Switch On-
Resistance (MAX1543)
RCOM(ON) VDEL = 1.1V
350
1800
Ω
_______________________________________________________________________________________ 5
5 Page 
TFT LCD DC-to-DC Converter with
Operational Amplifiers
Table 1. Component List
DESIGNATION
C1
C8, C9
D1
D2, D3, D4
L1
DESCRIPTION
10µF ±10%, 6.3V X5R ceramic capacitor
4.7µF ±10%, 10V X5R ceramic capacitors
1A, 30V Schottky diode
200mA, 100V dual ultra-fast diodes
4.7µH, 1.3A inductor
PART
TDK C3216X5R0J106K
TDK C3225X5R1A475K
Toshiba CRS02
Fairchild MMBD4148SE
Sumida CLS5D11HP-4R7
Table 2. Component Suppliers
SUPPLIER
Inductors
Sumida USA
Capacitors
TDK
Diodes
Fairchild
Toshiba
PHONE
847-956-0666
847-803-6100
888-522-5372
949-455-2000
FAX
847-956-0702
847-803-6296
408-822-2104
949-859-3963
WEBSITE
www.sumida.com
www.component.tdk.com
www.fairchildsemi.com
www.toshiba.com/taec/
The regulator controls the output voltage and the power
delivered to the outputs by modulating the duty cycle
(D) of the power MOSFET in each switching cycle. The
duty cycle of the MOSFET is approximated by:
D ≈ VMAIN − VIN
VMAIN
The device regulates the output voltage through a com-
bination of an error amplifier, two comparators, and
several signal generators (Figure 3). The error amplifier
compares the signal at FB to 1.24V and varies the
COMP output. The voltage at COMP determines the
current trip point each time the internal MOSFET turns
on. As the load varies, the error amplifier sources or
sinks current to the COMP output accordingly to pro-
duce the inductor peak current necessary to service
the load. To maintain stability at high duty cycles, a
slope compensation signal is summed with the current-
sense signal.
Operational Amplifiers
The MAX1542/MAX1543 include two operational ampli-
fiers that are typically used to drive the LCD backplane
VCOM and/or the gamma correction divider string. The
operational amplifiers feature ±150mA output short-cir-
cuit current, 7.5V/µs slew rate, and 12MHz bandwidth.
The rail-to-rail inputs and outputs maximize flexibility.
Short-Circuit Current Limit
The MAX1542/MAX1543 operational amplifiers limit
short-circuit current to ±150mA if the output is directly
shorted to SUP or AGND. In such a condition, the junc-
tion temperature of the IC rises until it reaches the ther-
mal shutdown threshold, typically +160°C. Once it
reaches this threshold, the IC shuts down and remains
inactive until IN falls below VUVLO.
Driving Pure Capacitive Loads
The operational amplifiers are typically used to drive
the LCD backplane (VCOM) or the gamma correction
divider string. The LCD backplane consists of a distrib-
uted series capacitance and resistance, a load easily
driven by the operational amplifiers. However, if the
operational amplifiers are used in an application with a
pure capacitive load, steps must be taken to ensure
stable operation.
As the operational amplifier’s capacitive load increases,
the amplifier bandwidth decreases and gain peaking
increases. A small 5Ω to 50Ω resistance placed between
OUT_ and the capacitive load reduces peaking but
reduces the amplifier gain. An alternative method of
reducing peaking is the use of a snubber circuit. A 150Ω
and 10nF (typ) shunt load, or snubber, does not continu-
ously load the output or reduce amplifier gain.
______________________________________________________________________________________ 11
11 Page | ||
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| PDF Descargar | [ Datasheet MAX1543ETP.PDF ] | |
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