19-2741; Rev 0; 4/03
KIT
ATION
EVALU
BLE
AVAILA
TFT LCD DC-to-DC Converter with
Operational Amplifiers
General Description
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)
MAX1542/MAX1543
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 (V
COM
) 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
DRN
CTL
DEL
FB
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)
TOP VIEW
20
19
18
17
COMP
COM
SRC
I.C.
PGND
AGND
1
2
3
4
5
NEG2 10
16
15
14
FREQ
IN
LX
SUP
POS2
MAX1543
13
12
11
6
7
8
OUT1
POS1
THIN QFN (5mm x 5mm)
Pin Configurations continued at end of data sheet.
NEG1
OUT2
9
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
1
________________________________________________________________
Maxim Integrated Products
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.
TFT LCD DC-to-DC Converter with
Operational Amplifiers
MAX1542/MAX1543
ABSOLUTE MAXIMUM RATINGS
IN, CTL, COMP, FB, DEL, FREQ (MAX1543)
to AGND ...............................................................-0.3V to +6V
COMP, FB, DEL to AGND .............................-0.3V to (IN + 0.3V)
PGND to AGND ..................................................................±0.3V
LX to PGND ............................................................-0.3V to +14V
SUP, POS1, NEG1, OUT1, POS2,
NEG2, OUT2 to AGND .......................................-0.3V to +14V
POS1, NEG1, OUT1, POS2, NEG2,
OUT2 to AGND ......................................-0.3V to (SUP + 0.3V)
SRC, COM to AGND...............................................-0.3V to +30V
SRC to COM ...........................................................-0.3V to +30V
SRC to DRN (MAX1543).........................................-0.3V to +30V
COM to AGND ...........................................-0.3V to (SRC + 0.3V)
DRN (MAX1543) to AGND .........................-0.3V to (SRC + 0.3V)
DRN (MAX1543) to COM.........................................-30V to +30V
MAX1542 COM RMS Output Current ...............................+75mA
MAX1543 COM RMS Output Current ...............................±50mA
OUT1, OUT2 Continuous Output Current.........................±75mA
Continuous Power Dissipation (T
A
= +70°C)
20-Pin Thin QFN 5mm x 5mm
(derate 20.8mW/°C above +70°C) .............................1667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
IN
= 3V, V
SUP
= 8V, V
SRC
= 28V, FREQ = IN (MAX1543), PGND = AGND = 0,
T
A
= 0°C to +85°C,
typical values at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
IN Supply Range
IN Undervoltage Lockout
Threshold
IN Quiescent Current
Duration to Trigger Fault
Condition
Thermal Shutdown
MAIN STEP-UP REGULATOR
Output Voltage Range
Operating Frequency
Oscillator Maximum Duty Cycle
FREQ Input Low Voltage
FREQ Input High Voltage
FREQ Pulldown Current
FB Regulation Voltage
FB Fault Trip Level
FB Load Regulation
FB Line Regulation
V
FB
MAX1543, V
IN
= 2.6V to 5.5V
MAX1543, V
IN
= 2.6V to 5.5V
MAX1543, V
FREQ
= 1.0V
No load
V
FB
falling
0
≤
I
MAIN
≤
full load
V
IN
= 2.6V to 5.5V
T
A
= +85°C
T
A
= 0°C to +85°C
0.7 x
V
IN
3.5
1.224
1.222
0.96
5
1.240
1.240
1
-1
-0.08
±0.15
6.5
1.256
1.258
1.04
V
MAIN
MAX1542
f
OSC
MAX1543
FREQ = AGND
FREQ = IN
V
IN
1020
512
1020
82
1200
600
1200
87
13
1380
768
1380
92
0.3 x V
IN
%
V
V
µA
V
V
%
%/V
kHz
V
SYMBOL
V
IN
V
UVLO
I
IN
V
IN
rising
V
IN
falling
V
FB
= 1.3V, LX not switching
V
FB
= 1.1V, LX switching
MAX1542
MAX1543
Rising edge
Hysteresis
FREQ = AGND
FREQ = IN
CONDITIONS
MIN
2.6
2.3
2.2
2.5
2.35
0.45
3.6
55
51
55
160
15
°C
ms
TYP
MAX
5.5
2.7
2.5
0.65
6.5
UNITS
V
V
mA
2
_______________________________________________________________________________________
TFT LCD DC-to-DC Converter with
Operational Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3V, V
SUP
= 8V, V
SRC
= 28V, FREQ = IN (MAX1543), PGND = AGND = 0,
T
A
= 0°C to +85°C,
typical values at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
FB Input Bias Current
FB Transconductance
FB Voltage Gain
LX On-Resistance
LX Leakage Current
LX Current Limit
Current-Sense Transresistance
MAX1542
Soft-Start Period
Soft-Start Step Size
OPERATIONAL AMPLIFIERS
SUP Supply Range
SUP Supply Current
Input Offset Voltage
Input Bias Current
Input Common-Mode Voltage
Range
Common-Mode Rejection Ratio
Open-Loop Gain
I
OUT_
= 100µA
Output Voltage Swing High
V
OH
I
OUT_
= 5mA
Output Voltage Swing Low
Short-Circuit Current
Output Source-and-Sink Current
Power-Supply Rejection Ratio
Slew Rate
-3dB Bandwidth
Gain-Bandwidth Product
GBW
R
L
= 10kΩ, C
L
=10pF, buffer configuration
Buffer configuration
PSRR
V
OL
I
OUT_
= -100µA
I
OUT_
= -5mA
To V
SUP
/2
Source
Sink
50
50
40
60
100
7.5
12
8
V
SUP
-
15
V
SUP
-
150
V
SUP
I
SUP
V
OS
I
BIAS
V
CM
CMRR
0
≤
V
NEG_
, V
POS_
≤
V
SUP
Buffer configuration, V
POS_
= 4V, no load
V
CM
= V
SUP
/2, T
A
= +25°C
NEG1, NEG2, POS1, POS2
0
50
90
125
V
SUP
-
2
mV
V
SUP
-
80
2
80
150
140
15
150
mV
mA
mA
dB
V/µs
MHz
MHz
4.5
1.3
0
+1
13.0
1.9
12
±50
V
SUP
V
mA
mV
nA
V
dB
dB
t
SS
MAX1543
FREQ = AGND
FREQ = IN
R
LX(ON)
I
LX
I
LIM
V
LX
= 13V
V
FB
= 1V, duty cycle = 65%
1.2
0.30
SYMBOL
V
FB
= 1.5V
∆I
COMP
= 5µA
FB to COMP
CONDITIONS
MIN
-40
75
160
700
210
0.01
1.5
0.50
14
13
14
I
LIM
/ 8
A
ms
400
20
1.8
0.65
TYP
MAX
+40
280
UNITS
nA
µS
V/V
mΩ
µA
A
Ω
MAX1542/MAX1543
Buffer configuration, V
POS_
= 4V,
|∆V
OS|
< 10mV
DC, 6V
≤
V
SUP
≤
13V, V
NEG_
, V
POS_
=
V
SUP
/2
POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES
DEL Capacitor Charge Current
During startup, V
DEL
= 1V
4
5
6
µA
_______________________________________________________________________________________
3
TFT LCD DC-to-DC Converter with
Operational Amplifiers
MAX1542/MAX1543
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3V, V
SUP
= 8V, V
SRC
= 28V, FREQ = IN (MAX1543), PGND = AGND = 0,
T
A
= 0°C to +85°C,
typical values at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
DEL Turn-On Threshold
DEL Discharge Switch On-
Resistance
CTL Input Low Voltage
CTL Input High Voltage
CTL Input Leakage Current
CTL-to-SRC Propagation Delay
SRC Input Voltage Range
SRC Input Current
I
SRC
V
DRN
= 8V, CTL = IN,
V
DEL
= 1.5V
MAX1542
MAX1543
70
100
15
90
5
15
30
350
1000
SYMBOL
V
TH(DEL)
During UVLO, V
IN
= 2.2V
V
IN
= 2.6V to 5.5V
V
IN
= 2.6V to 5.5V
CTL = AGND or IN
2
-1
100
28
130
180
30
150
10
30
60
1800
µA
Ω
Ω
Ω
µA
+1
CONDITIONS
MIN
1.178
TYP
1.240
20
0.6
MAX
1.302
UNITS
V
Ω
V
V
µA
ns
V
V
DRN
= 8V, CTL = AGND, V
DEL
= 1.5V
DRN Input Current
SRC to COM Switch On-
Resistance
DRN to COM Switch On-
Resistance (MAX1543)
COM to PGND Switch On-
Resistance (MAX1543)
I
DRC
R
SRC(ON)
R
DRN(ON)
R
COM(ON)
V
DRN
= 8V, CTL = AGND, V
DEL
= 1.5V,
MAX1543
V
DEL
= 1.5V,
CTL = IN
MAX1542
MAX1543
V
DEL
= 1.5V, CTL = AGND
V
DEL
= 1.1V
ELECTRICAL CHARACTERISTICS
(V
IN
= 3V, V
SUP
= 8V, V
SRC
= 28V, FREQ = IN (MAX1543), PGND = AGND = 0,
T
A
= -40°C to +85°C,
unless otherwise noted.)
PARAMETER
IN Supply Range
IN Undervoltage Lockout
Threshold
IN Quiescent Current
MAIN STEP-UP REGULATOR
Output Voltage Range
Operating Frequency
FB Regulation Voltage
FB Fault Trip Level
FB Line Regulation
FB Transconductance
LX On-Resistance
R
LX(ON)
V
MAIN
MAX1542
f
OSC
V
FB
MAX1543
No load
V
FB
falling
V
IN
= 2.6V to 5.5V
∆I
COMP
= 5µA
75
FREQ = AGND
FREQ = IN
V
IN
1000
512
1000
1.215
0.96
13
1400
768
1400
1.260
1.04
0.15
300
400
V
V
%/V
µS
mΩ
kHz
V
SYMBOL
V
IN
V
UVLO
I
IN
V
IN
rising
V
IN
falling
V
FB
= 1.3V, LX not switching
V
FB
= 1.1V, LX switching
CONDITIONS
MIN
2.6
2.3
2.2
TYP
MAX
5.5
2.7
2.5
0.65
6.5
UNITS
V
V
mA
4
_______________________________________________________________________________________
TFT LCD DC-to-DC Converter with
Operational Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3V, V
SUP
= 8V, V
SRC
= 28V, FREQ = IN (MAX1543), PGND = AGND = 0,
T
A
= -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
V
SUP
I
SUP
V
OS
I
BIAS
V
CM
I
OUT_
= 100µA
Output Voltage Swing High
V
OH
I
OUT_
= 5mA
Output Voltage Swing Low
Short-Circuit Current
Output Source-and-Sink Current
V
OL
I
OUT_
= -100µA
I
OUT_
= -5mA
To V
SUP
/2
Source
Sink
50
50
40
Buffer configuration, V
POS_
= 4V, no load
V
CM
= V
SUP
/2, T
A
= +25ºC
NEG1, NEG2, POS1, POS2
0
V
SUP
-
15
mV
V
SUP
-
150
15
150
mV
mA
mA
4.5
13.0
2.1
12
±50
V
SUP
V
mA
mV
nA
V
SYMBOL
I
LIM
CONDITIONS
V
FB
= 1V, duty cycle = 65%
MIN
1.2
0.30
TYP
MAX
1.8
0.65
UNITS
A
Ω
MAX1542/MAX1543
Buffer configuration, V
POS_
= 4V,
|
∆V
OS
| < 10mV
During startup, V
DEL
= 1.0V
V
TH (DEL)
V
IN
= 2.6V to 5.5V
V
IN
= 2.6V to 5.5V
V
DRN
= 8V, CTL = IN,
V
DEL
= 1.5V
MAX1542
MAX1543
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
SRC Input Current
I
SRC
4
1.178
2
28
130
180
30
150
10
30
60
350
1800
µA
Ω
Ω
Ω
µA
6
1.302
0.6
µA
V
V
V
V
V
DRN
= 8V, CTL = AGND, V
DEL
= 1.5V
DRN Input Current
SRC to COM Switch On-
Resistance
DRN to COM Switch On-
Resistance (MAX1543)
COM to PGND Switch On-
Resistance (MAX1543)
I
DRN
R
SRC(ON)
R
DRN(ON)
R
COM(ON)
V
DRN
= 8V, CTL = AGND, V
DEL
= 1.5V,
MAX1543
V
DEL
= 1.5V, CTL = IN
MAX1542
MAX1543
V
DEL
= 1.5V, CTL = AGND
V
DEL
= 1.1V
_______________________________________________________________________________________
5
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