EVALUATION KIT AVAILABLE
MAX8739
TFT, LCD, DC-DC Converter with
Operational Amplifiers
General Description
The MAX8739 includes a high-performance, step-up
regulator and two high-current operational amplifiers
for active-matrix thin-film transistor (TFT) liquid-crystal
displays (LCDs). The input supply voltage range of
the MAX8739 is from 1.8V to 5.5V. The device also
includes a logic-controlled, high-voltage switch with
adjustable delay.
The step-up DC-DC converter provides the regulated
supply voltage for the panel source driver ICs. The con-
verter is a high-frequency (600kHz/1.2MHz) current-mode
regulator with an integrated 14V n-channel MOSFET
that allows the use of ultra-small inductors and ceramic
capacitors. It provides fast transient response to pulsed
loads while achieving efficiencies over 85%.
The two high-performance operational amplifiers are
designed to drive the LCD backplane (VCOM) and/or the
gamma-correction-divider string. The devices feature high
output current (±150mA), fast slew rate (7.5V/µs), wide
bandwidth (12MHz), and rail-to-rail inputs and outputs.
The MAX8739 is available in a 20-pin, 5mm x 5mm TQFN
package with a maximum thickness of 0.8mm for ultra-
thin LCD panels.
Features
●
1.8V to 5.5V Input Supply Range
●
600kHz/1.2MHz Current-Mode Step-Up Regulator
• Fast Transient Response to Pulsed Load
• High-Accuracy Output Voltage (1.5%)
•
Built-In 14V, 1.9A, 0.2Ω n-Channel MOSFET
•
High Efficiency (> 85%)
• Digital Soft-Start
●
Two High-Performance Operational Amplifiers
• ±150mA Output Short-Circuit Current
• 7.5V/µs Slew Rate
• 12MHz, -3dB Bandwidth
• Rail-to-Rail Inputs/Outputs
●
Logic-Controlled, High-Voltage Switch with Adjustable
Delay
●
Built-In Power-Up Sequence
●
Input Supply Undervoltage Lockout
●
Timer Delay Fault Latch for All Regulator Outputs
●
Thermal-Overload Protection
Simplified Operating Circuit
V
IN
+1.8V TO +5.5V
LX
IN
MAX8739
FREQ
AGND
PGND
SUP
NEG1
TO VCOM
BACKPLANE
OUT1
NEG2
OUT2
LDO
POS1
POS2
FB
V
MAIN
Applications
●
Notebook Computer Displays
●
LCD Monitor Panels
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX8739ETP+
-40°C to +85°C
20 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pads.
COMP
Pin Configuration appears at end of data sheet.
FROM TCON
DEL
SRC
DRN
COM
CTL
19-3983; Rev 1; 7/14
MAX8739
TFT, LCD, DC-DC Converter with
Operational Amplifiers
Absolute Maximum Ratings
IN, CTL, FREQ, LDO to AGND ...............................-0.3V to +6V
COMP, FB, DEL to AGND ...................... -0.3V to (V
LDO
+ 0.3V)
PGND to AGND ..................................................................±0.3V
LX to PGND...........................................................-0.3V to +14V
SUP to AGND ........................................................-0.3V to +14V
POS1, POS2, NEG1, NEG2, OUT1,
OUT2 to AGND ................................... -0.3V to (V
SUP
+ 0.3V)
SRC to AGND........................................................-0.3V to +30V
COM, DRN to AGND .............................. -0.3V to (V
SRC
+ 0.3V)
COM RMS Output Current ...............................................±50mA
OUT1, OUT2 Maximum Continuous Output Current .......±75mA
LX Switch Maximum Continuous RMS Output Current .......1.6A
Continuous Power Dissipation (T
A
= +70°C)
20-Pin, 5mm x 5mm, TQFN (derate 20.8mW/°C
above +70°C) ............................................................1667mW
Operating Temperature Range ........................... -40°C to +85°C
Junction Temperature .........................................................+150°
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
= 2.5V, V
SUP
= 10V, V
SRC
= 28V, FREQ = CTL = IN, PGND = AGND = 0,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
IN Supply Range
IN Quiescent Current
IN Undervoltage Lockout
Threshold
LDO Output Voltage
LDO Undervoltage Lockout
Threshold
LDO Output Current
SUP Supply Voltage Range
SUP Undervoltage Fault
Threshold
SUP Supply Current
Thermal Shutdown
STEP-UP REGULATOR
Operating Frequency
Maximum Duty Cycle
FREQ Input Low Voltage
FREQ Input High Voltage
FREQ Pulldown Current
FB Regulation Voltage
FB Fault Trip Level
Duration to Trigger Fault
Condition
FREQ = AGND
FREQ = IN
FREQ = AGND
FREQ = IN
V
IN
= 1.8V to 5.5V
V
IN
= 1.8V to 2.4V
V
IN
= 2.4V to 5.5V
V
FREQ
= 1.0V
I
SWITCH
= 200mA
Falling edge
FREQ = AGND
FREQ = IN
1.4
2.0
3.5
1.225
0.96
43
47
5.0
1.240
1.00
51
55
6.0
1.255
1.04
64
65
512
1020
91
88
600
1200
95
92
768
1380
99
96
0.6
kHz
%
V
V
µA
V
V
ms
V
POS
_ = 4V, no load
Rising edge, 15°C hysteresis
LX not switching
LX switching
1.8
16
+160
V
IN
= 2.5V, V
FB
= 1.5V
IN rising, 200mV hysteresis
6V ≤ V
SUP
≤ 13V, I
LDO
= 12.5mA
LDO rising, 200mV hysteresis
4.6
2.4
15
4.5
13.0
1.4
3.0
30
CONDITIONS
MIN
1.8
15
1.30
5
2.7
TYP
MAX
5.5
30
1.75
5.4
3.0
UNITS
V
µA
V
V
V
mA
V
V
mA
°C
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MAX8739
TFT, LCD, DC-DC Converter with
Operational Amplifiers
Electrical Characteristics (continued)
(V
IN
= 2.5V, V
SUP
= 10V, V
SRC
= 28V, FREQ = CTL = IN, PGND = AGND = 0,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
FB Load Regulation
FB Line Regulation
FB Input Bias Current
FB Transconductance
FB Voltage Gain
LX On-Resistance
LX Leakage Current
LX Current Limit
Current-Sense Transresistance
Soft-Start Period
Soft-Start Step Size
OPERATIONAL AMPLIFIERS
Input Offset Voltage
Input Bias Current
Input Common-Mode Voltage
Range
Common-Mode Rejection Ratio
Open-Loop Gain
Output Voltage Swing High
I
OUT
_ = 100µA
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
DEL Capacitor Charge Current
DEL Turn-On Threshold
DEL Pin Discharge Switch On-
Resistance
CTL Input-Low Voltage
During UVLO, V
IN
= 1.3V
V
IN
= 1.8V to 5.5V
R
L
= 10kΩ, C
L
= 10pF, buffer configuration
Buffer configuration
During startup, V
DEL
= 1V
4
1.178
I
OUT
_ = -100µA
I
OUT
_ = -5mA
To V
SUP
/2
Source
Sink
50
50
40
60
100
7.5
12
8
5
1.24
20
0.6
6
1.302
V
SUP
-
15
V
SUP
-
150
V
CM
= V
SUP
/2, T
A
= +25°C
NEG1, POS1, NEG2, POS2
NEG1, POS1, NEG2, POS2
0 ≤ V
NEG
_, V
POS
_ ≤ V
SUP
-50
0
50
90
125
V
SUP
-2
V
SUP
-
80
2
80
150
140
15
150
0
+1
12
+50
V
SUP
mV
nA
V
dB
dB
mV
FREQ = AGND
FREQ = IN
V
IN
= 1.8V to 5.5V
V
FB
= 1.3V
DI
COMP
= 5µA
FB to COMP
I
LX
= 200mA
V
LX
= V
SUP
= 13V
V
FB
= 1.1V, duty cycle = 65%
1.5
0.22
75
CONDITIONS
0 < I
LOAD
< 200mA, transient only
-0.15
MIN
TYP
-1
-0.08
125
160
700
200
0.01
1.9
0.36
13
14
0.24
400
20
2.3
0.50
+0.15
200
280
MAX
UNITS
%
%/V
nA
µS
V/V
mΩ
µA
A
V/A
ms
A
mV
mA
mA
dB
V/µs
MHz
MHz
µA
V
Ω
V
Buffer configuration, V
POS
_ = 4V, |DV
OS
| < 10mV
DC, 6V ≤ V
SUP
≤ 13V, V
POS
_, V
NEG
_ = V
SUP
/2
POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES
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Maxim Integrated
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3
MAX8739
TFT, LCD, DC-DC Converter with
Operational Amplifiers
Electrical Characteristics (continued)
(V
IN
= 2.5V, V
SUP
= 10V, V
SRC
= 28V, FREQ = CTL = IN, PGND = AGND = 0,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
CTL Input-High Voltage
CTL Input-Leakage Current
CTL-to-SRC Propagation Delay
SRC Input-Voltage Range
SRC Input Current
DRN Input Current
SRC-to-COM Switch On-
Resistance
DRN-to-COM Switch On-
Resistance
V
DRN
= 8V, CTL = AGND, V
DEL
= 1.5V
V
DRN
= 8V, CTL = IN, V
DEL
= 1.5V
V
DRN
= 8V, CTL = AGND, V
DEL
= 1.5V
V
DEL
= 1.5V, CTL = IN
V
DEL
= 1.5V, CTL = AGND
15
100
90
15
30
V
IN
= 1.8V to 2.4V
V
IN
= 2.4V to 5.5V
CTL = AGND or IN
COM falling, no load on COM
COM rising, no load on COM
CONDITIONS
MIN
1.4
2.0
-1
100
100
28
30
180
150
30
60
+1
TYP
MAX
UNITS
V
µA
ns
V
µA
µA
Ω
Ω
Electrical Characteristics
(V
IN
= 2.5V, V
SUP
= 10V, V
SRC
= 28V, FREQ = CTL = IN, PGND = AGND = 0,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
IN Supply Range
IN Quiescent Current
IN Undervoltage Lockout
Threshold
LDO Output Voltage
LDO Undervoltage Lockout
Threshold
LDO Output Current
SUP Supply Voltage Range
SUP Undervoltage Fault
Threshold
SUP Supply Current
STEP-UP REGULATOR
Operating Frequency
Maximum Duty Cycle
FREQ Input Low Voltage
FREQ = AGND
FREQ = IN
FREQ = AGND
FREQ = IN
V
IN
= 1.8V to 5.5V
512
1020
91
88
768
1380
99
96
0.6
kHz
%
V
V
POS
_ = 4V, no load
LX not switching
LX switching
V
IN
= 2.5V, V
FB
= 1.5V
IN rising, 200mV hysteresis
6V ≤ V
SUP
≤ 13V, I
LDO
= 12.5mA
LDO rising, 200mV hysteresis
4.6
2.4
15
4.5
13.0
1.4
3.0
30
CONDITIONS
MIN
1.8
TYP
MAX
5.5
30
1.75
5.4
3.0
UNITS
V
µA
V
V
V
mA
V
V
mA
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Maxim Integrated
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4
MAX8739
TFT, LCD, DC-DC Converter with
Operational Amplifiers
Electrical Characteristics (continued)
(V
IN
= 2.5V, V
SUP
= 10V, V
SRC
= 28V, FREQ = CTL = IN, PGND = AGND = 0,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
FREQ Input-High Voltage
FREQ Pulldown Current
FB Regulation Voltage
FB Fault-Trip Level
Duration to Trigger-Fault
Condition
FB Line Regulation
FB Input Bias Current
FB Transconductance
LX On-Resistance
LX Current Limit
Current-Sense Transresistance
OPERATIONAL AMPLIFIERS
Input Offset Voltage
Input Common-Mode Voltage
Range
Common-Mode Rejection Ratio
V
CM
= V
SUP
/2, T
A
= +25°C
NEG1, POS1, NEG2, POS2
0 ≤ V
NEG
_, V
POS
_ ≤ V
SUP
I
OUT
_ = 100µA
I
OUT
_ = 5mA
Output Voltage Swing Low
Short-Circuit Current
Output Source-and-Sink Current
Power-Supply Rejection Ratio
I
OUT
_ = -100µA
I
OUT
_ = -5mA
To V
SUP
/2
Source
Sink
50
50
40
60
0
50
V
SUP
-
15
V
SUP
-
150
15
150
12
V
SUP
mV
V
dB
V
IN
= 1.8V to 2.4V
V
IN
= 2.4V to 5.5V
V
FREQ
= 1.0V
I
SWITCH
= 200mA
Falling edge
FREQ = AGND
FREQ = IN
V
IN
=1.8V to 5.5V
V
FB
= 1.3V
DI
COMP
= 5µA
I
LX
= 200mA
V
FB
= IV, duty cycle = 65%
1.5
0.22
75
CONDITIONS
MIN
1.4
2.0
3.5
1.220
0.96
41
47
-0.15
6.0
1.260
1.04
64
65
+0.15
200
280
400
2.3
0.50
TYP
MAX
UNITS
V
µA
V
V
ms
%/V
nA
µS
mΩ
A
V/A
Output Voltage Swing High
mV
mV
mA
mA
dB
Buffer configuration, V
POS
_ = 4V, |DV
OS
| < 10mV
DC, 6V ≤ V
SUP
≤ 13V, V
POS
_, V
NEG
_ = V
SUP
/2
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