MAX17108 DS

19-4347; Rev 0; 10/08
KIT
ATION
EVALU
E
L
B
A
IL
AVA
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
The MAX17108 includes a 10-channel high-voltage
level-shifting scan driver and a VCOM amplifier. The
device is optimized for thin-film transistor (TFT) liquidcrystal display (LCD) applications.
The high-voltage level-shifting scan driver can swing
from +38V to -12V and can swiftly drive capacitive
loads. There are two positive supply inputs, which provide flexibility for system design.
The operational amplifier features rail-to-rail output,
high short-circuit output current, fast slew rate, and
wide bandwidth.
The MAX17108 is available in a 28-pin, 5mm x 5mm,
lead-free thin QFN package with a maximum thickness
of 0.8mm for thin LCD panels.
Features
o High-Current, High-Speed Operational Amplifier
±200mA Output Short-Circuit Current
100V/µs Slew Rate
20MHz to 3dB Bandwidth
Rail-to-Rail Outputs
o High-Voltage Level-Shifting Scan Drivers
Logic-Level Inputs
+38V to -12V Outputs
o Thermal-Overload Protection
o 28-Pin, 5mm x 5mm Thin QFN Package
Ordering Information
Applications
LCD TVs
PART
LCD Monitors
MAX17108ETI+
TEMP RANGE
PIN-PACKAGE
-40oC to +85oC
28 Thin QFN-EP*
+Denotes a lead-free/RoHS-compliant package.
*EP = Exposed pad.
Simplified Operating Circuit
Pin Configuration
VCOM
100kΩ
MAX17108
GND
A7
A8
1μF
Y4
Y3
17
16
15
Y10 22
14
GND 23
13
Y1
AVDD 24
12
GON2
11
GOFF
NEG 26
10
GON1
POS 27
9
A1
8
A2
VCOM 25
MAX17108
*EP
A10 28
Y2
2
3
4
5
6
7
A3
1
A4
TO PANEL
A5
Y1
Y2
Y3
Y4
Y5
Y6
Y9
Y10
18
A6
A1
A2
A3
A4
A5
A6
A9
A10
19
A7
FROM
TCON
POS
20
A8
1μF
21
A9
GON1
Y5
GON2
1μF
Y6
TOP VIEW
Y7
100kΩ
Y8
0.1μF
NEG
Y9
AVDD
Y7
GOFF
EP
THIN QFN
5mm x 5mm
Y8
*EP = EXPOSED PAD.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX17108
General Description
MAX17108
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
ABSOLUTE MAXIMUM RATINGS
A1–A10 to GND .....................................................-0.3V to +7.5V
AVDD to GND.........................................................-0.3V to +22V
POS, NEG, VCOM to GND ..................-0.3V to (VAVDD to +0.3V)
POS to NEG.................................................................-6V to +6V
GON1, GON2 to GND ............................................-0.3V to +40V
GOFF to GND .........................................................-14V to +0.3V
Y1–Y6, Y9, Y10 to GND...........(VGOFF - 0.3V) to (VGON1 + 0.3V)
Y7, Y8 to GND .........................(VGOFF - 0.3V) to (VGON2 + 0.3V)
Y1–Y10 Load RMS Current ...............................................140mA
GON1, GON2 RMS Current .............................................350mA
GOFF RMS Current ..........................................................450mA
Continuous Power Dissipation (TA = +70°C)
28-Pin, 5mm x 5mm Thin QFN
(derate 34.5mW/°C above +70°C) .........................2758.6mW
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
(Figure 1 circuit, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
38
V
HIGH-VOLTAGE DRIVER BLOCK
GON_ Input Voltage Range
12
GOFF Input Voltage Range
-4
V
GOFF Supply Current
A1–A10 = GND, no load
150
300
μA
GON_ Total Supply Current
A1–A10 = GND, no load
330
540
μA
Output-Voltage Low (Y1–Y10)
I Y_ = 10mA
VGOFF
+ 0.03
VGOFF
+ 0.06
V
Output-Voltage High (Y1–Y10)
I Y_ = 10mA
Rise Time (Y9, Y10)
TA = +25°C, VGON1 = 30V and VGOFF = -6.2V (Note 1)
200
ns
Fall Time (Y9, Y10)
200
ns
Rise Time (Y1–Y6)
TA = +25°C, VGON1 = 30V and VGOFF = -6.2V (Note 1)
TA = +25°C, VGON1 = 30V and VGOFF = -6.2V (Note 1)
450
ns
Fall Time (Y1–Y6)
TA = +25°C, VGON1 = 30V and VGOFF = -6.2V (Note 1)
120
ns
Rise Time (Y7, Y8)
TA = +25°C, VGON1 = 30V and VGOFF = -6.2V (Note 1)
TA = +25°C, VGON1 = 30V and VGOFF = -6.2V (Note 1)
1600
ns
700
ns
Fall Time (Y7,Y8)
-12
VGON _
- 0.25
VGON _
- 0.15
V
Propagation Delay High-to-Low
Transition (Y1–Y10)
VGON_ = 30V and VGOFF = -6.2V (Note 1)
35
ns
Propagation Delay Low-to-High
Transition (Y1–Y10)
VGON_ = 30V and VGOFF = -6.2V (Note 1)
35
ns
2
_______________________________________________________________________________________
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
(Figure 1 circuit, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
6
20
V
OPERATIONAL AMPLIFIER
AVDD Supply Range
AVDD Supply Current
Buffer configuration, VPOS = VAVDD/2, no load
6
mA
Input Offset Voltage
2V < (VNEG, VPOS) < (VAVDD - 2V), TA = +25°C
-10
+10
mV
Input Bias Current
VNEG, V POS = VAVDD/2, TA = +25°C
-50
+50
nA
0
VAVDD
V
Input Common-Mode
Voltage Range
Input Common-Mode
Rejection Ratio
2V < (VNEG, VPOS) < (VAVDD - 2V)
Output-Voltage Swing High
I VCOM = 50mA
80
VAVDD 400
Output-Voltage Swing Low
I VCOM = -50mA
Large-Signal Voltage Gain
VVCOM = 1V to VAVDD - 1V
mV
400
Slew Rate
-3dB Bandwidth
Short-Circuit Current
dB
mV
80
dB
100
V/μs
20
MHz
Short to VAVDD/2, sourcing
230
Short to VAVDD/2, sinking
460
mA
FAULT DETECTION
Thermal Shutdown
Rising edge, typical hysteresis = 10°C, not latched
+155
°C
CONTROL INPUTS
Logic-Input Voltage Range (A1–A10)
(Note 3)
Logic-Input Voltage Low (A1–A10)
Logic-Input Voltage High (A1–A10)
Logic-Input Bias Current (A1–A10)
6
V
0.8
V
2
0 < VA < 6V, TA = +25°C
V
-1
+1
μA
MAX
UNITS
V
ELECTRICAL CHARACTERISTICS
(Figure 1 circuit, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
CONDITIONS
MIN
TYP
HIGH-VOLTAGE DRIVER BLOCK
GON_ Input Voltage Range
12
38
GOFF Input Voltage Range
-12
-4
V
300
μA
540
μA
VGOFF
+ 0.06
V
GOFF Supply Current
A1–A10 = GND, no load
GON_ Total Supply Current
A1–A10 = GND, no load
Output-Voltage Low (Y1–Y10)
I Y_ = 10mA
Output-Voltage High (Y1–Y10)
I Y_ = 10mA
VGON _
- 0.25
V
_______________________________________________________________________________________
3
MAX17108
ELECTRICAL CHARACTERISTICS (continued)
MAX17108
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
ELECTRICAL CHARACTERISTICS (continued)
(Figure 1 circuit, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
OPERATIONAL AMPLIFIER
AVDD Supply Range
6
AVDD Supply Current
20
V
6
mA
VAVDD
V
Buffer configuration, VPOS = VAVDD/2, no load
Input Common-Mode
Voltage Range
0
Output-Voltage Swing High
I VCOM = 50mA
Output-Voltage Swing Low
I VCOM = -50mA
VAVDD 400
mV
400
mV
6
V
0.8
V
CONTROL INPUTS
Logic-Input Voltage Range (A1–A10)
(Note 3)
Logic-Input Voltage Low (A1–A10)
Logic-Input Voltage High (A1–A10)
2
V
Note 1: The load models for different channels are illustrated in Figure 2.
Note 2: TA = -40°C specifications are guaranteed by design, not production tested.
Note 3: For 5.5V < VA_ < 6V, use the IC for no longer than 1% of IC lifetime. For continuous operation, voltage should not exceed 5.5V.
Typical Operating Characteristics
(Circuit of Figure 1, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
SCAN DRIVER OUTPUT RISING EDGE (Y1–Y6)
PROPAGATION DELAY AND RISE TIME
SCAN DRIVER OUTPUT FALLING EDGE (Y1–Y6)
PROPAGATION DELAY AND FALL TIME
MAX17108 toc01
200ns/div
4
MAX17108 toc02
VA
2V/div
VA
2V/div
0V
0V
VY
10V/div
VY
10V/div
0V
0V
200ns/div
_______________________________________________________________________________________
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
SCAN DRIVER OUTPUT RISING EDGE (Y7 AND Y8)
PROPAGATION DELAY AND RISE TIME
SCAN DRIVER OUTPUT FALLING EDGE (Y7 AND Y8)
PROPAGATION DELAY AND FALL TIME
MAX17108 toc03
MAX17108 toc04
VA
2V/div
VA
2V/div
0V
0V
VY
10V/div
VY
10V/div
0V
0V
200ns/div
200ns/div
SCAN DRIVER OUTPUT RISING EDGE (Y9 AND Y10)
PROPAGATION DELAY AND RISE TIME
SCAN DRIVER OUTPUT FALLING EDGE (Y9 AND Y10)
PROPAGATION DELAY AND FALL TIME
MAX17108 toc06
MAX17108 toc05
VA
5V/div
VA
5V/div
0V
0V
VY
10V/div
VY
10V/div
0V
0V
10ns/div
10ns/div
OPERATION AMPLIFIER
FREQUENCY RESPONSE
OPERATIONAL AMPLIFIER
POWER-SUPPLY REJECTION RATIO
100pF LOAD
-10
-20
1
-30
0
PSRR (dB)
GAIN (dB)
MAX17108 toc08
3
2
0
MAX17108 toc07
4
-1
-2
NO LOAD
-40
-50
-60
-3
-70
-4
-5
-80
-6
-90
100
1000
10k
FREQUENCY (Hz)
100k
10
100
1000
10k
100k
FREQUENCY (Hz)
_______________________________________________________________________________________
5
MAX17108
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
OPERATIONAL AMPLIFIER
LOAD-TRANSIENT RESPONSE
OPERATIONAL AMPLIFIER RAIL-TO-RAIL
INPUT/OUTPUT WAVEFORMS
MAX17108 toc10
MAX17108 toc09
VVCOM
(AC-COUPLED)
1V/div
0V
VPOS
5V/div
0V
IVCOM
50mA/div
0mA
VVCOM
5V/div
0V
10μs/div
20μs/div
OPERATIONAL AMPLIFIER
LARGE-SIGNAL STEP RESPONSE
OPERATIONAL AMPLIFIER
SMALL-SIGNAL STEP RESPONSE
MAX17108 toc11
MAX17108 toc12
VPOS
5V/div
VPOS
(AC-COUPLED)
100mV/div
0V
0mV
VVCOM
(AC-COUPLED)
100mV/div
0V
0mV
200ns/div
AVDD SUPPLY QUIESCENT CURRENT
vs. AVDD SUPPLY VOLTAGE
GON1 SUPPLY QUIESCENT CURRENT
vs. GON1 SUPPLY VOLTAGE
0.20
SUPPLY CURRENT (mA)
3.00
2.95
2.90
MAX17108 toc14
0.25
MAX17108 toc13
3.05
0.15
0.10
0.05
2.85
2.80
0
6
8
10
12
14
16
SUPPLY VOLTAGE (V)
6
VVCOM
5V/div
400ns/div
3.10
SUPPLY CURRENT (mA)
MAX17108
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
18
20
12
16
20
24
28
32
36
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
GON2 SUPPLY QUIESCENT CURRENT
vs. GON2 SUPPLY VOLTAGE
0.16
SUPPLY CURRENT (mA)
0.07
0.06
0.05
0.04
0.03
0.14
0.12
0.10
0.08
0.06
0.02
0.04
0.01
0.02
0
MAX17108 toc16
0.08
SUPPLY CURRENT (mA)
0.18
MAX17108 toc15
0.09
GOFF SUPPLY QUIESCENT CURRENT
vs. GOFF SUPPLY VOLTAGE
0
12
16
20
24
28
32
36
-12
-11
SUPPLY VOLTAGE (V)
-10
-9
-8
-7
-6
-5
-4
SUPPLY VOLTAGE (V)
Pin Description
PIN
NAME
1–9
A9–A1
Level-Shifter Logic-Level Input
10
GON1
Gate-On Supply Input 1. GON1 is the positive supply for the Y1–Y6, Y9, and Y10 level shifters.
Bypass GON1 with a minimum of 1μF ceramic capacitor to GND.
11
GOFF
Gate-Off Supply Input. GOFF is the negative supply for the Y1–Y10 level shifters. Bypass GOFF with
a minimum of 1μF ceramic capacitor to GND.
12
GON2
Gate-On Supply Input 2. GON2 is the positive supply for the Y7 and Y8 level shifters. Bypass GON2
with a minimum of 1μF ceramic capacitor to GND.
13–22
Y1–Y10
23
GND
Ground
24
AVDD
Operational Amplifier Supply Voltage. Bypass AVDD with a minimum of 1μF ceramic capacitor to GND.
25
VCOM
26
NEG
Operational Amplifier Negative Input
27
POS
Operational Amplifier Positive Input
28
A10
—
EP
FUNCTION
Level-Shifter Outputs
Operational Amplifier Output
Level-Shifter Logic-Level Input
Exposed Backside Pad. Connect to V GOFF. Copper area should be maximized for thermal
performance.
_______________________________________________________________________________________
7
MAX17108
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VAVDD = 16V, VGON_ = 38V, VGOFF = -12V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
MAX17108
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
Detailed Description
The MAX17108 includes a 10-channel, high-voltage levelshifting scan driver, an operational amplifier for VCOM,
and a linear regulator that provides the internal bias for
the step-up controller. Figure 1 shows the MAX17108
functional block diagram and typical operating circuit.
Load Models for
Different Channels
Figure 2 shows the load models for different channels.
MEASURING POINT
75Ω
A1–A6
33nF
900pF
AVDD
MAX17108
GON2
NEG
100kΩ
0.1μF
MEASURING POINT
330Ω
LDO
OP
VCOM
A7, A8
100kΩ
1μF
100pF
470pF
GND
GON1
MEASURING POINT
1μF
FROM
TCON
POS
A1
A2
A3
A4
A5
A6
A9
A10
Y1
Y2
Y3
Y4
Y5
Y6
Y9
Y10
A7
Y7
A8
Y8
GOFF
A9, A10
100pF
Figure 2. Load Models for Different Channels
TO PANEL
EP
1μF
Figure 1. Functional Block Diagram and Typical Operating Circuit
8
Operational Amplifier
The MAX17108 has one operational amplifier that is
typically used to drive the LCD backplane (VCOM). The
operational amplifier features a ±200mA output shortcircuit current, 100V/µs slew rate, 20MHz bandwidth,
and rail-to-rail output.
Short-Circuit Current Limit
The operational amplifier limits the short-circuit current
to approximately ±200mA. If the short-circuit condition
persists, the junction temperature of the IC rises until it
reaches the thermal-shutdown threshold (+155°C typ).
Once the junction temperature reaches the thermalshutdown threshold, an internal thermal sensor shuts off
the operational amplifier. The thermal protection is not
latched and the device recovers once the temperature
drops below the hysteretic threshold (+10°C typ).
_______________________________________________________________________________________
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
As the operational amplifier’s capacitive load increases,
the amplifier’s bandwidth decreases and gain peaking
increases. A 5Ω to 50Ω resistor placed between VCOM
and the capacitive load reduces peaking but also
reduces the gain. An alternative method of reducing
peaking is to place a series RC network (snubber) in
parallel with the capacitive load. The RC network does
not continuously load the output or reduce the gain.
Typical values of the resistor are between 100Ω and
200Ω and the typical value of the capacitor is 10pF.
Table 1. Component List
DESIGNATION
DESCRIPTION
1μF bypassing
capacitors
1μF ±10%, 50V X7R ceramic capacitors
(0805)
Murata GRM21BR71H105K
0.1μF bypassing
capacitors
0.1μF ±10%, 25V X5R ceramic capacitors
(0603)
Murata GRM188R61E104K
Table 2. Component Supplier
SUPPLIER
PHONE
WEBSITE
Murata Electronic North
America, Inc.
770-436-1300
www.murata.com
Applications Information
High-Voltage Level-Shifting Scan Driver
Power Dissipation
The MAX17108 includes 10 logic-level to high-voltage
level-shifting buffers, which can buffer 10 logic inputs
(A1–A10) and shift them to a desired level (Y1–Y10) to
drive TFT-LCD row logic. The driver outputs, Y1–Y10,
swing between their power-supply rails, according to
the input-logic level on A1–A10. The driver output is
V GOFF when its respective input is logic-low, and
VGON_ when its respective input is logic-high.
These 10 driver channels are grouped for different
high-level supplies. A1–A6 and A9–A10 are supplied
from GON1; A7 and A8 are supplied from GON2.
The high-voltage, level-shifting scan drivers swing from
+38V to -12V and can swiftly drive capacitive loads.
The typical propagation delays are 35ns.
An IC’s maximum power dissipation depends on the
thermal resistance from the die to the ambient environment and the ambient temperature. The thermal resistance depends on the IC package, PCB copper area,
other thermal mass, and airflow.
The MAX17108, with its exposed backside pad soldered to 1in2 of PCB copper, can dissipate approximately 2700mW into +70°C still air. More PCB copper,
cooler ambient air, and more airflow increase the possible dissipation, while less copper or warmer air
decreases the IC’s dissipation capability. The major
components of power dissipation are the power dissipated in the operational amplifier and the high-voltage
scan drivers.
Thermal Shutdown
Operational Amplifier
The power dissipated in the operational amplifiers
depends on the output current, the output voltage, and
the supply voltage:
The MAX17108 includes a thermal-protection circuit.
When the local IC temperature exceeds +155°C (typ),
the device shuts down and recovers when the die temperature drops by 10°C (typ).
Design Procedure
All MAX17108 designs should be prototyped and tested prior to production. Table 1 provides a list of components for the typical operating circuit. Table 2 shows a
component supplier.
PD SOURCE = I VCOM _ SOURCE × ( V AVDD - VVCOM )
PD SINK = I VCOM _ SINK × VVCOM
where IVCOM_SOURCE is the output current sourced by
one operational amplifier, and IVCOM_SINK is the output
current that the operational amplifier sinks.
In a typical case, where the supply voltage is 8V and
the output voltage is 4V with an output source current of
30mA for the operational amplifier, the power dissipated is 120mW.
_______________________________________________________________________________________
9
MAX17108
Driving Pure Capacitive Loads
The operational amplifier is typically used to drive the
LCD backplane (VCOM). The LCD backplane consists
of a distributed series capacitance and resistance, a
load that can be easily driven by the operational amplifier. However, if the operational amplifier is used in an
application with a pure capacitive load, steps must be
taken to ensure stable operation.
MAX17108
10-Channel High-Voltage Scan Driver and
VCOM Amplifier for TFT LCD Panels
Scan Driver Outputs
When driving a pure capacitive load, the power dissipated by the scan driver outputs (A1–A6; A7–A10 are
low-frequency outputs and the power dissipation by
these outputs can be omitted) depends on the scan frequency, the capacitive load, and the difference
between the GON1 and GOFF supply voltages:
PD SCAN = 6 × fSCAN × C PANEL × ( VGON1 - VGOFF )
•
Create VGOFF plane, connect it to EP.
•
Create a ground island (GND) consisting of the
input and output capacitor grounds and GND pin.
Connect all these together with short, wide traces or
a small ground plane.
•
Place the voltage-divider resistors as close as possible to the POS pin. The divider’s center trace
should be kept short. Placing the resistors far away
causes the POS trace to become an antenna that
can pick up switching noise.
•
Minimize the length and maximize the width of the
traces between the output capacitors and the load
for best transient responses.
2
If the six scan drivers operate at a frequency of 50kHz,
the load of the six outputs is 5nF, and the supply voltage
difference is 30V, then the power dissipated is 1.35W.
PCB Layout Guidelines
Careful PCB layout is important for proper operation.
Use the following guidelines for good PCB layout:
• Avoid using vias in the high-current paths. If vias
are unavoidable, use many vias in parallel to
reduce resistance and inductance.
Refer to the MAX17108 Evaluation Kit for an example of
proper board layout.
Package Information
Chip Information
TRANSISTOR COUNT: 2918
PROCESS: BiCMOS
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
28 TQFN
T2855-6
21-0140
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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is a registered trademark of Maxim Integrated Products, Inc.