19-4681; Rev 1; 3/10
TION KIT
EVALUA BLE
AVAILA
Multi-Output Power Supplies with VCOM Amplifier
and High-Voltage Gamma Reference for LCD TVs
General Description
The MAX17126/MAX17126A generate all the supply rails
for thin-film transistor liquid-crystal display (TFT LCD)
TV panels operating from a regulated 12V input. They
include a step-down and a step-up regulator, a positive
and a negative charge pump, an operational amplifier,
a high-accuracy high-voltage gamma reference, and
a high-voltage switch control block. The MAX17126/
MAX17126A can operate from input voltages from 8V
to 16.5V and is optimized for an LCD TV panel running
directly from 12V supplies.
The step-up and step-down switching regulators feature
internal power MOSFETs and high-frequency opera-
tion allowing the use of small inductors and capacitors,
resulting in a compact solution. The step-up regulator
provides TFT source driver supply voltage, while the
step-down regulator provides the system with logic sup-
ply voltage. Both regulators use fixed-frequency current-
mode control architectures, providing fast load-transient
response and easy compensation. A current-limit func-
tion for internal switches and output-fault shutdown pro-
tects the step-up and step-down power supplies against
fault conditions. The MAX17126/MAX17126A provide
soft-start functions to limit inrush current during startup.
In addition, the MAX17126/MAX17126A integrate a con-
trol block that can drive an external p-channel MOSFET
to sequence power to source drivers.
The positive and negative charge-pump regulators pro-
vide TFT gate-driver supply voltages. Both output volt-
ages can be adjusted with external resistive voltage-
dividers. A logic-controlled, high-voltage switch block
allows the manipulation of the positive gate-driver supply.
The MAX17126/MAX17126A include one high-current
operational amplifier designed to drive the LCD back-
plane (VCOM). The amplifier features high output cur-
rent (Q200mA), fast slew rate (45V/Fs), wide bandwidth
(20MHz), and rail-to-rail outputs.
Also featured in the MAX17126/MAX17126A is a high-
accuracy, high-voltage adjustable reference for gamma
correction.
The MAX17126/MAX17126A are available in a small (7mm
x 7mm), ultra-thin (0.8mm), 48-pin thin QFN package and
operate over the -40NC to +85NC temperature range.
Features
S
8.0V to 16.5V IN Supply-Voltage Range
S
Selectable Frequency (500kHz/750kHz)
S
Current-Mode Step-Up Regulator
MAX17126/MAX17126A
Fast Load-Transient Response
High-Accuracy Output Voltage (1.0%)
Built-In 20V, 4.2A, 100mI MOSFET
High Efficiency
Adjustable Soft-Start
Adjustable Current Limit
Low Duty-Cycle Operation (13.2V
IN
- 13.5V AVDD)
S
Current-Mode Step-Down Regulator
Fast Load-Transient Response
Built-In 20V, 3.2A, 100mI MOSFET
High Efficiency
3ms Internal Soft-Start
S
Adjustable Positive Charge-Pump Regulator
S
Adjustable Negative Charge-Pump Regulator
S
Integrated High-Voltage Switch with Adjustable
Turn-On Delay
S
High-Speed Operational Amplifier
Q200mA
Short-Circuit Current
45V/µs Slew Rate
S
High-Accuracy Reference for Gamma Buffer
Q1%
Feedback Voltage
Up to 30mA Load Current
Low-Dropout Voltage 0.5V at 60mA
S
External p-Channel Gate Control for AVDD
Sequencing
S
PGOOD Comparator
S
Input Undervoltage Lockout and Thermal-
Overload Protection
S
48-Pin, 7mm x 7mm, Thin QFN Package
Ordering Information
PART
MAX17126ETM+
MAX17126AETM+
TEMP RANGE
-40NC to +85NC
-40NC to +85NC
PIN-PACKAGE
48 Thin QFN-EP*
48 Thin QFN-EP*
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Applications
LCD TV Panels
Pin Configuration appears at end of data sheet.
_______________________________________________________________
Maxim Integrated Products
1
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.
Multi-Output Power Supplies with VCOM Amplifier
and High-Voltage Gamma Reference for LCD TVs
MAX17126/MAX17126A
ABSOLUTE MAXIMUM RATINGS
INVL, IN2, VOP, EN, FSEL to GND .......................-0.3V to +24V
PGND, OGND, CPGND to GND ..........................-0.3V to +0.3V
DLY1, GVOFF, THR, VL to GND ..........................-0.3V to +7.5V
REF, FBP, FBN, FB1, FB2, COMP, SS, CLIM,
PGOOD, VDET, VREF_FB, OUT to GND ........-0.3V, (V
L
+ 0.3)
GD, GD_I to GND ..................................................-0.3V to +24V
LX1 to PGND .........................................................-0.3V to +24V
OPP, OPN, OPO to OGND ......................... -0.3V to VOP + 0.3V
DRVP to CPGND ...................................... -0.3V to SUPP + 0.3V
DRVN to CPGND ...................................... -0.3V to SUPN + 0.3V
LX2 to PGND ................................................-0.7 to (IN2 + 0.3V)
SUPN to GND .............................................-0.3V to (IN2 + 0.3V)
SUPP to GND .......................................... -0.3V to (GD_I + 0.3V)
BST to VL...............................................................-0.3V to +30V
VGH to GND ..........................................................-0.3V to +40V
VGHM, DRN to GND ..................................... -0.3V, VGH + 0.3V
VGHM to DRN .......................................................-0.3V to +40V
VREF_I to GND ......................................................-0.3V to +24V
VREF_O to GND .......................................-0.3V, (V
REF_I
+ 0.3)V
REF Short Circuit to GND ..........................................Continuous
RMS LX1 Current (total for both pins) .................................3.2 A
RMS PGND CURRENT (total for both pins) ........................3.2 A
RMS IN2 Current (total for both pins) .................................3.2 A
RMS LX2 Current (total for both pins) .................................3.2 A
RMS DRVN, DRVP Current ..................................................0.8A
RMS VL Current..................................................................50mA
Continuous Power Dissipation (T
A
= +70NC)
48-Pin TQFN
(derated 38.5mW/NC above +70NC) .......................3076.9mW
Junction Temperature .....................................................+160NC
Storage Temperature Range............................ -65NC to +165NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
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
(Circuit of Figure 1, V
INVL
= V
IN2
= 12V, V
VOP
= V
VREF_I
= 15V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25NC, unless oth-
erwise noted.)
PARAMETER
GENERAL
INVL, IN2 Input-Voltage Range
INVL + IN2 Quiescent Current
INVL + IN2 Standby Current
SMPS Operating Frequency
INVL Undervoltage-Lockout
Threshold
VL REGULATOR
VL Output Voltage
VL Undervoltage-Lockout
Threshold
REFERENCE
REF Output Voltage
REF Load Regulation
REF Sink Current
REF Undervoltage-Lockout
Threshold
No external load
0V < I
LOAD
< 50FA
In regulation
Rising edge, 250mV typical hysteresis
10
1.0
1.2
1.2375
1.250
1.2625
5
V
mV
FA
V
I
VL
= 25mA, V
FB1
= V
FB2
= V
FBP
= 1.1V, V
FBN
= 0.4V
(all regulators switching)
VL rising, 50mV typical hysteresis
4.85
3.5
5
3.9
5.15
4.3
V
V
Only LX2 switching (V
FB1
= V
FBP
= 1.5V, V
FBN
= 0V)
EN = VL, FSEL = high
LX2 not switching (V
FB1
= V
FB2
= V
FBP
= 1.5V,
V
FBN
= 0V), EN = VL, FSEL = high
FSEL = INVL or high impedance
FSEL = GND
INVL rising, 150mV typical hysteresis
630
420
6.0
8
8.5
24
750
500
7.0
16.5
20
5
870
580
8.0
V
mA
mA
kHz
V
CONDITIONS
MIN
TYP
MAX
UNITS
2
______________________________________________________________________________________
Multi-Output Power Supplies with VCOM Amplifier
and High-Voltage Gamma Reference for LCD TVs
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
INVL
= V
IN2
= 12V, V
VOP
= V
VREF_I
= 15V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25NC, unless oth-
erwise noted.)
PARAMETER
STEP-DOWN REGULATOR
OUT Voltage in Fixed Mode
FB2 Voltage in Adjustable
Mode
FB2 Adjustable Mode
Threshold Voltage
Output Voltage Adjust Range
FB2 Fault-Trip Level
FB2 Input Leakage Current
DC Load Regulation
DC Line Regulation
LX2-to-IN2 nMOS Switch
On-Resistance
LX2-to-GND2 nMOS Switch
On-Resistance
BST-to-VL pMOS Switch
On-Resistance
Low-Frequency Operation
OUT Threshold
Low-Frequency Operation
Switching Frequency
LX2 Positive Current Limit
Soft-Start Ramp Time
Maximum Duty Factor
Minimum Duty Factor
Char/Design Limit Only
STEP-UP REGULATOR
Output Voltage Range
Oscillator Maximum Duty Cycle
FB1 Regulation Voltage
FB1 Fault Trip Level
FB1 Load Regulation
FB1 Line Regulation
FB1 Input Bias Current
FB1 Transconductance
FB1 Voltage Gain
LX1 Leakage Current
FB1 = COMP, C
COMP
= 1nF
Falling edge
0V < I
LOAD
< full
10.8V < V
IN
< 13.2V
V
FB1
= 1.25V
DI
=
Q2.5FA
at COMP, FB1 = COMP
FB1 to COMP
V
FB1
= 1.5V, V
LX1
= 20V
30
150
VIN
70
1.2375
0.96
78
1.25
1.0
0.5
0.08
125
320
1400
10
40
200
560
20
85
1.2625
1.04
V
%
V
V
%
%/V
nA
FS
V/V
FA
LX2 only
FSEL = INVL
FSEL = GND
MAX17126
MAX17126A
Zero to full limit
70
2.50
3.0
6
40
Falling edge
V
FB2
= 1.25V
0V < I
LOAD
< 2A
No load, 10.8V < V
IN2
< 13.2V
FB2 = GND, no load
(Note 1)
V
OUT
= 2.5V, no load
(Note 1)
Dual Mode™ comparator
0°C < T
A
= +85°C
T
A
= +25°C
0°C < T
A
= +85°C
T
A
= +25°C
3.25
3.267
1.23
1.2375
0.10
1.5
0.96
50
1.0
125
0.5
0.1
100
10
30
0.8
125
83
3.20
3.5
3
78
85
10
3.90
4.0
200
23
110
0.15
1.25
3.3
3.35
3.333
1.27
1.2625
0.20
5
1.04
200
V
V
V
V
V
nA
%
%/V
mI
I
I
V
kHz
A
ms
%
%
CONDITIONS
MIN
TYP
MAX
UNITS
MAX17126/MAX17126A
Dual Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
3
Multi-Output Power Supplies with VCOM Amplifier
and High-Voltage Gamma Reference for LCD TVs
MAX17126/MAX17126A
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
INVL
= V
IN2
= 12V, V
VOP
= V
VREF_I
= 15V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25NC, unless oth-
erwise noted.)
PARAMETER
LX1 Current Limit
CLIM Voltage
Current-Sense Transresistance
LX1 On-Resistance
Soft-Start Period
SS Charge Current
GD_I Input Supply Range
GD_I Input Supply Current
GD_I Overvoltage Threshold
FBP Regulation Voltage
FBP Line Regulation Error
FBP Input Bias Current
DRVP p-Channel MOSFET
On-Resistance
DRVP n-Channel MOSFET
On-Resistance
FBP Fault Trip Level
Positive Charge-Pump
Soft-Start Period
V
SUP
= 11V to 16V, not in dropout
V
FBP
= 1.5V, T
A
= +25°C
-50
1.5
1
Falling edge
7-bit voltage ramp with filtering to prevent high peak
currents 500kHz frequency
750kHz frequency
V
REF
- V
FBN
V
FBN
= 0mV, T
A
= +25°C
V
IN2
= 11V to 16V, not in dropout
1.5
1
Rising edge
7-bit voltage ramp with filtering to prevent high peak
currents 500kHz frequency
750kHz frequency
EN = GND
EN = VL
EN = VL, V
GD_I
- V
GD
5
5
8
720
800
3
2
25
10
6
50
15
7
20
I
FA
V
V
0.99
-50
0.96
1.0
4
3
1.00
1.01
+50
0.2
3
2
880
V
FBP
= 1.5V (not switching)
GD_I rising, 250mV typical hysteresis (Note 2)
20.1
1.2375
C
SS
< 200pF
V
SS
= 1.2V
4
8.0
0.15
21
1.25
CONDITIONS
V
FB1
= 1.1V, R
CLIM
= unconnected
V
FB1
= 1.1V, with R
CLIM
at CLIM pin
R
CLIM
= 60.5kI
MIN
3.6
-20%
0.56
0.19
TYP
4.2
4.2 -
(68k/
R
CLIM
)
0.625
0.21
100
16
5
6
20
0.3
22
1.2625
0.2
+50
3
2
1.04
MAX
4.8
+20%
0.69
0.25
185
A
V
V/A
mI
ms
FA
V
mA
V
V
%/V
nA
I
I
V
ms
ms
V
nA
%/V
I
I
mV
ms
UNITS
POSITIVE CHARGE-PUMP REGULATORS
NEGATIVE CHARGE-PUMP REGULATORS
FBN Regulation Voltage
FBN Input Bias Current
FBN Line Regulation Error
DRVN P
CH
On-Resistance
DRVN N
CH
On-Resistance
FBN Fault Trip Level
Negative Charge-Pump Soft-
Start Period
AVDD SWITCH GATE CONTROL
GD to GD_I Pullup Resistance
GD Output Sink Current
GD Done Threshold
OPERATIONAL AMPLIFIERS
VOP Supply Range
4
______________________________________________________________________________________
Multi-Output Power Supplies with VCOM Amplifier
and High-Voltage Gamma Reference for LCD TVs
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
INVL
= V
IN2
= 12V, V
VOP
= V
VREF_I
= 15V,
T
A
= 0°C to +85°C.
Typical values are at T
A
= +25NC, unless oth-
erwise noted.)
PARAMETER
VOP Overvoltage Fault
Threshold
VOP Supply Current
Input Offset Voltage
Input Bias Current
Input Common-Mode
Voltage Range
Input Common-Mode
Rejection Ratio
Output Voltage Swing High
Output Voltage Swing Low
Large-Signal Voltage Gain
Slew Rate
-3dB Bandwidth
Short-Circuit Current
2V < (V
OPP
, V
OPN
) < (V
VOP
- 2V)
I
OPO
= 25mA
I
OPO
= -25mA
2V < (V
OPP
, V
OPN
) < (V
OP
- 2V)
2V < (V
OPP
, V
OPN
) < (V
OP
- 2V)
2V < (V
OPP
, V
OPN
) < (V
OP
- 2V)
Short to V
VOP
/2, sourcing
Short to V
VOP
/2, sinking
200
200
35
150
V
DLY1
= 2V, GVOFF = VL
V
VGH
- V
VGHM
> 5V
V
DLY1
= 2V, GVOFF = GND
V
VGHM
- V
DRN
> 5V
DLY1 = GND
75
1.0
150
5
390
20
200
2.5
4.0
0.6
1.6
V
GVOFF
= 0V or VL, T
A
= +25°C
1kI from DRN to CPGND, V
GVOFF
= 0V to VL step, no
load on VGHM, measured from GVOFF = 2V to VGHM
= 20%
1kI from DRN to CPGND, V
GVOFF
= VL to 0V step, no
load on VGHM, DRN falling, no load on DRN and VGHM,
measured from V
GVOFF
= 0.6V to VGHM = 80%
9.4
-1
100
+1
50
300
10
VOP -
320
CONDITIONS
V
VOP
= rising, hysteresis = 200mV (Note 2)
Buffer configuration, V
OPP
= V
OPN
= VOP/2, no load
2V < (V
OPP
, V
OPN
) < (V
VOP
- 2V)
2V < (V
OPP
, V
OPN
) < (V
VOP
- 2V)
-1
0
80
VOP -
150
150
80
45
20
300
MIN
20.1
TYP
21
2
3
MAX
22
4
14
+1
VOP
UNITS
V
mA
mV
FA
V
dB
mV
mV
dB
V/Fs
MHz
mA
MAX17126/MAX17126A
HIGH-VOLTAGE SWITCH ARRAY
VGH Supply Range
VGH Supply Current
VGHM-to-VGH Switch
On-Resistance
VGHM-to-VGH Switch
Saturation Current
VGHM-to-DRN Switch
On-Resistance
VGHM-to-DRN Switch
Saturation Current
VGHM-to-GND Switch
On-Resistance
GVOFF Input Low Voltage
GVOFF Input High Voltage
GVOFF Input Current
GVOFF-to-VGHM Rising
Propagation Delay
GVOFF-to-VGHM Falling
Propagation Delay
THR-to-VGHM Voltage Gain
V
FA
I
mA
I
mA
kI
V
V
FA
ns
200
10
10.6
ns
V/V
_______________________________________________________________________________________
5
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