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Partno	Mfg	Dc	Qty	Available	Descript
MAX8784ETL+ |MAX8784ETL	MAXIM	N/a	3240	avai	Step-Up Regulator, Internal Charge Pumps, Switch Control, and Operational Amplifier for TFT LCDs

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MAX8784ETL+
Step-Up Regulator, Internal Charge Pumps, Switch Control, and Operational Amplifier for TFT LCDs
General Description
The MAX8784 generates supply rails for the thin-film
transistor (TFT) liquid-crystal display (LCD) panels in TVs
and monitors. It includes a step-up regulator, a regulated
positive and a negative charge-pump, three high-current
operational amplifiers, and Dual Mode™, logic-con-
trolled, high-voltage switch control block. HVS mode
automatically increases the output voltages of the boost
regulator and the positive charge-pump to stress test
display panels during production. The MAX8784 can
operate from input voltages of 4V to 5.5V and is opti-
mized for LCD TV panel and LCD monitor applications.
The step-up DC-DC regulator provides a regulated sup-
ply voltage for TFT source drivers. The step-up regulator
is a high-frequency (1.2MHz), high-efficiency, current-
mode regulator. The step-up regulator has a built-in
110mΩ(typ) power MOSFET. The high-switching fre-
quency allows the use of ultra-small inductors and
ceramic capacitors. The current-mode architecture pro-
vides fast transient response and easy compensation.
The step-up regulator features output undervoltage pro-
tection, soft-start, internal current limit, and adjustable
output voltage by an external resistive divider.
The three operational amplifiers drive the LCD back-
plane and the gamma-correction-divider string. Each
operational amplifier has a fast slew rate (45V/µs), a
wide bandwidth (20MHz), and a high-output short-cir-
cuit current (200mA). Each op amp has rail-to-rail input
and rail-to-rail output operation.
The positive charge-pump regulator and the negative
charge-pump regulator provide regulated supply volt-
ages for the TFT gate drivers. The positive charge
pump is a two-stage charge pump, which requires no
external diodes. The output voltages of both charge
pumps are resistor adjustable. The logic-controlled
high-voltage switch allows the manipulation of the posi-
tive TFT gate-driver supply.
The MAX8784 is available in a small (5mm x 5mm), low-
profile (0.8mm), 40-pin TQFN package and operates
over the -40°C to +85°C temperature range.
Applications
LCD TVs and LCD Monitors
FeaturesStep-Up Regulator Supply for LCD Panel Source
Driver
Fast Transient Response to Pulsed Load
Built-In 18V, 4A, 0.11Ωn-Channel Power
MOSFET with Lossless Current Sensing
Cycle-by-Cycle Current-Limit Comparator
90% Efficiency (5V In to 15V Out)
1.2MHz Switching FrequencyThree High-Current 19V Operational Amplifiers
180mA Output Short-Circuit Current
45V/µs Slew Rate
20MHz Bandwidth
Rail-to-Rail Input and Output OperationRegulated Charge-Pump Tripler with Integrated
Diodes for TFT Gate-On SupplyRegulated Charge Pump for TFT Gate-Off SupplyBuilt-In Sequencing
Internal Digital Soft-Start
36V Gate-On Switch
Startup Timing Capacitors for AVDD and GON Undervoltage and Thermal Protection4V to 5.5V Input Operating Range
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
Ordering Information
SHDN
DRVN
FBN
REF
AGND
COMP
VIN
VGOFF
STEP-UP
OUTPUT
STEP-UP
OUTPUT
VCC
PGND
ADEL
FBP
VGON
GDEL
SUP
POUT
C1NC2PC1P
DRN
CTLTCON
C2N
RSET
OUT3
POS3
OUT2
OUT1
POS1
NEG1
POS2
NEG2
HVSVIN
PGND
STEP-UP
OUTPUT
STEP-UP
OUTPUT
VCOM
VCOM
VCOM
ON/OFF
GON
MAX8784
Simplified Operating Circuit
19-0737; Rev 0; 1/07
PARTTEMP RANGEPIN-
PACKAGEPKG CODE
MAX8784ETL+-40°C to +85°C40 TQFN
5mm x 5mmT4055-1
+Denotes a lead(Pb)-free/RoHS-compliant package.
EVALUATION KITAVAILABLE
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC= +5V, Circuit of Figure 1, AVDD = SUP = +14V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.)
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.
VCC, CTL, HVS, SHDN, ADEL, GDEL to AGND....-0.3V to +7.5V
REF, COMP, FB, FBN, FBP to AGND.........-0.3V to (VCC+ 0.3V)
POS1, NEG1, POS2, NEG2, POS3, OUT1, OUT2,
OUT3 to AGND.......................................-0.3V to (VSUP+ 0.3)
PGND, BGND to AGND.........................................-0.3V to +0.3V
LX, RSET to PGND.................................................-0.3V to +22V
SUP to AGND.........................................................-0.3V to +22V
DRVN to AGND.........................................-0.3V to (VSUP+ 0.3V)
C1N, C2N to AGND..................................-0.3V to (VSUP+ 0.3V)
C1P to AGND.........................................................-0.3V to +30V
POUT to C2P, C1P to C2P......................................-0.3V to +22V
C2P, POUT to AGND..............................................-0.3V to +40V
GON, DRN to AGND..............................................-0.3V to +40V
DRN to GON............................................................-30V to +30V
REF Short Circuit to AGND.........................................Continuous
RMS VCCCurrent................................................................50mA
RMS DRVN Current...........................................................400mA
LX, PGND RMS Current Rating.............................................2.4A
Continuous Power Dissipation (TA= +70°C)
40-Pin TQFN (derate 35.7mW/°C above +70°C).......2857mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10s).................................+300°C
Soldering Temperature (reflow).......................................+260°C
PARAMETERCONDITIONSMINTYPMAXUNITS
VCC Input Supply Range4.05.5V
VCC Undervoltage Lockout ThresholdVCC rising, typical hysteresis = 50mV2.42.62.8V
VFB = 1.3V, not switching1.0
VFB = 1.1V, switching, no load, VSUP disconnected,
VFBP = VCC, VFBN = 0V46VCC Quiescent Current
SHDN = GND0.05
SHDN Input Low Voltage0.8V
SHDN Input High Voltage1.8V
SHDN Input Current-1+1µA
REFERENCE
REF Output VoltageNo external load1.2381.2501.262V
REF Load Regulation0 < ILOAD < 50µA10mV
REF Sink CurrentIn regulation10µA
REF Undervoltage Lockout ThresholdRising edge, typical hysteresis = 200mV1.01.15V
OSCILLATOR AND TIMING
Frequency100012001400kHz
Oscillator Maximum Duty Cycle879093%
Duration to Trigger Fault Condition475565ms
AD E L, G D E L C ap aci tor C har g e C ur r ent456µA
ADEL, GDEL Turn-On Threshold1.251.32V
STEP-UP REGULATOR
FB = COMP, CCOMP = 1nF1.2351.2461.256FB Regulation VoltageFB = COMP, CCOMP = 1nF, +25°C to +85°C1.2381.2461.256V
FB Fault-Trip LevelFalling edge0.961.001.04V
FB Load Regulation0 < ILOAD < full-1%
FB Line RegulationVCC = 4.5V to 5.5V0.25%/V
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
PARAMETERCONDITIONSMINTYPMAXUNITS
FB TransconductanceΔICOMP = ±2.5µA, FB = COMP75160280µS
LX Current LimitVFB = 1.1V, duty cycle = 75%3.54.04.6A
LX On-ResistanceILX = 1.0A0.100.19Ω
Current-Sense Transresistance0.100.200.26V/ASoft-Start Period7-bit current ramp3ms
POSITIVE CHARGE-PUMP REGULATOR
VSUP Input Supply Range619V
VSUP O ver vol tag e C har g e- P um p Inhi b i tVSUP = rising, typical hysteresis = 200mV202122V
FBP Regulation Voltage1.2251.251.275V
FBP Line Regulation ErrorVSUP = 10V ~ 19V, VPOUT = 28V0.1%/V
FBP Input Bias CurrentVFBP = 1.5V-100+100nA
POUT Output-Voltage RangeIVGON = 0mA36V
POUT Fixed Output VoltageHVS = VCC, IPOUT = 0mA29.13030.9V
POUT Output Current LimitNot in dropout, VSUP = 9V, VPOUT = 24V2050mA
C1N, C2N High-Side On-Resistance9.0Ω
C1N, C2N Low-Side On-Resistance6.0Ω
C1P Switch On-Resistance15.0Ω
C2P Switch On-Resistance10.0Ω
POUT Switch On-Resistance10.0Ω
FBP Fault-Trip Level Falling edge0.961.001.04VPositive Charge-Pump Soft-Start Period 7-bit voltage ramp3ms
NEGATIVE CHARGE-PUMP REGULATOR
FBN Regulation VoltageVREF - VFBN0.9851.001.015V
FBN Input Bias CurrentVFBN = 250mV-50+50nA
FBN Line Regulation ErrorVSUP = 11V to 19V, VGOFF = -9V, IVGOFF = -20mA0.1%/V
DRVN PCH On-Resistance10ΩDRVN NCH On-Resistance6Ω
FBN Fault-Trip Level Rising edge450mVN eg ati ve C har g e- P um p S oft- S tar t P er i od 7-bit voltage ramp3ms
POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES
CTL Input-Low Voltage0.8V
CTL Input-High Voltage1.8V
CTL Input CurrentCTL = 0V or VCC-1+1µA
CTL-to-GON Rising Propagation Delay200ns
CTL-to-GON Falling Propagation Delay200ns
GON-to-POUT Switch On-ResistanceVGDEL = 1.5V, CTL = VCC1020Ω
GO N - to- P OU T S w i tch S atur ati on C ur r entVPOUT - VGON > 5V180mA
GON-to-DRN Switch On-ResistanceVGDEL = 1.5V, CTL = 0V60Ω
GON-to-DRN Switch Saturation CurrentVGON - VDRN > 5V35mA
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +5V, Circuit of Figure 1, AVDD = SUP = +14V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.)
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +5V, Circuit of Figure 1, AVDD = SUP = +14V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.)
PARAMETERCONDITIONSMINTYPMAXUNITS
OPERATIONAL AMPLIFIERS
SUP Supply Range619V
SUP Overvoltage Fault Threshold(Note 1)19.12021.0V
SUP Supply CurrentBuffer configuration, VPOSx = VSUP / 2, no load1115mA
Input Offset VoltageVNEGx, VPOSx = VSUP / 2,12mV
Input Bias CurrentVNEGx, VPOSx = VSUP / 2-1+1µA
Input Common-Mode Voltage Range0VSUPV
Input Common-Mode Rejection Ratio1V < VNEGx, VPOSx < (VSUP - 1)80dB
IOUTx = 1mAVSUP -Output Voltage-Swing High
IOUTx = 25mAVSUP -
IOUTx = -1mA50 Output Voltage-Swing LowIOUTx = -25mA300mV
Large-Signal Voltage GainVOUTx = 1V to VSUP - 1V80dB
Slew RateCLOAD = 20pF45V/µs
-3dB BandwidthCLOAD = 20pF20MHz
Short to VSUP / 2, sourcing140Short-Circuit CurrentShort to VSUP / 2, sinking220mA
HVS FUNCTION
HVS Input-Low Voltage0.8V
HVS Input-High Voltage1.8V
HVS Input Pulldown Resistance51050kΩ
RSET Output On-ResistanceHVS = VCC520Ω
RSET Output LeakageHVS = AGND1µA
ELECTRICAL CHARACTERISTICS
(VCC= +5V, Circuit of Figure 1, AVDD = SUP = +14V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERCONDITIONSMINTYPMAXUNITS
VCC Input Supply Range4.05.5V
VCC Undervoltage Lockout ThresholdVCC rising, typical hysteresis = 50mV2.42.8V
VFB = 1.1V, switching, no load, AVDD isolated
from SUP, VFBP = VCC, VFBN = 0V6VCC Quiescent Current
SHDN = GND0.05
SHDN Input-Low Voltage0.8V
SHDN Input-High Voltage1.8V
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +5V, Circuit of Figure 1, AVDD = SUP = +14V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERCONDITIONSMINTYPMAXUNITS
REFERENCE
REF Output VoltageNo external load1.2321.262V
REF Load Regulation0 < ILOAD < 50µA10mV
REF Sink CurrentIn regulation10µA
REF Undervoltage Lockout ThresholdRising edge, typical hysteresis = 200mV1.15V
OSCILLATOR AND TIMING
Frequency9501400kHz
Oscillator Maximum Duty Cycle8793%
Duration-to-Trigger Fault Condition4769ms
ADEL, GDEL Capacitor Charge Current46µA
ADEL, GDEL Turn-On Threshold1.181.32V
STEP-UP REGULATOR
FB Regulation VoltageFB = COMP, CCOMP = 1nF1.2301.262V
FB Fault Trip LevelFalling edge0.961.04V
FB TransconductanceΔICOMP = ±2.5µA, FB = COMP75280µS
LX Current LimitVFB = 1.1V, duty cycle = 75%3.05.0A
LX On-ResistanceILX = 1.0A0.19Ω
Current-Sense Transresistance0.100.26V/A
POSITIVE CHARGE-PUMP REGULATOR
VSUP Input Supply Range619V
VSUP Overvoltage Charge-Pump InhibitVSUP = rising, typical hysteresis = 200mV2022V
FBP Regulation Voltage1.2251.275nA
POUT Output-Voltage RangeIPOUT = 0mAVSUP36V
POUT Fixed-Output VoltageHVS = VCC, IPOUT = 0mA29.130.9V
POUT Output-Current LimitNot in dropout, VSUP = 9V VPOUT = 24V20mA
C1N, C2N High-Side On-Resistance9Ω
C1N, C2N Low-Side On-Resistance6Ω
C1P Switch On-Resistance15Ω
CP2 Switch On-Resistance10Ω
POUT Switch On-Resistance10Ω
FBP Fault Trip Level Falling edge0.961.04V
NEGATIVE CHARGE-PUMP REGULATOR
FBN Regulation VoltageVREF - VFBN0.9851.015V
DRVN PCH On-Resistance10ΩDRVN NCH On-Resistance6Ω
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
Note 1: Step-up regulator switching is disabled above the threshold. This fault is not latched.
Note 2:-40°C specs are guaranteed by design, not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +5V, Circuit of Figure 1, AVDD = SUP = +14V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERCONDITIONSMINTYPMAXUNITS
POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES
CTL Input-Low Voltage0.8V
CTL Input-High Voltage1.8V
GON-to-POUT Switch On-ResistanceGDEL = 1.5V, CTL = VCC20Ω
GON-to-POUT Switch SaturationVPOUT - VGON > 5V180mA
GON-to-DRN Switch On-ResistanceGDEL = 1.5V, CTL = 0V60Ω
GON-to-DRN Switch Saturation CurrentVGON - VDRN > 5V35mA
OPERATIONAL AMPLIFIERS
SUP Supply Range619V
SUP Overvoltage Fault Threshold(Note 1)19.121.0V
SUP Supply CurrentBuffer configuration, VPOS = VSUP / 2, no load15mA
Input Offset VoltageVNEG, VPOS = VSUP / 213mV
Input Common-Mode Voltage Range0VSUPV
IOUT = 1mAVSUP -
Output-Voltage Swing High
IOUT = 25mAVSUP -
IOUT = -1mA50 Output-Voltage Swing LowIOUT = -25mA300mV
HVS FUNCTION
HVS Input-Low Voltage0.8V
HVS Input-High Voltage1.8V
HVS Input Pulldown Resistance550kΩ
RSET Output On-ResistanceHVS = VCC20Ω
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
STEP-UP REGULATOR EFFICIENCY
vs. LOAD CURRENT
MAX8784 toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
fOSC = 1.2MHz
VIN = 5.0V
STEP-UP REGULATOR LOAD REGULATION
MAX8784 toc02
LOAD CURRENT (mA)
AVDD ERROR (%)
VCC QUIESCENT CURRENT
vs. VCC
MAX8784 toc03
VCC (V)
IVCC
(mA)
SWITCHING
NOT SWITCHING
VCC QUIESCENT CURRENT
vs. TEMPERATURE
MAX8784 toc04
TEMPERATURE (°C)
IVCC
(mA)3510-15
SWITCHING
NOT SWITCHING
STEP-UP REGULATOR SOFT-START
(HEAVY LOAD)
MAX8784 toc05
10ms/div
AVDD
LX: 10V/div
ILOAD: 500mA/div
IL: 20A/div
AVDD: 10V/div
ILOAD
STEP-UP REGULATOR LOAD
TRANSIENT RESPONSE
MAX8784 toc06
20μs/div
AVDD
ILOAD: 200mA/div
AVDD: 100mV/div
ILOAD
STEP-UP REGULATOR PULSED
LOAD TRANSIENT RESPONSE
MAX8784 toc07
10μs/div
AVDD : 200mV/div
(AC-COUPLED)
IAVDD : 1A/div
IAVDD : 0.3A TO 1.3A,
AVDD
IAVDD
Typical Operating Characteristics
(Circuit of Figure 1, VCC= 5V, AVDD = 14V, VPOUT= 28V, VGOFF = -9V, TA= +25°C, unless otherwise noted.)
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
TIMER-DELAY LATCH RESPONSE
TO OVERLOAD
MAX8784 toc08
10ms/div
AVDD
AVDD: 10V/div
LX: 10V/div
IL: 5A/div
SWITCHING FREQUENCY vs. VCC
MAX8784 toc09
VCC (V)
SWITCHING FREQUENCY (MHz)
REFERENCE LOAD REGULATION
MAX8784 toc10
IREF (μA)
REF
(V)302010
SUP SUPPLY CURRENT
vs. SUP VOLTAGE
MAX8784 toc11
VSUP (V)
SUP
(mA)141612
ALL OUTPUTS ENABLED
POSITIVE CHARGE-PUMP REGULATOR
LINE REGULATION
MAX8784 toc12
VSUP (V)
OUTPUT-VOLTAGE ERROR (%)12159
POSITIVE CHARGE-PUMP REGULATOR
LOAD REGULATION
MAX8784 toc13
IPOUT (mA)
OUTPUT VOLTAGE ERROR (%)30402010
NEGATIVE CHARGE-PUMP REGULATOR
LINE REGULATION
MAX8784 toc114
VSUP (V)
OUTPUT-VOLTAGE ERROR (%)18121410
NEGATIVE CHARGE-PUMP REGULATOR
LOAD REGULATION
MAX8784 toc15
IVGOFF (mA)
OUTPUT-VOLTAGE ERROR (%)
VSUP = 16.0V
VSUP = 13.5V
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VCC= 5V, AVDD = 14V, VPOUT= 28V, VGOFF = -9V, TA= +25°C, unless otherwise noted.)
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
HIGH-VOLTAGE SWITCH
CONTROL FUNCTION
MAX8784 toc16
10μs/div
CTL: 5V/divGON: 10V/div
CTL
GON
CGON = 1.5nF
RDRN = 1kΩ TO AVDD
OPERATIONAL AMPLIFIER
FREQUENCY RESPONSE
MAX8784 toc17
FREQUENCY (MHz)
GAIN (dB)1
CLOAD = 56pF
CLOAD = 15pF
CLOAD = 33pF
OPERATIONAL AMPLIFIER
RAIL-TO-RAIL OPERATION
MAX8784 toc18
2μs/div
POS1: 5V/divOUT1: 5V/div
OUT1
POS1
OPERATIONAL AMPLIFIER
LOAD-TRANSIENT RESPONSE
MAX8784 toc19
2μs/div
VOUT1: 200mV/divILOAD: 100mA/div
VOUT1
ILOAD
OPERATIONAL AMPLIFIER
LARGE-SIGNAL RESPONSE
MAX8784 toc20
200ns/div
POS1
OUT1
OPERATIONAL AMPLIFIER
SMALL-SIGNAL STEP RESPONSE
MAX8784 toc21
100ns/div
POS1: 50mV/div (AC-COUPLED)
POS1
OUT1
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VCC= 5V, AVDD = 14V, VPOUT= 28V, VGOFF = -9V, TA= +25°C, unless otherwise noted.)
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
Pin Description
PINNAMEFUNCTIONC1NNegative Terminal of Flying Capacitor C1C1PPositive Terminal of Flying Capacitor C1BGNDOperational Amplifier and Charge-Pump Supply GroundSUPOperational Amplifier and Charge-Pump Supply Input. Connect SUP to AVDD. Bypass SUP to BGND with
0.1µF capacitor.POS1Operational Amplifier Noninverting InputNEG1Operational Amplifier Inverting InputOUT1Operational Amplifier OutputOUT2Operational Amplifier OutputNEG2Operational Amplifier Inverting InputPOS2Operational Amplifier Noninverting InputPOS3Operational Amplifier Noninverting InputOUT3Operational Amplifier Output
13, 19,
20, 26N.C.No Connection. Not internally connected.ADEL
Step-Up Regulator Delay Input. Connect a capacitor from ADEL to AGND to set the delay time. A 5µA current
source charges CADEL. ADEL is internally pulled to AGND by a 20Ω resistor in shutdown. For details, see the
Power-Up Sequence section.GDEL
Positive Charge-Pump Startup Delay and High-Voltage Switch Delay Input. Connect a capacitor from GDEL to
AGND to set the delay time. A 5µA current source charges CGDEL. GDEL is internally pulled to AGND by a
20Ω resistor in shutdown. For details, see the Power-Up Sequence section.CTL
High-Voltage Switch Control Input. When CTL is high, the switch between GON and POUT is turned on and
the switch between GON and DRN is turned off. When CTL is low, the switch between GON and DRN is
turned on and the switch between GON and POUT is turned off. For details, see the High-Voltage Switch
Control section.HVSHVS Mode Input. Connect HVS to VCC to enable HVS mode. For details, see the HVS Mode section.DRVNNegative Charge-Pump Regulator Output. Connect DRVN to the negative charge-pump flying capacitor(s).FBN
Negative Charge-Pump Regulator Feedback Input. Connect FBN to the center of a resistive voltage-divider
between the negative output and REF. Place the resistive voltage-divider within 5mm of FBN. For details, see
the Output-Voltage Selection section.REFReference Output. Connect a 0.22µF capacitor from REF to AGND.AGNDAnalog GroundVCCVCC Supplies the Internal Reference and Other Internal Circuitry. Connect VCC to the input supply voltage
and bypass VCC to AGND with a minimum 1µF ceramic capacitor.SHDNActive-Low Shutdown. When SHDN is low, the device enters its low-power shutdown mode.
27, 28PGNDPower Ground
29, 30LXStep-Up Regulator Switching Node. Connect inductor and Schottky diode to LX and minimize trace area for
lowest EMI.
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
Pin Description (continued)
PINNAMEFUNCTIONAGNDAnalog GNDRSETOpen-Drain HVS Mode Output. For details, see the HVS Mode section.COMPError-Amplifier Output. Connect a series RC network from COMP to AGND for compensation.FB
Step-Up Regulator Feedback Input. Connect FB to the center of a resistive voltage-divider between the step-
up regulator output and AGND. Place the resistive voltage-divider within 5mm of FB. For details, see the
Output-Voltage Selection section.GON
Inter nal H i g h- V ol tag e S w i tch C om m on Ter m i nal . GO N com m on ter m i nal b etw een the hi g h- si d e p - channel OS FE T and b ack- to- b ack p - channel M O S FE T. G O N i s i nter nal l y p ul l ed to P G N D b y a 100kΩ r esi stor i n
shutd ow n.DRNHigh-Voltage Switch Drain. Drain of the internal low-side, back-to-back p-channel MOSFET.FBP
Positive Charge-Pump Regulator Feedback Input. Connect FBP to the center of a resistive voltage-divider
between POUT and AGND. Place the resistive voltage-divider within 5mm of FBP. For details, see the Output-
Voltage Selection section.POUTPositive Charge-Pump Output and High-Voltage Switch Source InputC2PPositive Terminal of Flying Capacitor C2C2NNegative Terminal of Flying Capacitor C2
MAX8784
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
Typical Operating Circuit
The typical operating circuit (Figure 1) of the MAX8784
is a power-supply system for TFT-LCD panels in moni-
tors and TVs. The circuit generates a +14V source-dri-
ver supply, a +28V positive gate-driver supply, and a
-9V negative gate-driver supply from a 5V ±10% input
supply. Table 1 lists the selected components and
Table 2 lists the contact information of the component
suppliers.
Detailed Description
The MAX8784 is a multiple-output power supply
designed primarily for TFT-LCD panels used in monitors
SHDN
DRVN
FBN
REF
AGND
COMP
VIN = 4.5V TO 5.5V
VGOFF
-9V, 20mA
AVDD
14V, 0.75A
VCC
PGND
AVDD
ADEL
FBP
VGON
28V, 20mA
GDEL
SUP
POUT
C1NC2PC1P
DRN
CTL
AVDD
TCON
C2N
RSET
OUT3
POS3
OUT2
OUT1
POS1
NEG1
POS2
NEG2
HVS
PGND
VCOM
AVDD
VCOM
VCOM
VIN
GON
0.22μF
1μF
1μF
10μF
0.1μFC6
0.1μF
C14
10μF
C15
10μF
10kΩ
10kΩ
20kΩ
187kΩ
428kΩ
1μF
20kΩ
1kΩ
0.1μF
100kΩ
82kΩ
R11
204kΩ
R10
20kΩ
3μHD1
BGND
BGND
MAX8784
0.1μF
C12
10μF
C13
10μF
C10
0.01μF
C11
330pF
Figure 1. Typical Operating Circuit
Table 1. Component List1µF ±10%, 6.3V X5R ceramic capacitor (0402)
TDK C1005X5R0J105K
C14, C1510µF ±20%, 6.3V X5R ceramic capacitors (0603)
TDK C1608X5R0J106M
C12, C1310µF ±20%, 16V X5R ceramic capacitors (1206)
TDK C3216X5R1C106M3A, 30V Schottky diode (M-flat)
Toshiba CMS02 (top mark S2)220mA, 100V dual diode (SOT23)
Fairchild MMBD4148SE (top mark D4)3.0µH, 3ADC inductor

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