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19-3858; Rev 1; 2/06
High-Current VCOM Drive Buffers for TFT LCDs
General Description
The MAX9550/MAX9551/MAX9552 provide a VCOM source for TFT LCDs. The MAX9550/MAX9551/ MAX9552 source and sink a large current to quickly restore the VCOM voltage, making it ideal for TFT LCDs. The output settles to within 0.1% in less than 2s. In addition, the MAX9550/MAX9551/MAX9552 directly drive the capacitive load in the VCOM layer of the TFT LCDs without the need for a series resistor. The MAX9550/MAX9551/MAX9552 feature single, dual, and quad channel VCOM amplifiers, respectively. The MAX9550/MAX9551/MAX9552 can drive up to 800mA of peak current per channel and operate up to 20V. The devices feature soft-start to reduce inrush current, output short-circuit protection, and thermal shutdown. The MAX9550 is available in a space-saving 5-pin thin SOT23 package, and an 8-pin MAX(R) package with an exposed paddle. The MAX9551 is available in an 8-pin MAX package with an exposed paddle. The MAX9552 is available in a 14-pin TSSOP package. All devices are specified over the -40C to +85C temperature range. Operates Up To 20V 800mA Peak Output Current Settles to Within 0.1% of VOUT in Less than 2s Excellent Load Regulation Thermal-Shutdown Protection Short-Circuit Protection to Both Rails Soft-Start to Reduce Inrush Current
Features
MAX9550/MAX9551/MAX9552
Ordering Information
PART MAX9550EZK+T MAX9550EUA+* MAX9551EUA+* MAX9552EUD+* AMPS PIN-PACKAGE 1 1 2 4 5 Thin SOT23-5 8 MAX-EP** 8 MAX-EP** 14 TSSOP-EP** PKG CODE Z5-1 U8E-2 U8E-2 U14E-3 TOP MARK ADSG AABA -- --
Applications
TFT-LCD Panels Instrument Control Voltage Sources
Pin Configuration appears at end of data sheet.
Note: All devices specified over the -40C to +85C operating temperature range. +Denotes lead-free package. *Future product--contact factory for availability. **EP = Exposed paddle.
Typical Operating Circuit
16V SUPPLY
VDD
MAX9550
VREF IN+ OUT INGND VOUT TFT-LCD CAPACITANCE
TFT LCD
MAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products
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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.
High-Current VCOM Drive Buffers for TFT LCDs MAX9550/MAX9551/MAX9552
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VDD to GND) ................................-0.3V to +22V Any Other Pin to GND ................................-0.3V to (VDD + 0.3V) IN+/IN- (current) ...............................................................20mA OUT, OUT_ (current)................................................................1A Continuous Power Dissipation (TA = +70C) 5-Pin Thin SOT23 (derate 9.5mW/C above +70C) ....727mW 8-Pin MAX (derate 10.3mW/C above +70C) ........824.7mW 14-Pin TSSOP (derate 20.8mW/C above +70C) .....1667mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL = 1F, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER DC CHARACTERISTICS Supply Voltage Range Quiescent Current Low Output Voltage High Output Voltage Input Offset Voltage Input Bias Current Input Resistance Common-Mode Input Voltage Common-Mode Rejection Ratio Power-Supply Rejection Ratio Continuous Output Current Output Load Regulation Output Load Regulation Thermal Shutdown Thermal Hysteresis VDD ICC VOL VOH VOS IB RIN CMVR CMRR PSRR IO LR1 LR2 Inferred from CMRR 2V VIN (VDD - 2V) VOUT = 3.5V, VDD = 7V to 16V VDD = 7V, VOUT = 3.5V, guaranteed by load, regulation test IOUT = 0mA to 50mA IOUT = 0mA to -50mA VDD = 7V, VOUT = 3.5V IOUT = 0mA to -55mA IOUT = 0mA to 55mA 2 80 80 55 6 6 6.5 6.5 +160 15 13 13 15 15 96 96 Inferred from PSRR test and transient load test Per channel IL = -4mA IH = +4mA -10 7 2 0.04 VDD - 0.04 +1 0.01 1 VDD - 2 20 4 0.1 VDD - 0.1 +10 1 V mA V V mV A M V dB dB mA mV mV C C SYMBOL CONDITIONS MIN TYP MAX UNITS
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High-Current VCOM Drive Buffers for TFT LCDs
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL = 1F, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER AC CHARACTERISTICS Settling Time Input Capacitance Transconductance tS CIN gm IOUT = 50mA IOUT = 500mA VDD = 7V, VIN = 1.5V pulse for 100s Transient Output Current IOUTMAX AV = 1 VDD = 16V, VIN = 1.5V pulse for 100s 200 600 Settling to 0.1% of VOUT, IL = 0 to 600mA, CL = 1F, RS = 2.2, CS = 0.1F (Figure 1) 2.0 1.5 13 42 290 mA 830 s pF S SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX9550/MAX9551/MAX9552
Note 1: All devices are 100% production tested at TA = +25C. All temperature limits are guaranteed by design.
Typical Operating Characteristics
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL = 1F, TA = +25C, unless otherwise noted.)
INPUT OFFSET VOLTAGE DEVIATION vs. SUPPLY VOLTAGE
MAX9550 toc01
INPUT OFFSET VOLTAGE DEVIATION vs. TEMPERATURE
MAX9550 toc02
TRANSCONDUCTANCE vs. OUTPUT CURRENT
MAX9550 toc03
0.5 0.4 0.3 VOS (mV) 0.2 0.1 0 -0.1 -0.2 5 10 15 VDD (V) 20 TA = +25C TA = -40C
0.6 0.5 0.4 0.3 VOS (mV) 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4
60 50 TRANSCONDUCTANCE (S) 40 TA = +25C 30 20 10 0
TA = -40C
TA = +85C
TA = +85C
25
-50
-25
0
25
50
75
100
-600
-400
-200
0
200
400
600
TEMPERATURE (C)
OUTPUT CURRENT (mA)
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High-Current VCOM Drive Buffers for TFT LCDs MAX9550/MAX9551/MAX9552
Typical Operating Characteristics (continued)
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL = 1F, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX9550 toc04
SUPPLY CURRENT vs. TEMPERATURE
MAX9550 toc05
LOAD TRANSIENT (600mA)
RS = 2.2, CL = 1F, CS = 0.1F IOUT 500mA/div
MAX9550 toc06
4.0 3.5 SUPPLY CURRENT (mA) 3.0 2.5 2.0 1.5 1.0 0.5 0 -50 -25 0 25 50 75
3.0 SUPPLY CURRENT (mA) 2.5
TA = +85C
TA = +25C 2.0 1.5 1.0 0.5 0 5 10 15 SUPPLY VOLTAGE (V) 20 25 TA = -40C
VOUT 50mV/div AC-COUPLED
100
2s/div
TEMPERATURE (C)
SHORT-CIRCUIT WAVEFORMS
MAX9550 toc07
STARTUP WAVEFORM
MAX9550 toc08
ICC 200mA/div IOUT 200mA/div VOUT 5V/div
IOUT 200mA/div VCC 10V/div IN+ 5V/div VOUT 5V/div
VCC 5V/div 5ms/div
20s/div
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High-Current VCOM Drive Buffers for TFT LCDs
Pin Description
PIN MAX9550 THIN SOT23 1 2 3 4 5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- MAX 6 4 3 2 7 -- -- -- 1, 5, 8 -- -- -- -- -- -- -- -- -- EP MAX9551 -- 4 -- -- 8 1 3 2 -- 5 6 7 -- -- -- -- -- -- EP MAX9552 -- 11 -- -- 4 1 3 2 -- 5 6 7 8 9 10 12 13 14 EP NAME FUNCTION
MAX9550/MAX9551/MAX9552
OUT GND IN+ INVDD OUTA INA+ INAN.C. INB+ INBOUTB OUTC INCINC+ IND+ INDOUTD EP
VCOM Output Ground Positive Input Negative Input Positive Supply Input VCOM Output A Positive Input A Negative Input A No Connection. Not internally connected. Positive Input B Negative Input B VCOM Output B VCOM Output C Negative Input C Positive Input C Positive Input D Negative Input D VCOM Output D Exposed Paddle. EP is internally connected to GND. Connect EP to GND.
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High-Current VCOM Drive Buffers for TFT LCDs MAX9550/MAX9551/MAX9552
Detailed Description
The MAX9550/MAX9551/MAX9552 operational transconductance amplifiers (OTA) hold the VCOM voltage stable while providing the ability to source and sink a high current quickly (800mA typ) into a capacitive load such as the backplane of a TFT-LCD panel. The output settles to within 0.1% in less than 2s. The fast settling time is achieved by increasing the transconductance of the buffer as the output current increases (see the Typical Operating Characteristics). In addition, the MAX9550/MAX9551/MAX9552 directly drive the capacitive load in the VCOM layer of the TFT LCD without the need for a series resistor. The MAX9550/MAX9551/MAX9552 unity-gain bandwidth is: GBW = gM / 2COUT where COUT is the capacitive load at the output and gM is the transconductance. To insure buffer stability, place a 1F low-ESR capacitor as close to the OUT pin as possible. However, this value may be reduced if the TFT-LCD panel load provides some of the capacitance and the resistance in series when this capacitance is low. Connect the feedback at OUT using a Kelvin connection at the low-ESR capacitor.
Thermal Shutdown with Temperature Hysteresis
The MAX9550/MAX9551/MAX9552 are capable of high output currents and therefore, feature thermal-shutdown protection with temperature hysteresis. When the die temperature reaches +160C, the devices shut down. When the die cools down by 15C, the devices turn on again.
16V SUPPLY *C2 = 0.1F 16V SUPPLY VDD TEST LOAD *C1 = 4.7F
MAX9550
VREF IN+ OUT INGND CL = 1F 0V TO 1.5V AT 50kHz VOUT **RS = 2.2 CS = 0.1F
*PLACE 4.7F AND 0.1F CAPACITORS AS CLOSE TO PIN AS POSSIBLE. **RS INCLUDES THE GENERATOR RESISTANCE. NOTE: PLACE CL AS CLOSE TO OUT PIN AS POSSIBLE AND KELVIN SENSE THE FEEDBACK LOOP CONNECTION AS SHOWN.
Figure 1. Settling Time Test Circuit
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High-Current VCOM Drive Buffers for TFT LCDs MAX9550/MAX9551/MAX9552
Applications Information
Output Load Capacitor
The output load capacitor must have a low ESR value (50m or lower) and it must be placed as close as possible to the OUT pin to ensure buffer stability (see Figure 2). Ceramic capacitors are an excellent choice. the power-supply pin (VDD). See Figure 2. For dualsupply operation, use 4.7F and 0.1F bypass capacitors on both supplies (V DD and GND) with each capacitor placed as close as possible to the VDD and GND pins.
Layout and Grounding
The exposed paddle on the MAX and TSSOP packages provides a low thermal resistance for heat dissipation. Solder the exposed paddle to a ground plane for best results. Do not route traces under these packages. For dual-supply operation, the exposed paddle (EP) must be electrically connected to the negative supply or it can be left unconnected.
Power Supplies and Bypass Capacitors
The MAX9550/MAX9551/MAX9552 operate from a 6V to 20V single supply, or from 3V to 10V dual supplies. Proper supply bypassing ensures stability while driving high transient loads. The MAX9550/MAX9551/MAX9552 require minimum 4.7F (C1) and 0.1F (C2) power-supply bypass capacitors placed as close as possible to
16V SUPPLY *C2 = 0.1F *C1 = 4.7F
VDD
MAX9550
VREF IN+ OUT INGND CL = 1F VOUT
TFT LCD
TFT-LCD CAPACITANCE
*PLACE 4.7F AND 0.1F CAPACITORS AS CLOSE TO PIN AS POSSIBLE. NOTE: PLACE CL AS CLOSE TO THE OUT PIN AS POSSIBLE AND KELVIN SENSE THE FEEDBACK LOOP CONNECTION AS SHOWN.
Figure 2. Typical TFT-LCD Backplane Drive Circuit
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High-Current VCOM Drive Buffers for TFT LCDs MAX9550/MAX9551/MAX9552
Pin Configurations
TOP VIEW
MAX9550
OUT 1 5 VDD N.C. INGND 2 IN+ GND IN+ 3 4 IN1 2 3 4
MAX9550
8 7 6 5 N.C. VDD OUT N.C.
MAX-EP
THIN SOT23 MAX9552
OUTA 1 14 OUTD 13 IND12 IND+ 11 GND 10 INC+ 9 INC8 OUTC
MAX9551
OUTA INAINA+ GND 1 2 3 4 8 7 6 5 VDD OUTB INBINB+
INA- 2 INA+ 3 VDD 4 INB+ 5 INB- 6 OUTB 7
MAX-EP
TSSOP-EP
Chip Information
PROCESS: BiCMOS
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High-Current VCOM Drive Buffers for TFT LCDs
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
MAX9550/MAX9551/MAX9552
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THIN SOT23.EPS
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High-Current VCOM Drive Buffers for TFT LCDs MAX9550/MAX9551/MAX9552
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
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High-Current VCOM Drive Buffers for TFT LCDs
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
8L, MAX, EXP PAD.EPS
MAX9550/MAX9551/MAX9552
PACKAGE OUTLINE, 8L UMAX, EXPOSED PAD
21-0107
B
1
1
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High-Current VCOM Drive Buffers for TFT LCDs MAX9550/MAX9551/MAX9552
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
XX XX
PACKAGE OUTLINE, TSSOP, 4.40 MM BODY, EXPOSED PAD
21-0108
E
1
1
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
TSSOP 4.4mm BODY.EPS

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