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 2µs. 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 µMAX®package with an
exposed paddle. The MAX9551 is available in an 8-pin
µMAX package with an exposed paddle. The MAX9552
is available in a 14-pin TSSOP package. All devices are
specified over the -40°C to +85°C temperature range.
Applications
TFT-LCD Panels
Instrument Control Voltage Sources
Features
♦Operates Up To 20V
♦800mA Peak Output Current
♦Settles to Within 0.1% of VOUT in Less than 2µs
♦Excellent Load Regulation
♦Thermal-Shutdown Protection
♦Short-Circuit Protection to Both Rails
♦Soft-Start to Reduce Inrush Current
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
MAX9550
16V
SUPPLY
IN+
OUT VOUT
TFT-LCD
CAPACITANCE
VREF
VDD
TFT LCD
IN-
GND
Typical Operating Circuit
19-3858; Rev 1; 2/06
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.
Pin Configuration appears at end of data sheet.
Note: All devices specified over the -40°C to +85°C operating
temperature range.
+Denotes lead-free package.
*Future product—contact factory for availability.
**EP = Exposed paddle.
PART
AMPS
PIN-PACKAGE
PKG
CODE
TOP
MARK
MAX9550EZK+T
1
5 Thin SOT23-5 Z5-1
ADSG
MAX9550EUA+*
18 µMAX-EP**
U8E-2
AABA
MAX9551EUA+*
28 µMAX-EP**
U8E-2
—
MAX9552EUD+*
4
14 TSSOP-EP** U14E-3
—
µMAX is a registered trademark of Maxim Integrated Products, Inc.
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL= 1µF, TA= TMIN to TMAX, unless otherwise noted. Typical values are at
TA= +25°C.) (Note 1)
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.
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= +70°C)
5-Pin Thin SOT23 (derate 9.5mW/°C above +70°C)....727mW
8-Pin µMAX (derate 10.3mW/°C above +70°C) ........824.7mW
14-Pin TSSOP (derate 20.8mW/°C above +70°C) .....1667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP MAX
DC CHARACTERISTICS
Supply Voltage Range VDD Inferred from PSRR test and transient
load test 720V
Quiescent Current ICC Per channel 2 4 mA
Low Output Voltage VOL IL = -4mA 0.04 0.1 V
High Output Voltage VOH IH = +4mA
VDD - 0 . 0 4 V DD - 0.1
V
Input Offset Voltage VOS
-10
+1 +10 mV
Input Bias Current IB0.01 1 µA
Input Resistance RIN 1
Common-Mode Input Voltage CMVR Inferred from CMRR 2
VDD - 2
V
Common-Mode Rejection Ratio CMRR 2V ≤ VIN ≤ (VDD - 2V) 80 96 dB
Power-Supply Rejection Ratio PSRR VOUT = 3.5V, VDD = 7V to 16V 80 96 dB
Continuous Output Current IOVDD = 7V, VOUT = 3.5V, guaranteed by
load, regulation test 55 mA
IOUT = 0mA to 50mA 6 13
Output Load Regulation LR1 IOUT = 0mA to -50mA 6 13 mV
IOUT = 0mA to -55mA
6.5 15
Output Load Regulation LR2 VDD = 7V,
VOUT = 3.5V
IOUT = 0mA to 55mA
6.5 15 mV
Thermal Shutdown +160 °C
Thermal Hysteresis 15 °C
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
_______________________________________________________________________________________ 3
Note 1: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL= 1µF, TA= TMIN to TMAX, unless otherwise noted. Typical values are at
TA= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP MAX
UNITS
AC CHARACTERISTICS
Settling Time tS
Settling to 0.1% of VOUT, IL = 0 to 600mA,
CL = 1µF, RS = 2.2Ω, CS = 0.1µF
(Figure 1)
2.0 µs
Input Capacitance CIN 1.5 pF
IOUT = ±50mA 13
Transconductance gm IOUT = ±500mA 42 S
VDD = 7V, VIN = 1.5V
pulse for 100µs
±200
±290
Transient Output Current
IOUTMAX
AV = 1
VDD = 16V, VIN = 1.5V
pulse for 100µs
±600
±830
mA
Typical Operating Characteristics
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL= 1µF, TA = +25°C, unless otherwise noted.)
INPUT OFFSET VOLTAGE DEVIATION
vs. SUPPLY VOLTAGE
VDD (V)
VOS (mV)
201510
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.2
525
MAX9550 toc01
TA = -40°C
TA = +25°C
TA = +85°C
INPUT OFFSET VOLTAGE DEVIATION
vs. TEMPERATURE
MAX9550 toc02
TEMPERATURE (°C)
VOS (mV)
7550250-25
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
-0.4
-50 100
TRANSCONDUCTANCE
vs. OUTPUT CURRENT
MAX9550 toc03
OUTPUT CURRENT (mA)
TRANSCONDUCTANCE (S)
4002000-200-400
10
20
30
40
50
60
0
-600 600
TA = -40°C
TA = +25°C
TA = +85°C
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
4_______________________________________________________________________________________
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9550 toc04
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
201510
0.5
1.0
1.5
2.0
2.5
3.0
0
525
TA = +85°C
TA = -40°C
TA = +25°C
SUPPLY CURRENT
vs. TEMPERATURE
MAX9550 toc05
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
7550-25 0 25
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
-50 100
LOAD TRANSIENT (±600mA)
MAX9550 toc06
2µs/div
IOUT
500mA/div
VOUT
50mV/div
AC-COUPLED
RS = 2.2Ω, CL = 1µF, CS = 0.1µF
SHORT-CIRCUIT WAVEFORMS
MAX9550 toc07
5ms/div
VCC
5V/div
VOUT
5V/div
IOUT
200mA/div
ICC
200mA/div
STARTUP WAVEFORM
MAX9550 toc08
20µs/div
VOUT
5V/div
IN+
5V/div
VCC
10V/div
IOUT
200mA/div
Typical Operating Characteristics (continued)
(VDD = 16V, GND = 0V, VCM = VOUT = VDD / 2, CL= 1µF, TA = +25°C, unless otherwise noted.)
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
_______________________________________________________________________________________ 5
Pin Description
PIN
MAX9550
THIN
SOT23
µMAX MAX9551 MAX9552
NAME FUNCTION
16 —— OUT VCOM Output
24 411 GND Ground
33 —— IN+ Positive Input
42 —— IN- Negative Input
57 8 4 V
DD Positive Supply Input
—— 11 OUTA VCOM Output A
—— 33 INA+ Positive Input A
—— 22 INA- Negative Input A
—
1, 5, 8
—— N.C. No Connection. Not internally connected.
—— 55 INB+ Positive Input B
—— 66 INB- Negative Input B
—— 77 OUTB VCOM Output B
—— —8 OUTC VCOM Output C
—— —9 INC- Negative Input C
—— —10INC+ Positive Input C
—— —12IND+ Positive Input D
—— —13 IND- Negative Input D
—— —14 OUTD VCOM Output D
—EP EP EP EP Exposed Paddle. EP is internally connected to GND. Connect
EP to GND.
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
6_______________________________________________________________________________________
MAX9550
16V
SUPPLY
16V
SUPPLY
*C1 = 4.7µF
CL = 1µF
*C2 = 0.1µF
*PLACE 4.7µF AND 0.1µF 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.
0V TO 1.5V AT 50kHz
CS = 0.1µF**RS = 2.2Ω
IN+
OUT VOUT
TEST LOAD
VREF
VDD
IN-
GND
Figure 1. Settling Time Test Circuit
Detailed Description
The MAX9550/MAX9551/MAX9552 operational transcon-
ductance amplifiers (OTA) hold the VCOM voltage sta-
ble 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 2µs. 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 band-
width is:
GBW = gM / 2πCOUT
where COUT is the capacitive load at the output and gM
is the transconductance.
To insure buffer stability, place a 1µF low-ESR capaci-
tor as close to the OUT pin as possible. However, this
value may be reduced if the TFT-LCD panel load pro-
vides some of the capacitance and the resistance in
series when this capacitance is low. Connect the feed-
back 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 tem-
perature reaches +160°C, the devices shut down. When
the die cools down by 15°C, the devices turn on again.
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
_______________________________________________________________________________________ 7
Applications Information
Output Load Capacitor
The output load capacitor must have a low ESR value
(50mΩor lower) and it must be placed as close as pos-
sible to the OUT pin to ensure buffer stability (see
Figure 2). Ceramic capacitors are an excellent choice.
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 4.7µF (C1) and 0.1µF (C2) power-sup-
ply bypass capacitors placed as close as possible to
the power-supply pin (VDD). See Figure 2. For dual-
supply operation, use 4.7µF and 0.1µF bypass capaci-
tors on both supplies (VDD and GND) with each
capacitor placed as close as possible to the VDD and
GND pins.
Layout and Grounding
The exposed paddle on the µMAX and TSSOP pack-
ages provides a low thermal resistance for heat dissi-
pation. Solder the exposed paddle to a ground plane
for best results. Do not route traces under these pack-
ages. For dual-supply operation, the exposed paddle
(EP) must be electrically connected to the negative
supply or it can be left unconnected.
MAX9550
16V
SUPPLY
*C1 = 4.7µF
CL = 1µF
*C2 = 0.1µF
*PLACE 4.7µF AND 0.1µF 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.
IN+
OUT VOUT
TFT-LCD
CAPACITANCE
VREF
VDD
TFT LCD
IN-
GND
Figure 2. Typical TFT-LCD Backplane Drive Circuit
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
8_______________________________________________________________________________________
GND
IN-IN+
15V
DD
OUT
MAX9550
MAX9550
THIN SOT23
TOP VIEW
2
34
1
2
3
4
8
7
6
5
N.C.
VDD
OUT
N.C.GND
IN+
IN-
N.C.
µMAX-EP
MAX9551
MAX9552
1
2
3
4
8
7
6
5
VDD
OUTB
INB-
INB+GND
INA+
INA-
OUTA
µMAX-EP
14
13
12
11
10
9
8
1
2
3
4
5
6
7
OUTD
IND-
IND+
GNDVDD
INA+
INA-
OUTA
INC+
INC-
OUTCOUTB
INB-
INB+
TSSOP-EP
Pin Configurations
Chip Information
PROCESS: BiCMOS
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
_______________________________________________________________________________________ 9
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.)
THIN SOT23.EPS
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
10 ______________________________________________________________________________________
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.)
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
______________________________________________________________________________________ 11
8L, µMAX, EXP PAD.EPS
B
1
1
21-0107
PACKAGE OUTLINE, 8L UMAX, EXPOSED PAD
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.)
MAX9550/MAX9551/MAX9552
High-Current VCOM Drive Buffers
for TFT LCDs
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
©2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
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.)
TSSOP 4.4mm BODY.EPS
E1
1
21-0108
PACKAGE OUTLINE, TSSOP, 4.40 MM BODY,
EXPOSED PAD
XX XX