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General Description
The MAX4285/MAX4286 single and MAX4287/MAX4288/
MAX4387/MAX4388 dual ADC buffer amplifiers feature
high-speed performance and single +3V supply opera-
tion. The MAX4285/MAX4286/MAX4288 and MAX4388
offer a disable feature that reduces power-supply current
and places the outputs in a high-impedance state. All six
devices operate from a +2.85V to +6.5V single supply or
from ±1.425V to ±3.25V dual supplies. The common-
mode input voltage range extends to the negative power-
supply rail (ground in single-supply applications).
These devices require 20mA of quiescent supply current
per amplifier while achieving a 250MHz -3dB bandwidth
and a 350V/µs slew rate. The combination of an 8ns (to
0.1%) settling time, 88dBc (f = 5MHz) of SFDR, and up to
100mA output drive makes these amplifiers ideal for high-
speed ADC drivers for communications and instrumenta-
tion applications. In addition, when disabled, their high
output impedance makes them ideal for multiplexing
applications.
The MAX4285/MAX4286 are available in space-saving
6-pin SOT23 and 8-pin SO packages. The MAX4287/
MAX4387 come in 8-pin µMAX and 8-pin SO packages,
while the MAX4288/MAX4388 come in 10-pin µMAX and
14-pin SO packages.
Applications
High-Speed ADC Drivers
Communications Equipment
Instrumentation
CCD Imaging Systems
Ultrasound
Features
♦High Speed at 3V
250MHz -3dB Bandwidth (MAX4285/87/88)
150MHz -3dB Bandwidth (MAX4286, MAX4387/88)
350V/µs Slew Rate
♦+2.85V to +6.5V Single-Supply Operation
♦Input Common-Mode Range Extends to VEE
♦Low Distortion at 5MHz
-88dBc SFDR
♦High Output Current Drive: -106mA to +77mA
♦6ns Settling Time to 0.1%
♦High-Speed Enable/Disable
40ns Enable Time
50ns Disable Time
High Output Impedance
♦Space-Saving SOT23 and µMAX Packages
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
________________________________________________________________ Maxim Integrated Products 1
19-1500; Rev 0; 4/00
Ordering Information continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
Ordering Information
Selector Guide
MAX4285EUT-T -40°C to +85°C 6 SOT23-6 AABQ
SOT TOP
MARK
PIN-
PACKAGE
TEMP.
RANGE
PART
MAX4285ESA -40°C to +85°C 8 SO —
MAX4286EUT-T -40°C to +85°C 6 SOT23-6 AABR
MAX4286ESA -40°C to +85°C 8 SO —
MAX4287EUA -40°C to +85°C 8 µMAX —
MAX4287ESA -40°C to +85°C 8 SO —
PART OP AMPS
PER PKG
MIN GAIN -3dB BANDWIDTH
(AT MIN GAIN)
HIGH-SPEED
DISABLE PIN-PACKAGE
MAX4285 1 1 250MHz Yes 6-pin SOT23, 8-pin SO
MAX4286 1 5 150MHz Yes 6-pin SOT23, 8-pin SO
MAX4287 2 1 250MHz No 8-pin µMAX/SO
MAX4288 2 1 250MHz Yes 10-pin µMAX/14-pin SO
MAX4387 2 5 150MHz No 8-pin µMAX/SO
MAX4388 2 5 150MHz Yes 10-pin µMAX, 14-pin SO
Pin Configurations appear at end of data sheet.
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(VCC = +3V, VEE = 0, DISABLE_ = 3V, RL= ∞, VCM = 1V, and 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 (VCC - VEE) ...................................-0.3V to +7.5V
Input Voltage Range (IN+, IN-) ........(VEE - 0.3V) to (VCC + 0.3V)
Differential Input Voltage .......................................-0.3V to +7.5V
Voltage at DISABLE .........................(VEE - 0.3V) to (VCC + 0.3V)
Current into IN+, IN-, DISABLE ........................................±20mA
Output Short-Circuit Duration ........................................Indefinite
Continuous Power Dissipation (TA= +70°C)
6-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
14-Pin SO (derate 8.3mW/°C above +70°C)................667mW
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
Guaranteed by CMRR test
MAX4_87EU_/MAX4_88EU_/MAX4_8_ES_
Guaranteed by PSRR test
mV
±0.1 ±8
Common mode (VEE ≤VCM ≤VCC - 1.25V)
MAX4287/88 and MAX4387/88
Differential (-10mV ≤VIN ≤+10mV)
VEE ≤VCM ≤
VCC - 1.25V
CONDITIONS
VOS
Input Offset Voltage
µA
13 35
dB
50 73
CMRRCommon-Mode Rejection Ratio
µV/°C
26
TCVOS
Input Offset-Voltage
Temperature Coefficient
V
VEE VCC -
1.25
VCM
V
2.85 6.5
Operating Supply Voltage
Range
Input Common-Mode Voltage
Range
IB
Input Bias Current
µA
0.2 8
IOS
Input Offset Current
RIN 600
mV
±0.2
∆VOS
Input Offset-Voltage Matching
kΩ
38
Input Resistance
UNITSMIN TYP MAXSYMBOLPARAMETER
MAX4285EUT-T/MAX4286EUT-T ±1.5 ±12
MAX4_87EU_/
MAX4_88EU_/
MAX4_8_ES_
MAX4285EUT-T/
MAX4286EUT-T 45 68
RL= 2kΩ
RL= 100Ω60 85
VEE + 0.4V ≤
VOUT ≤VCC - 0.4V dB
75 94
AVOL
Open-Loop Gain 65 94
RL= 300Ω
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
_______________________________________________________________________________________ 3
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3V, VEE = 0, DISABLE_ = 3V, RL= ∞, VCM = 1V, and TA= TMIN to TMAX, unless otherwise noted. Typical values are at
TA= +25°C.) (Note 1)
DISABLE_ = VEE µA
±3 ±22
IIL
CONDITIONS
DISABLE_ Logic Input
Low Current
DISABLE_ = VCC
mA
±3 ±22
IIH
DISABLE_ Logic Input
High Current
VCC = 3V
µA
20 24
ISY
Quiescent Supply Current
(per Amplifier)
Normal mode
Disabled mode,
DISABLE_ = VEE 13
VCC = 5V
23 28
Normal mode
Disabled mode,
DISABLE_ = VEE 13
UNITSMIN TYP MAXSYMBOLPARAMETER
DISABLE_ = VEE, VEE ≤VOUT ≤VCC
RL= 20Ωto VEE
nA
700
ILEAK
Disabled Output Leakage
Current
mA
77
IOUT
Output Current Drive RL= 20Ωto VCC 106
VCC = 2.85V to 6.5V dB
40 50
PSRRPower-Supply Rejection Ratio
V
VCC - 2
VIL
DISABLE_ Logic Low Threshold
DISABLE_ Logic High Threshold VIH VCC - 1 V
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
4 _______________________________________________________________________________________
fC= 20MHz
MAX4286 and
MAX4387/88
MAX4285/87/88
MAX4285/87/88
MAX4286 and
MAX4387/88
VOUT = 100mVp-p
VOUT = 1V step, 10% to 90%
VOUT = 1V step
VOUT = 100mVp-p
MAX4285/87/88
MAX4286 and
MAX4387/88
VOUT= 1V step, 90% to 10%
VOUT = 1V step, 10% to 90%
CONDITIONS
dBm
34
IP3
Two-Tone Third-Order Intercept
25
14 ns
6
tS 0.1%
Settling Time (0.1%)
ns
2.8
tF
Fall Time
ns
2.2
tR
Rise Time
150 MHz
250
BWSS
Small-Signal -3dB Bandwidth
V/µs
350
SRSlew Rate
50 MHz
100
BW0.1dB
Bandwidth for 0.1dB Flatness
UNITSMIN TYP MAXSYMBOLPARAMETER
f = 1MHz
MAX4287/88 and MAX4387/88,
f = 10MHz, VOUT = 1Vp-p
VOUT = 1V, to within 0.1%
VOUT = 1V, to within 0.1%
f = 10MHz
dBc
85
XTALK
Crosstalk
50
tOFF
Disable Time ns
40
tON
Enable Time
Ω
0.5
ZOUT
Output Impedance
pF
2
CIN
Input Capacitance
pA/√Hz
2.1
in
Input Noise Current Density
AC ELECTRICAL CHARACTERISTICS
(VCC = +3V, VEE = 0, DISABLE_ = 3V, RL= 300Ωto VCC/2, VCM = 1V, AVCL = +1V/V for MAX4285/MAX4287/MAX4288, AVCL =
+5V/V for MAX4286 and MAX4387/MAX4388, TA= +25°C, unless otherwise noted.)
VOUT = 0.5Vp-p
fC= 100kHz
fC= 1MHz
50
70
Spurious-Free Dynamic Range 79
87
88
dBc
88
SFDR fC= 5MHz
fC= 10MHz
fC= 20MHz
fC= 60MHz
ns10% overdriveOverload Recovery Time
MHz
200
VOUT = 1Vp-pBWLS
Large-Signal -3dB Bandwidth
f = 1MHz nV/√Hz
10
en
Input Noise Voltage Density
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
_______________________________________________________________________________________ 5
AC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V, VEE = 0, DISABLE_ = 5V, RL= 300Ωto VCC/2, VCM = 2.5V, AVCL = +1V/V for MAX4285/MAX4287/MAX4288, AVCL =
+5V/V for MAX4286 and MAX4387/MAX4388, TA= +25°C, unless otherwise noted.)
f = 1MHz
fC= 20MHz
MAX4286 and
MAX4387/88
MAX4285/87/88
MAX4285/87/88
MAX4286 and
MAX4387/88
VOUT =
100mVp-p
VOUT = 1Vp-p
VOUT = 2V step, 10% to 90%
VOUT = 2V step
VOUT = 100mVp-p
MAX4285/87/88
VOUT = 1Vp-p
MAX4286 and
MAX4387/88
fC= 100kHz
VOUT= 2V step, 90% to 10%
fC= 1MHz
VOUT = 2V step, 10% to 90%
CONDITIONS
nV/√Hz
6.5
en
Input Noise Voltage Density
dBm
40
IP3Two-Tone Third-Order Intercept
45
64
Spurious-Free Dynamic Range 77
86
86
dBc
86
SFDR
10
fC= 5MHz
ns
8
tS 0.1%
Settling Time (0.1%)
ns
2.9
tF
Fall Time
ns
4.2
tR
Rise Time
MHz
195
BWLS
Large-Signal -3dB Bandwidth
130
fC= 10MHz
MHz
220
BWSS
Small-Signal -3dB Bandwidth
fC= 20MHz
V/µs
385
SRSlew Rate
40
fC= 60MHz
MHz
75
BW0.1dB
Bandwidth for 0.1dB Flatness
UNITSMIN TYP MAXSYMBOLPARAMETER
f = 1MHz
MAX4287/88 and MAX4387/88,
f = 10MHz, VOUT = 2Vp-p
VOUT = 1V, to within 0.1%
VOUT = 1V, to within 0.1%
f = 10MHz
dBc
85
XTALK
Crosstalk
35
tOFF
Disable Time ns
40tON
Enable Time
Ω
0.5
ZOUT
Output Impedance
pF
2
CIN
Input Capacitance
pA/√Hz
1.9
in
Input Noise Current Density
Note 1: The MAX428_EUT (SOT23) are 100% production tested at TA= +25°C. Specifications over temperature limits are guaran-
teed by design.
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
6 _______________________________________________________________________________________
100M 1G
-6
-3
-4
-5
-2
-1
0
2
1
3
4
100k 1M 10M
MAX4285/MAX4287/MAX4288
SMALL-SIGNAL GAIN vs. FREQUENCY
MA4285-01
FREQUENCY (Hz)
GAIN (dB)
AV = +1V/V
100M 1G
-6
-3
-4
-5
-2
-1
0
2
1
3
4
100k 1M 10M
MAX4286/MAX4387/MAX4388
SMALL-SIGNAL GAIN vs. FREQUENCY
MA4285-02
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
100M 1G
-0.5
-0.2
-0.3
-0.4
-0.1
0
0.1
0.3
0.2
0.4
0.5
100k 1M 10M
MAX4285/MAX4387/MAX4288
GAIN FLATNESS vs. FREQUENCY
(RLOAD = 100Ω)
MA4285-03
FREQUENCY (Hz)
GAIN (dB)
AV = +1V/V
100M 1G
-0.6
-0.3
-0.4
-0.5
-0.2
-0.1
0
0.2
0.1
0.3
0.4
100k 1M 10M
MAX4285/MAX4287/MAX4288
GAIN FLATNESS vs. FREQUENCY
(RLOAD = 300Ω)
MA4285-04
FREQUENCY (Hz)
GAIN (dB)
AV = +1V/V
100M 1G
-6
-3
-4
-5
-2
-1
0
2
1
3
4
100k 1M 10M
LARGE-SIGNAL GAIN vs. FREQUENCY
MA4285-07
FREQUENCY (Hz)
GAIN (dB)
100M 1G
-0.5
-0.2
-0.3
-0.4
-0.1
0
0.1
0.3
0.2
0.4
0.5
100k 1M 10M
MAX4285/MAX4287/MAX4288
GAIN FLATNESS vs. FREQUENCY
(RLOAD = 1kΩ)
MA4285-05
FREQUENCY (Hz)
GAIN (dB)
AV = +1V/V
100M 1G
-0.6
-0.3
-0.4
-0.5
-0.2
-0.1
0
0.2
0.1
0.3
0.4
100k 1M 10M
MAX4286/MAX4387/MAX4388
GAIN FLATNESS vs. FREQUENCY
MA4285-06
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
RLOAD = 100Ω
RLOAD = 300Ω
RLOAD = 1kΩ
0.1 1 10 100
MAX4285/MAX4287/MAX4288
DISTORTION vs. FREQUENCY
MAX4285-08
FREQUENCY (MHz)
GAIN (dB)
-40
-100
-90
-80
-70
-60
-50
R
L
= 300Ω
V
OUT
= 0.5Vp-p
A
V
= +1V/V
2ND HARMONIC
3RD HARMONIC
0.1 1 10 100
MAX4286/MAX4387/MAX4388
DISTORTION vs. FREQUENCY
MAX4285-09
FREQUENCY (MHz)
GAIN (dB)
-40
-100
-90
-80
-70
-60
-50
R
L
= 300Ω
V
OUT
= 0.5Vp-p
A
V
= +5V/V
2ND HARMONIC
3RD HARMONIC
Typical Operating Characteristics
(VCC = +3V, VEE = 0, DISABLE_ ≥2V, RL= 300Ωto VCC/2, VCM = +1.0V, TA=+25°C, unless otherwise noted.)
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
_______________________________________________________________________________________ 7
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ ≥2V, RL= 300Ωto VCC/2, VCM = +1.0V, TA=+25°C, unless otherwise noted.)
-120
-100
-110
-70
-80
-90
-50
-60
-40
100 400 500200 300 600 700 800 900 1000
MAX4285/MAX4287/MAX4288
DISTORTION vs. LOAD
MAX4285-11
RESISTIVE LOAD (Ω)
DISTORTION (dBc)
f
O
= 20MHz
V
OUT
= 0.5Vp-p
A
V
= +1V/V
2ND HARMONIC
3RD HARMONIC
-120
-100
-110
-70
-80
-90
-50
-60
-40
100 400 500200 300 600 700 800 900 1000
MAX4286/MAX4387/MAX4388
DISTORTION vs. LOAD
MAX4285-12
RESISTIVE LOAD (Ω)
DISTORTION (dBc)
f
O
= 20MHz
V
OUT
= 0.5Vp-p
A
V
= +5V/V 2ND HARMONIC
3RD HARMONIC
-120
-110
-100
-90
-80
-70
-60
-50
-40
0 0.25 0.50 0.75 1.00 1.25
MAX4285/MAX4287/MAX4288
DISTORTION vs. SWING
MAX4285-13
VOLTAGE (Vp-p)
DISTORTION (dBc)
RL = 300Ω
fO = 20MHz
AV = +1V/V
2ND HARMONIC
3RD HARMONIC
-120
-110
-100
-90
-80
-70
-60
-50
-40
0 0.25 0.50 0.75 1.00 1.25
MAX4286/MAX4387/MAX4388
DISTORTION vs. SWING
MAX4285-14
VOLTAGE (Vp-p)
DISTORTION (dBc)
RL = 300Ω
fO = 20MHz
AV = +5V/V
2ND HARMONIC
3RD HARMONIC
100M 1G
-120
-60
-80
-100
-40
-20
0
40
20
60
80
100k 1M 10M
MAX4285/MAX4286/MAX4288/MAX4388
OFF-ISOLATION vs. FREQUENCY
MA4285-15
FREQUENCY (Hz)
OFF-ISOLATION
80
-120
0.1 1 10 100 1000
MAX4287/MAX4288/MAX4387/MAX4388
CROSSTALK vs. FREQUENCY
-80
MAX4285-16
FREQUENCY (MHz)
GAIN (dB)
-40
0
40
20
-20
-60
-100
60
INPUT
100mV/
div
OUTPUT
500mV/
div
TIME (5ns/div)
MAX4286/MAX4387/MAX4388
LARGE-SIGNAL PULSE RESPONSE
(AV = +5V/V)
MA4285-18
VOLTAGE (V)
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
8 _______________________________________________________________________________________
INPUT
50mV/
div
OUTPUT
50mV/
div
MAX4285/MAX4287/MAX4288
SMALL-SIGNAL PULSE RESPONSE
(AV = +1V/V)
MA4285-19
VOLTAGE (V)
TIME (5ns/div)
INPUT
10mV/
div
OUTPUT
50mV/
div
TIME (5ns/div)
MAX4286/MAX4387/MAX4388
SMALL-SIGNAL PULSE RESPONSE
(AV = +5V/V)
MA4285-20
VOLTAGE (V)
INPUT
50mV/
div
OUTPUT
50mV/
div
MAX4285/MAX4287/MAX4288
SMALL-SIGNAL PULSE RESPONSE
(CLOAD = 22pF, AV = +1V/V)
MA4285-21
VOLTAGE (V)
TIME (5ns/div)
INPUT
10mV/
div
OUTPUT
50mV/
div
TIME (5ns/div)
MAX4286/MAX4387/MAX4388
SMALL-SIGNAL PULSE RESPONSE
(CLOAD = 47pF, AV = +5V/V)
MA4285-22
VOLTAGE (V)
100M 1G
-60
-50
-40
-20
-30
-10
0
100k 1M 10M
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MA4285-27
FREQUENCY (Hz)
PSRR (dB)
10
14
12
18
16
22
20
24
40 100 13070 160 190 220 250
ISOLATION RESISTANCE
vs. LOAD CAPACITANCE
MAX4285-23
CLOAD (pF)
RISO (Ω)
MAX4286/MAX4387/MAX4388
AV = +5V/V
MAX4285/87/88
AV = +1V/V
100M 1G
0
0.6
0.4
0.2
0.8
1.0
1.2
1.6
1.4
1.8
2.0
100k 1M 10M
GROUP DELAY vs. FREQUENCY
MA4285-26
FREQUENCY (Hz)
TIME (ns)
100M 1G
-100
-70
-80
-90
-60
-50
-40
-20
-30
-10
0
100k 1M 10M
COMMON-MODE REJECTION
vs. FREQUENCY
MA4285-28
FREQUENCY (Hz)
CMR (dB)
10k 100k 1M 10M 100M 1G
OUTPUT IMPEDANCE vs. FREQUENCY
MAX4285-29
FREQUENCY (Hz)
IMPEDANCE (Ω)
100
0.01
0.1
1
10
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ ≥2V, RL= 300Ωto VCC/2, VCM = +1.0V, TA=+25°C, unless otherwise noted.)
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
_______________________________________________________________________________________ 9
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ ≥2V, RL= 300Ωto VCC/2, VCM = +1.0V, TA=+25°C, unless otherwise noted.)
VOLTAGE NOISE DENSITY
vs. FREQUENCY
MAX4285-30
FREQUENCY (Hz)
VOLTAGE NOISE (nv/√Hz)
100
1
10
10 10k 100k 1M100 1k 10M
100
1
110k 100k 1M
100 1k 10M
CURRENT NOISE DENSITY
vs. FREQUENCY
10
MAX4285-31
FREQUENCY (Hz)
NOISE (pA/√Hz)
10
10
12
11
14
13
16
15
17
19
18
20
-50 -20 -5 10-35 25 40 55 8570 100
INPUT BIAS CURRENT
vs. TEMPERATURE
MAX4285-32
TEMPERATURE (°C)
INPUT BIAS CURRENT (µA)
0
0.1
0.2
0.3
0.4
0.5
-50 10 25-20 -5-35 40 55 70 85 100
INPUT OFFSET CURRENT
vs. TEMPERATURE
MAX4285-33
TEMPERATURE (°C)
INPUT OFFSET CURRENT (µA)
100M 1G
-10
-4
-6
-8
-2
0
2
6
4
8
10
100k 1M 10M
MAX4286
SMALL-SIGNAL GAIN vs. FREQUENCY
(CLOAD = 22pF)
MA4285-39
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
-5
-3
-4
-1
-2
1
0
2
4
3
5
-50 -20 -5 10-35 25 40 55 8570 100
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX4285-34
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE (mV)
18
19
21
20
22
-50 -20 -5 10 25-35 40 55 70 85 100
POWER-SUPPLY CURRENT
vs. TEMPERATURE
MAX4285-35
TEMPERATURE (°C)
POWER-SUPPLY CURRENT (mA)
100M 1G
-10
-4
-6
-8
-2
0
2
6
4
8
10
100k 1M 10M
MAX4286
SMALL-SIGNAL GAIN vs. FREQUENCY
(CLOAD = 37pF)
MA4285-40
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
100M 1G
-10
-4
-6
-8
-2
0
2
6
4
8
10
100k 1M 10M
MAX4286
SMALL-SIGNAL GAIN vs. FREQUENCY
(CLOAD = 47pF)
MA4285-41
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
10 ______________________________________________________________________________________
100M 1G
-2.5
-1.0
-1.5
-2.0
-0.5
0
0.5
1.5
1.0
2.0
2.5
100k 1M 10M
MAX4286
SMALL-SIGNAL GAIN vs. FREQUENCY
CLOAD || RISO (CLOAD = 37pF)
MA4285-42
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
RISO = 15Ω
100M 1G
-2.5
-1.0
-1.5
-2.0
-0.5
0
0.5
1.5
1.0
2.0
2.5
100k 1M 10M
MAX4286
SMALL-SIGNAL GAIN vs. FREQUENCY
CLOAD || RISO (CLOAD = 37pF)
MA4285-43
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
RISO = 22Ω
100M 1G
-2.5
-1.0
-1.5
-2.0
-0.5
0
0.5
1.5
1.0
2.0
2.5
100k 1M 10M
MAX4286
SMALL-SIGNAL GAIN vs. FREQUENCY
CLOAD || RISO (CLOAD = 37pF)
MA4285-44
FREQUENCY (Hz)
GAIN (dB)
AV = +5V/V
RISO = 25Ω
VCC - 1V
TIME (20ns/div)
ENABLE/DISABLE RESPONSE
TIME (VCC = 5V)
MA4285-45
VEE + 1V
VCC - 1V
TIME (20ns/div)
ENABLE/DISABLE RESPONSE
TIME (VCC = 3V)
MA4285-46
VEE + 1V
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ ≥2V, RL= 300Ωto VCC/2, VCM = +1.0V, TA=+25°C, unless otherwise noted.)
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
______________________________________________________________________________________ 11
Pin Description
14-PIN
SO
10-PIN
µMAX
8-PIN
SO
6-PIN
SOT23-6
8-PIN
µMAX/SO
Amplifier B Inverting Input
Amplifier B Noninverting Input
Amplifier B Output
12
11
13
8
7
9
—
—
—
—6 INB-
—5 INB+
—7OUTB
FUNCTION
Not Internally Connected. Connect to
ground or leave unconnected.
Amplifier Output
Negative Power Supply, or Ground in
Single-Supply Operation
Disable Amplifier A (active low)
Disable (active low)
Inverting Input
Noninverting Input
Amplifier A Noninverting Input
Amplifier A Inverting Input
Amplifier A Output
Positive Power Supply
Disable Amplifier B (active low)
5, 7, 8, 10
—
4
6
—
—
—
3
2
1
14
9
—
—
4
5
—
—
—
3
2
1
10
6
1, 5
6
4
—
8
2
3
—
—
—
7
—
NAME
— — N.C.
1—OUT
2 4 VEE
— — DISABLEA
5—DISABLE
4—IN-
3—IN+
—3 INA+
—2 INA-
—1OUTA
6 8 VCC
— — DISABLEB
Detailed Description
The MAX4285–MAX4288 and MAX4387/MAX4388 are
voltage-feedback op amps, intended for use as ADC
input buffers. They operate from a single +2.85V to
+6.5V supply or dual ±1.425V to ±3.25V supplies. Their
high output drive, wide bandwidth, fast settling, low
noise, and low distortion make them ideal for the brutal
task of meeting the dynamic input drive requirements of
high-speed ADCs or other demanding applications.
The MAX4285/MAX4286/MAX4288 and MAX4388 have
a high-speed disable mode that places the outputs in a
high-impedance state and lowers operating supply cur-
rent to 1mA. The enable time is typically 40ns, and the
disable time is typically 50ns. The MAX4285/MAX4286
have a single enable pin (DISABLE), and the MAX4288/
MAX4388 have dual disable pins (DISABLEA, DISA-
BLEB).
The MAX4285/MAX4287/MAX4288 are internally com-
pensated for unity-gain stability. The MAX4286/
MAX4387/MAX4388 are compensated for gains of
+5V/V or greater.
Applications Information
Inverting and Noninverting Configurations
Select the gain-setting feedback (RF) and input (RG)
resistor values considering the following criteria: large
resistor values increase voltage noise and interact with
the amplifier’s input and PC board capacitance to
effect system bandwidth. This generates undesirable
poles and zeros that decrease bandwidth or cause
oscillations.
PIN
MAX4285
MAX4286
MAX4287
MAX4387
MAX4288
MAX4388
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
12 ______________________________________________________________________________________
RGRF
RS
CICI
MAX4285
MAX4286
MAX4287
MAX4288
MAX4387
MAX4388
Figure 1. Using an Isolation Resistor (RS ) for High Capacitive
Loads
For example, a noninverting gain-of-two configuration
(RF= RG) using 1kΩresistors, combined with 2pF typi-
cal amplifier input capacitance, generates a pole at
159MHz. Since this pole is within the amplifier band-
width, it jeopardizes stability. Reducing these 1kΩ
resistors to 100Ωextends the pole frequency to
1.59GHz, but affects output swing by adding 200Ωin
parallel with the amplifier’s load resistor. The typical
value for RFis 300Ω.
Layout and Power-Supply Bypassing
These amplifiers operate from a single +2.85V to +6.5V
power supply or from ±1.425V to ±3.25V dual supplies.
For single-supply operation, bypass VCC to ground with
a 0.1nF capacitor as close to the pin as possible, with a
0.1µF capacitor in parallel. If operating with dual sup-
plies, bypass each supply with capacitors to ground.
Observe the following guidelines:
•A solid ground plane is essential for good high-fre-
quency behavior.
•Where possible, use multiple ground vias.
•Use a PC board with at least two layers. Avoid
areas of unreferenced copper-clad.
•Keep signal traces as short and as straight as pos-
sible. Do not make sharp turns; round all trace
corners.
•Use a constant-impedance board design if possi-
ble.
High-Speed Disable
The MAX4285/MAX4286/MAX4288 and MAX4388 fea-
ture a disable (DISABLE_) input that places the amplifi-
er in a low-power, high-output-impedance state. When
DISABLE_ is asserted, the amplifier’s output impedance
is typically 35kΩ. This high output impedance, com-
bined with the low 2pF output capacitance, make these
devices ideal for ADC input multiplexing applications or
switch applications. Typical enable/disable times are
40ns/50ns.
Output Capacitive Loading and Stability
These op amps are optimized for AC performance.
They are not designed to drive highly reactive loads,
which decrease phase margin and may produce
excessive ringing and oscillation. A small isolation
resistor (usually 20Ωto 30Ω) placed before the reactive
load reduces possible ringing and oscillation (Figure
1). At higher capacitive loads, AC performance is
dependent on the interaction of the load capacitance,
the isolation resistor, and on-board layout.
Output Drive Capability
The MAX4285–MAX4288 and MAX4387/MAX4388 have
an output sink capability of 106mA and a source capa-
bility of 77mA. This high current ability allows them to
drive low-impedance and dynamic-impedance ADC
inputs. The linear output range of these devices is (VEE
+ 0.4V) to (VCC - 0.4V). Operation beyond this range is
not recommended due to reduced gain and phase
margin.
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
______________________________________________________________________________________ 13
Ordering Information (continued) Typical Operating Circuit
RGRF
MAX4285
MAX4286
MAX4287
MAX4288
MAX4387
MAX4388
MAX157
A/D CONVERTER
VIN
Chip Information
TRANSISTOR COUNT: MAX4285/MAX4286 : 114
MA4287/MAX4288/
MAX4387/MAX4388 : 227
—14 SO-40°C to +85°CMAX4388ESD
—10 µMAX-40°C to +85°C
MAX4388EUB
—8 SO-40°C to +85°CMAX4387ESA
—8 µMAX-40°C to +85°C
MAX4387EUA
—14 SO-40°C to +85°CMAX4288ESD
—10 µMAX-40°C to +85°C
MAX4288EUB
PART SOT TOP
MARK
PIN-
PACKAGE
TEMP. RANGE
VEE
IN-IN+ IN+
16VCC
5DISABLEVEE
OUT
MAX4285
MAX4286
MAX4285
MAX4286
6-PIN SOT23
TOP VIEW
2
34
OUT
N.C.VEE
1
2
8
7
DISABLE
VCC
IN-
IN+
N.C.
8-PIN SO
3
4
6
5
MAX4287
MAX4387
INB-
INB+VEE
1
2
8
7
VCC
OUTBINA-
INA+
OUTA
8-PIN SO/µMAX
3
4
6
5
14
13
12
11
10
9
8
1
2
3
4
5
6
7
VCC
OUTB
INB-
INB+VEE
INA+
INA-
OUTA
MAX4288
MAX4388
N.C.
DISABLEB
N.C.N.C.
DISABLEA
N.C.
14-PIN SO
10
9
8
1
2
3
4
56
7
VCC
OUTB
INB-
INB+VEE
INA+
INA-
OUTA
MAX4288
MAX4388
DISABLEB
DISABLEA
10-PIN µMAX
Pin Configurations
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
14 ______________________________________________________________________________________
8LUMAXD.EPS
Package Information
6LSOT.EPS
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
______________________________________________________________________________________ 15
Package Information (continued)
10LUMAX.EPS
MAX4285–MAX4288/MAX4387/MAX4388
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers
with High-Speed Disable
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.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
SOICN.EPS
Package Information (continued)