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19-1500; Rev 0; 4/00
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable
General Description
The MAX4285/MAX4286 single and MAX4287/MAX4288/ MAX4387/MAX4388 dual ADC buffer amplifiers feature high-speed performance and single +3V supply operation. 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 commonmode input voltage range extends to the negative powersupply 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/s 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 highspeed ADC drivers for communications and instrumentation 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 MAX and 8-pin SO packages, while the MAX4288/MAX4388 come in 10-pin MAX and 14-pin SO packages.
Features
o High Speed at 3V 250MHz -3dB Bandwidth (MAX4285/87/88) 150MHz -3dB Bandwidth (MAX4286, MAX4387/88) 350V/s Slew Rate o +2.85V to +6.5V Single-Supply Operation o Input Common-Mode Range Extends to VEE o Low Distortion at 5MHz -88dBc SFDR o High Output Current Drive: -106mA to +77mA o 6ns Settling Time to 0.1% o High-Speed Enable/Disable 40ns Enable Time 50ns Disable Time High Output Impedance o Space-Saving SOT23 and MAX Packages
MAX4285-MAX4288/MAX4387/MAX4388
Applications
High-Speed ADC Drivers Communications Equipment Instrumentation CCD Imaging Systems Ultrasound
PART
Ordering Information
TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C PINPACKAGE 6 SOT23-6 8 SO 6 SOT23-6 8 SO 8 MAX 8 SO SOT TOP MARK AABQ -- AABR -- -- --
MAX4285EUT-T -40C to +85C MAX4285ESA MAX4286ESA MAX4287EUA MAX4287ESA MAX4286EUT-T -40C to +85C
Typical Operating Circuit appears at end of data sheet. Pin Configurations appear at end of data sheet.
Ordering Information continued at end of data sheet.
Selector Guide
PART MAX4285 MAX4286 MAX4287 MAX4288 MAX4387 MAX4388 OP AMPS PER PKG 1 1 2 2 2 2 MIN GAIN 1 5 1 1 5 5 -3dB BANDWIDTH (AT MIN GAIN) 250MHz 150MHz 250MHz 250MHz 150MHz 150MHz HIGH-SPEED DISABLE Yes Yes No Yes No Yes PIN-PACKAGE 6-pin SOT23, 8-pin SO 6-pin SOT23, 8-pin SO 8-pin MAX/SO 10-pin MAX/14-pin SO 8-pin MAX/SO 10-pin MAX, 14-pin SO
________________________________________________________________ Maxim Integrated Products
1
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
ABSOLUTE MAXIMUM RATINGS
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 = +70C) 6-Pin SOT23 (derate 7.1mW/C above +70C)............571mW 8-Pin MAX (derate 4.1mW/C above +70C) .............330mW 10-Pin MAX (derate 5.6mW/C above +70C) ...........444mW 8-Pin SO (derate 5.88mW/C above +70C)................471mW 14-Pin SO (derate 8.3mW/C above +70C)................667mW 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.
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 = +25C.) (Note 1) PARAMETER Operating Supply Voltage Range Input Common-Mode Voltage Range Input Offset Voltage Input Offset-Voltage Temperature Coefficient Input Offset-Voltage Matching Input Bias Current Input Offset Current Input Resistance VCM VOS TCVOS VOS IB IOS RIN Differential (-10mV VIN +10mV) Common mode (VEE VCM VCC - 1.25V) MAX4_87EU_/ MAX4_88EU_/ MAX4_8_ES_ MAX4285EUT-T/ MAX4286EUT-T RL = 2k RL = 300 RL = 100 75 65 60 MAX4287/88 and MAX4387/88 SYMBOL CONDITIONS Guaranteed by PSRR test Guaranteed by CMRR test MAX4_87EU_/MAX4_88EU_/MAX4_8_ES_ MAX4285EUT-T/MAX4286EUT-T MIN 2.85 VEE 0.1 1.5 26 0.2 13 0.2 38 600 50 73 dB 45 94 94 85 dB 68 35 8 TYP MAX 6.5 VCC 1.25 8 12 UNITS V V mV V/C mV A A k
Common-Mode Rejection Ratio
CMRR
VEE VCM VCC - 1.25V
Open-Loop Gain
AVOL
VEE + 0.4V VOUT VCC - 0.4V
2
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable
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 = +25C.) (Note 1) PARAMETER Output Current Drive Power-Supply Rejection Ratio Disabled Output Leakage Current DISABLE_ Logic Low Threshold DISABLE_ Logic High Threshold DISABLE_ Logic Input Low Current DISABLE_ Logic Input High Current SYMBOL IOUT PSRR ILEAK VIL VIH IIL IIH DISABLE_ = VEE DISABLE_ = VCC Normal mode VCC = 3V Quiescent Supply Current (per Amplifier) ISY VCC = 5V Disabled mode, DISABLE_ = VEE Normal mode Disabled mode, DISABLE_ = VEE VCC - 1 3 3 20 1 23 1 22 22 24 3 28 3 mA CONDITIONS RL = 20 to VEE RL = 20 to VCC VCC = 2.85V to 6.5V DISABLE_ = VEE, VEE VOUT VCC 40 MIN TYP 77 106 50 700 VCC - 2 MAX UNITS mA dB nA V V A A
MAX4285-MAX4288/MAX4387/MAX4388
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
AC ELECTRICAL CHARACTERISTICS
(VCC = +3V, VEE = 0, DISABLE_ = 3V, RL = 300 to VCC/2, VCM = 1V, AVCL = +1V/V for MAX4285/MAX4287/MAX4288, AVCL = +5V/V for MAX4286 and MAX4387/MAX4388, TA = +25C, unless otherwise noted.) PARAMETER Small-Signal -3dB Bandwidth Large-Signal -3dB Bandwidth Bandwidth for 0.1dB Flatness Slew Rate Rise Time Fall Time Settling Time (0.1%) Overload Recovery Time SYMBOL BWSS BWLS BW0.1dB SR tR tF tS 0.1% CONDITIONS MAX4285/87/88 VOUT = 100mVp-p VOUT = 1Vp-p MAX4285/87/88 VOUT = 100mVp-p MAX4286 and MAX4387/88 MAX4286 and MAX4387/88 MIN TYP 250 150 200 100 50 350 2.2 2.8 6 14 25 fC = 100kHz fC = 1MHz Spurious-Free Dynamic Range SFDR VOUT = 0.5Vp-p fC = 5MHz fC = 10MHz fC = 20MHz fC = 60MHz Two-Tone Third-Order Intercept Input Noise Voltage Density Input Noise Current Density Input Capacitance Output Impedance Enable Time Disable Time Crosstalk IP3 en in CIN ZOUT tON tOFF XTALK f = 10MHz VOUT = 1V, to within 0.1% VOUT = 1V, to within 0.1% MAX4287/88 and MAX4387/88, f = 10MHz, VOUT = 1Vp-p fC = 20MHz f = 1MHz f = 1MHz 88 88 87 79 70 50 34 10 2.1 2 0.5 40 50 85 dBm nV/Hz pA/Hz pF ns dBc dBc ns ns MHz V/s ns ns MHz MHz MAX UNITS
VOUT = 1V step, 10% to 90% VOUT = 1V step, 10% to 90% VOUT= 1V step, 90% to 10% MAX4285/87/88 VOUT = 1V step 10% overdrive MAX4286 and MAX4387/88
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
AC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V, VEE = 0, DISABLE_ = 5V, RL = 300 to VCC/2, VCM = 2.5V, AVCL = +1V/V for MAX4285/MAX4287/MAX4288, AVCL = +5V/V for MAX4286 and MAX4387/MAX4388, TA = +25C, unless otherwise noted.) PARAMETER Small-Signal -3dB Bandwidth Large-Signal -3dB Bandwidth Bandwidth for 0.1dB Flatness Slew Rate Rise Time Fall Time Settling Time (0.1%) SYMBOL BWSS BWLS BW0.1dB SR tR tF tS 0.1% VOUT = 100mVp-p VOUT = 1Vp-p MAX4285/87/88 VOUT = 100mVp-p MAX4286 and MAX4387/88 CONDITIONS MAX4285/87/88 MAX4286 and MAX4387/88 MIN TYP 220 130 195 75 40 385 4.2 2.9 8 10 86 86 86 77 64 45 40 6.5 1.9 2 f = 10MHz VOUT = 1V, to within 0.1% VOUT = 1V, to within 0.1% MAX4287/88 and MAX4387/88, f = 10MHz, VOUT = 2Vp-p 0.5 40 35 85 dBm nV/Hz pA/Hz pF ns dBc dBc ns MHz V/s ns ns MHz MHz MAX UNITS
VOUT = 2V step, 10% to 90% VOUT = 2V step, 10% to 90% VOUT= 2V step, 90% to 10% MAX4285/87/88 VOUT = 2V step MAX4286 and MAX4387/88 fC = 100kHz fC = 1MHz fC = 5MHz fC = 10MHz fC = 20MHz fC = 60MHz
Spurious-Free Dynamic Range
SFDR
VOUT = 1Vp-p
Two-Tone Third-Order Intercept Input Noise Voltage Density Input Noise Current Density Input Capacitance Output Impedance Enable Time Disable Time Crosstalk
IP3 en in CIN ZOUT tON tOFF XTALK
fC = 20MHz f = 1MHz f = 1MHz
Note 1: The MAX428_EUT (SOT23) are 100% production tested at TA = +25C. Specifications over temperature limits are guaranteed by design.
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Typical Operating Characteristics
(VCC = +3V, VEE = 0, DISABLE_ 2V, RL = 300 to VCC/2, VCM = +1.0V, TA =+25C, unless otherwise noted.)
MAX4285/MAX4287/MAX4288 SMALL-SIGNAL GAIN vs. FREQUENCY
MA4285-01
MAX4286/MAX4387/MAX4388 SMALL-SIGNAL GAIN vs. FREQUENCY
MA4285-02
MAX4285/MAX4387/MAX4288 GAIN FLATNESS vs. FREQUENCY (RLOAD = 100)
0.4 0.3 0.2 GAIN (dB) 0.1 0 -0.1 -0.2 -0.3 -0.4 AV = +1V/V
MA4285-03
4 3 2 1 GAIN (dB) AV = +1V/V
4 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 AV = +5V/V
0.5
0 -1 -2 -3 -4 -5 -6 100k 1M 10M FREQUENCY (Hz) 100M 1G
-6 100k
1M
10M FREQUENCY (Hz)
100M
1G
-0.5 100k
1M
10M FREQUENCY (Hz)
100M
1G
MAX4285/MAX4287/MAX4288 GAIN FLATNESS vs. FREQUENCY (RLOAD = 300)
MA4285-04
MAX4285/MAX4287/MAX4288 GAIN FLATNESS vs. FREQUENCY (RLOAD = 1k)
MA4285-05
MAX4286/MAX4387/MAX4388 GAIN FLATNESS vs. FREQUENCY
0.3 0.2 0.1 GAIN (dB) 0 -0.1 -0.2 -0.3 -0.4 -0.5 RLOAD = 1k RLOAD = 100 RLOAD = 300 AV = +5V/V
MA4285-06
0.4 0.3 0.2 0.1 GAIN (dB) AV = +1V/V
0.5 0.4 0.3 0.2 GAIN (dB) 0.1 0 -0.1 -0.2 -0.3 -0.4 AV = +1V/V
0.4
0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 100k 1M 10M FREQUENCY (Hz) 100M 1G
-0.5 100k
1M
10M FREQUENCY (Hz)
100M
1G
-0.6 100k
1M
10M FREQUENCY (Hz)
100M
1G
LARGE-SIGNAL GAIN vs. FREQUENCY
MA4285-07
MAX4285/MAX4287/MAX4288 DISTORTION vs. FREQUENCY
MAX4285-08
MAX4286/MAX4387/MAX4388 DISTORTION vs. FREQUENCY
RL = 300 VOUT = 0.5Vp-p AV = +5V/V
MAX4285-09
4 3 2 1 GAIN (dB)
-40 -50 -60 GAIN (dB) -70 -80
RL = 300 VOUT = 0.5Vp-p AV = +1V/V
-40 -50 -60 GAIN (dB) -70 -80
0 -1 -2 -3 -4 -5 -6 100k
2ND HARMONIC -90 3RD HARMONIC -100 1M 10M FREQUENCY (Hz) 100M 1G 0.1 1 10 100 FREQUENCY (MHz) -100 0.1 -90
2ND HARMONIC 3RD HARMONIC
1
10
100
FREQUENCY (MHz)
6
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ 2V, RL = 300 to VCC/2, VCM = +1.0V, TA =+25C, unless otherwise noted.)
MAX4285/MAX4287/MAX4288 DISTORTION vs. LOAD
MAX4285-11
MAX4286/MAX4387/MAX4388 DISTORTION vs. LOAD
MAX4285-12
MAX4285/MAX4287/MAX4288 DISTORTION vs. SWING
-50 -60 DISTORTION (dBc) -70 -80 -90 -100 -110 3RD HARMONIC -120 RL = 300 fO = 20MHz AV = +1V/V 2ND HARMONIC
MAX4285-13
-40 -50 -60 DISTORTION (dBc) -70 -80 -90 -100 -110 -120
fO = 20MHz VOUT = 0.5Vp-p AV = +1V/V 2ND HARMONIC
-40 -50 -60 DISTORTION (dBc) -70 -80 -90 -100 -110 -120
fO = 20MHz VOUT = 0.5Vp-p AV = +5V/V
-40
2ND HARMONIC
3RD HARMONIC
3RD HARMONIC
100 200 300 400 500 600 700 800 900 1000 RESISTIVE LOAD ()
100 200 300 400 500 600 700 800 900 1000 RESISTIVE LOAD ()
0
0.25
0.50
0.75
1.00
1.25
VOLTAGE (Vp-p)
MAX4286/MAX4387/MAX4388 DISTORTION vs. SWING
MAX4285-14
MAX4285/MAX4286/MAX4288/MAX4388 OFF-ISOLATION vs. FREQUENCY
MA4285-15
MAX4287/MAX4288/MAX4387/MAX4388 CROSSTALK vs. FREQUENCY
60 40 20 GAIN (dB) 0 -20 -40 -60 -80 -100 -120
MAX4285-16
-40 -50 -60 DISTORTION (dBc) -70 -80 -90 -100 -110 -120 0
RL = 300 fO = 20MHz AV = +5V/V 2ND HARMONIC
80 60 40 OFF-ISOLATION 20 0 -20 -40 -60 -80 -100
80
3RD HARMONIC
0.25
0.50
0.75
1.00
1.25
-120 100k
1M
10M FREQUENCY (Hz)
100M
1G
0.1
1
10 FREQUENCY (MHz)
100
1000
VOLTAGE (Vp-p)
MAX4285/MAX4287/MAX4288 LARGE-SIGNAL PULSE RESPONSE (AV = +1V/V)
MA4285-17
MAX4286/MAX4387/MAX4388 LARGE-SIGNAL PULSE RESPONSE (AV = +5V/V)
INPUT 100mV/ div VOLTAGE (V)
MA4285-18
INPUT 500mV/ div VOLTAGE (V) OUTPUT 500mV/ div
OUTPUT 500mV/ div TIME (5ns/div) TIME (5ns/div)
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ 2V, RL = 300 to VCC/2, VCM = +1.0V, TA =+25C, unless otherwise noted.)
MAX4285/MAX4287/MAX4288 SMALL-SIGNAL PULSE RESPONSE (AV = +1V/V)
MA4285-19
MAX4286/MAX4387/MAX4388 SMALL-SIGNAL PULSE RESPONSE (AV = +5V/V)
INPUT 10mV/ div VOLTAGE (V)
MA4285-20
MAX4285/MAX4287/MAX4288 SMALL-SIGNAL PULSE RESPONSE (CLOAD = 22pF, AV = +1V/V)
MA4285-21
VOLTAGE (V)
OUTPUT 50mV/ div
OUTPUT 50mV/ div TIME (5ns/div) TIME (5ns/div)
OUTPUT 50mV/ div
VOLTAGE (V)
INPUT 50mV/ div
INPUT 50mV/ div
TIME (5ns/div)
MAX4286/MAX4387/MAX4388 SMALL-SIGNAL PULSE RESPONSE (CLOAD = 47pF, AV = +5V/V)
MA4285-22
ISOLATION RESISTANCE vs. LOAD CAPACITANCE
MAX4285-23
GROUP DELAY vs. FREQUENCY
1.8 1.6 1.4 TIME (ns)
MA4285-26
24 22 20 RISO () 18 16 14 12 10 MAX4285/87/88 AV = +1V/V MAX4286/MAX4387/MAX4388 AV = +5V/V
2.0
INPUT 10mV/ div VOLTAGE (V)
1.2 1.0 0.8 0.6 0.4 0.2
OUTPUT 50mV/ div TIME (5ns/div)
40
70
100
130
160
190
220
250
0 100k
1M
10M FREQUENCY (Hz)
100M
1G
CLOAD (pF)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MA4285-27
COMMON-MODE REJECTION vs. FREQUENCY
MA4285-28
OUTPUT IMPEDANCE vs. FREQUENCY
MAX4285-29
0 -10 -20 PSRR (dB) -30 -40 -50 -60 100k
0 -10 -20
100
CMR (dB)
-40 -50 -60 -70 -80 -90
IMPEDANCE () 1M 10M FREQUENCY (Hz) 100M 1G
-30
10
1
0.1
1M
10M FREQUENCY (Hz)
100M
1G
-100 100k
0.01 10k 100k 1M 10M 100M 1G FREQUENCY (Hz)
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ 2V, RL = 300 to VCC/2, VCM = +1.0V, TA =+25C, unless otherwise noted.)
INPUT BIAS CURRENT vs. TEMPERATURE
MAX4285-31
VOLTAGE NOISE DENSITY vs. FREQUENCY
MAX4285-30
CURRENT NOISE DENSITY vs. FREQUENCY
100 20 19 INPUT BIAS CURRENT (A) 18 17 16 15 14 13 12 11
VOLTAGE NOISE (nv/Hz)
NOISE (pA/Hz)
10
10
1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
1 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
10 -50 -35 -20 -5 10 25 40 55 70 85 100 TEMPERATURE (C)
INPUT OFFSET CURRENT vs. TEMPERATURE
MAX4285-33
INPUT OFFSET VOLTAGE vs. TEMPERATURE
4 INPUT OFFSET VOLTAGE (mV) 3 2 1 0 -1 -2 -3 -4
MAX4285-34
POWER-SUPPLY CURRENT vs. TEMPERATURE
MAX4285-35
0.5
5
22 POWER-SUPPLY CURRENT (mA)
INPUT OFFSET CURRENT (A)
0.4
21
0.3
20
0.2
19
0.1
0 -50 -35 -20 -5 10 25 40 55 70 85 100 TEMPERATURE (C)
-5 -50 -35 -20 -5 10 25 40 55 70 85 100 TEMPERATURE (C)
18 -50 -35 -20 -5 10 25 40 55 70 85 100 TEMPERATURE (C)
MAX4286 SMALL-SIGNAL GAIN vs. FREQUENCY (CLOAD = 22pF)
MA4285-39
MAX4286 SMALL-SIGNAL GAIN vs. FREQUENCY (CLOAD = 37pF)
MA4285-40
MAX4286 SMALL-SIGNAL GAIN vs. FREQUENCY (CLOAD = 47pF)
8 6 4 GAIN (dB) 2 0 -2 -4 -6 -8 AV = +5V/V
MA4285-41
10 8 6 4 GAIN (dB) AV = +5V/V
10 8 6 4 GAIN (dB) 2 0 -2 -4 -6 -8 AV = +5V/V
10
2 0 -2 -4 -6 -8 -10 100k 1M 10M FREQUENCY (Hz) 100M 1G
-10 100k
1M
10M FREQUENCY (Hz)
100M
1G
-10 100k
1M
10M FREQUENCY (Hz)
100M
1G
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MAX4285-32
100
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Typical Operating Characteristics (continued)
(VCC = +3V, VEE = 0, DISABLE_ 2V, RL = 300 to VCC/2, VCM = +1.0V, TA =+25C, unless otherwise noted.)
MAX4286 SMALL-SIGNAL GAIN vs. FREQUENCY CLOAD || RISO (CLOAD = 37pF)
MA4285-42
MAX4286 SMALL-SIGNAL GAIN vs. FREQUENCY CLOAD || RISO (CLOAD = 37pF)
MA4285-43
MAX4286 SMALL-SIGNAL GAIN vs. FREQUENCY CLOAD || RISO (CLOAD = 37pF)
2.0 1.5 1.0 GAIN (dB) 0.5 0 -0.5 -1.0 -1.5 -2.0 AV = +5V/V RISO = 25
MA4285-44
2.5 2.0 1.5 1.0 GAIN (dB) AV = +5V/V RISO = 15
2.5 2.0 1.5 1.0 GAIN (dB) 0.5 0 -0.5 -1.0 -1.5 -2.0 AV = +5V/V RISO = 22
2.5
0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 100k 1M 10M FREQUENCY (Hz) 100M 1G
-2.5 100k
1M
10M FREQUENCY (Hz)
100M
1G
-2.5 100k
1M
10M FREQUENCY (Hz)
100M
1G
ENABLE/DISABLE RESPONSE TIME (VCC = 5V)
VCC - 1V
MA4285-45
ENABLE/DISABLE RESPONSE TIME (VCC = 3V)
VCC - 1V
MA4285-46
VEE + 1V
VEE + 1V
TIME (20ns/div)
TIME (20ns/div)
10
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Pin Description
PIN MAX4285 MAX4286 6-PIN SOT23-6 -- 1 2 3 4 5 -- -- 6 -- -- -- -- -- -- 8-PIN SO 1, 5 6 4 3 2 8 -- -- 7 -- -- -- -- -- -- MAX4287 MAX4387 8-PIN MAX/SO -- -- 4 -- -- -- -- -- 8 1 2 3 5 6 7 MAX4288 MAX4388 10-PIN MAX -- -- 4 -- -- -- 5 6 10 1 2 3 7 8 9 14-PIN SO 5, 7, 8, 10 -- 4 -- -- -- 6 9 14 1 2 3 11 12 13 N.C. OUT VEE IN+ INDISABLE DISABLEA DISABLEB VCC OUTA INAINA+ INB+ INBOUTB Not Internally Connected. Connect to ground or leave unconnected. Amplifier Output Negative Power Supply, or Ground in Single-Supply Operation Noninverting Input Inverting Input Disable (active low) Disable Amplifier A (active low) Disable Amplifier B (active low) Positive Power Supply Amplifier A Output Amplifier A Inverting Input Amplifier A Noninverting Input Amplifier B Noninverting Input Amplifier B Inverting Input Amplifier B Output
NAME
FUNCTION
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 current 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, DISABLEB). The MAX4285/MAX4287/MAX4288 are internally compensated 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.
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
For example, a noninverting gain-of-two configuration (RF = RG) using 1k resistors, combined with 2pF typical amplifier input capacitance, generates a pole at 159MHz. Since this pole is within the amplifier bandwidth, it jeopardizes stability. Reducing these 1k resistors to 100 extends the pole frequency to 1.59GHz, but affects output swing by adding 200 in parallel with the amplifier's load resistor. The typical value for RF is 300.
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 20 to 30) 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.
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 0.1F capacitor in parallel. If operating with dual supplies, bypass each supply with capacitors to ground. Observe the following guidelines: * * * * A solid ground plane is essential for good high-frequency 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 possible. Do not make sharp turns; round all trace corners. Use a constant-impedance board design if possible.
Output Drive Capability
The MAX4285-MAX4288 and MAX4387/MAX4388 have an output sink capability of 106mA and a source capability 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.
RG
RF
RS
*
CI
CI
High-Speed Disable
The MAX4285/MAX4286/MAX4288 and MAX4388 feature a disable (DISABLE_) input that places the amplifier in a low-power, high-output-impedance state. When DISABLE_ is asserted, the amplifier's output impedance is typically 35k. This high output impedance, combined 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.
MAX4285 MAX4286 MAX4287 MAX4288 MAX4387 MAX4388 Figure 1. Using an Isolation Resistor (RS ) for High Capacitive Loads
12
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+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable
Ordering Information (continued)
PART MAX4288EUB MAX4288ESD MAX4387EUA MAX4387ESA MAX4388EUB MAX4388ESD TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PINPACKAGE 10 MAX 14 SO 8 MAX 8 SO 10 MAX 14 SO SOT TOP MARK -- -- -- -- -- --
VIN RG RF
Typical Operating Circuit
MAX4285-MAX4288/MAX4387/MAX4388
MAX157 A/D CONVERTER
Chip Information
TRANSISTOR COUNT: MAX4285/MAX4286 : 114 MA4287/MAX4288/ MAX4387/MAX4388 : 227
MAX4285 MAX4286 MAX4287 MAX4288 MAX4387 MAX4388
Pin Configurations
TOP VIEW MAX4285 MAX4286
OUT 1 6 VCC N.C. 1 IN- 2 VEE VEE 2 5 DISABLE IN+ 3
MAX4285 MAX4286
8 7 6 5 DISABLE VCC OUT N.C. OUTA 1 INA- 2 INA+ 3
MAX4287 MAX4387
8 7 6 5 VCC OUTB INBINB+
IN+ IN+ 3
4
IN-
VEE 4
VEE 4
6-PIN SOT23
8-PIN SO
8-PIN SO/MAX
MAX4288 MAX4388
OUTA 1 INAINA+ 2 3 10 VCC 9 8 OUTB INBOUTA 1 INAINA+ 2 3
MAX4288 MAX4388
14 VCC 13 OUTB 12 INB11 INB+ 10 N.C. 9 8 DISABLEB N.C.
VEE 4 DISABLEA 5
7 INB+ 6 DISABLEB
VEE 4 N.C. 5 DISABLEA 6 N.C. 7
10-PIN MAX
14-PIN SO
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13
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Package Information
6LSOT.EPS
14
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8LUMAXD.EPS
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable
Package Information (continued)
10LUMAX.EPS
MAX4285-MAX4288/MAX4387/MAX4388
______________________________________________________________________________________
15
+3V/+5V, 250MHz, SOT23 ADC Buffer Amplifiers with High-Speed Disable MAX4285-MAX4288/MAX4387/MAX4388
Package Information (continued)
SOICN.EPS
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 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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