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19-4754; Rev 0; 12/97
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable
_________________General Description
The MAX4214/MAX4215/MAX4217/MAX4219/MAX4222 are precision, closed-loop, gain of +2 (or -1) buffers featuring high slew rates, high output current drive, and low differential gain and phase error. They operate with a single +3.15V to +11V supply or with 1.575V to 5.5V dual supplies. The input common-mode voltage range extends 100mV beyond the negative power-supply rail, and the output swings Rail-to-Rail(R). These devices require only 5.5mA of quiescent supply current while achieving a 230MHz -3dB bandwidth and a 600V/s slew rate. In addition, the MAX4215/ MAX4219 have a disable feature that reduces the supply current to 400A per buffer. Input voltage noise is only 10nV/Hz, and input current noise is only 1.3pA/Hz. This buffer family is ideal for low-power/lowvoltage applications requiring wide bandwidth, such as video, communications, and instrumentation systems. For space-sensitive applications, the MAX4214 comes in a miniature 5-pin SOT23 package.
____________________________Features
o Internal Precision Resistors for Closed-Loop Gains of +2V/V or -1V/V o High Speed: 230MHz -3dB Bandwidth 90MHz 0.1dB Gain Flatness (MAX4219/22) 600V/s Slew Rate o Single 3.3V/5.0V Operation o Outputs Swing Rail-to-Rail o Input Common-Mode Range Extends Beyond VEE o Low Differential Gain/Phase Error: 0.03%/0.04 o Low Distortion at 5MHz: -72dBc SFDR -71dB Total Harmonic Distortion o High Output Drive: 120mA o Low 5.5mA Supply Current o 400A Shutdown Supply Current (MAX4215/19) o Space-Saving SOT23-5, MAX, or QSOP Packages
MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
_______________Ordering Information
PART TEMP. RANGE PINPACKAGE 5 SOT23-5 8 SO 8 MAX 8 SO 8 MAX 14 SO 16 QSOP 14 SO 16 QSOP SOT TOP MARK ABAH -- -- -- -- -- -- -- --
______________________Selector Guide
PART MAX4214 MAX4215 MAX4217 MAX4219 MAX4222 NO. OF AMPS 1 1 2 3 4 ENABLE No Yes No Yes No PIN-PACKAGE 5 SOT23 8 SO/MAX 8 SO/MAX 14 SO, 16 QSOP 14 SO, 16 QSOP
MAX4214EUK-T -40C to +85C MAX4215ESA MAX4215EUA MAX4217ESA MAX4217EUA MAX4219ESD MAX4219EEE MAX4222ESD MAX4222EEE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
________________________Applications
Battery-Powered Instruments Video Line Driver Analog-to-Digital Converter Interface CCD Imaging Systems Video Routing and Switching Systems Video Multiplexing Applications
__________________Pin Configurations
TOP VIEW
OUT 1 5 VCC
VEE 2
MAX4214
IN+ 3
4
IN-
Typical Application Circuit appears at end of data sheet. Rail-to-Rail is a registered trademark of Nippon Motorola, Inc.
SOT23-5
Pin Configurations continued at end of data sheet.
1
________________________________________________________________ Maxim Integrated Products
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High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC to VEE) ..................................................12V IN_-, IN_+, OUT_, EN_ ....................(VEE - 0.3V) to (VCC + 0.3V) Output Short-Circuit Duration to VCC or VEE ..............Continuous Continuous Power Dissipation (TA = +70C) 5-pin SOT23 (derate 7.1mW/C above +70C).............571mW 8-pin SO (derate 5.9mW/C above +70C)...................471mW 8-pin MAX (derate 4.1mW/C above +70C) .............330mW 14-pin SO (derate 8.3mW/C above +70C)................667mW 16-pin QSOP (derate 8.3mW/C above +70C)...........667mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+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 = +5V, VEE = 0V, IN_- = 0V, EN_ = 5V, RL = to 0V, VOUT = VCC/2, noninverting configuration, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Operating Supply Voltage Range Input Voltage Range Input Offset Voltage Input Offset Voltage Drift Input Offset Voltage Matching Input Bias Current Input Resistance Voltage Gain Power-Supply Rejection Ratio (Note 2) Output Resistance Output Current Short-Circuit Output Current IB RIN AV PSRR ROUT IOUT ISC VIN VOS TCVOS Between any two channels for MAX4217/MAX4219/MAX4222 IN_+ IN_+, over input voltage range RL 50, (VEE + 0.5V) VOUT (VCC - 2.0V) VCC = 5V, VEE = 0V, VOUT = 2.0V VCC = 5V, VEE = -5V, VOUT = 0V VCC = 3.3V, VEE = 0V, VOUT = 0.90V f = DC RL = 20 to VCC or VEE Sinking or sourcing RL = 50 Output Voltage Swing VOUT RL = 150 RL = 2k Disabled Output Resistance EN_ Logic Low Threshold EN_ Logic High Threshold VCC - VOH VOL - VEE VCC - VOH VOL - VEE VCC - VOH VOL - VEE 100 1.9 55 60 SYMBOL CONDITIONS VCC to VEE, guaranteed by PSRR tests IN_+ IN_RL = 50 SO, QSOP SOT23-5, MAX MIN 3.15 VEE - 0.1 VEE - 0.1 4 4 8 1 5.4 3 2 58 66 45 25 120 150 1.60 0.04 0.75 0.04 0.06 0.06 1 VCC - 2.6 VCC - 1.6 k V V 1.90 0.075 1.00 0.075 V m mA mA dB 2.1 12 TYP MAX 11.0 VCC - 2.25 VCC + 0.1 10 15 UNITS V V mV V/C mV A M V/V
ROUT(OFF) MAX4215/MAX4219, EN_ = 0V, 0V VOUT 5V VIL VIH MAX4215/MAX4219 MAX4215/MAX4219
2
_______________________________________________________________________________________
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V, VEE = 0V, IN_- = 0V, EN_ = 5V, RL = to 0V, VOUT = VCC/2, noninverting configuration, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER EN_ Logic Input Low Current EN_ Logic Input High Current Quiescent Supply Current (per Buffer) Shutdown Supply Current SYMBOL IIL IIH ICC ISD MAX4215/MAX4219, disabled (EN_ = VEE) CONDITIONS MAX4215/MAX4219, (VEE + 0.2V) EN_ VCC MAX4215/MAX4219, EN_ = VEE MAX4215/MAX4219, EN_ = VCC MIN TYP 0.5 200 0.5 5.5 400 350 10 7.0 550 MAX UNITS A A mA A
MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
Note 1: The MAX421_EU_ is 100% production tested at TA = +25C. Specifications over temperature limits are guaranteed by design. Note 2: PSR for single +5V supply tested with VEE = 0V, VCC = +4.5V to +5.5V; for dual 5V supply with VEE = -4.5V to -5.5V, VCC = +4.5V to +5.5V; and for single +3V supply with VEE = 0V, VCC = +3.15V to +3.45V.
AC ELECTRICAL CHARACTERISTICS
(VCC = +5V, VEE = 0V, IN_- = 0V, EN_ = 5V, RL = 100 to VCC/2, noninverting configuration, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Small-Signal -3dB Bandwidth Full-Power -3dB Bandwidth Bandwidth for 0.1dB Gain Flatness Slew Rate Settling Time to 0.1% Rise/Fall Time Spurious-Free Dynamic Range Harmonic Distortion Third-Order Intercept Input 1dB Compression Point Differential Phase Error Differential Gain Error Input Noise-Voltage Density Input Noise-Current Density Input Capacitance Disabled Output Capacitance DP DG en in CIN COUT(OFF) MAX4215/MAX4219, EN_ = 0V SYMBOL BW-3dB FPBW BW0.1dB SR tS tR, tF SFDR VOUT = 100mVp-p VOUT = 2Vp-p VOUT = 100mVp-p CONDITIONS MAX4214/MAX4215/MAX4217 MAX4219/MAX4222 MAX4214/MAX4215/MAX4217 MAX4219/MAX4222 MAX4214/MAX4215/MAX4217 MAX4219/MAX4222 MIN TYP 230 200 220 200 50 90 600 45 1 -72 Second harmonic HD IP3 VOUT = 2Vp-p, fC = 5MHz f = 10MHz f = 10MHz NTSC, RL = 150 NTSC, RL = 150 f = 10kHz f = 10kHz Third harmonic Total harmonic distortion -72 -77 -71 35 11 0.04 0.03 10 1.3 1 2 dBm dBm degrees % nV/Hz pA/Hz pF pF dBc MAX UNITS MHz MHz MHz V/s ns ns dBc
VOUT = 2V step VOUT = 2V step VOUT = 100mVp-p fC = 5MHz, VOUT = 2Vp-p
_______________________________________________________________________________________
3
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
AC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V, VEE = 0V, IN_- = 0V, EN_ = 5V, RL = 100 to VCC/2, noninverting configuration, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Output Impedance Buffer Enable Time Buffer Disable Time Buffer Gain Matching All-Hostile Crosstalk XTALK SYMBOL ZOUT tON tOFF f = 10MHz MAX4215/MAX4219 MAX4215/MAX4219 MAX4217/MAX4219/MAX4222, f = 10MHz, VOUT = 100mVp-p MAX4217/MAX4219/MAX4222, f = 10MHz, VOUT = 2Vp-p CONDITIONS MIN TYP 200 100 1 0.1 -95 MAX UNITS m ns s dB dB
Note 2: PSR for single +5V supply tested with VEE = 0V, VCC = +4.5V to +5.5V; for dual 5V supply with VEE = -4.5V to -5.5V, VCC = +4.5V to +5.5V; and for single +3V supply with VEE = 0V, VCC = +3.15V to +3.45V.
__________________________________________Typical Operating Characteristics
(VCC = +5V, VEE = 0V, AVCL = +2V/V, RL = 100 to VCC/2, TA = +25C, unless otherwise noted.)
MAX4214/MAX4215/MAX4217 SMALL-SIGNAL GAIN vs. FREQUENCY
MAX4214-A
MAX4214/MAX4215/MAX4217 GAIN FLATNESS vs. FREQUENCY
MAX4214-B
MAX4214/MAX4215/MAX4217 LARGE-SIGNAL GAIN vs. FREQUENCY
9 8 7 GAIN (dB) 6 5 4 3 2 1 VOUT = 2Vp-p
MAX4214-C
10 9 8 7 GAIN (dB) 6 5 4 3 2 1 0 100k 1M 10M FREQUENCY (Hz) 100M VOUT = 100mVp-p
6.5 6.4 6.3 6.2 GAIN (dB) 6.1 6.0 5.9 5.8 5.7 5.6 5.5 VOUT = 100mVp-p
10
1G
100k
1M
10M FREQUENCY (Hz)
100M
1G
0 100k 1M 10M FREQUENCY (Hz) 100M 1G
4
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High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0V, AVCL = +2V/V, RL = 100 to VCC/2, TA = +25C, unless otherwise noted.)
MAX4219/MAX4222 SMALL-SIGNAL GAIN vs. FREQUENCY
MAX4214-D
MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
MAX4219/MAX4222 GAIN FLATNESS vs. FREQUENCY
MAX4214-E
MAX4219/MAX4222 LARGE-SIGNAL GAIN vs. FREQUENCY
9 8 7 GAIN (dB) 6 5 4 3 2 1 0 VOUT = 2Vp-p RL = 100
MAX4214-F
10 9 8 7 GAIN (dB) 6 5 4 3 2 1 0 100k 1M 10M FREQUENCY (Hz) 100M VOUT = 100mVp-p
6.5 6.4 6.3 6.2 GAIN (dB) 6.1 6.0 5.9 5.8 5.7 5.6 5.5 VOUT = 100mVp-p
10
1G
100k
1M
10M FREQUENCY (Hz)
100M
1G
100k
1M
10M FREQUENCY (Hz)
100M
1G
HARMONIC DISTORTION vs. FREQUENCY
MAX4214-G
HARMONIC DISTORTION vs. RESISTIVE LOAD
MAX4214-H
-10 HARMONIC DISTORTION (dBc) -20 -30 -40 -50 -60 -70 -80 -90 -100
VOUT = 2Vp-p
-10 HARMONIC DISTORTION (dBc) -20 -30 -40 -50 -60 -70 -80 -90 -100
-10 HARMONIC DISTORTION (dBc) -20 -30 -40 -50 -60 -70 -80 -90
f = 5MHz
2ND HARMONIC
2ND HARMONIC 3RD HARMONIC
2ND HARMONIC 3RD HARMONIC
3RD HARMONIC
100k
1M
10M
100M
0 100 200 300 400 500 600 700 800 900 RESISTIVE LOAD ()
1k
-100 0.5 1.0 1.5 2.0 2.5 3.0 3.5 VOLTAGE SWING (Vp-p)
FREQUENCY (Hz)
VOLTAGE-NOISE DENSITY vs. FREQUENCY
MAX4214-12
10
30 10 NOISE (pA/ Hz) CROSSTALK (dB)
NOISE (nV/Hz)
-10 -30 -50 -70 -90 -110 -130
10
1 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
1 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
-150 100k 1M 10M FREQUENCY (Hz) 100M 1G
_______________________________________________________________________________________
MAX4214-04
100
CURRENT-NOISE DENSITY vs. FREQUENCY
MAX4217/MAX4219/MAX4222 CROSSTALK vs. FREQUENCY
50
5
MAX4214 i
0
0 VOUT = 2Vp-p f = 5MHz
HARMONIC DISTORTION vs. VOLTAGE SWING
0
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0V, AVCL = +2V/V, RL = 100 to VCC/2, TA = +25C, unless otherwise noted.)
POWER-SUPPLY REJECTION vs. FREQUENCY
MAX4214-M
MAX4215/MAX4219 OFF ISOLATION vs. FREQUENCY
MAX4214-N
CLOSED-LOOP OUTPUT IMPEDANCE vs. FREQUENCY
MAX4214-O
20 10 POWER-SUPPLY REJECTION (dB) 0 -10 -20 -30 -40 -50 -60 -70 -80 100k 1M 10M FREQUENCY (Hz) 100M
10 0 -10 OFF ISOLATION (dB)
100
-30 -40 -50 -60 -70 -80 -90 100k 1M 10M FREQUENCY (Hz) 100M
IMPEDANCE ()
-20
10
1
0.1
0.01 100k 1M 10M FREQUENCY (Hz) 100M 1G
DIFFERENTIAL GAIN AND PHASE
0.04 0.03 0.02 0.01 0.00 -0.01 0 DIFF. PHASE (deg) 0.02 0.00 -0.02 -0.04 -0.06 0 IRE RL = 150 VCM = 1.35V 100 IRE 100 DIFF. GAIN (%)
MAX4214-P
CLOSED-LOOP BANDWIDTH vs. LOAD RESISTANCE
MAX4214-24-Q
OUTPUT SWING vs. LOAD RESISTANCE
4.5 OUTPUT SWING (Vp-p) 4.0 3.5 3.0 2.5 2.0 1.5 1.0
MAX4214-R
350 VOUT = 100mVp-p CLOSED-LOOP BANDWIDTH (MHz) 300 250 200 150 100 50 0 0 100 200 300 400 LOAD RESISTANCE () 500
5.0
RL = 150 VCM = 1.35V
25
50
75 100 125 150 175 200 225 250 LOAD RESISTANCE ()
SMALL-SIGNAL PULSE RESPONSE
MAX4214-S
LARGE-SIGNAL PULSE RESPONSE
MAX4214-T
ENABLE RESPONSE TIME
MAX4214-U
IN
5.0V (ENABLE) IN EN_ 0V (DISABLE)
500mV/div OUT OUT OUT
25mV/div
1V
0V 20ns/div VCM = 1.25V, RL = 100 to GROUND 20ns/div VCM = 0.9V, RL = 100 to GROUND VIN = 0.5V 1s/div
6
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High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0V, AVCL = +2V/V, RL = 100 to VCC/2, TA = +25C, unless otherwise noted.)
SMALL-SIGNAL PULSE RESPONSE (CL = 5pF)
MAX4214-V
MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
LARGE-SIGNAL PULSE RESPONSE (CL = 5pF)
MAX4214-W
VOLTAGE SWING vs. TEMPERATURE
RL = 150 to 0V
MAX4214-X
5.0
IN IN 500mV/div 25mV/div VOLTAGE SWING (Vp-p) 20ns/div VCM = 1.75V, RL = 100 to 0V
4.8
4.6
4.4
OUT
OUT
4.2
4.0 20ns/div VCM = 1.25V, RL = 100 to 0V -50 -25 0 25 50 TEMPERATURE (C) 75 100
INPUT OFFSET VOLTAGE vs. TEMPERATURE
MAX4214-Y
INPUT BIAS CURRENT vs. TEMPERATURE
MAX4214-Z
INPUT OFFSET CURRENT vs. TEMPERATURE
MAX4214-AA
5
6.0
0.20
5.5
3
INPUT OFFSET CURRENT (A) -50 -25 0 25 50 TEMPERATURE (C) 75 100
INPUT OFFSET VOLTAGE (mV)
INPUT BIAS CURRENT (A)
4
0.16
0.12
5.0
2
0.08
1
4.5
0.04
0 -50 -25 0 25 50 TEMPERATURE (C) 75 100
4.0
0 -50 -25 0 25 50 TEMPERATURE (C) 75 100
POWER-SUPPLY CURRENT (PER AMPLIFIER) vs. POWER-SUPPLY VOLTAGE
MAX4214-BB
POWER-SUPPLY CURRENT (PER AMPLIFIER) vs. TEMPERATURE
MAX4214-CC
10 POWER-SUPPLY CURRENT (mA) 8
7 POWER-SUPPLY CURRENT (mA)
6
6
5
4
2
4
0 3 4 5 6 7 8 9 10 POWER-SUPPLY VOLTAGE (V) 11
3 -50 -25 0 25 50 TEMPERATURE (C) 75 100
_______________________________________________________________________________________
7
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
_______________________________________________________________Pin Description
PIN MAX4214 SOT23-5 -- 1 2 3 4 5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- MAX4215 SO/MAX 1, 5 6 4 3 2 7 8 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- MAX4217 SO/MAX -- -- 4 -- -- 8 -- -- -- -- 1 2 3 7 6 5 -- -- -- -- -- -- MAX4219 SO -- -- 11 -- -- 4 -- 1 3 2 7 6 5 8 9 10 14 13 12 -- -- -- QSOP 8, 9 -- 13 -- -- 4 -- 1 3 2 7 6 5 10 11 12 16 15 14 -- -- -- MAX4222 SO -- -- 11 -- -- 4 -- -- -- -- 1 2 3 7 6 5 8 9 10 14 13 12 QSOP 8, 9 -- 13 -- -- 4 -- -- -- -- 1 2 3 7 6 5 10 11 12 16 15 14 N.C. OUT VEE IN+ INVCC EN ENA ENB ENC OUTA INAINA+ OUTB INBINB+ OUTC INCINC+ OUTD INDIND+ No Connect. Not internally connected. Tie to ground or leave open. Amplifier Output Negative Power Supply or Ground (in single-supply operation) Noninverting Input Inverting Input Positive Power Supply Enable Amplifier Enable Amplifier A Enable Amplifier B Enable Amplifier C Amplifier A Output Amplifier A Inverting Input Amplifier A Noninverting Input Amplifier B Output Amplifier B Inverting Input Amplifier B Noninverting Input Amplifier C Output Amplifier C Inverting Input Amplifier C Noninverting Input Amplifier D Output Amplifier D Inverting Input Amplifier D Noninverting Input NAME FUNCTION
8
_______________________________________________________________________________________
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable
________________Detailed Description
The MAX4214/MAX4215/MAX4217/MAX4219/MAX4222 are single-supply, rail-to-rail output, voltage-feedback, closed-loop buffers that employ current-feedback techniques to achieve 600V/s slew rates and 230MHz bandwidths. These buffers use internal 500 resistors to provide a preset closed-loop gain of +2V/V in the noninverting configuration or -1V/V in the inverting configuration. Excellent harmonic distortion and differential gain/phase performance make them an ideal choice for a wide variety of video and RF signal-processing applications. Local feedback around the buffer's output stage ensures low output impedance, which reduces gain sensitivity to load variations. This feedback also produces demand-driven current bias to the output transistors for 120mA drive capability, while constraining total supply current to less than 7mA. Since the inverting input exhibits a 500 input impedance, terminate the input with a 56 resistor when configured for an inverting gain in 50 applications (terminate with 88 in 75 applications). Terminate the input with a 49.9 resistor in the noninverting case. Output terminating resistors should directly match cable impedances in either configuration.
MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
Layout Techniques
Maxim recommends using microstrip and stripline techniques to obtain full bandwidth. To ensure the PC board does not degrade the buffer's performance, design it for a frequency greater than 1GHz. Pay careful attention to inputs and outputs to avoid large parasitic capacitance. Whether or not you use a constantimpedance board, observe the following guidelines when designing the board: * Don't use wire-wrapped boards. They are too inductive. * Don't use IC sockets. They increase parasitic capacitance and inductance. * Use surface-mount instead of through-hole components for better high-frequency performance. * Use a PC board with at least two layers; it should be as free from voids as possible. * Keep signal lines as short and as straight as possible. Do not make 90 turns; round all corners.
___________Applications Information
Power Supplies
These devices operate from a single +3.15V to +11V power supply or from dual supplies of 1.575V to 5.5V. For single-supply operation, bypass the VCC pin to ground with a 0.1F capacitor as close to the pin as possible. If operating with dual supplies, bypass each supply with a 0.1F capacitor.
Selecting Gain Configuration
Each buffer in the MAX4214 family can be configured for a voltage gain of +2V/V or -1V/V. For a gain of +2V/V, ground the inverting terminal. Use the noninverting terminal as the signal input of the buffer (Figure 1a). Grounding the noninverting terminal and using the inverting terminal as the signal input configures the buffer for a gain of -1V/V (Figure 1b).
Input Voltage Range and Output Swing
The MAX4214 family's input range extends from (VEE - 100mV) to (VCC - 2.25V). Input ground sensing increases the dynamic range for single-supply applications. The outputs drive a 2k load to within 60mV of the power-supply rails. With smaller resistive loads, the output swing is reduced as shown in the Electrical Characteristics and Typical Operating Characteristics.
IN RTIN
IN+ OUT RTO OUT RO 500 IN 500 INRS
IN+ OUT RTO OUT RO 500 INRTIN 500
MAX42_ _
MAX42_ _
Figure 1a. Noninverting Gain Configuration (AV = +2V/V)
Figure 1b. Inverting Gain Configuration (AV = -1V/V)
9
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High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
As the load resistance decreases, the useful input range is effectively limited by the output drive capability, since the buffers have a fixed voltage gain of +2V/V or -1V/V. For example, a 50 load can typically be driven from 40mV above VEE to 1.6V below VCC, or 40mV to 3.4V when operating from a single +5V supply. If the buffer is operated in the noninverting, gain of +2V/V configuration with the inverting input grounded, the useful input voltage range becomes 20mV to 1.7V instead of the -100mV to 2.75V indicated by the Electrical Charac teristics. Beyond the useful input range, the buffer output is a nonlinear function of the input, but it will not undergo phase reversal or latchup. sists of five back-to-back Schottky diodes between IN_+ and IN_-. These diodes reduce the disabled output resistance from 1k to 500 when the output voltage is 3V greater or less than the voltage at IN_+. Under these conditions, the input protection diodes will be forward biased, lowering the disabled output resistance to 500.
Output Capacitive Loading and Stability
The MAX4214 family provides maximum AC performance with no load capacitance. This is the case when the load is a properly terminated transmission line. These devices are designed to drive up to 20pF of load capacitance without oscillating, but AC performance will be reduced under these conditions.
Enable
The MAX4215 and MAX4219 have an enable feature (EN_) that allows the buffer to be placed in a low-power state. When the buffers are disabled, the supply current is reduced to 400A per buffer. As the voltage at the EN_ pin approaches the negative supply rail, the EN_ input current rises. Figure 2 shows a graph of EN_ input current versus EN_ pin voltage. Figure 3 shows the addition of an optional resistor in series with the EN pin, to limit the magnitude of the current increase. Figure 4 displays the resulting EN pin input current to voltage relationship.
ENABLE 10k EN_ OUT
IN+
MAX42_ _
Disabled Output Resistance
The MAX4214/MAX4215/MAX4217/MAX4219/MAX4222 include internal protection circuitry that prevents damage to the precision input stage from large differential input voltages (Figure 5). This protection circuitry conIN500 500
Figure 3. Circuit to Reduce Enable Logic-Low Input Current
20 0 -20 INPUT CURRENT (A) INPUT CURRENT (A) -40 -60 -80 -100 -120 -140 -160 0 100 200 300 400 500 VIL (mV ABOVE VEE)
0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 0 100 200 300 400 500 VIL (mV ABOVE VEE)
Figure 2. Enable Logic-Low Input Current vs. Enable LogicLow Threshold
10
Figure 4. Enable Logic-Low Input Current vs. Enable LogicLow Threshold with 10k Series Resistor
______________________________________________________________________________________
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
6 5 NORMALIZED GAIN (dB) CL = 15pF
IN+
MAX4214 MAX4215 MAX4217 MAX4219 MAX4222
OUT
4 3 2 1 0 -1 -2 -3 CL = 5pF CL = 10pF
IN500 500
-4 100k 1M 10M FREQUENCY (Hz) 100M 1G
Figure 5. Input Protection Circuit
Figure 6. Small-Signal Gain vs. Frequency with Load Capacitance and No Isolation Resistor
16 14
500
500 RISO () VOUT CL
12 10 8 6 4 2 0 0 50 100 150 CLOAD (pF) 200 250
RISO
MAX42_ _
VIN RTIN 50
Figure 7. Driving a Capacitive Load Through an Isolation Resistor
Figure 8. Isolation Resistance vs. Capacitive Load
Driving large capacitive loads increases the chance of oscillations occurring in most amplifier circuits. This is especially true for circuits with high loop gains, such as voltage followers. The buffer's output resistance and the load capacitor combine to add a pole and excess phase to the loop response. If the frequency of this pole is low enough to interfere with the loop response and degrade phase margin sufficiently, oscillations can occur. A second problem when driving capacitive loads results from the amplifier's output impedance, which looks inductive at high frequencies. This inductance forms an L-C resonant circuit with the capacitive load, which causes peaking in the frequency response and degrades the amplifier's gain margin.
Figure 6 shows the devices' frequency response under different capacitive loads. To drive loads with greater than 20pF of capacitance or to settle out some of the peaking, the output requires an isolation resistor like the one shown in Figure 7. Figure 8 is a graph of the optimal isolation resistor versus load capacitance. Figure 9 shows the frequency response of the MAX4214/MAX4215/MAX4217/MAX4219/MAX4222 when driving capacitive loads with a 27 isolation resistor. Coaxial cables and other transmission lines are easily driven when properly terminated at both ends with their characteristic impedance. Driving back-terminated transmission lines essentially eliminates the lines' capacitance.
11
______________________________________________________________________________________
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
3 2 1 NORMALIZED GAIN (dB) 0 -1 -2 -3 -4 -5 -6 -7 100k 1M 10M FREQUENCY (Hz) 100M 1G
GAIN OF +2 VIDEO/RF CABLE DRIVER IN500 500 IN+
_________Typical Application Circuit
RISO = 27 CL = 47pF
CL = 68pF CL = 120pF
75
VOUT
75
MAX4214
Figure 9. Small-Signal Gain vs. Frequency with Load Capacitance and 27 Isolation Resistor
____________________Chip Information
PART MAX4214 MAX4215 MAX4217 MAX4219 MAX4222 NO. OF TRANSISTORS 95 95 190 299 362
SUBSTRATE CONNECTED TO VEE
12
______________________________________________________________________________________
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable
_______________________________________________Pin Configurations (continued)
TOP VIEW
MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
N.C. 1 IN- 2
8 7
EN VCC OUT N.C.
OUTA 1 INA- 2
8 7
VCC OUTB INBINB+
MAX4215
IN+ 3 VEE 4 6 5
MAX4217
INA+ 3 VEE 4 6 5
SO/MAX
SO/MAX
ENA 1 ENC 2 ENB 3 VCC 4 INA+ 5 INA- 6 OUTA 7
14 OUTC 13 INC12 INC+
ENA 1 ENC 2 ENB 3 VCC 4 INA+ 5 INA- 6 OUTA 7 N.C. 8
16 OUTC 15 INC14 INC+
MAX4219
11 VEE 10 INB+ 9 8 INBOUTB
MAX4219
13 VEE 12 INB+ 11 INB10 OUTB 9 N.C.
SO QSOP
OUTA 1 INA- 2 INA+ 3 VCC 4 INB+ 5 INB- 6 OUTB 7
14 OUTD 13 IND12 IND+
OUTA 1 INA- 2 INA+ 3 VCC 4 INB+ 5 INB- 6 OUTB 7 N.C. 8
16 OUTD 15 IND14 IND+
MAX4222
11 VEE 10 INC+ 9 8 INCOUTC
MAX4222
13 VEE 12 INC+ 11 INC10 OUTC 9 N.C.
SO QSOP
______________________________________________________________________________________
13
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
__________________________________________________Tape-and-Reel Information
E D P0 P2 W B0
F
D1
t
NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD.
P A0
K0
A0 B0 D D1
3.200 3.099 1.499 0.991
0.102 0.102 +0.102 +0.000 +0.254 +0.000
E F K0 P
1.753 3.505 1.397 3.988
0.102 0.051 0.102 0.102
P0 P010 P2 t W
3.988 40.005 2.007 0.254 8.001
0.102 0.203 0.051 0.127 +0.305 -0.102
5 SOT23-5
________________________________________________________Package Information
SOT5L.EPS
14
______________________________________________________________________________________
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable
___________________________________________Package Information (continued)
8LUMAXD.EPS
MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
______________________________________________________________________________________
SOICN.EPS
15
High-Speed, Single-Supply, Gain of +2, Closed-Loop, Rail-to-Rail Buffers with Enable MAX4214/MAX4215/MAX4217/MAX4219/MAX4222
___________________________________________Package Information (continued)
QSOP.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) 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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