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19-1519 Rev 0; 8/99 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable General Description The MAX4447/MAX4448/MAX4449 single-ended-todifferential line drivers are designed for high-speed communications. Using current feedback for greater bandwidth, these devices deliver full-power bandwidths up to 405MHz and feature slew rates as high as 6500V/s. The MAX4447 has a fixed gain of +2V/V and a small-signal bandwidth of 430MHz. The MAX4448/ MAX4449 have small-signal bandwidths of 330MHz and 400MHz, respectively, and are internally compensated for minimum gain configurations of +2V/V and +5V/V, respectively. For greater design flexibility, the MAX4448/MAX4449 allow for variable gain selection using external gain-setting resistors. A low-power enable mode reduces current consumption below 5.5mA and places the outputs in a high-impedance state. The MAX4447/MAX4448/MAX4449 can deliver differential output swings of 6.2V from 5V supplies with a 50 load. Excellent differential gain/phase and noise specifications make these amplifiers ideal for a wide variety of video and RF signal-processing and transmission applications. o 6500V/s Slew Rate (MAX4449) o Small-Signal Bandwidth 430MHz (MAX4447) 330MHz (MAX4448) 400MHz (MAX4449) o 200MHz 0.1dB Gain Flatness (MAX4447) o 130mA Output Drive Current o +2V/V Internally Fixed Gain (MAX4447) o External Gain Selection +2V/V (MAX4448) +5V/V (MAX4449) o -78dB SFDR at 100kHz o Low Differential Gain/Phase: 0.01%/0.02 o Ultra-Low Noise: 23nV/Hz at fIN = 1MHz o 8ns Settling Time to 0.1% Features MAX4447/MAX4448/MAX4449 Applications Differential Line Driver Single-Ended-to-Differential Conversion High-Speed Differential Transmitter Coaxial to Twisted-Pair Converter Differential Pulse Amplifier Differential ADC Driver xDSL Applications Video and RF Signal Processing and Transmission PART MAX4447ESE MAX4448ESE MAX4449ESE Ordering Information TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 16 Narrow SO 16 Narrow SO 16 Narrow SO Typical Operating Circuit +5V Pin Configuration 0.1F TOP VIEW VCC 1 VCC 2 N.C. 3 N.C. (RG) 4 IN 5 N.C. 6 VEE 7 VEE 8 16 GND 15 OUT14 VEE 75 75 INPUT 75 VCC IN EN OUT+ RT TO LOAD OUTRT 75 MAX4447 MAX4448 MAX4449 13 VEE 12 VEE 11 VEE 10 OUT+ 9 EN MAX4447 VEE GND 0.1F SO ( ) ARE FOR MAX4448/MAX4449 ONLY -5V ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 ABSOLUTE MAXIMUM RATINGS VCC to VEE ..........................................................................+12V Voltage on IN, EN, OUT+, OUT-, RG ....(VEE - 0.3V) to (VCC + 0.3V) Output Short-Circuit Duration to GND ...........................Indefinite Continuous Power Dissipation (TA = +70C) 16-Pin Narrow SO (derate 20mW/C above +70C) ...1600mW 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 = -5V, VEN 2V, VOUT = VOUT+ - VOUT- , RL = , TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Operating Supply Voltage Range Input Voltage Range Input Offset Voltage Input Offset Voltage Temperature Coefficient Input Bias Current Input Resistance Gain SYMBOL VCC VEE VIN VOS TCVOS IB RIN AV CONDITIONS VCC guaranteed by PSRR test VEE guaranteed by PSRR test Guaranteed by gain-error test VIN = 0 VIN = 0 VIN = 0 -3.0V VIN 3.0V MAX4447 -6V VOUT 6V MAX4448/MAX4449 (Note 1) MIN 4.5 -5.5 -6/AV 1.3 25 7 50 2 2 * (1+300/RG) 0.1 -0.3 -0.002 0.01 7.4 6.2 130 140 75 4 2 5 V/V 45 TYP MAX 5.5 -4.5 +6/AV 50 UNITS V V mV V/C A k Gain Error Gain Drift Output Voltage Swing Output Current Drive Output Short-Circuit Current Power-Supply Rejection Ratio Output Leakage Current EN Logic Low Threshold EN Logic High Threshold EN Logic Input Low Current EN Logic Input High Current Quiescent Current VOUT IOUT ISC PSRR IOUT(OFF) VIL VIH IIL IIH IQ MAX4447 MAX4448/MAX4449 MAX4447 VOUT = 0 MAX4448/MAX4449 RL = 100 between OUT+ and OUTRL = 50 between OUT+ and OUTRL = 20 between OUT+ and OUTShort circuit to GND VS = 4.5V to 5.5V VEN = 0, VOUT+ = VOUT- = 3.15V or -3.15V -6V VOUT 6V % %/C V mA mA dB A V V A A mA 6.3 5.2 90 53 30 0.8 10 10 55 5.5 2 VEN = 0 VEN = 5V VIN = 0, VEN VIH VIN = 0, VEN VIL -2.5 0.8 46 3.2 2 _______________________________________________________________________________________ 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable AC ELECTRICAL CHARACTERISTICS (VCC = +5V, VEE = -5V, RL = 100 between OUT+ and OUT-, AVCL = +2V/V for MAX4447/MAX4448, AVCL = +5V/V for MAX4449, VOUT = VOUT+ - VOUT-, TA = +25C, unless otherwise noted.) PARAMETER Small-Signal -3dB Bandwidth SYMBOL BWSS CONDITIONS MAX4447 VOUT = 100mVp-p VOUT = 8Vp-p VOUT = 4Vp-p Large-Signal -3dB Bandwidth Large-Signal -3dB Bandwidth BWLS VOUT = 2Vp-p MAX4448 MAX4449 MAX4449 MAX4447 MAX4448 MAX4449 MAX4447 MAX4448 MAX4449 MAX4447 0.1dB Gain Flatness VOUT = 100mVp-p MAX4448 MAX4449 MAX4447 VOUT = 8V step MAX4448 MAX4449 MAX4447 Slew Rate (Note 2) SR VOUT = 4V step MAX4448 MAX4449 MAX4447 VOUT = 2V step MAX4448 MAX4449 MAX4447 VOUT = 8V step MAX4448 MAX4449 MAX4447 Rise Time (Note 2) tRISE VOUT = 4V step MAX4448 MAX4449 MAX4447 VOUT = 2V step MAX4448 MAX4449 MIN TYP 430 330 400 250 250 260 320 285 310 405 200 40 140 5700 4300 6500 3000 3000 3700 1700 1900 1800 670 1030 850 720 820 660 720 520 740 ps V/s MHz MHz MHz MAX UNITS MAX4447/MAX4448/MAX4449 _______________________________________________________________________________________ 3 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 AC ELECTRICAL CHARACTERISTICS (continued) (VCC = +5V, VEE = -5V, RL = 100 between OUT+ and OUT-, AVCL = +2V/V for MAX4447/MAX4448, AVCL = +5V/V for MAX4449, VOUT = VOUT+ - VOUT-, TA = +25C, unless otherwise noted.) PARAMETER SYMBOL VOUT = 8V step CONDITIONS MAX4447 MAX4448 MAX4449 MAX4447 Fall Time (Note 2) tFALL VOUT = 4V step MAX4448 MAX4449 MAX4447 VOUT = 2V step Settling Time fC = 100kHz Spurious-Free Dynamic Range SFDR VOUT = 2Vp-p fC = 5MHz fC = 20MHz fC = 100MHz fC = 100kHz 2nd Harmonic Distortion VOUT = 2Vp-p fC = 5MHz fC = 20MHz fC = 100MHz fC = 100kHz 3rd Harmonic Distortion VOUT = 2Vp-p fC = 5MHz fC = 20MHz fC = 100MHz Differential Phase Error Differential Gain Error Input Noise Voltage Density Input Noise Current Density Output Impedance Enable Time Disable Time Power-Up Time Power-Down Time tON tOFF DP DG eN iN ZOUT NTSC, RL = 150 NTSC, RL = 150 f = 1MHz (Note 3) f = 1MHz f = 10MHz, each output to ground VIN = 1V, VOUT settle to within 1% VIN = 1V, VOUT settle to within 1% VIN = 1V, VOUT settle to within 1% VIN = 1V, VOUT settle to within 1% MAX4448 MAX4449 MIN TYP 1100 900 900 900 810 780 800 770 660 8 -78 -78 -62 -46 -78 -78 -62 -46 -86 -86 -71 -54 0.02 0.01 24 1.8 1.0 55 0.4 0.08 0.5 degrees % nV/Hz pA/Hz ns s s s dBc dBc dBc ns ps MAX UNITS Note 1: RG is the gain resistor. See Figure 1. Note 2: Input step voltage has <100ps rise (fall) time. Measured at the output from 10% to 90% (90% to 10%) levels. Note 3: Includes the current noise contribution through the on-die feedback resistor. 4 _______________________________________________________________________________________ 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable Typical Operating Characteristics (VCC = +5V, VEE = -5V, VEN = +5V, VOUT = VOUT+ - VOUT-, RL = 100 between OUT+ and OUT-, AV = +2V/V for MAX4447/MAX4448, AV = +5V/V for MAX4449, TA = +25C, unless otherwise noted.) MAX4447 SMALL-SIGNAL GAIN vs. FREQUENCY (VOUT = 100mVp-p) MAX4447 TOC01 MAX4447/MAX4448/MAX4449 MAX4448 SMALL-SIGNAL GAIN vs. FREQUENCY (VOUT = 100mVp-p) MAX4447 TOC02 MAX4449 SMALL-SIGNAL GAIN vs. FREQUENCY (VOUT = 100mVp-p) 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 -6 MAX4447 TOC03 4 3 2 1 GAIN (dB) 4 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 -6 4 0 -1 -2 -3 -4 -5 -6 100k 1M 10M FREQUENCY (Hz) 100M 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G MAX4447 GAIN FLATNESS vs. FREQUENCY (VOUT = 100mVp-p) MAX4447 TOC04 MAX4448 GAIN FLATNESS vs. FREQUENCY (VOUT = 100mVp-p) MAX4447 TOC05 MAX4449 GAIN FLATNESS vs. FREQUENCY (VOUT = 100mVp-p) 0.4 0.3 0.2 GAIN (dB) 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 MAX4447 TOC06 0.5 0.4 0.3 0.2 GAIN (dB) 0.5 0.4 0.3 0.2 GAIN (dB) 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 0.5 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 100k 1M 10M FREQUENCY (Hz) 100M 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G MAX4447 LARGE-SIGNAL GAIN vs. FREQUENCY (VOUT = 2Vp-p) MAX4447 TOC07 MAX4448 LARGE-SIGNAL GAIN vs. FREQUENCY (VOUT = 2Vp-p) MAX4447 TOC08 MAX4449 LARGE-SIGNAL GAIN vs. FREQUENCY (VOUT = 2Vp-p) 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 -6 MAX4447 TOC09 4 3 2 1 GAIN (dB) 4 3 2 1 GAIN (dB) 0 -1 -2 -3 -4 -5 -6 4 0 -1 -2 -3 -4 -5 -6 100k 1M 10M FREQUENCY (Hz) 100M 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G _______________________________________________________________________________________ 5 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, VEN = +5V, VOUT = VOUT+ - VOUT-, RL = 100 between OUT+ and OUT-, AV = +2V/V for MAX4447/MAX4448, AV = +5V/V for MAX4449, TA = +25C, unless otherwise noted.) MAX4447 SMALL-SIGNAL GAIN vs. FREQUENCY (VOUT = 100mVp-p) MAX4447 TOC10 MAX4448 SMALL-SIGNAL GAIN vs. FREQUENCY (VOUT = 100mVp-p) MAX4447 TOC11 MAX4449 SMALL-SIGNAL GAIN vs. FREQUENCY (VOUT = 100mVp-p) 20 15 10 GAIN (dB) 5 0 -5 -10 -15 -20 -25 CLOAD = 5pF CLOAD = 15pF MAX4447 TOC12 25 20 15 10 GAIN (dB) 5 0 -5 -10 -15 -20 -25 100k 1M 10M FREQUENCY (Hz) 100M CLOAD = 5pF CLOAD = 15pF 25 20 15 10 GAIN (dB) 5 0 -5 -10 -15 -20 -25 CLOAD = 5pF CLOAD = 15pF 25 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G 100k 1M 10M FREQUENCY (Hz) 100M 1G MAX4447 SMALL-SIGNAL PULSE RESPONSE MAX4447 TOC13 MAX4448 SMALL-SIGNAL PULSE RESPONSE MAX4447 TOC14 MAX4449 SMALL-SIGNAL PULSE RESPONSE MAX4447 TOC15 INPUT 50mV/div INPUT 50mV/div INPUT 25mV/div OUTPUT 100mV/div OUTPUT 100mV/div OUTPUT 125mV/div (5ns/div) (5ns/div) (5ns/div) MAX4447 LARGE-SIGNAL PULSE RESPONSE MAX4447 TOC16 MAX4448 LARGE-SIGNAL PULSE RESPONSE MAX4447 TOC17 MAX4449 LARGE-SIGNAL PULSE RESPONSE MAX4447 TOC18 INPUT 500mV/div INPUT 500mV/div INPUT 200mV/div OUTPUT 1V/div OUTPUT 1V/div OUTPUT 1V/div (5ns/div) (5ns/div) (5ns/div) 6 _______________________________________________________________________________________ 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, VEN = +5V, VOUT = VOUT+ - VOUT-, RL = 100 between OUT+ and OUT-, AV = +2V/V for MAX4447/MAX4448, AV = +5V/V for MAX4449, TA = +25C, unless otherwise noted.) SLEW RATE vs. OUTPUT VOLTAGE MAX4447 TOC19 MAX4447/MAX4448/MAX4449 MAX4447 DIFFERENTIAL GAIN AND PHASE MAX4447 TOC20 MAX4448 DIFFERENTIAL GAIN AND PHASE DIFFERENTIAL GAIN (%) 0.002 0.000 -0.002 -0.004 -0.006 0 IRE 0.04 0.03 0.02 0.01 0 -0.01 0 10 20 30 40 50 60 70 80 90 100 IRE DIFFERENTIAL PHASE () MAX4447 TOC21 MAX4449 6000 MAX4447 SLEW RATE (V/s) 5000 4000 3000 2000 1000 0 0 2 4 6 8 10 MAX4448 DIFFERENTIAL GAIN (%) 7000 0.004 0.002 0.000 -0.002 -0.004 0 IRE 0.03 0.02 0.01 0 -0.01 0 100 100 DIFFERENTIAL PHASE () 12 10 20 30 40 50 60 70 80 90 100 IRE OUTPUT VOLTAGE (V) MAX4449 DIFFERENTIAL GAIN AND PHASE 0.02 0.00 -0.02 -0.04 -0.06 -0.08 0 IRE 0.015 0.010 0.005 0.000 -0.005 0 10 20 30 40 50 60 70 80 90 100 IRE DIFFERENTIAL PHASE () MAX4447 TOC22 MAX4447 HARMONIC DISTORTION vs. FREQUENCY (VOUT = 2Vp-p) MAX4447 TOC23 MAX4448 HARMONIC DISTORTION vs. FREQUENCY (VOUT = 2Vp-p) -10 -20 DISTORTION (dB) -30 -40 -50 -60 -70 -80 -90 -100 2ND 3RD MAX4447 TOC24 DIFFERENTIAL GAIN (%) 0 -10 -20 DISTORTION (dB) -30 -40 -50 -60 -70 -80 -90 -100 1M 10M FREQUENCY (Hz) 2ND 3RD 0 100 100M 1M 10M FREQUENCY (Hz) 100M MAX4449 HARMONIC DISTORTION vs. FREQUENCY (VOUT = 2Vp-p) MAX4447 TOC25 MAX4447 HARMONIC DISTORTION vs. OUTPUT VOLTAGE SWING (fC = 5MHz) MAX4447 TOC26 MAX4448 HARMONIC DISTORTION vs. OUTPUT VOLTAGE SWING (fC = 5MHz) -10 -20 DISTORTION (dB) -30 -40 -50 -60 -70 3RD 2ND MAX4447 TOC27 0 -10 -20 DISTORTION (dB) -30 -40 -50 -60 -70 -80 -90 -100 1M 10M FREQUENCY (Hz) 2ND 3RD 0 -10 -20 DISTORTION (dB) -30 -40 -50 -60 -70 -80 -90 -100 3RD 2ND 0 -80 -90 -100 100M 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE SWING (V) OUTPUT VOLTAGE SWING (V) _______________________________________________________________________________________ 7 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, VEN = +5V, VOUT = VOUT+ - VOUT-, RL = 100 between OUT+ and OUT-, AV = +2V/V for MAX4447/MAX4448, AV = +5V/V for MAX4449, TA = +25C, unless otherwise noted.) MAX4449 HARMONIC DISTORTION vs. OUTPUT VOLTAGE SWING (fC = 5MHz) MAX4447 TOC28 VOLTAGE NOISE DENSITY vs. FREQUENCY MAX4447 TOC29 CURRENT NOISE DENSITY vs. FREQUENCY MAX4447 TOC30 0 -10 -20 DISTORTION (dB) -30 -40 -50 -60 -70 -80 -90 -100 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE SWING (V) 2ND 3RD 1000 100 VOLTAGE NOISE DENSITY (nV/ Hz) CURRENT NOISE DENSITY (pA/ Hz) 100 10 10 1 10 100 1k 10k 100k 1M FREQUENCY (Hz) 1 1 10 100 1k 10k 100k 1M FREQUENCY (Hz) ISOLATION RESISTANCE vs. CAPACITIVE LOAD MAX4447 TOC31 OUTPUT IMPEDANCE vs. FREQUENCY DIFFERENTIAL OUTPUT VOLTAGE SWING (Vp-p) MAX4447 TOC32 DIFFERENTIAL OUTPUT VOLTAGE SWING vs. RESISTIVE LOAD 14 12 10 8 6 4 2 0 0 40 80 120 RL () 160 200 MAX4447 TOC33 22 20 18 16 14 12 10 0 20 40 60 80 100 100 16 ISOLATION RESISTANCE () CURRENT IMPEDANCE () 10 1 0.1 120 100k 1M 10M FREQUENCY (Hz) 100M 1G CAPACITIVE LOAD (pF) POWER-SUPPLY REJECTION vs. FREQUENCY MAX4447 TOC34 SHUTDOWN RESPONSE TIME EN VEN = 0.8V TO 2V VOS (mV) MAX4447 TOC35 OFFSET VOLTAGE vs. TEMPERATURE MAX4447 TOC36 0 -10 -20 -30 PSR (dB) -40 -50 -60 -70 -80 -90 0.1 1 10 FREQUENCY (MHz) 100 4 3 2 1 0 -1 -2 -3 OUTPUT VOLTAGE 1V/div 1000 (50ns/div) -40 -15 10 35 60 85 TEMPERATURE (C) 8 _______________________________________________________________________________________ 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 Typical Operating Characteristics (continued) (VCC = +5V, VEE = -5V, VEN = +5V, VOUT = VOUT+ - VOUT-, RL = 100 between OUT+ and OUT-, AV = +2V/V for MAX4447/MAX4448, AV = +5V/V for MAX4449, TA = +25C, unless otherwise noted.) QUIESCENT CURRENT vs. TEMPERATURE MAX4447 TOC37 INPUT BIAS CURRENT vs. TEMPERATURE MAX4447 TOC38 50 EN = VCC QUIESCENT CURRENT (mA) 40 12 INPUT BIAS CURRENT (A) EN = GND -40 -15 10 35 60 85 9 30 6 20 10 3 0 TEMPERATURE (C) 0 -40 -15 10 35 60 85 TEMPERATURE (C) Pin Description PIN MAX4447 1, 2 3, 4, 6 -- 5 7, 8, 11, 12, 13, 14 9 10 15 16 MAX4448 MAX4449 1, 2 3, 6 4 5 7, 8, 11, 12, 13, 14 9 10 15 16 NAME FUNCTION VCC N.C. RG IN VEE EN OUT+ OUTGND Positive Power Supply. Bypass with a 0.1F capacitor to GND. No Connection. Not internally connected. Connect to GND for best AC performance. Gain-Set Resistor. Connect gain-setting resistor from RG to GND. Amplifier Noninverting Input Negative Power-Supply Input. Bypass with a 0.1F capacitor to GND. Active-High, TTL-Compatible, Enable Input. Connect to VCC for normal operation. Connect to GND for low-power operation. Positive Polarity Output Negative Polarity Output Ground _______________________________________________________________________________________ 9 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 Detailed Description The MAX4447/MAX4448/MAX4449 single-ended-to-differential converters are capable of transmitting highspeed signals such as T1 or xDSL over twisted-pair cable. Excellent gain and phase characteristics, along with low distortion, make these devices suitable for video and RF signal processing and transmission. These converters can be interfaced directly to some of Maxim's wireless products, such as the MAX2450/ MAX2451. The MAX4447/MAX4448/MAX4449 offer wide small-signal bandwidths of 430MHz, 330MHz, and 400MHz, respectively. Internally trimmed resistors minimize gain errors to under 2% over the full output range. Other features include a high slew rate up to 6500V/s and high output current (130mA), which allow these amplifiers to be used in numerous high-speed communications applications. VCC INPUT IN OUT+ MAX4448 MAX4449 RG RGAIN OUT300 AVCL = 2 ( 1 + RGAIN ) Applications Information Grounding and Bypassing Use high-frequency design techniques when designing the PC board for the MAX4447/MAX4448/MAX4449: * Use a multilayer board with one layer dedicated as the ground plane. * Do not wire-wrap or use breadboards, due to high inductance. * Avoid IC sockets, due to high parasitic capacitance and inductance. * Bypass supplies with 0.1F. Use surface-mount capacitors to minimize lead inductance. * Keep signal lines as short and straight as possible. Do not make 90 turns; round all corners. Do not cross signals if possible. * Ensure that the ground plane is free from voids. INPUT IN OUT+ VEE Figure 1. Setting the Amplifier Gain VCC RISO CLOAD MAX4447 MAX4448 MAX4449 RG RGAIN RISO OUTCLOAD Output Short-Circuit Protection Output short-circuit protection typically limits the current to 140mA when shorted to GND, thereby keeping the power dissipation under the absolute maximum power dissipating rating. However, when shorted to either supply, the short-circuit current can be significantly higher and cause damage to the device. VEE Figure 2. Using an Isolation Resistor for High Capacitive Loads Low-Power Enable Mode The MAX4447/MAX4448/MAX4449 are disabled when EN goes low. This reduces supply current to only 3.2mA and places the outputs into a higher impedance. 10 ______________________________________________________________________________________ 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 IN 500mV/div IN 500mV/div CL = 15pF OUT 1V/div OUT 1V/div CL = 15pF Figure 3. Capacitive-Loaded Output Step Response Without Isolation Resistor Figure 4. Capacitive-Loaded Output Step Response with 14 Isolation Resistor Setting Gain The MAX4448/MAX4449 are stable with minimum gain of +2V/V and +5V/V, respectively. An external resistor, RGAIN, connected between RG and GND sets the gain of these devices. Calculate the gain as follows: Gain = 2 (1 + 300 / RGAIN) RGAIN for the MAX4449 must be 200. Twisted-Pair Line Driver The MAX4447/MAX4448/MAX4449 are well-suited to drive twisted-pair cables. The 24AWG telephone wire widely used produces losses at the higher frequencies. Compensate for these losses by increasing the gain slightly. Driving Capacitive Loads The MAX4447/MAX4448/MAX4449 are designed to drive capacitive loads. However, excessive capacitive loads may cause ringing or instability at the output as phase margin is reduced. Adding a small series isolation resistor at the output helps reduce the ringing but slightly increases gain error. TRANSISTOR COUNT: 291 Chip Information ______________________________________________________________________________________ 11 6500V/s, Wideband, High-Output-Current, SingleEnded-to-Differential Line Drivers with Enable MAX4447/MAX4448/MAX4449 Package Information 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. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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