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19-2299; Rev 0; 1/02
ADSL Drivers/Receivers for Customer Premise Equipment
General Description
The MAX4361/MAX4362/MAX4363 are a family of highperformance ADSL drivers and drivers/receivers ideal for the upstream transmit path and the downstream receive path of customer premise equipment. These devices operate from a single 5V supply and deliver up to 12.5dBm average line power for DMT modulated signals, meeting the requirements of full-rate ADSL. Spurious-free dynamic range (SFDR) at full output power is typically -75dBC at 100kHz. The MAX4361 is a differential IN/differential OUT driver with a fixed gain of 3.1V/V. The MAX4362 is a dual amplifier with shutdown intended for use as a differential IN/differential OUT driver with gain set with external resistors. The MAX4363 is a quad amplifier with shutdown intended for use as a differential IN/differential OUT driver/receiver combination with gain set with external resistors. The MAX4361 is offered in a space-saving 8-pin MAX package. o Low-Noise Driver 4.8nV/Hz Voltage-Noise Density 1.5pA/Hz Current-Noise Density o Full-Rate ADSL ATU-R Line Drivers and Receivers o Single 5V Supply o -75dBc SFDR at Full Output Power at 100kHz o -95dB Driver-to-Receiver Crosstalk (MAX4363) o +12.5dBm Average Line Power (DMT) o 280mA (min) Peak Output Current o Rail-to-Rail(R) Output Swing o Thermal and Short-Circuit Protection
Features
MAX4361/MAX4362/MAX4363
Ordering Information
PART MAX4361EUA MAX4361ESA MAX4362EUB MAX4362ESD MAX4363EUP MAX4363ESP TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 MAX 8 SO 10 MAX 14 SO 20 TSSOP 20 SO
Applications
ADSL Line Interface HDSL Line Driver
Pin Configurations
TOP VIEW
GND 1 IN+ 2
MAX4361
8 OUT+ T1IN+ 1 7 V+ 6 V+ T1INSHDN T2IN2 3 4 5
MAX4362
10 GND 9 8 7 6 T1OUT V+ T2OUT
N.C. 1 T1IN+ T1IN2 3
MAX4362
14 N.C. 13 GND 12 T1OUT 11 V+ 10 T2OUT 9 8 GND N.C.
T1IN+ 1 T1IN- 2 SHDN 3
MAX4363
20 GND (TX) 19 T1OUT 18 V+ (TX) 17 T2OUT 16 GND (TX) 15 N.C. 14 V+ (RX) 13 GND (RX) 12 R1OUT 11 R2OUT
IN- 3 GND 4
SHDN 4 T2IN- 5
T2IN- 4 T2IN+ 5 GND 6 R1IN+ 7 R1IN- 8
5 OUT- T2IN+
GND
T2IN+ 6 N.C. 7
MAX/SO
MAX
SO
R2IN- 9 R2IN+ 10
SO/TSSOP
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
ADSL Drivers/Receivers for Customer Premise Equipment MAX4361/MAX4362/MAX4363
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V+ to GND) ....................................-0.3V to +6V Analog Input Voltage .......................(GND - 0.3V) to (V+ + 0.3V) SHDN Input Voltage.........................(GND - 0.3V) to (V+ + 0.3V) Output Short-Circuit Duration .................................................10s Driver Output Current...............................................................1A Receiver Output Current ...................................................150mA Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.5mW/C above +70C) ..............362mW 10-Pin MAX (derate 5.6mW/C above +70C) ............444mW 8-Pin SO (derate 5.88mW/C above +70C).................471mW 14-Pin SO (derate 8.33mW/C above +70C)...............667mW 20-Pin SO (derate 10.0mW/C above +70C)...............800mW 20-Pin TSSOP (derate 10.9mW/C above +70C) ........879mW 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.
ELECTRICAL CHARACTERISTICS--Driver
(V+ = 5V, GND = 0, VCM = 2.5V, RL = 12.5, SHDN = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values specified at TA = +25C.)
PARAMETER Supply Voltage Range (Note 1) SYMBOL VCC MAX4361, RL = MAX4362, RL = Supply Current IQ MAX4363, measured at V+ (TX), RL = MAX4363, measured at V+ (RX), RL = Maximum Average Output Power (Notes 2, 3) Gain Open-Loop Gain Second Harmonic Distortion (Notes 3, 4) Third Harmonic Distortion (Notes 3, 4) Peak Output Current Input Offset Voltage Input Bias Current Input Offset Current Differential Input Resistance IOUT VOS IB IOS RIN(DIFF) MAX4361 MAX4362/MAX4363 MAX4361 MAX4362/MAX4363 POUT G AVOL DMT modulation CAP modulation MAX4361 (0.7V VOUT (V+) - 0.7V) MAX4362/MAX4363 (0.7V VOUT (V+) - 0.7V) G = 3.1, f = 100kHz, VOUT(DIFF) = 7.1VP-P G = 3.1, f = 100kHz, VOUT(DIFF) = 7.1VP-P Inferred from Output Voltage Swing test SHDN = 0 SHDN = 5V SHDN = 0 SHDN = 5V SHDN = 0 SHDN = 5V 15.5 18 3.0 68 -66 -68 280 3.1 81 -76 -79 330 0.5 1.6 30 10 25 40 10 4.5 600 500 3.2 CONDITIONS MIN 4.5 22 22 60 22 60 4 70 TYP MAX 5.5 33 33 200 33 200 6.5 200 UNITS V mA mA A mA A mA A dBm V/V dB dBc dBc mA mV A nA M k
2
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ADSL Drivers/Receivers for Customer Premise Equipment
ELECTRICAL CHARACTERISTICS--Driver (continued)
(V+ = 5V, GND = 0, VCM = 2.5V, RL = 12.5, SHDN = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values specified at TA = +25C.)
PARAMETER Input Common-Mode Voltage Range Common-Mode Rejection Ratio Power-Supply Rejection Ratio AC Power-Supply Rejection Ratio Differential Output-Voltage Swing (Note 4) SYMBOL VCM CMRR PSRR PSRRAC VOUT(DIFF) CONDITIONS Inferred from CMRR test 1.25V VCM 4.5V V+ = 4.5V to 5.5V f = 100kHz MAX4361 MAX4362/MAX4363 MAX4361 MAX4362/MAX4363 MAX4361 MAX4362/MAX4363 7.4 MIN 1.25 60 70 60 60 73 85 89 74 63 49 8.2 215 230 400 430 400 430 650 MAX4361 MAX4362/MAX4363, G = 1 2.0 SHDN = 0 or SHDN = V+ f = 1MHz MAX4361 MAX4362/MAX4363, G = 1 VOUT(DIFF) = 7.1VP-P step MAX4361 Settling Time (1%) Voltage-Noise Density Current-Noise Density Capacitive-Load Stability Shutdown Delay Time Enable Delay Time tSHDN tENABLE tS en in VOUT(DIFF) = 7.1VP-P step f = 100kHz to 1.1MHz f = 100kHz to 1.1MHz MAX4362/MAX4363, G=3 1.8 40 60 30 115 165 4.8 1.5 10 400 2.8 ns nV/Hz pA/Hz nF ns s 10 0.3 0.001 0.8 550 550 600 650 600 650 mA V V A k MHz V/s mV TYP MAX 4.50 UNITS V dB dB dB VP-P
MAX4361/MAX4362/MAX4363
Inferred from Output Voltage Swing test RL = 100 (V+) - VOH VOL (V+) - VOH VOL (V+) - VOH VOL
Output-Voltage Swing (Note 4)
VOH, VOL
MAX4362/MAX4363 RL = 12.5 MAX4361, RL = 12.5, TA = -20C to 85C
Output Short-Circuit Current Output Resistance SHDN Logic Low SHDN Logic High SHDN Input Current Shutdown Output Impedance -3dB Bandwidth Slew Rate
ISC ROUT VIL VIH IIH, IIL ZOUT(SD) BW SR
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ADSL Drivers/Receivers for Customer Premise Equipment MAX4361/MAX4362/MAX4363
ELECTRICAL CHARACTERISTICS--Receiver (MAX4363 only)
(V+ = 5V, GND = 0, VCM = 2.5V, RL = , SHDN = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values specified at TA = +25C.)
PARAMETER Spurious-Free Dynamic Range Gain-Bandwidth Product Open-Loop Gain Peak Output Current Input Offset Voltage Input Bias Current Input Offset Current Input Capacitance Differential Input Resistance Input Common-Mode Voltage Range Common-Mode Rejection Ratio Power-Supply Rejection Ratio AC Power-Supply Rejection Ratio SYMBOL SFDR GBW AVOL IOUT VOS IB IOS CIN RIN(DIFF) VCM CMRR PSRR PSRRAC Inferred from CMRR test 0.25V VCM 3.8V V+ = 4.5V to 5.5V f = 1MHz RL = Output-Voltage Swing VOH, VOL RL = 50 Output Short-Circuit Current Output Resistance Slew Rate Settling Time (1%) Voltage-Noise Density Current-Noise Density Driver-Receiver Crosstalk ISC ROUT SR tS en in XTALK G=1 VOUT = 1VP-P step VOUT = 100mVP-P step, G = 1 f = 1MHz f = 1MHz f = 100kHz (V+) - VOH VOL (V+) - VOH VOL 0.25 70 60 87 75 47 0.64 0.73 1.27 1.37 130 0.001 160 40 8.5 0.5 95 1 1 1.5 1.6 mA V/s ns nV/Hz pA/Hz dB V 1.5V VOUT 3.5V RL = 50, inferred from Output-Voltage Swing test 65 18 CONDITIONS G = 1, f = 1MHz, VOUT = 1VP-P MIN TYP -75 190 77 25 0.5 -0.75 20 1.6 76 3.80 10 -2 250 MAX UNITS dBc MHz dB mA mV A nA pF k V dB dB dB
Note 1: Guaranteed by the Power-Supply Rejection Ratio (PSRR) test. Note 2: Implied by worst-case output-voltage swing (VOUT(DIFF)), crest factor (Cr) and load resistance (RL): PDriver = 10log((250 (VOUT(DIFF) )^2 / ((Cr)^2 RL)) dBmW Note 3: Guaranteed by design. Note 4: May exceed absolute maximum ratings for power dissipation if unit is subject to full-scale sinusoids for long periods (see Applications Information section).
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ADSL Drivers/Receivers for Customer Premise Equipment
Typical Operating Characteristics
(V+ = 5V, GND = 0, VCM = 2.5V, RL = 12.5, SHDN = 0, TA = +25C.)
DRIVER DIFFERENTIAL DISTORTION vs. FREQUENCY
MAX4361 toc01
MAX4361/MAX4362/MAX4363
DRIVER DIFFERENTIAL DISTORTION vs. PEAK-TO-PEAK OUTPUT VOLTAGE
MAX4361 toc02
DRIVER DIFFERENTIAL DISTORTION vs. LOAD RESISTANCE
VOUT = 5VP-P f = 100kHz G=3 RL = 12.5
MAX4361 toc03
-40 DIFFERENTIAL DISTORTION (dB) -50 -60 2ND HARMONIC -70 -80 -90 -100 10k 100k FREQUENCY (Hz) 3RD HARMONIC VOUT = 7.2VP-P G=3 RL = 12.5
-40 DIFFERENTIAL DISTORTION (dBc) -50 -60 3RD HARMONIC -70 -80 -90 -100 2ND HARMONIC f = 100kHz G=3 RL = 12.59
-60 DIFFERENTIAL DISTORTION (dBc)
-70
-80
3RD HARMONIC 2ND HARMONIC
-90
-100 2 3 4 5 6 7 8 5 25 45 RLOAD () 65 85 PEAK-TO-PEAK OUTPUT VOLTAGE (V)
1M
DRIVER LINE POWER vs. TURNS RATIO
16.0 15.5 15.0 14.5 14.0 PLINE (dBm) 13.5 13.0 12.5 12.0 11.5 11.0 10.5 10.0 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 TRANSFORMER TURNS RATIO
MAX4361 toc04
DRIVER CURRENT AND VOLTAGE NOISE vs. FREQUENCY
100 INPUT CURRENT NOISE (pA/Hz)
MAX4361 toc05
DRIVER OUTPUT IMPEDANCE vs. FREQUENCY
MAX4361 toc06
100 INPUT VOLTAGE NOISE (nV/Hz)
100k 10k OUTPUT IMPEDANCE () 1k 100 10 1 0.1 SHDN = GND SHDN = VCC
V+ = 5.5V
V+ = 5V
10 VNOISE
10
V+ = 4.5V
INOISE 1 1k 10k 100k 1M FREQUENCY (Hz) 1
0.01 100k 1M 10M 100M FREQUENCY (Hz)
DRIVER GAIN AND PHASE vs. FREQUENCY
20 15 10 5 GAIN (dB) 0 -5 -10 -15 -20 -25 -30 10k 100k 1M 10M 100M 1G FREQUENCY (Hz) PHASE GAIN
MAX4361 toc07
DRIVER POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
90 60 PHASE (DEGREES) 30 0 -30 -60 -90 -120 -150 -180 0 -10 -20 PSRR (dB) -30 -40 -50 -60 -70 -80 1k 10k 100k 1M 10M 1G FREQUENCY (Hz) G=1
MAX4361 toc08
DRIVER OUTPUT SWING vs. LOAD RESISTANCE
2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 1
MAX4361 toc09
120
10
G=3 RL = 12.5
+SWING -SWING
OUTPUT SWING (V)
10
100
1k
10k
LOAD RESISTANCE ()
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ADSL Drivers/Receivers for Customer Premise Equipment MAX4361/MAX4362/MAX4363
Typical Operating Characteristics (continued)
(V+ = 5V, GND = 0, VCM = 2.5V, RL = 12.5, SHDN = 0, TA = +25C.)
RECEIVER DIFFERENTIAL DISTORTION vs. FREQUENCY
MAX4361 toc010
RECEIVER CURRENT AND VOLTAGE NOISE vs. FREQUENCY
100 INPUT CURRENT NOISE (pA/Hz)
MAX4361 toc11
RECEIVER GAIN AND PHASE vs. FREQUENCY
100 INPUT VOLTAGE NOISE (nV/Hz) 70 60 50 40 GAIN (dB) 30 20 10 0 -10 -20 PHASE GAIN
MAX4361 toc12
-40 DIFFERENTIAL DISTORTION (dB) -50 -60 2ND HARMONIC -70 -80 -90 -100 10k 100k FREQUENCY (Hz) 3RD HARMONIC VOUT = 1VP-P G=1 RL = 150
120 90 60 PHASE (DEGREES) 30 0 -30 -60 -90 -120 -150 -180
G = 1000 RL = 500
10
VNOISE
10
1
INOISE
1
0.1 1M 1k 10k 100k 1M FREQUENCY (Hz)
0.1
-30 10k 100k 1M 10M 100M 1G FREQUENCY (Hz)
RECEIVER POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
0 -10 -20 PSRR (dB) -30 -40 -50 -60 -100 -70 -80 1k 10k 100k 1M 10M 100M FREQUENCY (Hz) -120 10k G=1
MAX4361 toc13
DRIVER-TO-RECEIVER CROSSTALK vs. FREQUENCY
MAX4361 toc14
RECEIVER-TO-RECEIVER CROSSTALK vs. FREQUENCY
MAX4361 toc15
10
0 -20 CROSSTALK (dB) -40 -60 -80 RL = 12.5
0 -20 CROSSTALK (dB) -40 -60 NO LOAD -80 -100
RL = 150
NO LOAD -120 100k 1M 10M 100M 1G 10k 100k 1M 10M 100M 1G FREQUENCY (Hz) FREQUENCY (Hz)
RECEIVER OUTPUT AMPLITUDE vs. FREQUENCY
RF = 500 RF = 1k
MAX4361 toc16
4 2 0 GAIN (dB) -2 -4 -6 -8 -10 10k 100k 1M 10M 100M G = -1 RL = 150 VP-P = 100mV RF = 100
1G
FREQUENCY (Hz)
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ADSL Drivers/Receivers for Customer Premise Equipment
Pin Descriptions
MAX4361
PIN 1, 4 2 3 5 6, 7 8 NAME GND IN+ INOUTV+ OUT+ Ground First Driver Input Second Driver Input Second Driver Output Positive Power-Supply Voltage. Bypass V+ to GND with a 0.1F capacitor. First Driver Output FUNCTION
MAX4361/MAX4362/MAX4363
MAX4362
PIN MAX 1 2 3 4 5 6, 10 7 8 9 -- SO 2 3 4 5 6 9, 13 10 11 12 1, 7, 8, 14 NAME T1IN+ T1INSHDN T2INT2IN+ GND T2OUT V+ T1OUT N.C. First Driver Noninverting Input First Driver Inverting Input Shutdown. Connect to GND for normal operation. Second Driver Inverting Input Second Driver Noninverting Input Ground Second Driver Output Positive Power-Supply Voltage. Bypass V+ to GND with a 0.1F capacitor. First Driver Output No Connection. Not internally connected. FUNCTION
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ADSL Drivers/Receivers for Customer Premise Equipment MAX4361/MAX4362/MAX4363
Pin Descriptions (continued)
MAX4363
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16, 20 17 18 19 NAME T1IN+ T1INSHDN T2INT2IN+ GND R1IN+ R1INR2INR2IN+ R2OUT R1OUT GND (RX) V+ (RX) N.C. GND (TX) T2OUT V+ (TX) T1OUT First Driver Noninverting Input First Driver Inverting Input Shutdown. Connect to GND for normal operation. Second Driver Inverting Input Second Driver Noninverting Input Ground First Receiver Noninverting Input First Receiver Inverting Input Second Receiver Inverting Input Second Receiver Noninverting Input Second Receiver Output First Receiver Output Ground for Receiver Amplifiers Positive Power-Supply Voltage for Receiver Amplifiers. Bypass V+ (RX) to GND (RX) with a separate 0.1F capacitor. No Connection. Not internally connected. Ground for Driver Amplifier Second Driver Output Positive Power-Supply Voltage for Driver Amplifiers. Bypass V+ (TX) to GND (TX) with a separate 0.1F capacitor. First Driver Output FUNCTION
Detailed Description
The MAX4361/MAX4362/MAX4363 are a family of highperformance ADSL drivers and drivers/receivers ideal for the upstream transmit path and the downstream receive path of customer premise equipment. These devices operate from a single 5V supply and deliver up to 12.5dBm average line power for DMT modulated signals, meeting the requirements of full-rate ADSL. SFDR at full output power is typically -75dBc at 100kHz.
Uncommitted Dual Amplifier for ADSL Driver (MAX4362)
The MAX4362 is a dual amplifier with shutdown intended for use as a differential IN/differential OUT driver with gain set with external resistors
Uncommitted Quad Amplifier for ADSL Driver/Receiver (MAX4363)
The MAX4363 is a quad amplifier with shutdown intended for use as a differential IN/differential OUT driver/receiver combination with gain set with external resistors.
Differential In/Differential Out ADSL Driver (MAX4361)
The MAX4361 is a differential line driver with a fixed gain of 3.1V/V. The gain is set by three internal resistors.
Shutdown
The MAX4362/MAX4363 feature a low-power shutdown mode. When the SHDN pin is pulled high, the supply current drops to 70A, and the amplifier's outputs are placed in a high-impedance disable mode. Connect SHDN to GND for normal operation.
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ADSL Drivers/Receivers for Customer Premise Equipment
Applications Information
Power Supply and Decoupling
The MAX4361/MAX4362/MAX4363 should be powered from a well-regulated, low-noise, 4.5V to 5.5V supply in order to optimize the ADSL upstream drive capability to +12.5dBm and maintain the best SFDR. High-quality capacitors with low equivalent series resistance (ESR) such as multilayer ceramic capacitors (MLCCs) should be used to minimize supply voltage ripple and power dissipation. A larger capacitor located in proximity to the MAX4361/MAX4362/MAX4363 improves decoupling for lower frequency signals. In addition, 0.1F MLCC decoupling capacitors should be located as close as possible to each of the powersupply pins, no more than 1/8 inch away. An additional large (4.7F to 10F) tantalum capacitor should be placed on the board near the supply terminals to supply current for fast, large-signal changes at the MAX4361/MAX4362/MAX4363 outputs. MAX4361/MAX4362 The MAX4361/MAX4362 require a single 0.1F bypass from V+ to ground located as close as possible to the IC leads. MAX4363 The MAX4363 features separate supply and ground pins for the receiver and driver amplifiers. Bypass the V+ (RX) supply to the GND (RX) pin with a 0.1F capacitor. Bypass the V+ (TX) supply to the GND (TX) pin with a separate 0.1F capacitor. Both capacitors should be placed as close as possible to their respective IC leads.
3.1
MAX436 _
MAX4361/MAX4362/MAX4363
500
1k
OUTPUT CLOAD
INPUT
Figure 1. Driving Capacitive Load
5V
R1 2.7k VREF R2 2.7k 0.1F
Figure 2. Voltage-Divider Reference
and the load to reduce ringing on the output signal. In a typical hybrid the back-matching resistors provide sufficient isolation for most any capacitive-loading condition (see Figure 1).
Method for Generating a Midsupply Voltage
To operate an amplifier on a single-voltage supply, a voltage midway between the supply and ground must be generated to properly bias the inputs and the outputs. A voltage divider can be created with two equal-value resistors (Figure 2). There is a trade-off between the power consumed by the divider and the voltage drop across these resistors due to the positive input bias currents. Selecting 2.7k for R1 and R2 will create a voltage divider that draws less than 1mA from a 5V supply. Use a decoupling capacitor (0.1F) at the node where VREF is generated.
USB Applications
The 5V supplied at the universal serial bus (USB) port may be poorly regulated or unable to supply the peak currents required by an ADSL modem. Improving the quality of the supply will optimize the performance of the MAX4361/MAX4362/MAX4363 in a USB-supplied CPE ADSL modem. This can be accomplished through the use of a step-up DC-to-DC converter or switching power supply followed by a low-dropout (LDO) regulator. Careful attention must be paid to decoupling the power supply at the output of the DC-to-DC converter, the output of the LDO regulator and the supply pins of the MAX4361/MAX4362/MAX4363.
Power Dissipation
It is important to consider the total power dissipation of the MAX4361/MAX4362/MAX4363 in order to properly size the heat sink area of an application. With some simplifying assumptions we can estimate the total power dissipated in the driver (see Typical Operating
Driving a Capacitive Load
The MAX4361/MAX4362/MAX4363 are capable of driving capacitive loads up to 2nF. Most hybrid circuits are well under this limit. For additional capacitive-drive capability use isolation resistors between the output
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ADSL Drivers/Receivers for Customer Premise Equipment MAX4361/MAX4362/MAX4363
Circuit). If the output current is large compared to the quiescent current, computing the dissipation in the output devices and adding it to the quiescent power dissipation will give a close approximation of the total power dissipation in the package. For a 12.5dBm average line power on a 100 line, the RMS current is 13.4mA. With a one-to-four transformer the driver therefore supplies 53.6mA RMS. It can be shown for a DMT signal the ratio of RMS current to the average rectified current is 0.8. The total power consumption is approximately PCONS = 0.8 53.6 x 5V = 214mW of which 18mW is delivered as line power and 18mW is dissipated in the back-matching resistors. Hence the average power consumption of the IC is approximately 178mW + quiescent power (110mW), or 288mW. For the MAX4361 in an 8-pin MAX package, this corresponds to a temperature rise of 64C. With an ambient temperature of +85C this corresponds to a junction temperature of +148C, just below the absolute maximum of +150C. Please note the part is capable of over 200mA RMS, which could cause thermal shutdown in applications with elevated ambient temperatures and/or signals with low crest factors. See Figure 3 for a guide to power derating for each of the MAX4361/MAX4362/MAX4363 packages.
2.5 MAXIMUM POWER DISSIPATION (W) MAX4362 14-PIN SO 2.0 MAX4363 20-PIN SO MAX4363 20-PIN TSSOP
1.5
1.0
0.5
0
MAX4361 8-PIN MAX MAX4362 10-PIN MAX -40 -20 0 20 40
MAX4361 8-PIN SO 60 80
TEMPERATURE (C)
Figure 3. Maximum Power Dissipation vs. Temperature
Receive Channel Considerations
A transformer used at the output of the differential line driver to step up the differential output voltage to the line has the inverse effect on signals received from the line. A voltage reduction or attenuation equal to the inverse of the turns ratio is realized in the receive channel of a typical bridge hybrid. The turns ratio of the transformer may also be dictated by the ability of the receive circuitry to resolve low-level signals in the noisy, twisted-pair telephone plant. Higher turns-ratio transformers effectively reduce the received signal-to-noise ratio due to the reduction in the received signal strength. The MAX4363 includes an amplifier with typical voltage noise of only 8.5nV/Hz and a low-supply current of 2mA/amplifier to be used as the receive channel.
Transformer Selection
Full-rate, customer premise ADSL requires the transmission of a +12.5dBm (18mW) DMT signal. The DMT signal has a typical crest factor of 5.3, requiring the line driver to provide peak line power of 27.5dBm (560mW). The 27.5dBm peak line power translates into a 28.4V peak-to-peak differential voltage on the 100 telephone line. The maximum low-distortion output swing available from the MAX4361/MAX4362/MAX4363 line driver on a 5V supply is 3.8V and, taking into account the power lost due to the back-matching resistance, a step-up transformer with turns ratio of 3.8 or greater is needed. In the Typical Operating Circuit, the MAX4363 is coupled to the phone line through a step-up transformer with a 1:4 turns ratio. R1 and R2 are back-matching resistors, each 3.1 (100 / (2 42)), where 100 is the approximate phone-line impedance. The total differential load for the MAX4361/MAX4362/MAX4363, including the termination resistors, is therefore 12.5. Even under these conditions the MAX4361/MAX4362/ MAX4363 provide low distortion signals to within 0.6V of the power rails.
Layout Considerations
Good layout techniques optimize performance by decreasing the amount of stray capacitance at the amplifier's inputs and outputs. Excess capacitance will produce peaking in the amplifier's frequency response. To decrease stray capacitance, minimize trace lengths by placing external components as close to the amplifier as possible.
Chip Information
MAX4361 TRANSISTOR COUNT: 1400 MAX4362 TRANSISTOR COUNT: 1400 MAX4363 TRANSISTOR COUNT: 1750 PROCESS: Bipolar
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ADSL Drivers/Receivers for Customer Premise Equipment
Typical Operating Circuit
5V 0.1F 1k 2.7k 1k 0.1F 2.7k 10k VCC 0.047F 3.125 IN1+ IN10.047F 10k 1k IN2IN2+ OUTDRIVER 3.125 OUT+ LINE IMPEDANCE 100 1:4 TRANSFORMER 1k 1k 500 IN1IN1+ IN2+ OUT- RECEIVER IN25V 500
MAX4361/MAX4362/MAX4363
5V
ADSL CHIPSET MAX4363 5V OUT+
10k GND 1k 1k 0.1F 10k
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ADSL Drivers/Receivers for Customer Premise Equipment MAX4361/MAX4362/MAX4363
Package Information
8LUMAXD.EPS
12
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10LUMAX.EPS
ADSL Drivers/Receivers for Customer Premise Equipment
Package Information (continued)
SOICN.EPS
MAX4361/MAX4362/MAX4363
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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