19-1700; Rev 1; 6/05 KIT ATION EVALU E L B AVAILA Upstream CATV Amplifier The MAX3509 is a programmable power amplifier for use in CATV upstream applications. The device outputs up to 66dBmV QPSK through a 1:1 transformer. It features variable gain controlled by a 3-wire digital serial bus. Gain control is available in 1dB steps. The device operates over a 5MHz to 65MHz frequency range. The MAX3509 offers a transmit-disable mode, which places the device in a high-isolation state for use between bursts in TDMA systems. In this mode, all analog functions are shut down, minimizing output noise and power consumption. When entering and leaving transmit-disable mode, transients are kept to 25mV nominal at full gain. In addition, supply current is reduced to 7.8mA. An additional power-down mode is available. Shutdown mode disables all circuitry and reduces current consumption to less than 1µA. The MAX3509 is available in a 20-pin TSSOP-EP package for the extended-industrial temperature range (-40°C to +85°C). Applications Telephony-Over-Cable OPENCATV Set-Top Boxes CATV Status Monitors CATV Infrastructures Features ♦ Ultra-Low Power-Up/Down Transients, 25mV (typ) at 66dBmV Output ♦ Single-Supply Operation ♦ Output Level Ranges from <12dBmV to 67dBmV (QPSK) ♦ Gain Programmable in 1dB Steps ♦ Low Transmit Output Noise Floor: -41dBmV (160kHz BW) ♦ Low Transmit-Disable Output Noise: -70dBmV ♦ Shutdown Mode Ordering Information PART TEMP RANGE PINPACKAGE MAX3509EUP -40°C to +85°C 20 TSSOP-EP* MAX3509EUP+ -40°C to +85°C 20 TSSOP-EP* *EP = Exposed paddle. +Denotes lead-free package. Cable Modems Pin Configuration Typical Operating Circuit 3 IN ANTI-ALIAS FILTER +9V 0.1µF 4 1000pF 1000pF +9V 0.1µF LOGIC INPUTS *EXPOSED PADDLE 5 6 8 7 2 1 20 19 18 VCC2 17 VCC1 TOP VIEW +9V 0.1µF GND1 MAX3509 IN+ IN- VCC1 GND1 SHDN TXEN SCLK SDA CS OUT+ OUT- 4700pF 16 OUT VCC2 14 20 SCLK SHDN 2 19 SDA VCC1 3 18 CS GND1 4 T1 1:1 4700pF 15 TXEN 1 IN+ 5 +9V 0.1µF GND2 * 9 GND 10 GND 11 GND 12 GND 13 GND 17 VCC2 MAX3509 16 OUT+ IN- 6 15 OUT- GND1 7 14 VCC2 VCC1 8 13 GND GND 9 12 GND GND 10 EXPOSED PADDLE 11 GND TSSOP-EP †Covered by U.S. Patent numbers 5,748,027 and 5,994,955. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX3509† General Description MAX3509 Upstream CATV Amplifier ABSOLUTE MAXIMUM RATINGS VCC1, VCC2 to GND, GND1 .................................-0.3V to +10.0V SCLK, SDA, CS, TXEN, SHDN to GND and GND1 .........................................................-0.3V to +5.5V Continuous Input Voltage (IN+, IN-)....................................2VP-P Continuous Current (OUT+, OUT-) .....................................80mA Continuous Power Dissipation (TA = +70°C) 20-Pin TSSOP-EP (derate at 27mW/°C above +70°C)........................................................................2200mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 (VCC1 = VCC2 = 8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, TA = -40°C to +85°C, unless otherwise noted. No input signal applied. Typical parameters are at TA = +25°C.) (Note 2.) PARAMETER SYMBOL CONDITIONS Supply Voltage VCC Supply Current Transmit Mode ICC Supply Current Transmit-Disable Mode ICC TXEN = low or D7 = 0 Supply Current Shutdown Mode ICC SHDN = low, TXEN = low Input High Voltage VINH MIN TYP 8.5 MAX UNITS 9.5 V 84 115 mA 7.8 10 mA 10 µA 2.0 V Input Low Voltage VINL 0.8 V Input High Current IBIASH 100 µA Input Low Current IBIASL -100 µA AC ELECTRICAL CHARACTERISTICS (MAX3509 EV kit, VCC1 = VCC2 = 8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, VINPUT = 34dBmV differential, output impedance = 75Ω through a 1:1 transformer, TA = -40°C to +85°C, unless otherwise noted. Typical parameters are at TA = +25°C.) (Note 2.) PARAMETER SYMBOL CONDITIONS TA = +25°C, fINPUT = 42MHz, gain-control word = 63 MIN TYP AV TA = +25°C, fINPUT = 42MHz, gain-control word = 50 -22 22.8 24.2 fINPUT = 42MHz, gain-control word = 63 Gain Fariness (note 1) Gain Step Size 2 26.7 dB 31 fINPUT = 42MHz, gain-control word = 0 -21 fINPUT = 42MHz, gain-control word = 50 21.3 24.2 26.7 VOUTPUT = 60dBmV, fINPUT = 5MHz to 42MHz 0.1 0.4 VOUTPUT = 60dBmV, fINPUT = 5MHz to 65MHz 0.3 0.9 1 1.3 fINPUT = 5MHz to 65MHz, AV = -20dB to +33dB UNITS 33 TA = +25°C, fINPUT = 42MHz, gain-control word = 0 Voltage Gain MAX 0.7 _______________________________________________________________________________________ dB dB dB Upstream CATV Amplifier (MAX3509 EV kit, VCC1 = VCC2 = 8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, VINPUT = 34dBmV differential, output impedance = 75Ω through a 1:1 transformer, TA = -40°C to +85°C, unless otherwise noted. Typical parameters are at TA = +25°C.) (Note 2.) PARAMETER SYMBOL CONDITIONS MIN TYP BW = 160kHz, AV = 32dB BW = 160kHz, AV = -20dB, TA = +25°C Transmit Mode Noise (Note 1) -41 BW = 160kHz, AV = -20dB, TA = +85°C MAX UNITS -85 dBc -39.5 -38.5 dBmV Transmit-Disable Mode Noise Floor TXEN = low, BW = 160kHz, AV = +32dB, fINPUT = 5MHz to 65MHz (Note 1) TXEN Enable Transient Duration TXEN rise time <0.1µs, TA = +25°C (Note 1) TXEN Disable Transient Duration TXEN fall time <0.1µs, TA = +25°C (Note 1) TXEN Transient Step Size (Note 1) AV = 32dB, TA = +25°C AV = 2dB or lower, TA = +25°C 1.5 9 fINPUT = 5MHz to 65MHz, single-ended, TA = +25°C (Note 1) 1.2 kΩ ZINPUT Input Impedance -70 dBmV 2 µs 1 1.5 µs 25 100 1.4 mVP-P Output Impedance in Transmit Mode ZOUTPUT fINPUT = 5MHz to 65MHz, TA = +25°C (Note 1) 1.2 Ω Output Impedance in Transmit-Disable Mode TXEN = low, fINPUT = 5MHz to 65MHz, ZOUTPUT T = +25°C (Note 1) A 170 Ω -53 dBc Two-Tone Third-Order Distortion IM3 Input tones at 65MHz and 65.2MHz, VINPUT = 31dBmV/tone, AV = 32dB (Note 1) fINPUT = 33MHz 2nd Harmonic Distortion HD2 fINPUT = 65MHz (Note 1) fINPUT = 22MHz 3rd Harmonic Distortion HD3 fINPUT = 65MHz (Note 1) Output 1dB Compression Point P1dB VOUTPUT = +60dBmV -56 -53 VOUTPUT = +66dBmV -56 -50 VOUTPUT = 66dBmV -56 -50 VOUTPUT = +60dBmV -56 -53 VOUTPUT = +66dBmV -53 -48.5 VOUTPUT = 66dBmV -43 -40 dBc dBc AV = 32dB, 65MHz (Note 1) 26 dBm 0.1 dB 1.7 degrees AM to AM AM/AM AV = 32dB, VINPUT swept from 34dBmV to 38dBmV (Note 1) AM to PM AM/PM AV = 32dB, VINPUT swept from 34dBmV to 38dBmV (Note 1) _______________________________________________________________________________________ 3 MAX3509 AC ELECTRICAL CHARACTERISTICS (continued) TIMING CHARACTERISTICS (VCC1 = VCC2 = 8.5V to 9.5V, TXEN = SHDN = high, D7 = 1, TA = +25°C, unless otherwise noted.) (Note 1.) PARAMETER SYMBOL COMMENT MIN TYP MAX UNITS CS to SCK Rise Setup Time tSENS 10 ns CS to SCK Rise Hold Time tSENH 20 ns SDA to SCK Setup Time tSDAS 10 ns SDA to SCK Hold Time tSDAH 20 ns SDA Pulse-Width High tDATAH 50 ns SDA Pulse-Width Low tDATAL 50 ns SCK Pulse-Width High tSCKH 50 ns SCK Pulse-Width Low tSCKL 50 ns Note 1: Guaranteed by design and characterization. Note 2: Tested parameters specified from -40°C to +85°C are guaranteed by design and characterization to ±3 sigma for temperatures less than 25°C. Typical Operating Characteristics (MAX3509 EV kit, VCC1 = VCC2 = +9V, VIN = +34dBmV, TXEN = SHDN = high, D7 = 1, fINPUT = 10MHz, ZLOAD = 75Ω through a 1:1 transformer, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. TEMPERATURE TRANSMIT ENABLE 85 80 75 8.0 7.5 7.0 130 70 6.5 65 -40 -15 10 35 85 TA = +85°C 110 TA = +25°C TA = -40°C 100 90 70 -40 -15 10 35 60 85 30 36 42 48 54 60 66 TEMPERATURE (°C) TEMPERATURE (°C) OUTPUT POWER (dBmV) VOLTAGE GAIN vs. SUPPLY VOLTAGE (CONTROL WORD = 25) VOLTAGE GAIN vs. SUPPLY VOLTAGE (CONTROL WORD = 50) VOLTAGE GAIN vs. TEMPERATURE (CONTROL WORD = 25) 0.28 0.26 TA = -40°C 0.24 24.8 24.6 24.4 TA = +25°C TA = +25°C 0.22 24.2 0.20 24.0 8.5V 0.4 72 MAX3509-06 TA = +85°C 0.3 VOLTAGE GAIN (dB) 25.0 VOLTAGE GAIN (dB) TA = +85°C 0.5 MAX3509-05 25.2 MAX3509-04 0.32 0.30 60 120 80 6.0 60 MAX3509-03 8.5 SUPPLY CURRENT (mA) 90 140 MAX3509-02 9.0 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 95 SUPPLY CURRENT vs. OUTPUT POWER SUPPLY CURRENT vs. TEMPERATURE TRANSMIT DISABLE MAX3509-01 100 VOLTAGE GAIN (dB) MAX3509 Upstream CATV Amplifier 0.2 0.1 9.5V 9.0V 0 -0.1 -0.2 -0.3 TA = -40°C -0.4 4 -0.5 8.5 8.6 8.7 8.8 8.9 9.0 9.1 9.2 9.3 9.4 9.5 8.5 8.6 8.7 8.8 8.9 9.0 9.1 9.2 9.3 9.4 9.5 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) -40 -15 10 35 TEMPERATURE (°C) _______________________________________________________________________________________ 60 85 Upstream CATV Amplifier E -10 F G -20 5 60MHz 0 1.0 0.8 -20 -30 10 100 0.7 0 500 MAX3509-09 1.1 0.9 10 20 30 40 50 60 0 10 20 30 40 50 60 FREQUENCY (MHz) CONTROL WORD (DECIMAL) CONTROL WORD (DECIMAL) TRANSMIT OUTPUT NOISE vs. GAIN POWER-UP/DOWN TRANSIENTS vs. CONTROL WORD 2ND HARMONIC DISTORTION vs. INPUT FREQUENCY -24 TRANSIENT LEVEL (mVp-p) -26 -28 -30 -32 -34 -36 -38 10 -58 MAX3509-12 -22 2ND HARMONIC DISTORTION (dBc) 100 MAX3509-10 -20 MAX3509-11 -50 10 -10 GAIN-CONTROL WORD A = 63, B = 57, C = 48, D = 36, E = 24, F = 12, G=6 -40 20 GAIN STEP (dB) VOLTAGE GAIN (dB) VOLTAGE GAIN (dB) D 0 1.2 10MHz 20 -30 OUTPUT NOISE (dBmV IN 160kHz) 30 C 10 1.3 MAX3509-08 A B 30 40 MAX3509-07 50 40 GAIN STEP vs. CONTROL WORD VOLTAGE GAIN vs. CONTROL WORD VOLTAGE GAIN vs. FREQUENCY 66dBmV -62 60dBmV -66 -70 -40 -14 -4 6 16 26 36 10 20 30 50 40 60 0 70 CONTROL WORD 2ND HARMONIC DISTORTION vs. INPUT FREQUENCY 3RD HARMONIC DISTORTION vs. INPUT FREQUENCY AND OUTPUT POWER 10dBmV -60 30dBmV -65 -70 -75 -80 10 20 30 40 50 FREQUENCY (MHz) 60 70 MAX3509-14 66dBmV -45 -50 10 20 30 40 50 60 70 FREQUENCY (MHz) -40 3RD HARMONIC DISTORTION (dBc) MAX3509-13 -55 0 0 GAIN (dB) -50 2ND HARMONIC DISTORTION (dBc) -74 1 -24 60dBmV QPSK OUTPUT SPECTRUM -10 -20 -30 MAX3509-15 -42 VOUT = 66dBmV 1280ksps α = 0.25 -40 -55 -50 -60 30dBmV -60 -65 -70 -70 10dBmV -75 -80 -80 -90 -85 -100 -90 -110 0 10 20 30 40 50 60 70 SPAN 5MHz CENTER 22MHz 500kHz/div FREQUENCY (MHz) ____________________________________________________________________________________ 5 MAX3509 Typical Operating Characteristics (continued) (MAX3509 EV kit, VCC1 = VCC2 = +9V, VIN = +34dBmV, TXEN = SHDN = high, D7 = 1, fINPUT = 10MHz, ZLOAD = 75Ω through a 1:1 transformer, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (MAX3509 EV kit, VCC1 = VCC2 = +9V, VIN = +34dBmV, TXEN = SHDN = high, D7 = 1, fINPUT = 10MHz, ZLOAD = 75Ω through a 1:1 transformer, TA = +25°C, unless otherwise noted.) -30 -40 VOUT = 66dBmV 160ksps α = 0.25 -30 -50 -50 -60 -60 -70 -70 -80 -80 -90 -90 -100 -100 -110 -110 -120 -120 SPAN 1MHz CENTER 22MHz VOUT = 66dBmV 1280ksps α = 0.25 -40 MAX3509-17 OUTPUT SPECTRUM QPSK OUTPUT SPECTRUM -20 MAX3509-16 MAX3509 Upstream CATV Amplifier STOP 70MHz START 15MHz -130 5.5MHz/div 100kHz/div Pin Description PIN NAME FUNCTION 1 TXEN Transmit Enable. To disable the MAX3509 and provide high input/output isolation, drive TXEN low. Drive TXEN high for normal operation. 2 SHDN Shutdown. To enable low-power shutdown, drive SHDN low. Drive SHDN high for normal operation. 3, 8 VCC1 Programmable-Gain Amplifier (PGA) +9V Supply. Bypass to GND1 with a 0.1µF decoupling capacitor as close to the part as possible. 4, 7 GND1 PGA Ground. Connect to ground with a low inductance path. 5 IN+ Noninverting PGA Input. Along with IN-, this port forms a high-impedance differential input to the PGA. Driving this port differentially increases the rejection of second-order distortion at low output levels. Inverted PGA Input. When not used, AC-coupled to ground. See IN+. 6 IN- 9–13 GND Ground 14,17 VCC2 Power Amplifier Bias +9V Supply. Bypass to GND2 (exposed paddle) with a 0.1µF decoupling capacitor as close to the part as possible. 15 OUT- Inverted Output. AC-couple to output transformer. Used in conjunction with OUT+. 16 OUT+ Noninverted Output. See OUT-. 18 CS Serial-Interface Enable. TTL-compatible input. See the Serial Interface section. 19 SDA Serial-Interface Data. TTL-compatible input. See the Serial Interface section. 20 SCLK Serial-Interface Clock. TTL-compatible input. See the Serial Interface section. Exposed Paddle GND2 Power Amplifier Bias Ground. Connect to ground with a low inductance path. Ensure a low thermal resistive path to PC board. See Layout Issues. 6 _______________________________________________________________________________________ Upstream CATV Amplifier MAX3509 SHDN TXEN VCC1 PGA BIAS PA BIAS VCC2 IN+ OUT+ IN- OUT- DAC MAX3509 SERIAL DATA INTERFACE CS SDA SCLK Figure 1. MAX3509 Functional Diagram Detailed Description The following sections describe the blocks shown in the functional diagram (Figure 1). Programmable-Gain Amplifier The PGA consists of the variable-gain amplifier (VGA) and the digital-to-analog converter (DAC), which provide better than 55dB of output level control in 1dB steps. The PGA is implemented as a programmable Gilbertcell attenuator. It uses a differential architecture to achieve maximum linearity. The gain of the PGA is determined by a 6-bit word (D5–D0) programmed through the serial data interface (Tables 1 and 2). Specified performance is achieved when the input is driven differentially. The device may be driven single ended; however, a slight increase in even-order distortion may result at low output levels. To drive the device in this manner, one of the input pins must be capacitively coupled to ground. Use a capacitor value large enough to allow for a low-impedance path to ground at the lowest frequency of operation. Power Amplifier The power amplifier has two current-feedback amplifiers in an instrumentation amplifier configuration. This architecture provides superior even-order distortion performance but requires an external transformer to convert to a single-ended output. In transmit-disable mode, bias to the power amplifier is reduced to a minimal level, which provides high input to output isolation and low output noise. Serial Interface The serial interface has an active-low enable (CS) to bracket the data, with data clocked in MSB first on the rising edge of SCLK. Data is stored in the storage latch on the rising edge of CS. The serial interface controls the state of the PGA. Tables 1 and 2 show the register format. Serial-interface timing is shown in Figure 2. PGA Bias Cell The bias cell in the MAX3509 is controlled by the logic levels present at TXEN and SHDN, as well as the program state of D7, the MSB of the 8-bit program word. Transmit-disable mode is actuated when the TXEN pin is driven to a logic low or when D7 = 0. In this mode, current to the PGA and power amps is reduced significantly while maintaining normal current flow to the serial data interface and DAC. This preserves the program stored in the serial data interface. A logic low at the SHDN pin overrides the state of the TXEN pin or D7. In shutdown mode, the current to the PGA, power amp, serial data interface, and DAC is cut off, allowing only leakage currents to flow. The stored gain control program is lost in this mode. _______________________________________________________________________________________ 7 MAX3509 Upstream CATV Amplifier Power Amp Bias Cell G A The power amp bias cell is used to enable and disable bias to the output power amplifier. This is controlled by TXEN and SHDN. C B D E F Functional Modes The MAX3509 has three functional modes controlled through the serial interface or external pins (Table 2): transmit mode, transmit-disable mode, and shutdown. Transmit Mode Transmit mode is the normal active mode of the MAX3509. Drive TXEN and SHDN high, and set D7 = 1 to activate transmit mode. D7 D6 D5 D4 D2 D1 D0 E. tSCKH F. tSENH G. tDATAH/tDATAL A. tSENS B. tSDAS C. tSDAH D. tSCKL Transmit-Disable Mode When in transmit-disable mode, all analog circuitry is shut down. This mode is activated by driving TXEN low or setting D7 = 1 while keeping SHDN high. This mode is typically used between bursts in TDMA systems. Transients are controlled by the transformer balance. D3 Figure 2. Serial-Interface Timing Diagram Table 1. Serial-Interface Control Word Shutdown Mode In normal operation, the shutdown pin (SHDN) is held high. When SHDN is driven low, all circuits within the IC are disabled. Only leakage currents flow in this mode. Data stored within the serial-data interface latches will be lost upon entering this mode. Current draw is reduced to 1µA (typ) in shutdown mode. BIT MNEMONIC MSB 7 D7 Transmit Disable DESCRIPTION 6 D6 Not used 5 D5 Gain Control, Bit 5 4 D4 Gain Control, Bit 4 3 D3 Gain Control, Bit 3 2 D2 Gain Control, Bit 2 1 D1 Gain Control, Bit 1 LSB 0 D0 Gain Control, Bit 0 Table 2. Truth Table SHDN TXEN D7 D6 D5 D4 D3 D2 D1 D0 GAIN CONTROL WORD 0 X X X X X X X X X X Shutdown Mode 1 0 X X X X X X X X X Transmit-Disable Mode 1 X 0 X X X X X X X X Transmit-Disable Mode 1 1 1 X X X X X X X X Transmit Mode 1 1 1 X 0 0 0 0 0 0 0 Gain = -25dB* 1 1 1 X 0 0 0 0 0 1 1 Gain = -24dB* 1 1 1 X — — — — — — — 1 1 1 X 0 1 1 0 0 1 25 1 1 1 X — — — — — — — — 1 1 1 X 1 1 1 1 1 0 62 Gain = 35dB* 1 1 1 X 1 1 1 1 1 1 63 Gain = 36dB* STATE — Gain = 0dB* *Typical gain at +25°C and VCC = +9V. 8 _______________________________________________________________________________________ Upstream CATV Amplifier Transformer To maintain rated performance into a 75Ω load, a 1:1 impedance ratio output transformer with adequate bandwidth is required. A step-up transformer with a 1:1.5 impedance ratio will increase gain and output voltage swing nominally by 1.7dB, but output noise performance will increase by the same amount. Input Circuit To achieve rated performance, the input of the MAX3509 must be driven differentially with 34dBmV or lower input level. The MAX3509 can be driven from a single-ended source. A slight degradation in evenorder distortion at a 10W output level will result. The differential input impedance is approximately 1.2kΩ. Most applications require a differential lowpass filter preceding the MAX3509. The filter design dictates a terminating resistance of a specified value. Place this resistance across the AC-coupled inputs (see Typical Operating Circuit). The MAX3509 has sufficient gain to produce an output level of 66dBmV when driven with a 34dBmV input signal. Rated performance is achieved with this input level. When a lower input level is present, the maximum output level will be reduced proportionally and output linearity will improve. If an input level greater than 34dBmV is used, distortion performance degrades. If a single-ended source drives the MAX3509, one of the input terminals must be capacitively coupled to ground (IN+ or IN-). The value of this capacitor must be large enough to look like a short circuit at the lowest frequency of interest. For operation at 5MHz with a 50Ω source impedance, a value of 0.1µF will suffice. A typical model for the MAX3509 input impedance is shown in Figure 3. Layout Issues A well-designed PC board is an essential part of an RF circuit. For best performance, pay attention to powersupply layout issues, as well as the output circuit layout. It is recommended that the EP be soldered to a ground plane on the PC board, either directly or through an array of plated via holes. Output Circuit Layout The differential implementation of the MAX3509’s output has the benefit of reducing even-order distortion, the most significant of which is second-harmonic distortion. The degree of distortion cancellation depends on the amplitude and phase balance of the overall circuit. It is important that the traces that lead from the output pins be the same length. Power-Supply Layout To achieve minimal coupling between different sections of the IC, the ideal power-supply layout is a star configuration. This configuration has a large-value decoupling capacitor at the central power-supply node. The powersupply traces branch out from this node, each going to a separate power-supply node in the MAX3509 circuit. At the end of each of these traces is a decoupling capacitor that provides a very low impedance at the frequency of interest. This arrangement provides local power-supply decoupling at each power-supply pin. The power-supply traces must be made as thick as practical to keep resistance well below 1Ω. Ground inductance degrades distortion performance. Therefore, ground plane connections to GND, GND1, and GND2 should be made with multiple vias if possible. IN+ 2.5kΩ 1.9pF IN- Figure 3. Typical Equivalent Input Circuit Exposed Paddle Thermal Considerations The exposed paddle (EP) of the MAX3509’s 20-pin TSSOP-EP package provides a low thermal resistance path to the die. It is important that the PC board on which the MAX3509 is mounted be designed to conduct heat from this contact. In addition, the EP should be provided with a low inductance path to electrical ground. Chip Information TRANSISTOR COUNT: 1085 _______________________________________________________________________________________________________ 9 MAX3509 Applications Information Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) TSSOP4.40mm.EPS MAX3510 Upstream CATV Amplifier PACKAGE OUTLINE, TSSOP 4.40mm BODY 21-0066 G 1 1 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. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.