19-4700; Rev 0; 7/09 Receiver for Optical Distance Measurement Features The MAX3806 is a high-gain linear preamplifier for distance measurement applications using a laser beam. ♦ +5V Supply Voltage ♦ Linearity Range Up to 40µAP The device operates from a single +5.0V supply and converts current from an AC-coupled photodiode into a single-ended voltage signal. The input accepts single pulses or bursts of pulses with widths down to 30ns. The amplifier remains linear with input amplitudes from 42nAP (SNR = 3) to 40µAP. It can also withstand overload signals as large as 2mAP. The output stage is designed to drive a high-impedance load to deliver the output-voltage swing at the lowest possible power dissipation. The gain of the preamplifier stage is selected using the GAIN pin to be 60kΩ or 30kΩ. There is also an internal 14dB attenuator that is selected using the ATT pin. The output stage can be disabled (high impedance). The device is available in a 3mm x 3mm, 12-pin TQFN package and operates over the -40°C to +105°C temperature range. ♦ Overload Current Up to 2mAP ♦ 50mW Power Dissipation at +5.0V √Hz Noise Density at 60kΩ Gain ♦ 1.5pA/√ ♦ 14nARMS Input-Referred Noise at 60kΩ Gain ♦ Selectable Gains (60kΩ, 30kΩ) ♦ Selectable 14dB Attenuation Ordering Information PART TEMP RANGE PINPACKAGE MAX3806GTC+ -40°C to +105°C 12 TQFN-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Applications TOP MARK ABN Pin Configuration appears at end of data sheet. LIDAR Sensors for Automotive Applications (ACC, Stop&Go) Laser Sensors for Portable Distance Measurement Laser Sensors for Industrial Applications Typical Application Circuits +5V +5V TO +12V SUPPLY FILTER SUPPLY FILTER VCC SINGLE-CHANNEL RECEIVER 0.01μF PIN 0.01μF MAX3806 IN OUT MAX1446 BUFF LINEAR LIDAR Rx C* ADC 0.01μF L* GAIN DIS ATT GND +5V * L AND C SET THE LOW-FREQUENCY CUTOFF REQUIRED FOR THE APPLICATION. Typical Application Circuits continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX3806 General Description MAX3806 Receiver for Optical Distance Measurement ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70°C) 12-Pin TQFN-EP (derate 16.7mW/°C above +70°C)...1333mW Storage Temperature Range .............................-55°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Supply Voltage Range, VCC........................................-0.5V to +6.0V Voltage Range at ATT, DIS, GAIN ................-0.5V to (VCC + 0.5V) Current Range at IN, OUT ...........................................-4mA to +4mA 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 (VCC = +4.5V to +5.5V, AC-coupled (C = 0.01µF) output load ≥ 2kΩ, TA = -40°C to +105°C. Typical values are at VCC = +5V, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL TYP MAX UNITS (Note 2) 10 15 mA Input-Referred Noise CIN = 5pF, GAIN = 1 Output noise up to 100MHz/(gain at 5MHz) CIN = 5pF, GAIN = 0 14 20 21 27 Output noise centered at 5MHz over 100Hz band/(gain at 5MHz) CIN = 5pF, GAIN = 1 1.5 1.8 Input-Referred Noise Density CIN = 5pF, GAIN = 0 1.7 2.3 Power-Supply Current ICC CONDITIONS MIN INPUT SPECIFICATIONS Input Impedance nARMS pA/Hz At 1MHz, GAIN = 1 800 At 1MHz, GAIN = 0 300 CMOS/TTL INPUT SPECIFICATIONS Input High Voltage VIH 2 VCC V Input Low Voltage VIL 0 0.8 V Input Current Input Impedance I IH, I IL I IH RPULLUP DIS input ±150 GAIN and ATT inputs -180 DIS input 60 RPULLDOWN GAIN and ATT inputs 40 μA k GENERAL SPECIFICATIONS I IN 15μAP, GAIN = 1 44 60 77 I IN 50μAP, GAIN = 0 23 30 37 GAIN = 1, ATT = 0 25 49 GAIN = 0, ATT = 0 55 98 Gain Peaking 5pF C IN 15pF Attenuation Stability ATT = 1; 20log(VOUT_ATT_ON/VOUT_ATT_OFF) -13 -14 Small-Signal Transimpedance Small-Signal Bandwidth f3dB CIN = 5pF k MHz 1 dB -15 dB OUTPUT SPECIFICATIONS Total Harmonic Distortion Power-Supply Noise Rejection (Note 3) 2 THD PSNR Frequency = 1MHz, VOUT = 0.5VP GAIN = 1 -54 GAIN = 0 -53 Frequency = 10MHz, VOUT = 0.5VP GAIN = 1 -38 GAIN = 0 -47 Noise frequency < 1MHz GAIN = 1 -16 GAIN = 0 -23 _______________________________________________________________________________________ dB dB Receiver for Optical Distance Measurement (VCC = +4.5V to +5.5V, AC-coupled (C = 0.01µF) output load ≥ 2kΩ, TA = -40°C to +105°C. Typical values are at VCC = +5V, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS Frequency < 5MHz, 20log(VOUT_DISABLED/ VOUT_ENABLED) Attenuation in Disable Mode Output Impedance MIN TYP ATT = 0 -71 ATT = 1 -57 MAX UNITS dB At 1MHz, DIS = 0, ATT = 0, GAIN = 0 or 1 51 At 1MHz, DIS = 0, ATT = 1, GAIN = 0 or 1 114 At 1MHz, DIS = 1, ATT = 0 or 1, GAIN = 0 or 1 9 k Note 1: AC specifications are guaranteed by design and characterization. Note 2: Supply current is measured with OUT unterminated or AC-coupled. Note 3: Measured by applying 100mVP-P sinusoidal noise to the supply voltage. PSNR is defined as 20log(VOUT_NOISE/VCC_NOISE). Typical Operating Characteristics (Typical values are at VCC = +5V, TA = +25°C, CIN = 5pF, ATT = 0, unless otherwise noted.) OUTPUT VOLTAGE vs. INPUT CURRENT 12 10 DIS = 1 8 6 1 GAIN = 0, ATT = 0 0.1 GAIN = 1, ATT = 1 0.01 4 -40 -15 10 35 60 TEMPERATURE (NC) 85 110 0.1 1 10 INPUT CURRENT (µAP) GAIN = 0, ATT = 0 90 85 GAIN = 1, ATT = 1 80 GAIN = 0, ATT = 1 75 65 0.001 0 GAIN = 1, ATT = 0 95 70 GAIN = 0, ATT = 1 2 100 MAX3806 toc03 GAIN = 1, ATT = 0 OUTPUT VOLTAGE (VP) DIS = 0 FREQUENCY RESPONSE 105 MAX3806 toc02 MAX3806 toc01 14 SUPPLY CURRENT (mA) 10 TRANSIMPEDANCE (dBI) SUPPLY CURRENT vs. TEMPERATURE 16 100 1000 60 0.1 1 10 100 FREQUENCY (MHz) _______________________________________________________________________________________ 3 MAX3806 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (Typical values are at VCC = +5V, TA = +25°C, CIN = 5pF, ATT = 0, unless otherwise noted.) 30 20 TA = +105 NC 10 30 20 7 9 11 13 15 MAX3806 toc06 MAX3806 toc05 0.8 0.6 GAIN = 0 0.4 VCC = +4.5V 0.2 GAIN = 1 0 0 5 5 7 9 11 13 5 15 7 9 11 INPUT CAPACITANCE (pF) INPUT CAPACITANCE (pF) BANDWIDTH vs. INPUT CAPACITANCE (GAIN = 0) BANDWIDTH vs. INPUT CAPACITANCE (GAIN = 0) POWER-SUPPLY NOISE REJECTION (SUPPLY NOISE = 100mVP-P) TA = +105NC 60 40 20 GAIN = 0, ATT = 0 -10 60 -20 7 9 11 13 40 15 -40 VCC = +4.5V GAIN = 0, ATT = 1 -50 -60 5 7 9 11 13 10k 15 100k 10M 1M FREQUENCY (Hz) INPUT-REFERRED NOISE vs. INPUT CAPACITANCE INPUT-REFERRED NOISE vs. INPUT CAPACITANCE OUTPUT-REFERRED NOISE vs. INPUT CAPACITANCE 15 14 TA = +105NC TA = -40NC 13 12 TA = +25NC 11 10 16 TA = +25NC GAIN = 1 BW = 100MHz 15 VCC = +5.5V 14 13 VCC = +5.0V 12 VCC = +4.5V 11 9 11 INPUT CAPACITANCE (pF) 13 15 TA = +25NC 950 GAIN = 1 BW = 100MHz 900 VCC = +5.5V 850 VCC = +5.0V 800 750 VCC = +4.5V 700 650 600 10 7 1000 OUTPUT-REFERRED NOISE (µVRMS) GAIN = 1 BW = 100MHz INPUT-REFERRED NOISE (nARMS) VCC = +5V MAX3806 toc11 INPUT CAPACITANCE (pF) MAX3806 toc10 INPUT CAPACITANCE (pF) 16 5 GAIN = 1, ATT = 1 -30 0 5 GAIN = 1, ATT = 0 0 VCC = +5.0V 80 20 0 10 PSNR (dB) 80 VCC = +5.5V 100 BANDWIDTH (MHz) TA = +25NC TA = +25NC MAX3806 toc08 TA = -40NC 100 120 MAX3806 toc07 VCC = +5V 15 13 INPUT CAPACITANCE (pF) 120 BANDWIDTH (MHz) 40 10 0 4 VCC = +5.0V MAX3806 toc09 40 1.0 GAIN PEAKING (dB) TA = +25 NC TA = +25NC VCC = +5.5V 50 BANDWIDTH (MHz) BANDWIDTH (MHz) VCC = +5.0V TA = -40 NC 50 60 MAX3806 toc04 60 GAIN PEAKING vs. INPUT CAPACITANCE BANDWIDTH vs. INPUT CAPACITANCE (GAIN = 1) MAX3806 toc12 BANDWIDTH vs. INPUT CAPACITANCE (GAIN = 1) INPUT-REFERRED NOISE (nARMS) MAX3806 Receiver for Optical Distance Measurement 5 7 9 11 INPUT CAPACITANCE (pF) 13 15 5 7 9 11 INPUT CAPACITANCE (pF) _______________________________________________________________________________________ 13 15 Receiver for Optical Distance Measurement TA = +25NC 22 21 20 TA = -40NC 19 25 GAIN = 0 BW = 100MHz VCC = +5.5V 24 23 VCC = +5.0V 22 21 VCC = +4.5V 20 700 TA = +25NC OUTPUT-REFERRED NOISE (µVRMS) 23 TA = +25NC OUTPUT-REFERRED NOISE vs. INPUT CAPACITANCE MAX3806 toc14 TA = +105NC 24 26 INPUT-REFERRED NOISE (nARMS) 25 GAIN = 0 BW = 100MHz MAX3806 toc13 VCC = +5V 650 GAIN = 0 BW = 100MHz VCC = +5.5V VCC = +5.0V 600 550 VCC = +4.5V 500 19 18 18 7 9 11 13 15 450 5 7 INPUT CAPACITANCE (pF) 9 11 13 15 5 7 INPUT CAPACITANCE (pF) 9 11 13 15 INPUT CAPACITANCE (pF) DISABLE SWITCH (DC-BLOCK = 0.01µF, LOAD = 2kI) TOTAL HARMONIC DISTORTION vs. FREQUENCY MAX3806 toc17 0 VOUT = 0.5VP -10 MAX3806 toc16 5 DIS (5V/div) -20 THD (dB) INPUT-REFERRED NOISE (nARMS) 26 INPUT-REFERRED NOISE vs. INPUT CAPACITANCE MAX3806 toc15 INPUT-REFERRED NOISE vs. INPUT CAPACITANCE GAIN = 1 OUT (200mV/div) -30 -40 GAIN = 0 -50 -60 0.1 1 100 10 100ns/div FREQUENCY (MHz) GAIN SWITCH (DC-BLOCK = 0.01µF, LOAD = 2kI) ATT SWITCH (DC-BLOCK = 0.01µF, LOAD = 2kI) MAX3806 toc18 MAX3806 toc19 GAIN (5V/div) ATT (5V/div) OUT (200mV/div) OUT (500mV/div) 40µs/div 40µs/div _______________________________________________________________________________________ 5 MAX3806 Typical Operating Characteristics (continued) (Typical values are at VCC = +5V, TA = +25°C, CIN = 5pF, ATT = 0, unless otherwise noted.) MAX3806 Receiver for Optical Distance Measurement Typical Operating Characteristics (continued) (Typical values are at VCC = +5V, TA = +25°C, CIN = 5pF, ATT = 0, unless otherwise noted.) TRANSIENT RESPONSE (OVERLOAD REGION, GAIN = 1) TRANSIENT RESPONSE (OVERLOAD REGION, GAIN = 1) TRANSIENT RESPONSE (LINEAR REGION, GAIN = 1) MAX3806 toc22 MAX3806 toc21 MAX3806 toc20 ZOOM OUT ZOOM IN 1µAP 2mAP 2mAP IN OUT IN IN OUT OUT 60µs SETTLING TIME 60mVP 1.4VP 1.4VP 0.01µF DC-BLOCK 2kI LOAD 20MHz BW LIMIT 20MHz BW LIMIT 10µs/div 100ns/div 20ns/div Functional Diagram MAX3806 IN ATTENUATOR OUT VCC SWITCHABLE IMPEDANCE 60kΩ OR 30kΩ 60kΩ 40kΩ GAIN 6 40kΩ ATT DIS _______________________________________________________________________________________ Receiver for Optical Distance Measurement PIN NAME FUNCTION 1, 12 VCC 2 IN 3, 4 GND Supply Ground 5 ATT CMOS/TTL Input. Assert this pin high to enable a 14dB attenuator in the amplifier. Force this pin low to disable the attenuator. Contains internal 40k pulldown resistor. Connect to GND if not used. 6, 8, 11 N.C. Not Connected. This pin is not internally connected. 7 GAIN CMOS/TTL Input. Selects amplifier gain setting. Force high for 60k. Force low for 30k. Contains internal 40k pulldown resistor. 9 OUT Amplifier Output. An increase in current into the IN pin causes the voltage at the OUT pin to decrease. OUT must be AC-coupled to a load of 2k or greater. 10 DIS CMOS/TTL Input. Force high to disable the output of the MAX3806. Force low to enable the output. Contains internal 60k pullup resistor. — EP Exposed Pad. The exposed pad must be soldered to circuit board ground for proper thermal and electrical performance. 5V Power-Supply Connection Amplifier Input. Accepts AC-coupled photodiode input current. Detailed Description Output Driver Transimpedance Amplifier The output driver is designed to drive an AC-coupled load with an impedance of 2kΩ or greater. The output can be disabled by asserting the DIS pin high. When the output is disabled, the OUT pin goes to a highimpedance state. See Figure 1 for the equivalent output circuit. WARNING: The output is designed to be AC-coupled to a high-impedance load. Operating the part with its output DC-coupled to GND through a 2kΩ or less load may damage the output. The selectable-gain transimpedance amplifier is controlled by the GAIN pin. See Table 1 for gain settings. Applications Information The MAX3806 preamplifier consists of a selectable-gain transimpedance amplifier, a selectable 14dB attenuator, and an output-driver block. The selectable-gain transimpedance amplifier linearly boosts the signal from the photodiode. This block is followed by an attenuator block that allows the user to attenuate the signal by 14dB selected by the ATT pin. The final block is the output driver that can be disabled by asserting the DIS pin. Attenuator The attenuator block can be set to pass the signal through to the output stage with 0dB of attenuation (ATT forced low) or with 14dB of attenuation (ATT forced high). Settling Time Settling time is the required time for the output to achieve the final steady-state or AC amplitude swing after a setting has been changed on the MAX3806. The output common-mode voltage shifts when a change is Table 1. Transimpedance Gain Settings GAIN TRANSIMPEDANCE (k) LINEAR RANGE (μAP) BANDWIDTH (MHz) 0 30 I IN 40 98 1 60 I IN 20 49 _______________________________________________________________________________________ 7 MAX3806 Pin Description Receiver for Optical Distance Measurement 200Ω VCC made to either the GAIN or ATT setting. Table 2 provides typical output common-mode voltages for the combination of settings. Settling time is proportional to the RC time constant set by the output DC-blocking capacitor, load, and MAX3806 output impedance. For example, a 0.01µF DC-blocking capacitor, 2kΩ load, and 51Ω output impedance provide an RC time constant of approximately 20µs. After changing the GAIN or ATT setting, the system should wait at least three to four time constants before analyzing received signals. Settling time is also required when changing the DIS setting. When DIS is asserted high, the output disables to high impedance and typically settles to steady state within 200ns. When DIS is deasserted, the output enables and typically settles to steady state within 50ns. Pin Configuration TOP VIEW 9 8 7 DIS 10 N.C. 11 VCC 12 Overload Recovery Time MAX3806 *EP + 1 VCC Transistors saturate when the amplifier is overloaded, resulting in output distortion. Overload typically occurs with signals greater than 20µAP (GAIN = 1) or 40µAP (GAIN = 0). It can withstand overload signals as large as 2mAP. Recovery time depends on the amplitude and duration of the overload pulse. GAIN Figure 1. Equivalent Output Circuit The exposed pad on the 12-pin TQFN provides a very low thermal resistance path for heat removal from the IC. The pad is also electrical ground on the MAX3806 and must be soldered to the circuit board ground for proper thermal and electrical performance. Refer to Application Note 862: HFAN-08.1: Thermal Considerations of QFN and Other Exposed-Paddle Packages for additional information. 2 3 GND 100Ω Exposed-Pad Package and Thermal Considerations N.C. OUT IN 400Ω Use broadband power-supply filtering techniques to achieve the best sensitivity and noise performance. OUT MAX3806 Layout Considerations Noise performance and bandwidth are adversely affected by capacitance at the IN pad. Minimize capacitance on this pad and select a low-capacitance photodiode. Reducing PCB capacitance can be accomplished by removing the ground plane underneath the connection from the photodiode to the IN pin and by keeping the photodiode as close as possible to the MAX3806. VCC 6 N.C. 5 ATT 4 GND THIN QFN (3mm × 3mm) *EXPOSED PAD Table 2. Output Common-Mode Voltages GAIN OUTPUT COMMON-MODE VOLTAGE (V) Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 0 0 1.65 0 1 0.33 1 0 1.82 PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 0.36 12 TQFN-EP T1233+1 21-0136 1 8 ATT 1 _______________________________________________________________________________________ Receiver for Optical Distance Measurement +5V +5V TO +12V SUPPLY FILTER SUPPLY FILTER VCC +5V 7kΩ PIN 0.01μF MAX3806 IN OUT LINEAR LIDAR Rx C* 3kΩ L* GAIN DIS ATT GND +5V MULTIPLE-CHANNEL RECEIVER DIS0 +5V +5V TO +12V SUPPLY FILTER SUPPLY FILTER VCC +5V 7kΩ PIN +5V 0.01μF MAX3806 IN OUT LINEAR LIDAR Rx C* 3kΩ L* DIS GAIN ATT GND MAX4311 4:1 MUX/AMP +5V IN0 DIS1 0.01μF 0.01μF IN1 MAX1446 BUFF IN2 +5V ADC IN3 +5V TO +12V SUPPLY FILTER SUPPLY FILTER VCC 0.01μF +5V A0 A1 7kΩ PIN 0.01μF MAX3806 IN OUT LINEAR LIDAR Rx C* 3kΩ L* DIS GAIN ATT GND +5V DIS2 +5V +5V TO +12V DIS0 DIS1 SUPPLY FILTER +5V SUPPLY FILTER DIS2 VCC 7kΩ PIN DIS3 0.01μF MAX3806 IN OUT MICROCONTROLLER/DSP LINEAR LIDAR Rx C* 3kΩ L* GAIN DIS ATT GND +5V DIS3 * L AND C SET THE LOW-FREQUENCY CUTOFF REQUIRED FOR THE APPLICATION. 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 _____________________ 9 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX3806 Typical Application Circuits (continued)