MAXIM MAX3806GTC+

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)