TI1 ADC12L066CIVY/NOPB 450 mhz bandwidth a/d converter Datasheet

ADC12L066
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ADC12L066 12-Bit, 66 MSPS, 450 MHz Bandwidth A/D Converter with Internal Sample-andHold
Check for Samples: ADC12L066
FEATURES
DESCRIPTION
•
•
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The ADC12L066 is a monolithic CMOS analog-todigital converter capable of converting analog input
signals into 12-bit digital words at 66 Megasamples
per second (Msps), minimum, with typical operation
possible up to 80 Msps. This converter uses a
differential, pipeline architecture with digital error
correction and an on-chip sample-and-hold circuit to
minimize die size and power consumption while
providing excellent dynamic performance. A unique
sample-and-hold stage yields a full-power bandwidth
of 450 MHz. Operating on a single 3.3V power
supply, this device consumes just 357 mW at 66
Msps, including the reference current. The Power
Down feature reduces power consumption to just 50
mW.
1
23
Single Supply Operation
Low Power Consumption
Power Down Mode
On-Chip Reference Buffer
APPLICATIONS
•
•
•
•
•
•
•
•
Ultrasound and Imaging
Instrumentation
Cellular Base Stations/Communications
Receivers
Sonar/Radar
xDSL
Wireless Local Loops
Data Acquisition Systems
DSP Front Ends
KEY SPECIFICATIONS
•
•
•
•
•
•
•
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•
Resolution: 12 Bits
Conversion Rate: 66 Msps
Full Power Bandwidth: 450 MHz
DNL: ±0.4 LSB (typ)
SNR (fIN = 10 MHz): 66 dB (typ)
SFDR (fIN = 10 MHz): 80 dB (typ)
Data Latency: 6 Clock Cycles
Supply Voltage: +3.3V ± 300 mV
Power Consumption, 66 MHz: 357 mW (typ)
The differential inputs provide a full scale input swing
equal to ±VREF with the possibility of a single-ended
input. Full use of the differential input is
recommended for optimum performance. For ease of
use, the buffered, high impedance, single-ended
reference input is converted on-chip to a differential
reference for use by the processing circuitry. Output
data format is 12-bit offset binary.
This device is available in the 32-lead LQFP package
and will operate over the industrial temperature range
of −40°C to +85°C. An evaluation board is available
to facilitate the evaluation process.
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
1
2
3
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
TRI-STATE is a registered trademark of National Semiconductor Corporation.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2001–2013, Texas Instruments Incorporated
ADC12L066
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Connection Diagram
Block Diagram
2
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PIN DESCRIPTIONS and EQUIVALENT CIRCUITS
Pin No.
Symbol
Equivalent Circuit
Description
ANALOG I/O
2
VIN+
3
VIN−
1
VREF
31
VRP
32
VRM
30
VRN
Analog signal Input pins. With a 1.0V reference voltage the
differential input signal level is 2.0 VP-P. The VIN- pin may be
connected to VCM for single-ended operation, but a differential input
signal is required for best performance.
Reference input. This pin should be bypassed to AGND with a 0.1
µF monolithic capacitor. VREF is 1.0V nominal and should be
between 0.8V and 1.5V.
These pins are high impedance reference bypass pins. Connect a
0.1 µF capacitor from each of these pins to AGND. DO NOT LOAD
these pins.
DIGITAL I/O
10
11
8
CLK
Digital clock input. The range of frequencies for this input is 1 MHz to
80 MHz (typical) with specified performance at 66 MHz. The input is
sampled on the rising edge of this input.
OE
OE is the output enable pin that, when low, enables the TRI-STATE®
data output pins. When this pin is high, the outputs are in a high
impedance state.
PD
PD is the Power Down input pin. When high, this input puts the
converter into the power down mode. When this pin is low, the
converter is in the active mode.
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PIN DESCRIPTIONS and EQUIVALENT CIRCUITS (continued)
Pin No.
Symbol
14–19,
22–27
D0–D11
Equivalent Circuit
Description
Digital data output pins that make up the 12-bit conversion results.
D0 is the LSB, while D11 is the MSB of the offset binary output
word.
ANALOG POWER
5, 6, 29
VA
4, 7, 28
AGND
Positive analog supply pins. These pins should be connected to a
quiet +3.3V source and bypassed to AGND with 0.1 µF monolithic
capacitors located within 1 cm of these power pins, and with a 10 µF
capacitor.
The ground return for the analog supply.
DIGITAL POWER
13
VD
9, 12
DGND
21
20
4
Positive digital supply pin. This pin should be connected to the same
quiet +3.3V source as is VA and bypassed to DGND with a 0.1 µF
monolithic capacitor in parallel with a 10 µF capacitor, both located
within 1 cm of the power pin.
The ground return for the digital supply.
VDR
Positive digital supply pin for the ADC12L066's output drivers. This
pin should be connected to a voltage source of +1.8V to VD and
bypassed to DR GND with a 0.1 µF monolithic capacitor. If the
supply for this pin is different from the supply used for VA and VD, it
should also be bypassed with a 10 µF tantalum capacitor. The
voltage at this pin should never exceed the voltage on VD by more
than 300 mV. All bypass capacitors should be located within 1 cm of
the supply pin.
DR GND
The ground return for the digital supply for the ADC12L066's output
drivers. This pin should be connected to the system digital ground,
but not be connected in close proximity to the ADC12L066's DGND
or AGND pins. See Layout and Grounding for more details.
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Absolute Maximum Ratings (1) (2) (3)
VA, VD, VDR
4.2V
≤ 100 mV
|VA–VD|
−0.3V to (VA or VD +0.3V)
Voltage on Any Pin
Input Current at Any Pin (4)
Package Input Current
±25 mA
(4)
±50 mA
Package Dissipation at TA = 25°C
See
Human Body Model (6)
ESD Susceptibility
Machine Model
2500V
(6)
250V
Soldering Temperature, Infrared, 10 sec. (7)
235°C
−65°C to +150°C
Storage Temperature
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(5)
All voltages are measured with respect to GND = AGND = DGND = 0V, unless otherwise specified.
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is functional, but do not ensure specific performance limits. For ensured specifications and test conditions, see the
Electrical Characteristics. The ensured specifications apply only for the test conditions listed. Some performance characteristics may
degrade when the device is not operated under the listed test conditions.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
When the input voltage at any pin exceeds the power supplies (that is, VIN < AGND, or VIN > VA, VD or VDR), the current at that pin
should be limited to 25 mA. The 50 mA maximum package input current rating limits the number of pins that can safely exceed the
power supplies with an input current of 25 mA to two.
The absolute maximum junction temperature (TJmax) for this device is 150°C. The maximum allowable power dissipation is dictated by
TJmax, the junction-to-ambient thermal resistance (θJA), and the ambient temperature, (TA), and can be calculated using the formula
PDMAX - (TJmax - TA )/θJA. The values for maximum power dissipation will be reached only when the device is operated in a severe
fault condition (e.g. when input or output pins are driven beyond the power supply voltages, or the power supply polarity is reversed).
Obviously, such conditions should always be avoided.
Human body model is 100 pF capacitor discharged through a 1.5 kΩ resistor. Machine model is 220 pF discharged through 0Ω.
The 235°C reflow temperature refers to infrared reflow. For Vapor Phase Reflow (VPR), the following Conditions apply: Maintain the
temperature at the top of the package body above 183°C for a minimum 60 seconds. The temperature measured on the package body
must not exceed 220°C. Only one excursion above 183°C is allowed per reflow cycle.
Operating Ratings (1) (2)
Operating Temperature
−40°C ≤ TA ≤ +85°C
Supply Voltage (VA, VD)
+3.0V to +3.60V
Output Driver Supply (VDR)
+1.8V to VD
VREF Input
0.8V to 1.5V
−0.05V to (VD + 0.05V)
CLK, PD, OE
−0V to (VA − 0.5V)
VIN Input
VCM
0.5V to (VA -1.5V)
≤100 mV
|AGND–DGND|
(1)
(2)
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is functional, but do not ensure specific performance limits. For ensured specifications and test conditions, see the
Electrical Characteristics. The ensured specifications apply only for the test conditions listed. Some performance characteristics may
degrade when the device is not operated under the listed test conditions.
All voltages are measured with respect to GND = AGND = DGND = 0V, unless otherwise specified.
Package Thermal Resistances
Package
θJA
32-Lead LQFP
79°C / W
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Converter Electrical Characteristics
Unless otherwise specified, the following specifications apply for AGND = DGND = DR GND = 0V, VA = VD = +3.3V, VDR =
+2.5V, PD = 0V, VREF = +1.0V, VCM = 1.0V, fCLK = 66 MHz, tr = tf = 2 ns, CL = 15 pF/pin. Boldface limits apply for TJ = TMIN
to TMAX: all other limits TJ = 25°C (1) (2) (3) (4)
Symbol
Parameter
Typical
Conditions
(4)
Limits
(4)
Units
(Limits)
STATIC CONVERTER CHARACTERISTICS
Resolution with No Missing Codes
Integral Non Linearity (5)
INL
DNL
GE
±1.2
Differential Non Linearity
Gain Error
±0.4
Positive Error
−0.15
Negative Error
+0.4
12
Bits
+2.7
LSB (max)
−3
LSB (min)
+1
LSB (max)
−0.95
LSB (min)
±3
%FS (max)
+4
%FS (max)
−5
%FS (min)
+0.2
±1.3
%FS (max)
Under Range Output Code
0
0
Over Range Output Code
4095
4095
Offset Error (VIN+ = VIN−)
REFERENCE AND ANALOG INPUT CHARACTERISTICS
VCM
Common Mode Input Voltage
CIN
VIN Input Capacitance (each pin to GND)
VREF
1.0
VIN + 1.0 Vdc + 1 VP-P
(CLK LOW)
8
(CLK HIGH)
7
Reference Voltage (6)
1.0
Reference Input Resistance
100
0.5
V (min)
1.5
V (max)
pF
pF
0.8
1.5
V (min)
V (max)
MΩ (min)
(1)
The inputs are protected as shown below. Input voltages above VA or below GND will not damage this device, provided current is limited
per Note 4 under Absolute Maximum Ratings. However, errors in the A/D conversion can occur if the input goes above VA or below
GND by more than 100 mV. As an example, if VA is 3.3V, the full-scale input voltage must be ≤3.4V to ensure accurate conversions.
(2)
(3)
(4)
To ensure accuracy, it is required that |VA–VD| ≤ 100 mV and separate bypass capacitors are used at each power supply pin.
With the test condition for VREF = +1.0V (2 VP-P differential input), the 12-bit LSB is 488 µV.
Typical figures are at TA = TJ = 25°C, and represent most likely parametric norms. Test limits are specified to TI's AOQL (Average
Outgoing Quality Level).
Integral Non Linearity is defined as the deviation of the analog value, expressed in LSB, from the straight line that passes through
positive and negative full-scale.
Optimum dynamic performance will be obtained by keeping the reference input in the 0.8V to 1.5V range. The LM4051CIM3-ADJ or the
LM4051CIM3-1.2 bandgap voltage reference is recommended for this application.
(5)
(6)
6
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Converter Electrical Characteristics (continued)
Unless otherwise specified, the following specifications apply for AGND = DGND = DR GND = 0V, VA = VD = +3.3V, VDR =
+2.5V, PD = 0V, VREF = +1.0V, VCM = 1.0V, fCLK = 66 MHz, tr = tf = 2 ns, CL = 15 pF/pin. Boldface limits apply for TJ = TMIN
to TMAX: all other limits TJ = 25°C (1)(2)(3)(4)
Symbol
Parameter
Typical
Conditions
(4)
Limits
(4)
Units
(Limits)
64.6
dB (min)
65
dB (min)
64.6
dB (min)
DYNAMIC CONVERTER CHARACTERISTICS
BW
Full Power Bandwidth
0 dBFS Input, Output at −3 dB
450
85°C
fIN = 10 MHz, VIN =
−0.5 dBFS
25°C
66
−40°C
SNR
Signal-to-Noise Ratio
fIN = 25 MHz, VIN =
−0.5 dBFS
65
85°C
fIN = 150 MHz, VIN =
−6 dBFS
25°C
55
−40°C
fIN = 240 MHz, VIN =
−6 dBFS
25°C
66
−40°C
SINAD
Signal-to-Noise & Distortion
fIN = 25 MHz, VIN =
−0.5 dBFS
25°C
55
−40°C
fIN = 240 MHz, VIN =
−6 dBFS
25°C
Effective Number of Bits
fIN = 25 MHz, VIN =
−0.5 dBFS
25°C
25°C
fIN = 25 MHz, VIN =
−0.5 dBFS
−80
dB (min)
63
dB (min)
dB
51.8
dB (min)
53.9
dB (min)
50
dB (min)
dB
10.5
25°C
Bits (min)
Bits
8.6
Bits (min)
Bits
−73
dB (max)
−73
dB (max)
−68
dB (max)
−80
85°C
−81
−40°C
fIN = 240 MHz, VIN =
−6 dBFS
dB (min)
64.8
8.2
−40°C
fIN = 150 MHz, VIN =
−6 dBFS
64.3
8.0
85°C
Second Harmonic Distortion
dB
8.3
8.8
−40°C
2nd
Harm
dB (min)
10.3
fIN = 240 MHz, VIN =
−6 dBFS
fIN = 10 MHz, VIN =
−0.5 dBFS
dB (min)
51
10.2
85°C
fIN = 150 MHz, VIN =
−6 dBFS
54
10.3
10.7
−40°C
ENOB
dB (min)
51
85°C
fIN = 10 MHz, VIN =
−0.5 dBFS
52
64
85°C
fIN = 150 MHz, VIN =
−6 dBFS
dB
52
85°C
fIN = 10 MHz, VIN =
−0.5 dBFS
MHz
−61
dB
−66
dB (max)
−66
dB (max)
−56
dB (max)
dB
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Converter Electrical Characteristics (continued)
Unless otherwise specified, the following specifications apply for AGND = DGND = DR GND = 0V, VA = VD = +3.3V, VDR =
+2.5V, PD = 0V, VREF = +1.0V, VCM = 1.0V, fCLK = 66 MHz, tr = tf = 2 ns, CL = 15 pF/pin. Boldface limits apply for TJ = TMIN
to TMAX: all other limits TJ = 25°C (1)(2)(3)(4)
Symbol
Parameter
Typical
Conditions
(4)
85°C
fIN = 10 MHz, VIN =
−0.5 dBFS
25°C
−84
−40°C
3rd Harm Third Harmonic Distortion
fIN = 25 MHz, VIN =
−0.5 dBFS
25°C
−78
−40°C
fIN = 240 MHz, VIN =
−6 dBFS
25°C
−77
−40°C
THD
Total Harmonic Distortion
fIN = 25 MHz, VIN =
−0.5 dBFS
25°C
−69
−40°C
fIN = 240 MHz, VIN =
−6 dBFS
25°C
Spurious Free Dynamic Range
fIN = 25 MHz, VIN =
−0.5 dBFS
8
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dB (max)
dB
−68
dB (max)
−68
dB (max)
−64
dB (max)
dB
−72
dB (max)
−72
dB (max)
−66
dB (max)
dB
−63
dB (max)
−63
dB (max)
−53
dB (max)
dB
73
73
25°C
dB (min)
dB
66
74
−40°C
fIN = 240 MHz, VIN =
−6 dBFS
dB (max)
−71
68
85°C
fIN = 150 MHz, VIN =
−6 dBFS
−74
73
80
−40°C
SFDR
dB (max)
−57
85°C
fIN = 10 MHz, VIN =
−0.5 dBFS
−74
−71
85°C
fIN = 150 MHz, VIN =
−6 dBFS
Units
(Limits)
−78
85°C
fIN = 10 MHz, VIN =
−0.5 dBFS
(4)
−79
85°C
fIN = 150 MHz, VIN =
−6 dBFS
Limits
66
dB (min)
56
61
dB
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DC and Logic Electrical Characteristics
Unless otherwise specified, the following specifications apply for AGND = DGND = DR GND = 0V, VA = VD = +3.3V, VDR =
+2.5V, PD = 0V, VREF = +1.0V, VCM = 1.0V, fCLK = 66 MHz, tr = tf = 2 ns, CL = 15 pF/pin. Boldface limits apply for TJ = TMIN
to TMAX: all other limits TJ = 25°C (1) (2) (3) (4)
Symbol
Parameter
Conditions
Typical
(4)
Limits
(4)
Units
(Limits)
CLK, PD, OE DIGITAL INPUT CHARACTERISTICS
VIN(1)
Logical “1” Input Voltage
VD = 3.3V
2.0
V (min)
VIN(0)
Logical “0” Input Voltage
VD = 3.3V
0.8
V (max)
IIN(1)
Logical “1” Input Current
VIN+, VIN− = 3.3V
10
µA
IIN(0)
Logical “0” Input Current
VIN+, VIN− = 0V
−10
µA
CIN
Digital Input Capacitance
5
pF
D0–D11 DIGITAL OUTPUT CHARACTERISTICS
VOUT(1)
Logical “1” Output Voltage
IOUT = −0.5 mA
VOUT(0)
Logical “0” Output Voltage
IOUT = 1.6 mA
VOUT = 3.3V
100
VDR −
0.18
V (min)
0.4
V (max)
nA
IOZ
TRI-STATE Output Current
VOUT = 0V
−100
nA
+ISC
Output Short Circuit Source Current
VOUT = 0V
−20
mA
−ISC
Output Short Circuit Sink Current
VOUT = 2.5V
20
mA
POWER SUPPLY CHARACTERISTICS
IA
Analog Supply Current
PD Pin = DGND, VREF = 1.0V
PD Pin = VDR
103
4
139
mA (max)
mA
ID
Digital Supply Current
PD Pin = DGND
PD Pin = VDR
5.3
2
6.2
mA (max)
mA
IDR
Digital Output Supply Current
PD Pin = DGND, (5)
PD Pin = VDR
<1
0
Total Power Consumption
PD Pin = DGND, CL = 0 pF (6)
PD Pin = VDR
357
50
Power Supply Rejection
Rejection of Full-Scale Error with
VA = 3.0V vs. 3.6V
58
PSRR1
mA
mA
479
mW (max)
mW
dB
(1)
The inputs are protected as shown below. Input voltages above VA or below GND will not damage this device, provided current is limited
per Note 4 under Absolute Maximum Ratings. However, errors in the A/D conversion can occur if the input goes above VA or below
GND by more than 100 mV. As an example, if VA is 3.3V, the full-scale input voltage must be ≤3.4V to ensure accurate conversions.
(2)
(3)
(4)
To ensure accuracy, it is required that |VA–VD| ≤ 100 mV and separate bypass capacitors are used at each power supply pin.
With the test condition for VREF = +1.0V (2 VP-P differential input), the 12-bit LSB is 488 µV.
Typical figures are at TA = TJ = 25°C, and represent most likely parametric norms. Test limits are specified to TI's AOQL (Average
Outgoing Quality Level).
IDR is the current consumed by the switching of the output drivers and is primarily determined by load capacitance on the output pins,
the supply voltage, VDR, and the rate at which the outputs are switching (which is signal dependent). IDR=VDR(C0 x f0 + C1 x f1 +....C11 x
f11) where VDR is the output driver power supply voltage, Cn is total capacitance on the output pin, and fn is the average frequency at
which that pin is toggling.
Power consumption excludes output driver power. See Note 5
(5)
(6)
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AC Electrical Characteristics
Unless otherwise specified, the following specifications apply for AGND = DGND = DR GND = 0V, VA = VD = +3.3V, VDR =
+2.5V, PD = 0V, VREF = +1.0V, VCM = 1.0V, fCLK = 66 MHz, tr = tf = 2 ns, CL = 15 pF/pin. Boldface limits apply for TA = TJ =
TMIN to TMAX: all other limits TA = TJ = 25°C (1) (2) (3) (4) (5)
Symbol
Parameter
Conditions
Typical
Limits
(4)
Units
(Limits)
80
66
MHz (min)
(4)
fCLK1
Maximum Clock Frequency
fCLK2
Minimum Clock Frequency
1
MHz
DC
Clock Duty Cycle
40
60
% (min)
% (max)
tCH
Clock High Time
6.5
ns (min)
tCL
Clock Low Time
6.5
tCONV
Conversion Latency
tOD
Data Output Delay after Rising CLK Edge
tAD
Aperture Delay
2
ns
tAJ
Aperture Jitter
1.2
ps rms
tDIS
Data outputs into TRI-STATE Mode
10
ns
tEN
Data Outputs Active after TRI-STATE
10
ns
tPD
Power Down Mode Exit Cycle
300
ns
ns (min)
6
Clock Cycles
VDR = 2.5V
7.5
11
ns (max)
VDR = 3.3V
6.7
10.5
ns (max)
0.1 µF on pins 30, 31, 32
(1)
The inputs are protected as shown below. Input voltages above VA or below GND will not damage this device, provided current is limited
per Note 4 under Absolute Maximum Ratings. However, errors in the A/D conversion can occur if the input goes above VA or below
GND by more than 100 mV. As an example, if VA is 3.3V, the full-scale input voltage must be ≤3.4V to ensure accurate conversions.
(2)
(3)
(4)
To ensure accuracy, it is required that |VA–VD| ≤ 100 mV and separate bypass capacitors are used at each power supply pin.
With the test condition for VREF = +1.0V (2 VP-P differential input), the 12-bit LSB is 488 µV.
Typical figures are at TA = TJ = 25°C, and represent most likely parametric norms. Test limits are specified to TI's AOQL (Average
Outgoing Quality Level).
Timing specifications are tested at TTL logic levels, VIL = 0.4V for a falling edge and VIH = 2.4V for a rising edge.
(5)
10
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Specification Definitions
APERTURE DELAY is the time after the rising edge of the clock to when the input signal is acquired or held for
conversion.
APERTURE JITTER (APERTURE UNCERTAINTY) is the variation in aperture delay from sample to sample.
Aperture jitter manifests itself as noise in the output.
CLOCK DUTY CYCLE is the ratio of the time that a repetitive digital waveform is high to the total time of one
period. The specification here refers to the ADC clock input signal.
COMMON MODE VOLTAGE (VCM) is the d.c. potential present at both signal inputs to the ADC.
CONVERSION LATENCY is the number of clock cycles between initiation of conversion and when that data is
presented to the output driver stage. Data for any given sample is available at the output pins the Pipeline Delay
plus the Output Delay after the sample is taken. New data is available at every clock cycle, but the data lags the
conversion by the pipeline delay.
DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1
LSB.
EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE BITS) is another method of specifying Signal-to-Noise
and Distortion or SINAD. ENOB is defined as (SINAD - 1.76) / 6.02 and says that the converter is equivalent to a
perfect ADC of this (ENOB) number of bits.
FULL POWER BANDWIDTH is a measure of the frequency at which the reconstructed output fundamental
drops 3 dB below its low frequency value for a full scale input.
GAIN ERROR is the deviation from the ideal slope of the transfer function. It can be calculated as:
Gain Error = Positive Full-Scale Error − Negative Full-Scale Error
(1)
Gain Error can also be separated into Positive Gain Error and Negative Gain Error, which are
Positive Gain Error = Positive Full-Scale Error − Offset Error
Negative Gain Error = Offset Error − Negative Full-Scale Error
(2)
(3)
LSB (LEAST SIGNIFICANT BIT) is the bit that has the smallest value or weight of all bits. This value is VREF/2n,
where “n” is the ADC resolution in bits, which is 12 in the case of the ADC12DL066.
INTEGRAL NON LINEARITY (INL) is a measure of the deviation of each individual code from a line drawn from
negative full scale (½ LSB below the first code transition) through positive full scale (½ LSB above the last code
transition). The deviation of any given code from this straight line is measured from the center of that code value.
INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components as a result of two
sinusoidal frequencies being applied to the ADC input at the same time. It is defined as the ratio of the power in
the second and third order intermodulation products to the power in one of the original frequencies. IMD is
usually expressed in dBFS.
MISSING CODES are those output codes that will never appear at the ADC outputs. The ADC12L066 is ensured
not to have any missing codes.
MSB (MOST SIGNIFICANT BIT) is the bit that has the largest value or weight. Its value is one half of full scale.
NEGATIVE FULL SCALE ERROR is the difference between the input voltage (VIN+ − VIN−) just causing a
transition from negative full scale to the first code and its ideal value of 0.5 LSB. Negative Full-Scale Error can be
calculated as:
OFFSET ERROR is the input voltage that will cause a transition from a code of 01 1111 1111 to a code of 10
0000 0000.
OUTPUT DELAY is the time delay after the rising edge of the clock before the data update is presented at the
output pins.
PIPELINE DELAY (LATENCY) See Conversion Latency
POSITIVE FULL SCALE ERROR is the difference between the actual last code transition and its ideal value of
1½ LSB below positive full scale.
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POWER SUPPLY REJECTION RATIO (PSRR) is a measure of how well the ADC rejects a change in the power
supply voltage. For the ADC12L066, PSRR1 is the ratio of the change in Full-Scale Error that results from a
change in the d.c. power supply voltage, expressed in dB. PSRR2 is a measure of how well an a.c. signal riding
upon the power supply is rejected at the output.
SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in dB, of the rms value of the input signal to the rms
value of the sum of all other spectral components below one-half the sampling frequency, not including
harmonics or d.c.
SIGNAL TO NOISE PLUS DISTORTION (S/N+D or SINAD) Is the ratio, expressed in dB, of the rms value of the
input signal to the rms value of all of the other spectral components below half the clock frequency, including
harmonics but excluding d.c.
SPURIOUS FREE DYNAMIC RANGE (SFDR) is the difference, expressed in dB, between the desired signal
amplitude to the amplitude of the peak spurious spectral component, where a spurious spectral component is
any signal present in the output spectrum that is not present at the input and may or may not be a harmonic.
TOTAL HARMONIC DISTORTION (THD) is the ratio, expressed in dBc, of the rms total of the first nine
harmonic levels at the output to the level of the fundamental at the output. THD is calculated as
(4)
where f1 is the RMS power of the fundamental (output) frequency and f2 through f10 are the RMS power in the
first 9 harmonic frequencies.
SECOND HARMONIC DISTORTION (2ND HARM) is the difference expressed in dB, between the RMS power in
the input frequency at the output and the power in its 2nd harmonic level at the output.
THIRD HARMONIC DISTORTION (3RD HARM) is the difference, expressed in dB, between the RMS power in
the input frequency at the output and the power in its 3rd harmonic level at the output.
12
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Timing Diagram
Figure 1. Output Timing
Transfer Characteristic
Figure 2. Transfer Characteristic
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Typical Performance Characteristics
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
14
DNL
DNL vs. fCLK
Figure 3.
Figure 4.
DNL vs. Clock Duty Cycle
DNL vs. Temperature
Figure 5.
Figure 6.
INL
INL vs. fCLK
Figure 7.
Figure 8.
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Typical Performance Characteristics (continued)
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
INL vs. Clock Duty Cycle
INL vs. Temperature
Figure 9.
Figure 10.
SNR vs. VA
SNR vs. VDR
Figure 11.
Figure 12.
SNR vs. VCM
SNR vs. fCLK
Figure 13.
Figure 14.
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Typical Performance Characteristics (continued)
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
16
SNR vs. Clock Duty Cycle
SNR vs. VREF
Figure 15.
Figure 16.
SNR vs. Temperature
THD vs. VA
Figure 17.
Figure 18.
THD vs. VDR
THD vs. VCM
Figure 19.
Figure 20.
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Typical Performance Characteristics (continued)
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
THD vs. fCLK
THD vs. Clock Duty Cycle
Figure 21.
Figure 22.
THD vs. VREF
THD vs. Temperature
Figure 23.
Figure 24.
SINAD vs. VA
SINAD vs. VDR
Figure 25.
Figure 26.
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Typical Performance Characteristics (continued)
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
18
SINAD vs. VCM
SINAD vs. fCLK
Figure 27.
Figure 28.
SINAD vs. Clock Duty Cycle
SINAD vs. VREF
Figure 29.
Figure 30.
SINAD vs. Temperature
SFDR vs. VA
Figure 31.
Figure 32.
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Typical Performance Characteristics (continued)
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
SFDR vs. VDR
SFDR vs. VCM
Figure 33.
Figure 34.
SFDR vs. fCLK
SFDR vs. Clock Duty Cycle
Figure 35.
Figure 36.
SFDR vs. VREF
SFDR vs. Temperature
Figure 37.
Figure 38.
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Typical Performance Characteristics (continued)
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
20
Power Consumption vs. fCLK
tOD vs. VDR
Figure 39.
Figure 40.
Spectral Response @ 10 MHz Input
Spectral Response @ 25 MHz Input
Figure 41.
Figure 42.
Spectral Response @ 50 MHz Input
Spectral Response @ 75MHz Input
Figure 43.
Figure 44.
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Typical Performance Characteristics (continued)
VA = VD = 3.3V, VDR = 2.5V, fCLK = 66 MHz, fIN = 25 MHz, VREF = 1.0V, unless otherwise stated.
Spectral Response @ 100 MHz Input
Spectral Response @ 150 MHz Input
Figure 45.
Figure 46.
Spectral Response @ 240 MHz Input
Figure 47.
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FUNCTIONAL DESCRIPTION
Operating on a single +3.3V supply, the ADC12L066 uses a pipeline architecture and has error correction
circuitry to help ensure maximum performance.
Differential analog input signals are digitized to 12 bits. Each analog input signal should have a peak-to-peak
voltage equal to the input reference voltage, VREF, be centered around a common mode voltage, VCM, and be
180° out of phase with each other. Table 1 and Table 2 indicate the input to output relationship of the
ADC12L066. Biasing one input to VCM and driving the other input with its full range signal results in a 6 dB
reduction of the output range, limiting it to the range of ¼ to ¾ of the minimum output range obtainable if both
inputs were driven with complimentary signals. Signal Inputs explains how to avoid this signal reduction.
Table 1. Input to Output Relationship–Differential Input
VIN
VIN−
Output
VCM − VREF/2
VCM + VREF/2
0000 0000 0000
VCM − VREF/4
VCM + VREF/4
0100 0000 0000
+
VCM
VCM
1000 0000 0000
VCM + VREF/4
VCM − VREF/4
1100 0000 0000
VCM + VREF/2
VCM − VREF/2
1111 1111 1111
Table 2. Input to Output Relationship–Single-Ended Input
VIN+
VIN−
Output
VCM −VREF
VCM
0000 0000 0000
VCM − VREF/2
VCM
0100 0000 0000
VCM
VCM
1000 0000 0000
VCM + VREF/2
VCM
1100 0000 0000
VCM +VREF
VCM
1111 1111 1111
The output word rate is the same as the clock frequency, which can be between 1 Msps and 80 Msps (typical).
The analog input voltage is acquired at the rising edge of the clock and the digital data for that sample is delayed
by the pipeline for 6 clock cycles.
A logic high on the power down (PD) pin reduces the converter power consumption to 50 mW.
Applications Information
OPERATING CONDITIONS
We recommend that the following conditions be observed for operation of the ADC12L066:
• 3.0 V ≤ VA ≤ 3.6V
• VD = VA
• 1.8V ≤ VDR ≤ VD
• 1 MHz ≤ fCLK ≤ 80 MHz
• 0.8V ≤ VREF ≤ 1.5V
• 0.5V ≤ VCM ≤ 1.5V
Analog Inputs
The ADC12L066 has two analog signal inputs, VIN+ and VIN−. These two pins form a differential input pair. There
is one reference input pin, VREF.
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Reference Pins
The ADC12L066 is designed to operate with a 1.0V reference, but performs well with reference voltages in the
range of 0.8V to 1.5V. Lower reference voltages will decrease the signal-to-noise ratio (SNR) of the ADC12L066.
Increasing the reference voltage (and the input signal swing) beyond 1.5V may degrade THD for a full-scale
input, especially at higher input frequencies. It is important that all grounds associated with the reference voltage
and the input signal make connection to the analog ground plane at a single, quiet point in that plane to minimize
the effects of noise currents in the ground path.
The ADC12L066 will perform well with reference voltages up to 1.5V for full-scale input frequencies up to 10
MHz. However, more headroom is needed as the input frequency increases, so the maximum reference voltage
(and input swing) will decrease for higher full-scale input frequencies.
The three Reference Bypass Pins (VRP, VRM and VRN) are made available for bypass purposes only. These pins
should each be bypassed to ground with a 0.1 µF capacitor. Smaller capacitor values will allow faster recovery
from the power down mode, but may result in degraded noise performance. DO NOT LOAD these pins. Loading
any of these pins may result in performance degradation.
The nominal voltages for the reference bypass pins are as follows:
VRM = VA / 2
VRP = VRM + VREF / 2
VRN = VRM − VREF / 2
The VRM pin may be used as a common mode voltage source (VCM) for the analog input pins as long as no d.c.
current is drawn from it. However, because the voltage at this pin is half that of the VA supply pin, using these
pins for a common mode source will result in reduced input headroom (the difference between the VA supply
voltage and the peak signal voltage at either analog input) and the possibility of reduced THD and SFDR
performance. For this reason, it is recommended that VA always exceed VREF by at least 2 Volts. For high input
frequencies it may be necessary to increase this headroom to maintain THD and SFDR performance.
Alternatively, use VRN for a VCM source.
Signal Inputs
The signal inputs are VIN+ and VIN−. The input signal, VIN, is defined as
VIN = (VIN+) – (VIN−)
(5)
Figure 48 shows the expected input signal range.
Note that the nominal input common mode voltage is VREF and the nominal input signals each run between the
limits of VREF/2 and 3VREF/2. The Peaks of the input signals should never exceed the voltage described as
Peak Input Voltage = VA − 0.8
(6)
to maintain dynamic performance.
The ADC12L066 performs best with a differential input with each input centered around a common mode
voltage, VCM (minimum of 0.5V). The peak-to-peak voltage swing at both VIN+ and VIN− should each not exceed
the value of the reference voltage or the output data will be clipped.
The two input signals should be exactly 180° out of phase from each other and of the same amplitude. For single
frequency (sine wave) inputs, angular errors result in a reduction of the effective full scale input. For a complex
waveform, however, angular errors will result in distortion.
Figure 48. Expected Input Signal Range
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For angular deviations of up to 10 degrees from these two signals being 180 out of phase with each other, the
full scale error in LSB can be described as approximately
EFS = dev1.79
(7)
Where dev is the angular difference between the two signals having a 180° relative phase relationship to each
other (see Figure 49). Drive the analog inputs with a source impedance less than 100Ω.
Figure 49. Angular Errors Between Two Input Signals Will Reduce the Output Level or Cause Distortion
For differential operation, each analog input pin of the differential pair should have a peak-to-peak voltage equal
to the input reference voltage, VREF, and be centered around VCM.
SINGLE-ENDED INPUT OPERATION
Single-ended performance is inferior to that with differential input signals, so single-ended operation is not
recommended, However, if single-ended operation is required and the resulting performance degradation is
acceptable, one of the analog inputs should be connected to the d.c. mid point voltage of the driven input. The
peak-to-peak differential input signal should be twice the reference voltage to maximize SNR and SINAD
performance (Figure 48b).
For example, set VREF to 0.5V, bias VIN− to 1.0V and drive VIN+ with a signal range of 0.5V to 1.5V.
Because very large input signal swings can degrade distortion performance, better performance with a singleended input can be obtained by reducing the reference voltage while maintaining a full-range output. Table 1 and
Table 2 indicate the input to output relationship of the ADC12L066.
DRIVING THE ANALOG INPUTS
The VIN+ and the VIN− inputs of the ADC12L066 consist of an analog switch followed by a switched-capacitor
amplifier. The capacitance seen at the analog input pins changes with the clock level, appearing as 8 pF when
the clock is low, and 7 pF when the clock is high.
As the internal sampling switch opens and closes, current pulses occur at the analog input pins, resulting in
voltage spikes at the signal input pins. As a driving amplifier attempts to counteract these voltage spikes, a
damped oscillation may appear at the ADC analog input. The best amplifiers for driving the ADC12L066 input
pins must be able to react to these spikes and settle before the switch opens and another sample is taken. The
LMH6702 LMH6628, LMH6622 and the LMH6655 are good amplifiers for driving the ADC12L066.
To help isolate the pulses at the ADC input from the amplifier output, use RCs at the inputs, as can be seen in
Figure 51 and Figure 52. These components should be placed close to the ADC inputs because the input pins of
the ADC is the most sensitive part of the system and this is the last opportunity to filter that input.
For Nyquist applications the RC pole should be at the ADC sample rate. The ADC input capacitance in the
sample mode should be considered with setting the RC pole. Setting the pole in this manner will provide best
SINAD performance.
To obtain best SNR performance, leave the RC values as calculated. To obtain best SINAD and ENOB
performance, reduce the RC time constant until SNR and THD are numerically equal to each other. To obtain
best distortion and SFDR performance, eliminate the RC altogether.
For undersampling applications, the RC pole should be set at about 1.5 to 2 times the maximum input frequency
for narrow band applications. For wide band applications, the RC pole should be set at about 1.5 times the
maximum input frequency to maintain a linear delay response.
A single-ended to differential conversion circuit is shown in Figure 51.
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INPUT COMMON MODE VOLTAGE
The input common mode voltage, VCM, should be in the range of 0.5V to 1.5V and be of a value such that the
peak excursions of the analog signal does not go more negative than ground or more positive than 0.8 Volts
below the VA supply voltage. The nominal VCM should generally be about 1.0V, but VRM or VRN can be used as a
VCM source as long as no d.c. current is drawn from either of these pins.
DIGITAL INPUTS
Digital inputs are TTL/CMOS compatible and consist of CLK, OE and PD.
CLK
The CLK signal controls the timing of the sampling process. Drive the clock input with a stable, low jitter clock
signal in the range of 1 MHz to 80 MHz with rise and fall times of less than 2 ns. The trace carrying the clock
signal should be as short as possible and should not cross any other signal line, analog or digital, not even at
90°.
The CLK signal also drives an internal state machine. If the CLK is interrupted, or its frequency is too low, the
charge on internal capacitors can dissipate to the point where the accuracy of the output data will degrade. This
is what limits the lowest sample rate to 1 Msps.
The duty cycle of the clock signal can affect the performance of any A/D Converter. Because achieving a precise
duty cycle is difficult, the ADC12L066 is designed to maintain performance over a range of duty cycles. While it is
specified and performance is specified with a 50% clock duty cycle, performance is typically maintained over a
clock duty cycle range of 40% to 60%.
The clock line should be series terminated at the clock source in the characteristic impedance of that line if the
clock line is longer than
(8)
where tr is the clock rise time and tprop is the propagation rate of the signal along the trace. For a typical board of
FR-4 material, tPROP is about 150 ps/in, or 60 ps/cm. The CLOCK pin may need to be a.c. terminated with a
series RC such that the resistor value is equal to the characteristic impedance of the clock line and the capacitor
value is
(9)
where "I" is the line length in inches and Zo is the characteristic impedance of the clock line. This termination
should be located as close as possible to, but within one centimeter of, the ADC12L066 clock pin as shown in
Figure 52. It should also be located beyond the ADC clock pin as seen from the clock source.
Take care to maintain a constant clock line impedance throughout the length of the line and to properly terminate
the source end of the line with its characteristic impedance. Refer to Application Notes AN-905 (SNLA035) and
AN-1113 (SNLA011) for information on setting characteristic impedance.
OE
The OE pin, when high, puts the output pins into a high impedance state. When this pin is low the outputs are in
the active state. The ADC12L066 will continue to convert whether this pin is high or low, but the output can not
be read while the OE pin is high.
Since ADC noise increases with increased output capacitance at the digital output pins, do use the TRI-STATE
outputs of the ADC12L066 to drive a bus. Rather, each output pin should be located close to and drive a single
digital input pin. To further reduce ADC noise, a 100 Ω resistor in series with each ADC digital output pin, located
close to their respective pins, should be added to the circuit. See Data Outputs
PD
The PD pin, when high, holds the ADC12L066 in a power-down mode to conserve power when the converter is
not being used. The power consumption in this state is 50 mW with a 66 MHz clock and 30 mW if the clock is
stopped. The output data pins are undefined in this mode. The data in the pipeline is corrupted while in the
power down mode.
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The Power Down Mode Exit Cycle time is determined by the value of the capacitors on pins 30, 31 and 32 and is
about 300 ns with the recommended 0.1 µF on these pins. These capacitors loose their charge in the Power
Down mode and must be recharged by on-chip circuitry before conversions can be accurate. Smaller capacitor
values allow faster recovery from the power down mode, but can result in a reduction in SNR, SINAD and ENOB
performance.
DATA OUTPUTS
The ADC12L066 has 12 TTL/CMOS compatible Data Output pins and the output format is offset binary. Valid
offset binary data is present at these outputs while the OE and PD pins are low. While the tOD time provides
information about output timing, a simple way to capture a valid output is to latch the data on the edge of the
conversion clock (pin 10). Which edge to use will depend upon the clock frequency and duty cycle as well as the
set-up and hold times of the receiving device or circuit. If the rising edge is used, the tOD time can be used to
determine maximum hold time acceptable of the driven device data inputs. If the falling edge of the clock is used,
care must be taken to be sure that adequate setup and hold times are allowed for capturing the ADC output
data.
Be very careful when driving a high capacitance bus. The more capacitance the output drivers must charge for
each conversion, the more instantaneous digital current flows through VDR and DR GND. These large charging
current spikes can cause on-chip noise that can couple into the analog circuitry, degrading dynamic
performance. Adequate power supply bypassing and careful attention to the ground plane will reduce this
problem. Additionally, bus capacitance beyond the specified 15 pF/pin will cause tOD to increase, making it
difficult to properly latch the ADC output data. The result could be an apparent reduction in dynamic
performance.
To minimize noise due to output switching, minimize the load currents at the digital outputs. This can be done by
connecting buffers (74AC541, for example) between the ADC outputs and any other circuitry. Only one driven
input should be connected to each output pin. Additionally, inserting series 100Ω resistors at the digital outputs,
close to the ADC pins, will isolate the outputs from trace and other circuit capacitances and limit the output
currents, which could otherwise result in performance degradation. See Figure 50.
While the ADC12L066 will operate with VDR voltages down to 1.8V, tOD increases with reduced VDR. Be careful of
external timing when using reduced VDR.
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+1.8V to 3.6V
+3.3V
10 PF
470
1.50k
1%
MF
V RE
0.1 PF
F
5
1.00k
1%
MF
LM4050-2.5
*
10 PF
6
10 PF
0.1 PF
29
0.1 PF
13
VA
21
VD
VD
Power Down
R
1 PF
*
1
*
V RE
PD
8
F
31
V RP
0.1 PF
* Ground for the 1.00k resistor, the
0.1 PF bypass capacitor, the ground
pin for the LM4050-2.5, the bypass
capacitors on pins 30, 31 and 32 of
the ADC12L066 and pin 28 of the
ADC12L066 should be connected to
a common point in the analog
ground plane.
*
D11 (MSB)
D10
30
VR
0.1 PF
D9
N
*
D8
32
V R
M
0.1 PF
*
D7
D6
VC
D5
M
2
D4
V IN+
Differential
Drive
See Fig 5
SIGNAL
INPUT
D3
D2
D1
3
V IN-
D0 (LSB)
10
CLOCK
INPUT
OE
CLK
12 x 100:
27
26
25
24
74ACQ541
23
22
19
CLK
17
16
15
14
11
74ACQ541
47
AGND
See
Text
4
7
DGND
28
See
Text
DRGND
9 12
12 BIT
DATA
OUTPUT
18
1/4
74ACQ04
20
47
CLK
*
LE
OE
INPUT
Figure 50. Simple Application Circuit with Single-Ended to Differential Buffer
511, 1%
51
255, 1%
50:
SIGNAL
INPUT
To ADC
VIN82 pF
+
49.9,
1%
280, 1%
Amplifier:
LMH6550
-
82 pF
511, 1%
51
To ADC
VIN+
Figure 51. Differential Drive Circuit of Figure 50
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Figure 52. Driving the Signal Inputs with a Transformer
POWER SUPPLY CONSIDERATIONS
The power supply pins should be bypassed with a 10 µF capacitor and with a 0.1 µF ceramic chip capacitor
within a centimeter of each power pin. Leadless chip capacitors are preferred because they have low series
inductance.
As is the case with all high-speed converters, the ADC12L066 is sensitive to power supply noise. Accordingly,
the noise on the analog supply pin should be kept below 100 mVP-P.
No pin should ever have a voltage on it that is in excess of the supply voltages, not even on a transient basis. Be
especially careful of this during turn on and turn off of power.
The VDR pin provides power for the output drivers and may be operated from a supply in the range of 1.8V to VD.
This can simplify interfacing to devices and systems operating with supplies less than VD. Note, however, that tOD
increases with reduced VDR. DO NOT operate the VDR pin at a voltage higher than VD.
LAYOUT AND GROUNDING
Proper grounding and proper routing of all signals are essential to ensure accurate conversion. Maintaining
separate analog and digital areas of the board, with the ADC12L066 between these areas, is required to achieve
specified performance.
The ground return for the data outputs (DR GND) carries the ground current for the output drivers. The output
current can exhibit high transients that could add noise to the conversion process. To prevent this from
happening, the DR GND pins should NOT be connected to system ground in close proximity to any of the
ADC12L066's other ground pins.
28
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Capacitive coupling between the typically noisy digital circuitry and the sensitive analog circuitry can lead to poor
performance. The solution is to keep the analog circuitry separated from the digital circuitry, and to keep the
clock line as short as possible.
Digital circuits create substantial supply and ground current transients. The logic noise thus generated could
have significant impact upon system noise performance. The best logic family to use in systems with A/D
converters is one which employs non-saturating transistor designs, or has low noise characteristics, such as the
74LS, 74HC(T) and 74AC(T) families. The worst noise generators are logic families that draw the largest supply
current transients during clock or signal edges, like the 74F and the 74AC(T) families.
The effects of the noise generated from the ADC output switching can be minimized through the use of 100Ω
resistors in series with each data output line. Locate these resistors as close to the ADC output pins as possible.
Since digital switching transients are composed largely of high frequency components, total ground plane copper
weight will have little effect upon the logic-generated noise. This is because of the skin effect. Total surface area
is more important than is total ground plane volume.
Generally, analog and digital lines should cross each other at 90° to avoid crosstalk. To maximize accuracy in
high speed, high resolution systems, however, avoid crossing analog and digital lines altogether. It is important to
keep clock lines as short as possible and isolated from ALL other lines, including other digital lines. Even the
generally accepted 90° crossing should be avoided with the clock line as even a little coupling can cause
problems at high frequencies. This is because other lines can introduce jitter into the clock line, which can lead to
degradation of SNR. Also, the high speed clock can introduce noise into the analog chain.
Best performance at high frequencies and at high resolution is obtained with a straight signal path. That is, the
signal path through all components should form a straight line wherever possible.
Figure 53. Example of a Suitable Layout
Be especially careful with the layout of inductors. Mutual inductance can change the characteristics of the circuit
in which they are used. Inductors should not be placed side by side, even with just a small part of their bodies
beside each other.
The analog input should be isolated from noisy signal traces to avoid coupling of spurious signals into the input.
Any external component (e.g., a filter capacitor) connected between the converter's input pins and ground or to
the reference input pin and ground should be connected to a very clean point in the ground plane.
Figure 53 gives an example of a suitable layout. All analog circuitry (input amplifiers, filters, reference
components, etc.) should be placed in the analog area of the board. All digital circuitry and I/O lines should be
placed in the digital area of the board. The ADC12L066 should be between these two areas. Furthermore, all
components in the reference circuitry and the input signal chain that are connected to ground should be
connected together with short traces and enter the ground plane at a single, quiet point. All ground connections
should have a low inductance path to ground.
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DYNAMIC PERFORMANCE
To achieve the best dynamic performance, the clock source driving the CLK input must be free of jitter. Isolate
the ADC clock from any digital circuitry with buffers, as with the clock tree shown in Figure 54.
As mentioned in Layout and Grounding, it is good practice to keep the ADC clock line as short as possible and to
keep it well away from any other signals. Other signals can introduce jitter into the clock signal, which can lead to
reduced SNR performance, and the clock can introduce noise into other lines. Even lines with 90° crossings
have capacitive coupling, so try to avoid even these 90° crossings of the clock line.
Figure 54. Isolating the ADC Clock from other Circuitry with a Clock Tree
COMMON APPLICATION PITFALLS
Driving the inputs (analog or digital) beyond the power supply rails. For proper operation, all inputs should
not go more than 100 mV beyond the supply rails (more than 100 mV below the ground pins or 100 mV above
the supply pins). Exceeding these limits on even a transient basis may cause faulty or erratic operation. It is not
uncommon for high speed digital components (e.g., 74F and 74AC devices) to exhibit overshoot or undershoot
that goes above the power supply or below ground. A resistor of about 50Ω to 100Ω in series with any offending
digital input, close to the signal source, will eliminate the problem.
Do not allow input voltages to exceed the supply voltage, even on a transient basis. Not even during power up or
power down.
Be careful not to overdrive the inputs of the ADC12L066 with a device that is powered from supplies outside the
range of the ADC12L066 supply. Such practice may lead to conversion inaccuracies and even to device
damage.
Attempting to drive a high capacitance digital data bus. The more capacitance the output drivers must
charge for each conversion, the more instantaneous digital current flows through VDR and DR GND. These large
charging current spikes can couple into the analog circuitry, degrading dynamic performance. Adequate
bypassing and maintaining separate analog and digital areas on the pc board will reduce this problem.
Additionally, bus capacitance beyond the specified 15 pF/pin will cause tOD to increase, making it difficult to
properly latch the ADC output data. The result could, again, be a reduction in dynamic performance.
The digital data outputs should be buffered (with 74AC541, for example). Dynamic performance can also be
improved by adding series resistors at each digital output, close to the ADC12L066, which reduces the energy
coupled back into the converter output pins by limiting the output current. A reasonable value for these resistors
is 100Ω.
Using an inadequate amplifier to drive the analog input. As explained in Signal Inputs, the capacitance seen
at the input alternates between 8 pF and 7 pF, depending upon the phase of the clock. This dynamic load is
more difficult to drive than is a fixed capacitance.
If the amplifier exhibits overshoot, ringing, or any evidence of instability, even at a very low level, it will degrade
performance. A small series resistor at each amplifier output and a capacitor across the analog inputs (as shown
in Figure 51 Figure 52) will improve performance. The LMH6702, LMH6628, LMH6622 and LMH6655 have been
successfully used to drive the analog inputs of the ADC12L066.
30
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Also, it is important that the signals at the two inputs have exactly the same amplitude and be exactly 180º out of
phase with each other. Board layout, especially equality of the length of the two traces to the input pins, will
affect the effective phase between these two signals. Remember that an operational amplifier operated in the
non-inverting configuration will exhibit more time delay than will the same device operating in the inverting
configuration.
Operating with the reference pins outside of the specified range. As mentioned in Reference Pins, VREF
should be in the range of
0.8V ≤ VREF ≤ 1.5V
(10)
Operating outside of these limits could lead to performance degradation.
Using a clock source with excessive jitter, using excessively long clock signal trace, or having other
signals coupled to the clock signal trace. This will cause the sampling interval to vary, causing excessive
output noise and a reduction in SNR and SINAD performance.
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REVISION HISTORY
Changes from Revision H (March 2013) to Revision I
•
32
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 31
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PACKAGE OPTION ADDENDUM
www.ti.com
26-Sep-2015
PACKAGING INFORMATION
Orderable Device
Status
(1)
ADC12L066CIVY/NOPB
ACTIVE
Package Type Package Pins Package
Drawing
Qty
LQFP
NEY
32
250
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
Op Temp (°C)
Device Marking
(4/5)
-40 to 85
ADC12L0
66CIVY
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
26-Sep-2015
Addendum-Page 2
MECHANICAL DATA
NEY0032A
VF0032A
TYPICAL
VBE32A (Rev F)
www.ti.com
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