TI1 ADC10464 10-bit 600 ns a/d converter with input multiplexer and sample/hold Datasheet

ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
ADC10461/ADC10462/ADC10464 10-Bit 600 ns A/D Converter with Input Multiplexer and
Sample/Hold
Check for Samples: ADC10461, ADC10462, ADC10464
FEATURES
DESCRIPTION
•
•
•
•
NOTE: The ADC10461 and ADC10462 are obsolete.
They are described here for reference only.
1
2
Built-In Sample-and-Hold
Single +5V Supply
No External Clock Required
Speed Adjust Pin for Faster Conversions
(ADC10462 and ADC10464)
APPLICATIONS
•
•
•
•
Digital Signal Processor Front Ends
Instrumentation
Disk Drives
Mobile Telecommunications
KEY SPECIFICATIONS
•
•
•
•
•
Conversion Time 600 ns (Typical)
Sampling Rate 800 kHz
Low Power Consumption 235 mW (Max)
Total Harmonic Distortion (50 kHz) −60 dB
(Max)
No Missing Codes Over Temperature
Using an innovative, patented multistep (U.S. Patent
Number 4918449) conversion technique, these 10-bit
CMOS analog-to-digital converters offer submicrosecond conversion times yet dissipate a
maximum of only 235 mW. These converters perform
10-bit conversion in two lower-resolution “flashes”,
yielding a fast A/D without the cost, power
consumption, and other problems associated with
true flash approaches. Dynamic performance (THD,
S/N) is ensured.
The analog input voltage is sampled and held by an
internal sampling circuit. Input signals at frequencies
from DC to over 200 kHz can, therefore, be digitized
accurately without the need for an external sampleand-hold circuit.
The ADC10462 and ADC10464 include a “speed-up”
pin. Connecting an external resistor between this pin
and ground reduces the typical conversion time to as
little as 350 ns with only a small increase in linearity
error.
For ease of interface to microprocessors, the
ADC10461, ADC10462, and ADC10464 have been
designed to appear as a memory location or I/O port
without the need for external interface logic.
Simplified Block Diagram
*ADC10461, **ADC10462 and ADC10464, ***ADC10464; These devices are obsolete; shown for reference only.
1
2
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.
All 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 © 1999–2013, Texas Instruments Incorporated
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
Connection Diagrams
Figure 1. Top View
Figure 2. Top View
Figure 3. Top View
NOTE: The ADC10461 and ADC10462 are obsolete; shown for reference only.
PIN DESCRIPTIONS
Pin Function
Description
DVCC, AVCC
Digital and analog positive supply voltage inputs. Connect both to the same voltage source, but bypass separately with
a 0.1 µF ceramic capacitor in parallel with a 10 µF tantalum capacitor to ground at each pin.
INT
Active low interrupt output. INT goes low at the end of each conversion, and returns high following the rising edge of
RD.
S/H
Sample/Hold control input. When this pin is forced low (and CS is low), the analog input signal is sampled and a new
conversion is initiated.
RD
Active low read control input. When this RD and CS are low, any data present in the output registers will be placed
onto the data bus.
CS
Active low Chip Select control input. When low, this pin enables the RD and S/H pins.
S0, S1
On the multiple-input devices (ADC10462 and ADC10464), these pins select the analog input that will be connected to
the A/D during the conversion. The input is selected based on the state of S0 and S1 when S/H makes its High-to-Low
transition (See Timing Diagrams). The ADC10464 includes both S0 and S1. The ADC10462 includes just S0, and the
ADC10461 has neither.
VREF−, VREF+
Reference voltage inputs. They may be placed at any voltage between GND and VCC, but VREF+ must be greater than
VREF−. An input voltage equal to VREF− produces an output code of 0, and an input voltage equal to (VREF+ − 1 LSB)
produces an output code of 1023.
VIN, VIN0, VIN1,
VIN2, VIN3
Analog input pins. The ADC10461 has one input (VIN), the ADC10462 has two inputs (VIN0 and VIN1), and the
ADC10464 has four inputs (VIN0, VIN1, VIN2 and VIN3). The impedance of the input source should be less than 500Ω for
best accuracy and conversion speed. For accurate conversions, no input pin (even one that is not selected) should be
driven more than 50 mV above VCC or 50 mV below ground.
GND, AGND,
DGND
Power supply ground pins. The ADC10461 has a single ground pin (GND), and the ADC10462 and ADC10464 have
separate analog and digital ground pins (AGND and DGND) for separate bypassing of the analog and digital supplies.
The ground pins should be connected to a stable, noise-free system ground. For the devices with two ground pins,
both pins should be returned to the same potential.
DB0–DB9
TRI-STATE data output pins.
SPEED ADJ
(ADC10462 and ADC10464 only). This pin is normally left unconnected, but by connecting a resistor between this pin
and ground, the conversion time can be reduced. See Typical Performance Characteristics and the table of Electrical
Characteristics.
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.
2
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
Absolute Maximum Ratings (1) (2) (3)
Supply Voltage (V+ = AVCC = DVCC)
−0.3V to +6V
−0.3V to V+ + 0.3V
Voltage at Any Input or Output
Input Current at Any Pin (4)
5 mA
Package Input Current (4)
20 mA
Power Consumption (5)
875 mW
ESD Susceptibility (6)
2000V
N Package (10 Sec)
Soldering Information
SOIC Package
260°C
Vapor Phase (60 Sec)
215°C
Infrared (15 Sec)
220°C
−65°C to +150°C
Storage Temperature Range
Junction Temperature
(1)
(2)
(3)
(4)
(5)
(6)
150°C
All voltages are measured with respect to GND, 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. These ratings do not ensure specific performance limits, however. 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 (VIN) at any pin exceeds the power supply rails (VIN < GND or VIN > V+) the absolute value of current at that pin
should be limited to 5 mA or less. The 20 mA package input current limits the number of pins that can safely exceed the power supplies
with an input current of 5 mA to four.
The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA and the ambient temperature,
TA. The maximum allowable power dissipation at any temperature is PD = (TJMAX − TA)/θJA or the number given in the Absolute
Maximum Ratings, whichever is lower. In most cases, the maximum derated power dissipation will be reached only during fault
conditions. For these devices, TJMAX for a board-mounted device can be in from Package Thermal Resistance.
Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Operating Ratings (1) (2)
Temperature Range (TMIN ≤ TA ≤ TMAX)
−40°C ≤ TA ≤ +85°C
Supply Voltage Range
(1)
(2)
+4.5V to +5.5V
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is functional. These ratings do not ensure specific performance limits, however. 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, unless otherwise specified.
Package Thermal Resistance
Device
θJA (°C/W)
ADC10461CIWM
85
ADC10462CIWM
82
ADC10464CIWM
78
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
3
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
Converter Characteristics
The following specifications apply for V+ = +5V, VREF(+) = +5V, VREF(−) = GND, and Speed Adjust pin unconnected unless
otherwise specified. Boldface limits apply for TA = TJ = TMin to TMax; all other limits TA = TJ = +25°C.
Symbol
Parameter
Conditions
Typical (1)
Resolution
Limit (2)
10
RSA ≥ 18 kΩ
Integral Linearity Error
±0.5
Offset Error
Full-Scale Error
RSA ≥ 18 kΩ
Total Unadjusted Error
V+ = 5V ±5%, VREF = 4.5V
Power Supply Sensitivity
Bits
LSB
±1.5
LSB (max)
±1
LSB (max)
0
(max)
±0.5
Missing Codes
Units
(Limit)
LSB
±1/16
LSB
V = 5V ±10%, VREF = 4.5V
±⅛
LSB
−68
−66
−62
−58
dB
dB (max)
dB
dB
+
THD
Total Harmonic Distortion
fIN = 1 kHz, 4.85 VP-P
fIN = 50 kHz, 4.85 VP-P
fIN = 100 kHz, 4.85 VP-P
fIN = 240 kHz, 4.85 VP-P
SNR
Signal-to-Noise Ratio
fIN = 1 kHz, 4.`85 VP-P
fIN = 50 kHz, 4.85 VP-P
fIN = 100 kHz, 4.85 VP-P
61
60
60
ENOB
Effective Number of Bits
fIN = 1 kHz, 4.85 VP-P
fIN = 50 kHz, 4.85 VP-P
9.6
9.5
9
Bits
Bits (min)
RREF
Reference Resistance
650
400
Ω (min)
RREF
Reference Resistance
650
900
Ω (max)
VREF(+)
VREF(+) Input Voltage
V+ + 0.05
V (max)
VREF(−)
VREF(−) Input Voltage
GND − 0.05
V (min)
VREF(+)
VREF(+) Input Voltage
VREF(−)
V (min)
VREF(−)
VREF(−) Input Voltage
VREF(+)
V (max)
VIN
Input Voltage
V+ + 0.05
V (max)
VIN
Input Voltage
GND − 0.05
V (min)
(1)
(2)
4
+
+
−60
58
dB
dB (min)
dB
OFF Channel Input Leakage Current
CS = V , VIN = V
0.01
3
µA (max)
ON Channel Input Leakage Current
CS = V+, VIN = V+
±1
−3
µA (max)
Typical figures represent most likely parametric norm.
Limits are specified to TI's AOQL (Average Outgoing Quality Level).
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
DC Electrical Characteristics
The following specifications apply for V+ = +5V, VREF(+) = 5V VREF(−) = GND, and Speed Adjust pin unconnected unless
otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = +25°C.
Symbol
Parameter
Conditions
Typical (1)
Limit (2)
Units
(Limits)
VIN(1)
Logical “1” Input Voltage
V+ = 5.5V
2.0
V (min)
VIN(0)
Logical “0” Input Voltage
V+ = 4.5V
0.8
V (max)
IIN(1)
Logical “1” Input Current
VIN(1) = 5V
0.005
3.0
µA (max)
IIN(0)
Logical “0” Input Current
VIN(0) 0V
−0.005
−3.0
µA (max)
V = 4.5V, IOUT = −360 µA
2.4
V (min)
V+ = 4.5V, IOUT = −10 µA
4.25
V (min)
0.4
V (max)
+
VOUT(1)
Logical “1” Output Voltage
VOUT(0)
Logical “0” Output Voltage
V+ = 4.5V, IOUT = 1.6 mA
IOUT
TRI-STATE Output Current
VOUT = 5V
VOUT = 0V
0.1
−0.1
50
−50
µA (max)
µA (max)
DICC
DVCC Supply Current
CS = S /H = RD = 0, RSA = ∞
CS = S /H = RD = 0, RSA = 18 kΩ
1.0
1.0
2
mA (max)
mA (max)
AICC
AVCC Supply Current
CS = S /H = RD = 0, RSA = ∞
CS = S /H = RD = 0, RSA = 18 kΩ
30
30
45
mA (max)
mA (max)
(1)
(2)
Typical figures represent most likely parametric norm.
Limits are specified to TI's AOQL (Average Outgoing Quality Level).
AC Electrical Characteristics
The following specifications apply for V+ = +5V, tr = tf = 20 ns, VREF(+) = 5V, VREF(−) = GND, and Speed Adjust pin unconnected
unless otherwise specified. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = +25°C.
Symbol
Parameter
Conditions
Typical (1)
Limit (2)
Units
(Limits)
tCONV
Mode 1 Conversion Time from Rising Edge CIN, CIWM Suffixes
of S /H to Falling Edge of INT
RSA = 18k
600
375
750/900
ns (max)
ns
tCRD
Mode 2 Conversion Time
CIN, CIWM Suffixes
Mode 2, RSA = 18k
850
530
1400
ns (max)
ns
tACC1
Access Time (Delay from Falling Edge of
RD to Output Valid)
Mode 1; CL = 100 pF
30
60
ns (max)
Access Time (Delay from Falling Edge of
RD to Output Valid)
Mode 2; CL = 100 pF
900
tCRD + 50
ns (max)
tSH
Minimum Sample Time
(Figure 4) (3)
250
ns (max)
t1H, t0H
TRI-STATE Control (Delay from Rising
Edge of RD to High-Z State)
RL = 1k, CL = 10 pF
30
60
ns (max)
tINTH
Delay from Rising Edge of RD to Rising
Edge of INT
CL = 100 pF
25
50
ns (max)
tP
Delay from End of Conversion to Next
Conversion
50
ns (max)
tMS
Multiplexer Control Setup Time
10
75
ns (max)
tMH
Multiplexer Hold Time
10
40
CVIN
Analog Input Capacitance
35
pF (max)
COUT
Logic Output Capacitance
5
pF (max)
CIN
Logic Input Capacitance
5
pF (max)
tACC2
(1)
(2)
(3)
ns (max)
Typical figures represent most likely parametric norm.
Limits are specified to TI's AOQL (Average Outgoing Quality Level).
Accuracy may degrade if tSH is shorter than the value specified. See curves of Accuracy vs. tSH.
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
5
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
TRI-STATE Test Circuits and Waveforms
Timing Diagrams
The conversion time (tCONV) is set by the internal timer.
Figure 4. Mode 1
6
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
The conversion time (tCRD) includes the
sampling time and is determined by the internal timer.
Figure 5. Mode 2 (RD Mode)
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
7
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
Typical Performance Characteristics
8
Zero (Offset) Error
vs. Reference Voltage
Linearity Error
vs. Reference Voltage
Figure 6.
Figure 7.
Analog Supply Current
vs. Temperature
Digital Supply Current
vs. Temperature
Figure 8.
Figure 9.
Conversion Time
vs. Temperature
Conversion Time
vs. Temperature
Figure 10.
Figure 11.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
Typical Performance Characteristics (continued)
Conversion Time
vs. Speed-Up Resistor
(ADC10462 and ADC10464 Only)
Conversion Time
vs. Speed-Up Resistor
(ADC10462 and ADC10464 Only)
Figure 12.
Figure 13.
Spectral Response with
100 kHz Sine Wave Input
Spectral Response with
100 kHz Sine Wave Input
Figure 14.
Figure 15.
Signal-to-Noise + THD Ratio
vs. Signal Frequency
Linearity Change
vs. Speed-Up Resistor
(ADC10462 and ADC10464 Only)
Figure 16.
Figure 17.
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
9
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
Typical Performance Characteristics (continued)
10
Linearity Change
vs. Speed-Up Resistor
(ADC10462 and ADC10464 Only)
Linearity Error Change
vs. Sample Time
Figure 18.
Figure 19.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
Functional Description
The ADC10461 and the ADC10462 are obsolete and discussed here for reference only.
The ADC10461, ADC10462 and ADC10464 digitize an analog input signal to 10 bits accuracy by performing two
lower-resolution “flash” conversions. The first flash conversion provides the six most significant bits (MSBs) of
data, and the second flash conversion provides the four least significant bits LSBs).
Figure 20 is a simplified block diagram of the converter. Near the center of the diagram is a string of resistors. At
the bottom of the string of resistors are 16 resistors, each of which has a value 1/1024 the resistance of the
whole resistor string. These lower 16 resistors (the LSB Ladder ) therefore have a voltage drop of 16/1024, or
1/64 of the total reference voltage (VREF+ − VREF−) across them. The remainder of the resistor string is made up
of eight groups of eight resistors connected in series. These comprise the MSB Ladder . Each section of the
MSB Ladder has ⅛ of the total reference voltage across it, and each of the LSB resistors has 1/64 of the total
reference voltage across it. Tap points across these resistors can be connected, in groups of sixteen, to the
sixteen comparators at the right of the diagram.
On the left side of the diagram is a string of seven resistors connected between VREF+ and VREF−. Six
comparators compare the input voltage with the tap voltages on this resistor string to provide a low-resolution
“estimate” of the input voltage. This estimate is then used to control the multiplexer that connects the MSB
Ladder to the sixteen comparators on the right. Note that the comparators on the left needn't be very accurate;
they simply provide an estimate of the input voltage. Only the sixteen comparators on the right and the six on the
left are necessary to perform the initial six-bit flash conversion, instead of the 64 comparators that would be
required using conventional half-flash methods.
To perform a conversion, the estimator compares the input voltage with the tap voltages on the seven resistors
on the left. The estimator decoder then determines which MSB Ladder tap points will be connected to the sixteen
comparators on the right. For example, assume that the estimator determines that VIN is between 11/16 and
13/16 of VREF. The estimator decoder will instruct the comparator MUX to connect the 16 comparators to the taps
on the MSB ladder between 10/16 and 14/16 of VREF. The 16 comparators will then perform the first flash
conversion. Note that since the comparators are connected to ladder voltages that extend beyond the range
indicated by the estimator circuit, errors in the estimator as large as 1/16 of the reference voltage (64 LSBs) will
be corrected. This first flash conversion produces the six most significant bits of data—four bits in the flash itself,
and 2 bits in the estimator.
The remaining four LSBs are now determined using the same sixteen comparators that were used for the first
flash conversion. The MSB Ladder tap voltage just below the input voltage (as determined by the first flash) is
subtracted from the input voltage and compared with the tap points on the sixteen LSB Ladder resistors. The
result of this second, four-bit flash conversion is then decoded, and the full 10-bit result is latched.
Note that the sixteen comparators used in the first flash conversion are reused for the second flash. Thus, the
multistep conversion technique used in the ADC10461, ADC10462, and ADC10464 needs only a small fraction
of the number of comparators that would be required for a traditional flash converter, and far fewer than would be
used in a conventional half-flash approach. This allows the ADC10461, ADC10462, and ADC10464 to perform
high-speed conversions without excessive power drain.
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
11
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
Figure 20. Block Diagram of the Multistep Converter Architecture
SIMILAR PRODUCT DIFFERENCES
The ADC1046x, ADC1046x and ADC1066x (where "x" indicates the number of multiplexer inputs) are similar
devices with different specification limits. The differences in these device families are summarized below.
Device Family
ILE, TUE, PSS
THD, SNR, ENOB
Max. Conversion Time
ADC1046x
Ensured
-
900ns
ADC1046x
-
Ensured
900ns
ADC1066x
-
Ensured
466ns
12
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
APPLICATIONS INFORMATION
MODES OF OPERATION
The ADC10461, ADC10462, and ADC10464 have two basic digital interface modes. Figure 4 and Figure 5 are
timing diagrams for the two modes. The ADC10462 and ADC10464 have input multiplexers that are controlled by
the logic levels on pins S0 and S1 when S/H goes low. Table 1 and Table 2 are truth tables showing how the
input channels are assigned.
Mode 1
In this mode, the S/H pin controls the start of conversion. S/H is pulled low for a minimum of 250 ns. This causes
the comparators in the “coarse” flash converter to become active. When S/H goes high, the result of the coarse
conversion is latched and the “fine” conversion begins. After 600 ns (typical), INT goes low, indicating that the
conversion results are latched and can be read by pulling RD low. Note that CS must be low to enable S/H or
RD. CS is internally “ANDed” with S/H and RD; the input voltage is sampled when CS and S/H are low, and data
is read when CS and RD are low. INT is reset high on the rising edge of RD.
Table 1. Input Multiplexer Programming ADC10464
S1
S0
Channel
0
0
VIN0
0
1
VIN1
1
0
VIN2
1
1
VIN3
Table 2. Input Multiplexer Programming ADC10462
S0
Channel
0
VIN0
1
VIN1
Mode 2
In Mode 2, also called “RD mode”, the S/H and RD pins are tied together. A conversion is initiated by pulling both
pins low. The A/D converter samples the input voltage and causes the coarse comparators to become active. An
internal timer then terminates the coarse conversion and begins the fine conversion. 850 ns (typical) after S/H
and RD are pull low, INT goes low, indicating that the conversion is completed. Approximately 20 ns later the
data appearing on the TRI-STATE output pins will be valid. Note that data will appear on these pins throughout
the conversion, but until INT goes low the data at the output pins will be the result of the previous conversion.
REFERENCE CONSIDERATIONS
The ADC10461, ADC10462, and ADC10464 each have two reference inputs. These inputs, VREF+ and VREF−, are
fully differential and define the zero to full-scale range of the input signal. The reference inputs can be connected
to span the entire supply voltage range (VREF− = 0V, VREF+ = VCC) for ratiometric applications, or they can be
connected to different voltages (as long as they are between ground and VCC) when other input spans are
required.
Reducing the overall VREF span to less than 5V increases the sensitivity of the converter (e.g., if VREF = 2V, then
1 LSB = 1.953 mV). Note, however, that linearity and offset errors become larger when lower reference voltages
are used. See Typical Performance Characteristics for more information. For this reason, reference voltages less
than 2V are not recommended.
In most applications, VREF− will simply be connected to ground, but it is often useful to have an input span that is
offset from ground. This situation is easily accommodated by the reference configuration used in the ADC10461,
ADC10462, and ADC10464. VREF− can be connected to a voltage other than ground as long as the voltage
source connected to this pin is capable of sinking the converter's reference current (12.5 mA Max @ VREF = 5V).
If VREF− is connected to a voltage other than ground, bypass it with multiple capacitors.
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
13
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
Since the resistance between the two reference inputs can be as low as 400Ω, the voltage source driving the
reference inputs should have low output impedance. Any noise on either reference input is a potential cause of
conversion errors, so each of these pins must be supplied with a clean, low noise voltage source. Each reference
pin should be bypassed with a 10 µF tantalum and a 0.1 µF ceramic.
THE ANALOG INPUT
The ADC10461, ADC10462, and ADC10464 sample the analog input voltage once every conversion cycle.
When this happens, the input is briefly connected to an impedance approximately equal to 600Ω in series with 35
pF. Short-duration current spikes can be observed at the analog input during normal operation. These spikes are
normal and do not degrade the converter's performance.
Large source impedances can slow the charging of the sampling capacitors and degrade conversion accuracy.
Therefore, only signal sources with output impedances less than 500Ω should be used if rated accuracy is to be
achieved at the minimum sample time (250 ns maximum). If the sampling time is increased, the source
impedance can be larger. If a signal source has a high output impedance, its output should be buffered with an
operational amplifier. The operational amplifier's output should be well-behaved when driving a switched 35
pF/600Ω load. Any ringing or voltage shifts at the op amp's output during the sampling period can result in
conversion errors.
Correct conversion results will be obtained for input voltages greater than GND − 50 mV and less than V+ +
50 mV. Do not allow the signal source to drive the analog input pin beyond the Absolute Maximum Rating. If an
analog input pin is forced beyond these voltages, the current flowing through the pin should be limited to 5 mA or
less to avoid permanent damage to the IC. The sum of all the overdrive currents into all pins must be less than
the Absolute Maximum Rating for Package Input Current. When the input signal is expected to extend beyond
this limit, an input protection scheme should be used. A simple input protection network using diodes and
resistors is shown in Figure 21. Note the multiple bypass capacitors on the reference and power supply pins. If
VREF− is not grounded, it should also be bypassed to analog ground using multiple capacitors (see POWER
SUPPLY CONSIDERATIONS). AGND and DGND should be at the same potential. VIN0 is shown with an input
protection network. Pin 17 is normally left open, but optional “speedup” resistor RSA can be used to reduce the
conversion time.
Figure 21. Typical Connection
INHERENT SAMPLE-AND-HOLD
Because the ADC10461, ADC10462, and ADC10464 sample the input signal once during each conversion, they
are capable of measuring relatively fast input signals without the help of an external sample-hold. In a nonsampling successive-approximation A/D converter, regardless of speed, the input signal must be stable to better
than ±1/2 LSB during each conversion cycle or significant errors will result. Consequently, even for many
relatively slow input signals, the signals must be externally sampled and held constant during each conversion if
a SAR with no internal sample-and-hold is used.
14
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
Because they incorporate a direct sample/hold control input, the ADC10461, ADC10462, and ADC10464 are
suitable for use in DSP-based systems. The S/H input allows synchronization of the A/D converter to the DSP
system's sampling rate and to other ADC10461s, ADC10462s, and ADC10464s.
POWER SUPPLY CONSIDERATIONS
The ADC10461, ADC10462, and ADC10464 are designed to operate from a +5V (nominal) power supply. There
are two supply pins, AVCC and DVCC. These pins allow separate external bypass capacitors for the analog and
digital portions of the circuit. To ensure accurate conversions, the two supply pins should be connected to the
same voltage source, and each should be bypassed with a 0.1 µF ceramic capacitor in parallel with a 10 µF
tantalum capacitor. Depending upon the circuit board layout and other system considerations, more bypassing
may be necessary.
The ADC10461 has a single ground pin, and the ADC10462 and ADC10464 each have separate analog and
digital ground pins for separate bypassing of the analog and digital supplies. The devices with separate analog
and digital ground pins should have their ground pins connected to the same potential, and all grounds should be
“clean” and free of noise.
In systems with multiple power supplies, careful attention to power supply sequencing may be necessary to avoid
over-driving inputs. The A/D converter's power supply pins should be at the proper voltage before digital or
analog signals are applied to any of the other pins.
LAYOUT AND GROUNDING
In order to ensure fast, accurate conversions from the ADC10461, ADC10462, and ADC10464, it is necessary to
use appropriate circuit board layout techniques. The analog ground return path should be low-impedance and
free of noise from other parts of the system. Noise from digital circuitry can be especially troublesome.
All bypass capacitors should be located as close to the converter as possible and should connect to the
converter and to ground with short traces. The analog input should be isolated from noisy signal traces to avoid
having spurious signals couple to the input. Any external component (e.g., a filter capacitor) connected across
the converter's input should be connected to a very clean ground return point. Grounding the component at the
wrong point will result in reduced conversion accuracy.
DYNAMIC PERFORMANCE
Many applications require the A/D converter to digitize AC signals, but conventional DC integral and differential
nonlinearity specifications don't accurately predict the A/D converter's performance with AC input signals. The
important specifications for AC applications reflect the converter's ability to digitize AC signals without significant
spectral errors and without adding noise to the digitized signal. Dynamic characteristics such as signal-to-noise
ratio (SNR) and total harmonic distortion (THD), are quantitative measures of this capability.
An A/D converter's AC performance can be measured using Fast Fourier Transform (FFT) methods. A sinusoidal
waveform is applied to the A/D converter's input, and the transform is then performed on the digitized waveform.
The resulting spectral plot might look like the ones shown in the typical performance curves. The large peak is
the fundamental frequency, and the noise and distortion components (if any are present) are visible above and
below the fundamental frequency. Harmonic distortion components appear at whole multiples of the input
frequency. Their amplitudes are combined as the square root of the sum of the squares and compared to the
fundamental amplitude to yield the THD specification. Ensured limits for THD are given in the table of Electrical
Characteristics.
Signal-to-noise ratio is the ratio of the amplitude at the fundamental frequency to the rms value at all other
frequencies, excluding any harmonic distortion components. Ensured limits are given in the Electrical
Characteristics table. An alternative definition of signal-to-noise ratio includes the distortion components along
with the random noise to yield a signal-to-noise-plus-distortion ration, or S/(N + D).
The THD and noise performance of the A/D converter will change with the frequency of the input signal, with
more distortion and noise occurring at higher signal frequencies. One way of describing the A/D's performance
as a function of signal frequency is to make a plot of “effective bits” versus frequency. An ideal A/D converter
with no linearity errors or self-generated noise will have a signal-to-noise ratio equal to (6.02n + 1.76) dB, where
n is the resolution in bits of the A/D converter. A real A/D converter will have some amount of noise and
distortion, and the effective bits can be found by:
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
15
ADC10461, ADC10462, ADC10464
SNAS074E – JUNE 1999 – REVISED MARCH 2013
www.ti.com
where
•
S/(N + D) is the ratio of signal to noise and distortion, which can vary with frequency
(1)
As an example, an ADC10461 with a 4.85 VP-P, 100 kHz sine wave input signal will typically have a signal-tonoise-plus-distortion ratio of 59.2 dB, which is equivalent to 9.54 effective bits. As the input frequency increases,
noise and distortion gradually increase, yielding a plot of effective bits or S/(N + D) as shown in the typical
performance curves.
SPEED ADJUST
In applications that require faster conversion times, the Speed Adjust pin (pin 14 on the ADC10462, pin 17 on the
ADC10464) can significantly reduce the conversion time. The speed adjust pin is connected to an on-chip current
source that determines the converter's internal timing. By connecting a resistor between the speed adjust pin and
ground as shown in Figure 21, the internal programming current is increased, which reduces the conversion time.
As an example, an 18k resistor reduces the conversion time of a typical part from 600 ns to 350 ns with no
significant effect on linearity. Using smaller resistors to further decrease the conversion time is possible as well,
although the linearity will begin to degrade somewhat (see Typical Performance Characteristics). Note that the
resistor value needed to obtain a given conversion time will vary from part to part, so this technique will generally
require some “tweaking” to obtain satisfactory results.
For applications that require ensured performance using the speed adjust pin, the ADC10662 and ADC10664 are
tested and ensured for static and dynamic performance with a fixed value of speed-up resistor.
16
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
ADC10461, ADC10462, ADC10464
www.ti.com
SNAS074E – JUNE 1999 – REVISED MARCH 2013
REVISION HISTORY
Changes from Revision D (March 2013) to Revision E
•
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 16
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: ADC10461 ADC10462 ADC10464
Submit Documentation Feedback
17
PACKAGE OPTION ADDENDUM
www.ti.com
12-Jul-2014
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
ADC10464CIWM/NOPB
ACTIVE
SOIC
DW
28
26
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 85
ADC10464
CIWM
ADC10464CIWMX/NOPB
ACTIVE
SOIC
DW
28
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 85
ADC10464
CIWM
(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.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
12-Jul-2014
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 2
PACKAGE MATERIALS INFORMATION
www.ti.com
5-Jun-2015
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
ADC10464CIWMX/NOPB
Package Package Pins
Type Drawing
SOIC
DW
28
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
1000
330.0
24.4
Pack Materials-Page 1
10.8
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
18.4
3.2
12.0
24.0
Q1
PACKAGE MATERIALS INFORMATION
www.ti.com
5-Jun-2015
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
ADC10464CIWMX/NOPB
SOIC
DW
28
1000
367.0
367.0
45.0
Pack Materials-Page 2
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other
changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest
issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and
complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale
supplied at the time of order acknowledgment.
TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily
performed.
TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and
applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information
published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or
endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration
and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered
documentation. Information of third parties may be subject to additional restrictions.
Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service
voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice.
TI is not responsible or liable for any such statements.
Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements
concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support
that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which
anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause
harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use
of any TI components in safety-critical applications.
In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to
help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and
requirements. Nonetheless, such components are subject to these terms.
No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties
have executed a special agreement specifically governing such use.
Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in
military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components
which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and
regulatory requirements in connection with such use.
TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of
non-designated products, TI will not be responsible for any failure to meet ISO/TS16949.
Products
Applications
Audio
www.ti.com/audio
Automotive and Transportation
www.ti.com/automotive
Amplifiers
amplifier.ti.com
Communications and Telecom
www.ti.com/communications
Data Converters
dataconverter.ti.com
Computers and Peripherals
www.ti.com/computers
DLP® Products
www.dlp.com
Consumer Electronics
www.ti.com/consumer-apps
DSP
dsp.ti.com
Energy and Lighting
www.ti.com/energy
Clocks and Timers
www.ti.com/clocks
Industrial
www.ti.com/industrial
Interface
interface.ti.com
Medical
www.ti.com/medical
Logic
logic.ti.com
Security
www.ti.com/security
Power Mgmt
power.ti.com
Space, Avionics and Defense
www.ti.com/space-avionics-defense
Microcontrollers
microcontroller.ti.com
Video and Imaging
www.ti.com/video
RFID
www.ti-rfid.com
OMAP Applications Processors
www.ti.com/omap
TI E2E Community
e2e.ti.com
Wireless Connectivity
www.ti.com/wirelessconnectivity
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2015, Texas Instruments Incorporated