1
2
3 4
5
6
VACS
GND SDATA
VIN SCLK
ADC081S101
ADC081S101
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SNAS310D –JANUARY 2006–REVISED JANUARY 2014
ADC081S101 Single Channel, 0.5 to 1 Msps, 8-Bit A/D Converter
Check for Samples: ADC081S101
1FEATURES DESCRIPTION
The ADC081S101 is a low-power, single channel
2• Specified Over a Range of Sample Rates. CMOS 8-bit analog-to-digital converter with a high-
• 6-Lead WSON and SOT-23 Packages speed serial interface. Unlike the conventional
• Variable Power Management practice of specifying performance at a single sample
rate only, the ADC081S101 is fully specified over a
• Single Power Supply with 2.7V - 5.25V Range sample rate range of 500 ksps to 1 Msps. The
• SPI™/QSPI™/MICROWIRE/DSP Compatible converter is based upon a successive-approximation
register architecture with an internal track-and-hold
APPLICATIONS circuit.
• Portable Systems The output serial data is straight binary, and is
• Remote Data Aquisitions compatible with several standards, such as SPI™,
QSPI™, MICROWIRE, and many common DSP
• Instrumentation and Control Systems serial interfaces.
KEY SPECIFICATIONS The ADC081S101 operates with a single supply that
can range from +2.7V to +5.25V. Normal power
• DNL ± 0.07 LSB (typ) consumption using a +3V or +5V supply is 2.0 mW
• INL ± 0.05 LSB (typ) and 10.0 mW, respectively. The power-down feature
• SNR 49.7 dB (typ) reduces the power consumption to just 2.5 µW using
a +5V supply.
• Power Consumption The ADC081S101 is packaged in an 6-lead WSON
– 3V Supply 2.0 mW (typ) and SOT-23 packages. Operation over the industrial
– 5V Supply 10.0 mW (typ) temperature range of −40°C to +85°C is ensured.
Table 1. Pin-Compatible Alternatives by Resolution and Speed(1)
Resolution Specified for Sample Rate Range of:
50 to 200 ksps 200 to 500 ksps 500 ksps to 1 Msps
12-bit ADC121S021 ADC121S051 ADC121S101
10-bit ADC101S021 ADC101S051 ADC101S101
8-bit ADC081S021 ADC081S051 ADC081S101
(1) All devices are fully pin and function compatible.
Connection Diagram
Figure 1. 6-Lead SOT-23 or WSON
See DBV or NGF Package
1Please 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.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Copyright © 2006–2014, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
T/H
8-BIT
SUCCESSIVE
APPROXIMATION
ADC
SCLK
CS
SDATA
CONTROL
LOGIC
VIN
ADC081S101
SNAS310D –JANUARY 2006–REVISED JANUARY 2014
www.ti.com
Block Diagram
PIN DESCRIPTIONS AND EQUIVALENT CIRCUITS
Pin No. Symbol Description
ANALOG I/O
3 VIN Analog input. This signal can range from 0V to VA.
DIGITAL I/O
4 SCLK Digital clock input. This clock directly controls the conversion and readout processes.
5 SDATA Digital data output. The output samples are clocked out of this pin on falling edges of the SCLK pin.
6 CS Chip select. On the falling edge of CS, a conversion process begins.
POWER SUPPLY
Positive supply pin. This pin should be connected to a quiet +2.7V to +5.25V source and bypassed to
1 VAGND with a 1 µF capacitor and a 0.1 µF monolithic capacitor located within 1 cm of the power pin.
2 GND The ground return for the supply and signals.
PAD GND For package suffix CISD(X) only, it is recommended that the center pad should be connected to ground.
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.
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Absolute Maximum Ratings (1)(2)(3)
Analog Supply Voltage VA−0.3V to 6.5V
Voltage on Any Pin to GND −0.3V to (VA+0.3)V
Input Current at Any Pin (4) ±10 mA
Package Input Current (4) ±20 mA
Power Consumption at TA= 25°C See (5)
ESD Susceptibility (6)
Human Body Model 3500V
Machine Model 300V
Junction Temperature +150°C
Storage Temperature −65°C to +150°C
(1) 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.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
(3) All voltages are measured with respect to GND = 0V, unless otherwise specified.
(4) When the input voltage at any pin exceeds the power supply (that is, VIN < GND or VIN > VA), the current at that pin should be limited to
10 mA. The 20 mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an
input current of 10 mA to two. The Absolute Maximum Rating specification does not apply to the VApin. The current into the VApin is
limited by the Analog Supply Voltage specification.
(5) 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 listed above 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.
(6) Human body model is 100 pF capacitor discharged through a 1.5 kΩresistor. Machine model is 220 pF discharged through zero ohms.
Operating Ratings (1)(2)
Operating Temperature Range −40°C ≤TA≤+85°C
VASupply Voltage +2.7V to +5.25V
Digital Input Pins Voltage Range −0.3V to +5.25V
(regardless of supply voltage)
Clock Frequency 25 kHz to 20 MHz
Sample Rate Up to 1 Msps
Analog Input Voltage 0V to VA
(1) 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.
(2) All voltages are measured with respect to GND = 0V, unless otherwise specified.
Package Thermal Resistance(1)
Package θJA
6-lead WSON 94°C / W
6-lead SOT-23 265°C / W
Soldering process must comply with Texas Instrument's Reflow Temperature Profile specifications. Refer to www.ti.com and
http://www.ti.com/lit/SNOA549.
(1) Reflow temperature profiles are different for lead-free and non-lead-free packages.
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ADC081S101 Converter Electrical Characteristics (1)(2)
The following specifications apply for VA= +2.7V to 5.25V, GND = 0V, fSCLK = 10 MHz to 20 MHz, CL= 15 pF, fSAMPLE = 500
ksps to 1 Msps, unless otherwise noted. Boldface limits apply for TA= TMIN to TMAX: all other limits TA= 25°C.
Limits
Symbol Parameter Conditions Typical Units
(2)
STATIC CONVERTER CHARACTERISTICS
Resolution with No Missing 8Bits
Codes LSB
INL Integral Non-Linearity VA= +2.7V to +5.25V ±0.05 ±0.3 (max)
LSB
DNL Differential Non-Linearity VA= +2.7V to +5.25V ±0.07 ±0.3 (max)
LSB
VOFF Offset Error VA= +2.7V to +5.25V ±0.03 ±0.3 (max)
LSB
GE Gain Error VA= +2.7V to +5.25V ±0.08 ±0.4 (max)
LSB
TUE Total Unadjusted Error VA= +2.7V to +5.25V ±0.07 ±0.3 (max)
DYNAMIC CONVERTER CHARACTERISTICS
Signal-to-Noise Plus VA= +2.7 to 5.25V
SINAD 49.7 49 dB (min)
Distortion Ratio fIN = 100 kHz, −0.02 dBFS
VA= +2.7 to 5.25V
SNR Signal-to-Noise Ratio 49.7 dB (min)
fIN = 100 kHz, −0.02 dBFS
VA= +2.7 to 5.25V
THD Total Harmonic Distortion −77 −65 dB (max)
fIN = 100 kHz, −0.02 dBFS
Spurious-Free Dynamic VA= +2.7 to 5.25V
SFDR 68 65 dB (min)
Range fIN = 100 kHz, −0.02 dBFS
VA= +2.7 to 5.25V
ENOB Effective Number of Bits 7.9 7.8 Bits (min)
fIN = 100 kHz, −0.02 dBFS
Intermodulation Distortion, VA= +5.25V −68 dB
Second Order Terms fa= 103.5 kHz, fb= 113.5 kHz
IMD Intermodulation Distortion, VA= +5.25V −68 dB
Third Order Terms fa= 103.5 kHz, fb= 113.5 kHz
VA= +5V 11 MHz
FPBW -3 dB Full Power Bandwidth VA= +3V 8 MHz
ANALOG INPUT CHARACTERISTICS
VIN Input Range 0 to VAV
IDCL DC Leakage Current ±1 µA (max)
Track Mode 30 pF
CINA Input Capacitance Hold Mode 4 pF
DIGITAL INPUT CHARACTERISTICS
VA= +5.25V 2.4
VIH Input High Voltage V (min)
VA= +3.6V 2.1
VA= +5V 0.8 V (max)
VIL Input Low Voltage VA= +3V 0.4 V (max)
IIN Input Current VIN = 0V or VA±10 nA ±1 µA (max)
CIND Digital Input Capacitance 2 4pF (max)
DIGITAL OUTPUT CHARACTERISTICS
ISOURCE = 200 µA VA−0.07 VA−0.2 V (min)
VOH Output High Voltage ISOURCE = 1 mA VA−0.1 V
ISINK = 200 µA 0.03 0.4 V (max)
VOL Output Low Voltage ISINK = 1 mA 0.1 V
(1) Tested limits are specified to TI's AOQL (Average Outgoing Quality Level).
(2) Data sheet min/max specification limits are ensured by design, test, or statistical analysis.
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ADC081S101 Converter Electrical Characteristics (1)(2) (continued)
The following specifications apply for VA= +2.7V to 5.25V, GND = 0V, fSCLK = 10 MHz to 20 MHz, CL= 15 pF, fSAMPLE = 500
ksps to 1 Msps, unless otherwise noted. Boldface limits apply for TA= TMIN to TMAX: all other limits TA= 25°C.
Limits
Symbol Parameter Conditions Typical Units
(2)
TRI-STATE® Leakage
IOZL, IOZH ±0.1 ±10 µA (max)
Current
TRI-STATE® Output
COUT 24pF (max)
Capacitance
Output Coding Straight (Natural) Binary
POWER SUPPLY CHARACTERISTICS
2.7 V (min)
VASupply Voltage 5.25 V (max)
SOT-23 3.2 mA
VA= +5.25V, fSAMPLE = 1 Msps 2.0 (max)
WSON 2.6
Supply Current, Normal
Mode (Operational, CS low) SOT-23 1.5 mA
VA= +3.6V, fSAMPLE = 1 Msps 0.6
IA(max)
WSON 1.1
VA= +5.25V, fSCLK = 0 MHz, fSAMPLE = 0 ksps 500 nA
Supply Current, Shutdown VA= +5.25V, fSCLK = 20 MHz,
(CS high) 60 µA
fSAMPLE = 0 ksps SOT-23 16 mW
VA= +5V 10
Power Consumption, (max)
WSON 13
Normal Mode (Operational, SOT-23 4.5 mW
CS low) VA= +3V 2.0 (max)
WSON 3.3
PDVA= +5V, fSCLK = 0 MHz, 2.5 µW
fSAMPLE = 0 ksps
Power Consumption,
Shutdown (CS high) VA= +5V, fSCLK = 20 MHz, 300 µW
fSAMPLE = 0 ksps
AC ELECTRICAL CHARACTERISTICS
MHz
10 (min)
fSCLK Clock Frequency (3) MHz
20 (max)
ksps
50 500 (min)
fSSample Rate (3) Msps
1(max)
SCLk
tHOLD Hold Time 13 Falling
Edges
40 % (min)
DC SCLK Duty Cycle fSCLK = 20 MHz 50 60 % (max)
Minimum Time Required for
tACQ 350 ns (max)
Acquisition
tQUIET (4) 50 ns (min)
tAD Aperture Delay 3 ns
tAJ Aperture Jitter 30 ps
(3) This is the frequency range over which the electrical performance is ensured. The device is functional over a wider range which is
specified under Operating Ratings.
(4) Minimum Quiet Time required by bus relinquish and the start of the next conversion.
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IOL
200 PA
IOH
200 PA
1.6 V
To Output Pin
CL
25 pF
ADC081S101
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www.ti.com
ADC081S101 Timing Specifications
The following specifications apply for VA= +2.7V to 5.25V, GND = 0V, fSCLK = 10.0 MHz to 20.0 MHz, CL= 25 pF, fSAMPLE =
500 ksps to 1 Msps, Boldface limits apply for TA= TMIN to TMAX: all other limits TA= 25°C.
Symbol Parameter Conditions Typical Limits Units
tCS Minimum CS Pulse Width 10 ns (min)
tSU CS to SCLK Setup Time 10 ns (min)
tEN Delay from CS Until SDATA TRI-STATE Disabled (1) 20 ns (max)
VA= +2.7 to +3.6 40 ns (max)
tACC Data Access Time after SCLK Falling Edge (2) VA= +4.75 to +5.25 20 ns (max)
tCL SCLK Low Pulse Width 0.4 x tSCLK ns (min)
tCH SCLK High Pulse Width 0.4 x tSCLK ns (min)
VA= +2.7 to +3.6 7ns (min)
tHSCLK to Data Valid Hold Time VA= +4.75 to +5.25 5ns (min)
25 ns (max)
VA= +2.7 to +3.6 6ns (min)
tDIS SCLK Falling Edge to SDATA High Impedance (3) 25 ns (max)
VA= +4.75 to +5.25 5ns (min)
tPOWER- Power-Up Time from Full Power-Down 1 µs
UP
(1) Measured with the timing test circuit shown in Figure 2 and defined as the time taken by the output signal to cross 1.0V.
(2) Measured with the timing test circuit shown in Figure 2 and defined as the time taken by the output signal to cross 1.0V or 2.0V.
(3) tDIS is derived from the time taken by the outputs to change by 0.5V with the timing test circuit shown in Figure 2. The measured number
is then adjusted to remove the effects of charging or discharging the output capacitance. This means that tDIS is the true bus relinquish
time, independent of the bus loading.
Timing Diagrams
Figure 2. Timing Test Circuit
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Z2 Z1 Z0 DB7 Zero Zero Zero Zero
tQUIET
Track
3 leading zero bits 8 data bits
CS
SCLK
SDATA
1 2 3 4 5 12 13 14 15 16
TRI-STATE
||
|
tSU tCL
tEN tCH tACC tHtDIS
tCS
Hold
tACQ
17 18 19 20
4 trailing zeroes
ADC081S101
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Figure 3. ADC081S101 Serial Timing Diagram
Specification Definitions
ACQUISITION TIME is the time required to acquire the input voltage. That is, it is time required for the hold
capacitor to charge up to the input voltage. Acquisition time is measured backwards from the falling edge
of CS when the signal is sampled and the part moves from track to hold. The start of the time interval that
contains TACQ is the 13th rising edge of SCLK of the previous conversion when the part moves from hold
to track. The user must ensure that the time between the 13th rising edge of SCLK and the falling edge of
the next CS is not less than TACQ to meet performance specifications.
APERTURE DELAY is the time after the falling edge of CS 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.
CONVERSION TIME is the time required, after the input voltage is acquired, for the ADC to convert the input
voltage to a digital word. This is from the falling edge of CS when the input signal is sampled to the 16th
falling edge of SCLK when the SDATA output goes into TRI-STATE.
DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1
LSB.
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 SCLK.
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 of the last code transition (111...110) to (111...111) from the ideal (VREF −1 LSB),
after adjusting for offset error.
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 sum of the power in both of the
original frequencies. IMD is usually expressed in dB.
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2
1f
2
6f
2
2f
10
AA++A
log20=THD
ADC081S101
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MISSING CODES are those output codes that will never appear at the ADC outputs. The ADC081S101 is
ensured not to have any missing codes.
OFFSET ERROR is the deviation of the first code transition (000...000) to (000...001) from the ideal (i.e. GND +
1 LSB).
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 dB or dBc, of the rms total of the first five
harmonic components at the output to the rms level of the input signal frequency as seen at the output.
THD is calculated as
where
• Af1is the RMS power of the input frequency at the output
• Af2through Af6are the RMS power in the first 5 harmonic frequencies (1)
TOTAL UNADJUSTED ERROR is the worst deviation found from the ideal transfer function. As such, it is a
comprehensive specification which includes full scale error, linearity error, and offset error.
THROUGHPUT TIME is the minimum time required between the start of two successive conversion. It is the
acquisition time plus the conversion time.
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Typical Performance Characteristics
TA= +25°C, fSAMPLE = 500 ksps to 1 Msps, fSCLK = 10 MHz to 20 MHz, fIN = 100 kHz unless otherwise stated.
DNL INL
fSCLK = 10 MHz fSCLK = 10 MHz
Figure 4. Figure 5.
DNL INL
fSCLK = 20 MHz fSCLK = 20 MHz
Figure 6. Figure 7.
DNL INL
vs vs
Clock Frequency Clock Frequency
Figure 8. Figure 9.
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Typical Performance Characteristics (continued)
TA= +25°C, fSAMPLE = 500 ksps to 1 Msps, fSCLK = 10 MHz to 20 MHz, fIN = 100 kHz unless otherwise stated.
Total Unadjusted Error SNR
vs vs
Clock Frequency Clock Frequency
Figure 10. Figure 11.
SINAD THD
vs. vs.
Clock Frequency Clock Frequency
Figure 12. Figure 13.
SFDR
vs. Spectral Response, VA= 5V
Clock Frequency fSCLK = 10 MHz
Figure 14. Figure 15.
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Typical Performance Characteristics (continued)
TA= +25°C, fSAMPLE = 500 ksps to 1 Msps, fSCLK = 10 MHz to 20 MHz, fIN = 100 kHz unless otherwise stated.
Power Consumption
vs.
Spectral Response, VA= 5V Throughput,
fSCLK = 20 MHz fSCLK = 20 MHz
Figure 16. Figure 17.
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GND
SAMPLING
CAPACITOR
SW1
-
+CONTROL
LOGIC
CHARGE
REDISTRIBUTION
DAC
SW2
VIN
VA
2
GND
SAMPLING
CAPACITOR
SW1
-
+CONTROL
LOGIC
CHARGE
REDISTRIBUTION
DAC
SW2
VIN
VA
2
ADC081S101
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APPLICATIONS INFORMATION
ADC081S101 Operation
The ADC081S101 is a successive-approximation analog-to-digital converter designed around a charge-
redistribution digital-to-analog converter core. Simplified schematics of the ADC081S101 in both track and hold
operation are shown in Figure 18 and Figure 19, respectively. In Figure 18, the device is in track mode: switch
SW1 connects the sampling capacitor to the input, and SW2 balances the comparator inputs. The device is in
this state until CS is brought low, at which point the device moves to hold mode.
Figure 19 shows the device in hold mode: switch SW1 connects the sampling capacitor to ground, maintaining
the sampled voltage, and switch SW2 unbalances the comparator. The control logic then instructs the charge-
redistribution DAC to add or subtract fixed amounts of charge from the sampling capacitor until the comparator is
balanced. When the comparator is balanced, the digital word supplied to the DAC is the digital representation of
the analog input voltage. The device moves from hold mode to track mode on the 13th rising edge of SCLK.
Figure 18. ADC081S101 in Track Mode
Figure 19. ADC081S101 in Hold Mode
Using the ADC081S101
The serial interface timing diagram for the ADC is shown in Figure 3. CS is chip select, which initiates
conversions on the ADC and frames the serial data transfers. SCLK (serial clock) controls both the conversion
process and the timing of serial data. SDATA is the serial data out pin, where a conversion result is found as a
serial data stream.
Basic operation of the ADC begins with CS going low, which initiates a conversion process and data transfer.
Subsequent rising and falling edges of SCLK will be labelled with reference to the falling edge of CS; for
example, "the third falling edge of SCLK" shall refer to the third falling edge of SCLK after CS goes low.
At the fall of CS, the SDATA pin comes out of TRI-STATE, and the converter moves from track mode to hold
mode. The input signal is sampled and held for conversion on the falling edge of CS. The converter moves from
hold mode to track mode on the 13th rising edge of SCLK (see Figure 3). It is at this point that the interval for the
TACQ specification begins. At least 350ns must pass between the 13th rising edge of SCLK and the next falling
edge of CS. The SDATA pin will be placed back into TRI-STATE after the 16th falling edge of SCLK, or at the
rising edge of CS, whichever occurs first. After a conversion is completed, the quiet time tQUIET must be satisfied
before bringing CS low again to begin another conversion.
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000...001
000...010
0V
011...111
111...000
000...000
111...111
111...110
ADC CODE
ANALOG INPUT
1 LSB = VA/256
1 LSB +VA-1 LSB
||
|
ADC081S101
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Sixteen SCLK cycles are required to read a complete sample from the ADC. The sample bits (including leading
or trailing zeroes) are clocked out on falling edges of SCLK, and are intended to be clocked in by a receiver on
subsequent falling edges of SCLK. The ADC will produce three leading zero bits on SDATA, followed by eight
data bits, most significant first. After the data bits, the ADC will clock out four trailing zeros.
If CS goes low before the rising edge of SCLK, an additional (fourth) zero bit may be captured by the next falling
edge of SCLK.
Determining Throughput
Throughput depends on the frequency of SCLK and how much time is allowed to elapse between the end of one
conversion and the start of another. At the maximum specified SCLK frequency, the maximum ensured
throughput is obtained by using a 20 SCLK frame. As shown in Figure 3, the minimum allowed time between CS
falling edges is determined by 1) 12.5 SCLKs for Hold mode, 2) the larger of two quantities: either the minimum
required time for Track mode (tACQ) or 2.5 SCLKs to finish reading the result and 3) 0, 1/2 or 1 SCLK padding to
ensure an even number of SCLK cycles so there is a falling SCLK edge when CS next falls. For example, at the
fastest rate for this family of parts, SCLK is 20MHz and 2.5 SCLKs are 125ns, so the minimum time between CS
falling edges is calculated by:
12.5*50ns + 350ns + 0.5*50ns = 1000ns (2)
(12.5 SCLKs + tACQ + 1/2 SCLK) which corresponds to a maximum throughput of 1MSPS. At the slowest rate for
this family, SCLK is 1MHz. Using a 20-cycle conversion frame as shown in Figure 3 yields a 20μs time between
CS falling edges for a throughput of 50KSPS.
It is possible, however, to use fewer than 20 clock cycles provided the timing parameters are met. With a 1MHz
SCLK, there are 2500ns in 2.5 SCLK cycles, which is greater than tACQ. After the last data bit has come out, the
clock will need one full cycle to return to a falling edge. Thus the total time between falling edges of CS is
12.5*1μs +2.5*1μs +1*1μs=16μs which is a throughput of 62.5KSPS.
ADC081S101 Transfer Function
The output format of the ADC is straight binary. Code transitions occur midway between successive integer LSB
values. The LSB width for the ADC is VA/256. The ideal transfer characteristic is shown in Figure 20. The
transition from an output code of 0000 0000 to a code of 0000 0001 is at 1/2 LSB, or a voltage of VA/512. Other
code transitions occur at steps of one LSB.
Figure 20. Ideal Transfer Characteristic
Copyright © 2006–2014, Texas Instruments Incorporated Submit Documentation Feedback 13
Product Folder Links: ADC081S101
VIN
D1
R1
C2
26 pF
VA
D2
C1
4 pF
Conversion Phase - Switch Open
Track Phase - Switch Closed
ADC081S101
SNAS310D –JANUARY 2006–REVISED JANUARY 2014
www.ti.com
Typical Application Circuit
A typical application of the ADC is shown in Figure 21. Power is provided in this example by the TI LP2950 low-
dropout voltage regulator, available in a variety of fixed and adjustable output voltages. The power supply pin is
bypassed with a capacitor network located close to the ADC. Because the reference for the ADC is the supply
voltage, any noise on the supply will degrade device noise performance. To keep noise off the supply, use a
dedicated linear regulator for this device, or provide sufficient decoupling from other circuitry to keep noise off the
ADC supply pin. Because of the ADC's low power requirements, it is also possible to use a precision reference
as a power supply to maximize performance. The four-wire interface is also shown connected to a
microprocessor or DSP.
Figure 21. Typical Application Circuit
Analog Input
An equivalent circuit for the ADC's input channel is shown in Figure 22. Diodes D1 and D2 provide ESD
protection for the analog inputs. At no time should any input go beyond (VA+ 300 mV) or (GND −300 mV), as
these ESD diodes will begin conducting, which could result in erratic operation. For this reason, the ESD diodes
should not be used to clamp the input signal.
The capacitor C1 in Figure 22 has a typical value of 4 pF, and is mainly the package pin capacitance. Resistor
R1 is the on resistance of the multiplexer and track / hold switch, and is typically 500Ω. Capacitor C2 is the ADC
sampling capacitor and is typically 26 pF. The ADC will deliver best performance when driven by a low-
impedance source to eliminate distortion caused by the charging of the sampling capacitance. This is especially
important when using the ADC to sample AC signals. Also important when sampling dynamic signals is an anti-
aliasing filter.
Figure 22. Equivalent Input Circuit
Digital Inputs and Outputs
The ADC digital inputs (SCLK and CS) are not limited by the same absolute maximum ratings as the analog
inputs. The digital input pins are instead limited to +5.25V with respect to GND, regardless of VA, the supply
voltage. This allows the ADC to be interfaced with a wide range of logic levels, independent of the supply
voltage.
14 Submit Documentation Feedback Copyright © 2006–2014, Texas Instruments Incorporated
Product Folder Links: ADC081S101
ADC081S101
www.ti.com
SNAS310D –JANUARY 2006–REVISED JANUARY 2014
Modes of Operation
The ADC has two possible modes of operation: normal mode, and shutdown mode. The ADC enters normal
mode (and a conversion process is begun) when CS is pulled low. The device will enter shutdown mode if CS is
pulled high before the tenth falling edge of SCLK after CS is pulled low, or will stay in normal mode if CS remains
low. Once in shutdown mode, the device will stay there until CS is brought low again. By varying the ratio of time
spent in the normal and shutdown modes, a system may trade-off throughput for power consumption, with a
sample rate as low as zero.
Normal Mode
The fastest possible throughput is obtained by leaving the ADC in normal mode at all times, so there are no
power-up delays. To keep the device in normal mode continuously, CS must be kept low until after the 10th
falling edge of SCLK after the start of a conversion (remember that a conversion is initiated by bringing CS low).
If CS is brought high after the 10th falling edge, but before the 16th falling edge, the device will remain in normal
mode, but the current conversion will be aborted, and SDATA will return to TRI-STATE (truncating the output
word).
Sixteen SCLK cycles are required to read all of a conversion word from the device. After sixteen SCLK cycles
have elapsed, CS may be idled either high or low until the next conversion. If CS is idled low, it must be brought
high again before the start of the next conversion, which begins when CS is again brought low.
After sixteen SCLK cycles, SDATA returns to TRI-STATE. Another conversion may be started, after tQUIET has
elapsed, by bringing CS low again.
Shutdown Mode
Shutdown mode is appropriate for applications that either do not sample continuously, or it is acceptable to trade
throughput for power consumption. When the ADC is in shutdown mode, all of the analog circuitry is turned off.
To enter shutdown mode, a conversion must be interrupted by bringing CS back high anytime between the
second and tenth falling edges of SCLK, as shown in Figure 23. Once CS has been brought high in this manner,
the device will enter shutdown mode; the current conversion will be aborted and SDATA will enter TRI-STATE. If
CS is brought high before the second falling edge of SCLK, the device will not change mode; this is to avoid
accidentally changing mode as a result of noise on the CS line.
Figure 23. Entering Shutdown Mode
Figure 24. Entering Normal Mode
To exit shutdown mode, bring CS back low. Upon bringing CS low, the ADC will begin powering up (power-up
time is specified in the ADC081S101 Timing Specifications table). This power-up delay results in the first
conversion result being unusable. The second conversion performed after power-up, however, is valid, as shown
in Figure 24.
Copyright © 2006–2014, Texas Instruments Incorporated Submit Documentation Feedback 15
Product Folder Links: ADC081S101
ADC081S101
SNAS310D –JANUARY 2006–REVISED JANUARY 2014
www.ti.com
If CS is brought back high before the 10th falling edge of SCLK, the device will return to shutdown mode. This is
done to avoid accidentally entering normal mode as a result of noise on the CS line. To exit shutdown mode and
remain in normal mode, CS must be kept low until after the 10th falling edge of SCLK. The ADC will be fully
powered-up after 16 SCLK cycles.
Power Management
The ADC takes time to power-up, either after first applying VA, or after returning to normal mode from shutdown
mode. This corresponds to one "dummy" conversion for any SCLK frequency within the specifications in this
document. After this first dummy conversion, the ADC will perform conversions properly. Note that the tQUIET time
must still be included between the first dummy conversion and the second valid conversion.
When the VAsupply is first applied, the ADC may power up in either of the two modes: normal or shutdown. As
such, one dummy conversion should be performed after start-up, as described in the previous paragraph. The
part may then be placed into either normal mode or the shutdown mode, as described in Normal Mode and
Shutdown Mode.
When the ADC is operated continuously in normal mode, the maximum ensured throughput is fSCLK / 20 at the
maximum specified fSCLK. Throughput may be traded for power consumption by running fSCLK at its maximum
specified rate and performing fewer conversions per unit time, raising the ADC CS line after the 10th and before
the 15th fall of SCLK of each conversion. A plot of typical power consumption versus throughput is shown in the
Typical Performance Characteristics section. To calculate the power consumption for a given throughput, multiply
the fraction of time spent in the normal mode by the normal mode power consumption and add the fraction of
time spent in shutdown mode multiplied by the shutdown mode power consumption. Note that the curve of power
consumption vs. throughput is essentially linear. This is because the power consumption in the shutdown mode
is so small that it can be ignored for all practical purposes.
Power Supply Noise Considerations
The charging of any output load capacitance requires current from the power supply, VA. The current pulses
required from the supply to charge the output capacitance will cause voltage variations on the supply. If these
variations are large enough, they could degrade SNR and SINAD performance of the ADC. Furthermore,
discharging the output capacitance when the digital output goes from a logic high to a logic low will dump current
into the die substrate, which is resistive. Load discharge currents will cause "ground bounce" noise in the
substrate that will degrade noise performance if that current is large enough. The larger the output capacitance,
the more current flows through the die substrate and the greater is the noise coupled into the analog channel,
degrading noise performance.
To keep noise out of the power supply, keep the output load capacitance as small as practical. It is good practice
to use a 100Ωseries resistor at the ADC output, located as close to the ADC output pin as practical. This will
limit the charge and discharge current of the output capacitance and improve noise performance.
REVISION HISTORY
Changes from Revision C (March 2013) to Revision D Page
• Changed sentence in the "Using the ADC081S101" section ............................................................................................. 12
Changes from Revision B (March 2013) to Revision C Page
• Changed layout of National Data Sheet to TI format .......................................................................................................... 16
16 Submit Documentation Feedback Copyright © 2006–2014, Texas Instruments Incorporated
Product Folder Links: ADC081S101
PACKAGE OPTION ADDENDUM
www.ti.com 10-Dec-2020
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
ADC081S101 MWC ACTIVE WAFERSALE YS 0 1 RoHS & Green Call TI Level-1-NA-UNLIM -40 to 85
ADC081S101CIMF/NOPB ACTIVE SOT-23 DBV 6 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 X03C
ADC081S101CIMFX/NOPB ACTIVE SOT-23 DBV 6 3000 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 X03C
ADC081S101CISD/NOPB ACTIVE WSON NGF 6 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 X3C
(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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(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 finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material 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
PACKAGE OPTION ADDENDUM
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Addendum-Page 2
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.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
ADC081S101CIMF/NOPB SOT-23 DBV 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
ADC081S101CIMFX/NOP
BSOT-23 DBV 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
ADC081S101CISD/NOPB WSON NGF 6 1000 178.0 12.4 2.8 2.5 1.0 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 24-Aug-2017
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
ADC081S101CIMF/NOPB SOT-23 DBV 6 1000 210.0 185.0 35.0
ADC081S101CIMFX/NOP
BSOT-23 DBV 6 3000 210.0 185.0 35.0
ADC081S101CISD/NOPB WSON NGF 6 1000 210.0 185.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 24-Aug-2017
Pack Materials-Page 2
www.ti.com
PACKAGE OUTLINE
C
0.22
0.08 TYP
0.25
3.0
2.6
2X 0.95
1.45 MAX
0.15
0.00 TYP
6X 0.50
0.25
0.6
0.3 TYP
8
0 TYP
1.9
A
3.05
2.75
B
1.75
1.45
(1.1)
SOT-23 - 1.45 mm max heightDBV0006A
SMALL OUTLINE TRANSISTOR
4214840/B 03/2018
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. Body dimensions do not include mold flash or protrusion. Mold flash and protrusion shall not exceed 0.15 per side.
4. Leads 1,2,3 may be wider than leads 4,5,6 for package orientation.
5. Refernce JEDEC MO-178.
0.2 C A B
1
34
5
2
INDEX AREA
PIN 1
6
GAGE PLANE
SEATING PLANE
0.1 C
SCALE 4.000
www.ti.com
EXAMPLE BOARD LAYOUT
0.07 MAX
ARROUND 0.07 MIN
ARROUND
6X (1.1)
6X (0.6)
(2.6)
2X (0.95)
(R0.05) TYP
4214840/B 03/2018
SOT-23 - 1.45 mm max heightDBV0006A
SMALL OUTLINE TRANSISTOR
NOTES: (continued)
6. Publication IPC-7351 may have alternate designs.
7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
SYMM
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE:15X
PKG
1
34
5
2
6
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
SOLDER MASK
DEFINED
EXPOSED METAL
METAL
SOLDER MASK
OPENING
NON SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK DETAILS
EXPOSED METAL
www.ti.com
EXAMPLE STENCIL DESIGN
(2.6)
2X(0.95)
6X (1.1)
6X (0.6)
(R0.05) TYP
SOT-23 - 1.45 mm max heightDBV0006A
SMALL OUTLINE TRANSISTOR
4214840/B 03/2018
NOTES: (continued)
8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
9. Board assembly site may have different recommendations for stencil design.
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
SCALE:15X
SYMM
PKG
1
34
5
2
6
MECHANICAL DATA
NGF0006A
www.ti.com
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