THS12082QDAR [TI]
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| 型号： | THS12082QDAR |
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TEXAS INSTRUMENTS |
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
DA PACKAGE
(TOP VIEW)
features
Simultaneous Sampling of 2 Single-Ended
Signals or 1 Differential Signal
D0
D1
D2
D3
D4
D5
OV_FL
RESET
AINP
1
32
31
30
29
28
27
26
25
24
23
22
Integrated 16 Word FIFO
2
Signal-to-Noise and Distortion Ratio: 66 dB
3
AINM
at f = 2 MHz
4
I
REFIN
REFOUT
REFP
5
Differential Nonlinearity Error: ±1 LSB
Integral Nonlinearity Error: ±1.5 LSB
Auto-Scan Mode for 2 Inputs
6
BV
7
DD
BGND
D6
REFM
AGND
8
3-V or 5-V Digital Interface Compatible
Low Power: 216 mW Max
9
D7
AV
10
11
DD
D8
CS0
5-V Analog Single Supply Operation
D9 12
RA0/D10 13
RA1/D11 14
21 CS1
Internal Voltage References . . . 50 PPM/°C
and ±5% Accuracy
20 WR (R/W)
19 RD
Parallel µC/DSP Interface
15
16
18
17
CONV_CLK (CONVST)
DATA_AV
DV
DD
DGND
applications
Radar Applications
Communications
Control Applications
High-Speed DSP Front-End
Automotive Applications
description
The THS12082 is a CMOS, low-power, 12-bit, 8 MSPS analog-to-digital converter (ADC). The speed,
resolution, bandwidth, and single-supply operation are suited for applications in radar, imaging, high-speed
acquisition, and communications. A multistage pipelined architecture with output error correction logic provides
for no missing codes over the full operating temperature range. Internal control registers allow for programming
the ADC into the desired mode. The THS12082 consists of two analog inputs, which are sampled
simultaneously. These inputs can be selected individually and confugured to single-ended or differential inputs.
An integrated 16 word deep FIFO allows the storage of data in order to take the load off of the processor
connected to the ADC. Internal reference voltages for the ADC (1.5 V and 3.5 V) are provided.
An external reference can also be chosen to suit the dc accuracy and temperature drift requirements of the
application. Two different conversion modes can be selected. In the single conversion mode, a single and
simultaneousconversion can be initiated by using the single conversion start signal (CONVST). The conversion
clock in the single conversion mode is generated internally using a clock oscillator circuit. In the continuous
conversion mode, an external clock signal is applied to the CONV_CLK input of the THS12082. The internal
clock oscillator is switched off in the continuous conversion mode.
The THS12082C is characterized for operation from 0°C to 70°C, and the THS12082I is characterized for
operation from –40°C to 85°C.
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.
Copyright 2000, Texas Instruments Incorporated
PRODUCT PREVIEW information concerns products in the formative or
design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the right to
change or discontinue these products without notice.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
AVAILABLE OPTIONS
PACKAGED DEVICE
T
A
TSSOP
(DA)
0°C to 70°C
THS12082CDA
THS12082IDA
–40°C to 85°C
functional block diagram
AV
DD
DV
DD
3.5 V
1.5 V
2.5 V
REFP
1.225 V
REF
REFOUT
REFM
REFIN
DATA_AV
OV_FL
REFP
REFM
12
BV
DD
Single-Ended
and/or
Differential
MUX
+
–
12-Bit
Pipeline
ADC
12
FIFO
16 × 12
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
S/H
AINP
AINM
S/H
Buffers
CONV_CLK (CONVST)
D10/RA0
D11/RA1
CS0
CS1
Logic
and
Control
Control
Register
BGND
RD
WR (R/W)
RESET
AGND
DGND
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
Terminal Functions
TERMINAL
NAME
AINP
AINM
AV
I/O
DESCRIPTION
NO.
30
29
23
24
7
I
I
I
I
I
I
I
Analog input, single-ended or positive input of differential channel A
Analog input, single-ended or negative input of differential channel A
Analog supply voltage
DD
AGND
BV
Analog ground
Digital supply voltage for buffer
DD
BGND
8
Digital ground for buffer
CONV_CLK
(CONVST)
15
Digitalinput. Thisinputisusedtoapplyanexternalconversionclockinthecontinuousconversionmode.
In the single conversion mode, this input functions as the conversion start (CONVST)input. Ahightolow
transition on this input holds simultaneously the selected analog input channels and initiates a single
conversion of all selected analog inputs.
CS0
22
21
16
I
I
Chip select input (active low)
Chip select input (active high)
CS1
DATA_AV
O
Data available signal, which can be used to generate an interrupt for processors and as a level
information of the internal FIFO. This signal can be configured to be active low or high and can be
configured as a static level or pulse output. See Table 7.
DGND
17
18
I
I
Digital ground. Ground reference for digital circuitry.
Digital supply voltage
DV
DD
D0 – D9
1–6, 9–12
13
I/O/Z Digital input, output; D0 = LSB
RA0/D10
I/O/Z Digital input, output. The data line D10 is also used as an address line (RA0) for the control register. This
is required for writing to control register 0 and control register 1. See Table 8.
RA1/D11
OV_FL
REFIN
REFP
14
32
28
26
I/O/Z Digital input, output (D11 = MSB). The data line D11 is also used as an address line (RA1) for the control
register. This is required for writing to control register 0 and control register 1. See Table 8.
O
Overflow output. Indicates whether an overflow in the FIFO occurred. OV_FL is set to active high level if
an overflow occurs. It is set back to low level with a reset of the THS12082 or a reset of the FIFO.
I
Common-mode reference input for the analog input channels. It is recommended that this pin be
connected to the reference output REFOUT.
I
Reference input, requires a bypass capacitor of 10 µF to AGND in order to bypass the internal reference
voltage. An external reference voltage at this input can be applied. This option can be programmed
through control register 0. See Table 6.
REFM
25
I
Reference input, requires a bypass capacitor of 10 µF to AGND in order to bypass the internal reference
voltage. An external reference voltage at this input can be applied. This option can be programmed
through control register 0. See Table 6.
RESET
31
27
I
Hardware reset of the THS12082. Sets the control register to default values.
REFOUT
O
Analog fixed reference output voltage of 2.5 V. Sink and source capability of 250 µA. The reference
output requires a capacitor of 10 µF to AGND for filtering and stability.
†
RD
19
20
I
I
TheRDinputisusedonlyiftheWRinputisconfiguredasawriteonlyinput.Inthiscase,itisadigitalinput,
active low as a data read select from the processor. See timing section.
†
WR (R/W)
This input is programmable. It functions as a read-write input (R/W) and can also be configured as a
write-only input (WR), which is active low and used as data write select from the processor. In this case,
the RD input is used as a read input from the processor. See timing section.
†
The start-conditions of RD and WR (R/W) are unknown. The first access to the ADC has to be a write access to initialize the ADC.
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
†
absolute maximum ratings over operating free-air temperature (unless otherwise noted)
Supply voltage range: DGND to DV
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6.5 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6.5 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6.5 V
DD
DD
DD
BGND to BV
AGND to AV
Analog input voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AGND – 0.3 V to AV
Reference input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 + AGND to AV
Digital input voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to BV /DV
Operating virtual junction temperature range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 150°C
+ 1.5 V
+ 0.3 V
+ 0.3 V
DD
DD
DD
DD
J
Operating free-air temperature range: THS12082C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
THS12082I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 85°C
Storage temperature range, T
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
stg
†
Stresses beyond those listed under “absolute maximum ratings” may cause permenent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
recommended operating conditions
power supply
MIN NOM
MAX
5.25
5.25
5.25
UNIT
AV
DD
4.75
3
5
3.3
3.3
Supply voltage
DV
V
DD
DD
BV
3
analog and reference inputs
MIN NOM
MAX
UNIT
Analog input voltage in single-ended configuration
V
V
V
V
V
V
V
REFM
REFP
4
Common-mode input voltage V
in differential configuration
(optional)
1
2.5
CM
External reference voltage,V
3.5 AV –1.2
DD
REFP
External reference voltage, V
REFM
(optional)
1.4
1.5
2
Input voltage difference, REFP – REFM
digital inputs
MIN NOM
MAX
UNIT
V
BV
BV
BV
BV
DV
DV
= 3 V
2
DD
DD
DD
DD
DD
DD
High-level input voltage, V
IH
= 5.25 V
2.6
V
= 3 V
0.6
0.6
V
Low-level input voltage, V
IL
= 5.25 V
V
Input CONV_CLK frequency
= 3 V to 5.25 V
= 3 V to 5.25 V
0.1
62
8
MHz
ns
CONV_CLK pulse duration, clock high, t
83
83
5000
w(CONV_CLKH)
CONV_CLK pulse duration, clock low, t
DV
= 3 V to 5.25 V
62
0
5000
70
ns
w(CONV_CLKL)
DD
THS12082CDA
THS12082IDA
Operating free-air temperature, T
°C
A
–40
85
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
electrical characteristics over recommended operating conditions, V
(unless otherwise noted)
= 3.5 V, V
= 1.5 V
REFP
REFM
digital specifications
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Digital inputs
I
I
High-level input current
DV
= digital inputs
DD
–50
–50
50
50
µA
µA
pF
IH
Low-level input current
Input capacitance
Digital input = 0 V
IL
C
5
i
Digital outputs
V
High-level output voltage
I
I
= –50 µA, BV
= 3.3 V, 5 V BV –0.5
DD
V
V
OH
OL
OH
DD
V
Low-level output voltage
= 50 µA,
BV
= 3.3 V, 5 V
0.4
10
OL
DD
I
High-impedance-state output current
Output capacitance
CS1 = DGND,
CS0 = DVDD
–10
µA
pF
pF
OZ
C
C
5
O
L
Load capacitance at databus D0 – D11
30
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
electrical characteristics over recommended operating conditions, AV
= 5 V,
DD
DV
= BV
= 3.3-V, f = 8 MSPS, V
= internal (unless otherwise noted)
DD
DD
s
REF
dc specifications
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Resolution
12
Bits
Accuracy
Integral nonlinearity, INL
±1.5
±1
LSB
LSB
mV
Differential nonlinearity, DNL
After calibration in single-ended mode
After calibration in differential mode
–15
–5
15
Offset error
5
mV
Gain error
1%
FSR
Analog input
Input capacitance
15
pF
Input leakage current
V
AIN
= V
to V
REFP
±10
µA
REFM
Internal voltage reference
Accuracy, V
3.33
1.42
3.5
1.5
50
3.67
1.58
V
REFP
REFM
Accuracy, V
V
PPM/°C
µV
Temperature coefficient
Reference noise
100
Accuracy, REFOUT
2.475
2.5 2.525
V
Power supply
I
I
I
I
Analog supply current
AV
AV
AV
AV
AV
AV
=5 V, BV
= 5 V, BV
= 5 V, BV
= 5 V, BV
= 5 V, DV
= 5 V, DV
= DV
= DV
= DV
= DV
= BV
= BV
= 3.3 V
= 3.3 V
= 3.3 V
= 3.3 V
= 3.3 V
= 3.3 V
36
0.5
1.5
40
1
mA
mA
mA
mA
mW
mW
DDA
DDD
DDB
DD_P
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
Digital supply voltage
Buffer supply voltage
4
Supply current in power-down mode
Power dissipation
7
186
30
216
Power dissipation in power down
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
electrical characteristics over recommended operating conditions, V
I
= internal, f = 8 MSPS,
s
REF
f = 2 MHz at –1dBFS (unless otherwise noted)
ac specifications, AV
= 5 V, BV
= DV
= 3.3 V, C < 30 pF
DD L
DD
DD
PARAMETER
TEST CONDITIONS
MIN
TYP
68
MAX
UNIT
dB
Differential mode
63
SINAD Signal-to-noise ratio + distortion
Single-ended mode (see Note 1)
Differential mode
64
dB
64
69
dB
SNR
THD
Signal-to-noise ratio
Single-ended mode (see Note 1)
Differential mode
65
dB
–73
–73
11
–69
–69
dB
Total harmonic distortion
Effective number of bits
Single-ended mode
dB
Differential mode
10.3
Bits
Bits
dB
ENOB
(SNR)
Single-ended mode (see Note 1)
Differential mode
10.4
75
68
68
SFDR Spurious free dynamic range
Single-ended mode
75
dB
Analog Input
Full-power bandwidth with a source impedance of
150 Ω in differential configuration.
Full scale sinewave, –3 dB
Full scale sinewave, –3 dB
100 mVpp sinewave, –3 dB
100 mVpp sinewave, –3 dB
96
54
96
54
MHz
MHz
MHz
MHz
Full-power bandwidth with a source impedance of
150 Ω in single-ended configuration.
Small-signal bandwidth with a source impedance of
150 Ω in differential configuration.
Small-signal bandwidth with a source impedance of
150 Ω in single-ended configuration.
NOTE 1: The SNR (ENOB) and SINAD is degraded typically by 2 dB in single-ended mode when the reading of data is asynchronous to the
sampling clock.
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
timing specifications (AV
= BV
= DV
= 5 V, V
= 3.5 V, V
= 1.5 V, C < 30 pF
REFM L
DD
DD
DD
REFP
PARAMETER
TEST CONDITIONS
MIN
TYP
5
MAX
UNIT
ns
t
t
Delay time
Delay time
d(DATA_AV)
5
ns
d(o)
CONV
CLK
t
Latency
5
d(pipe)
timing specification of the single conversion mode
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ns
t
t
t
Clock cycle of the internal clock oscillator
Pulse duration, CONVST
Aperture time
119
125
131
c
1.5×t
ns
w1
dA
c
1
ns
1 analog input
2×t
3×t
c
t
Time between consecutive start of single conversion
ns
ns
ns
ns
ns
2
2 analog inputs
c
1 analog input, TL = 1
2 analog inputs, TL = 2
1 analog input, TL = 4
2 analog inputs, TL = 4
1 analog input, TL = 8
2 analog inputs, TL = 8
1 analog input, TL = 14
2 analog inputs, TL = 12
6×t
7×t
c
c
c
c
c
c
c
c
3×t +6×t
2
t
2
+7×t
Delay time, DATA_AV becomes active for the trigger
level condition: TRIG0 = 1, TRIG1 = 1
t
d(DATA_AV)
7×t +6×t
2
3×t +7×t
2
13×t +6×t
2
5×t +7×t
2
8
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
detailed description
reference voltage
The THS12082 has a built-in reference, which provides the reference voltages for the ADC. VREFP is set to
3.5 V and VREFM is set to 1.5 V. Anexternalreferencecanalsobeusedthroughtworeferenceinputpins, REFP
andREFM, ifthereferencesourceisprogrammedasexternal. Thevoltagelevelsappliedtothesepinsestablish
the upper and lower limits of the analog inputs to produce a full-scale and zero-scale reading respectively.
analog inputs
The THS12082 consists of two analog inputs, which are sampled simultaneously. These inputs can be selected
individually and configured as single-ended or differential inputs. The desired analog input channel can be
programmed.
analog-to-digital converter
The THS12082 uses a 12-bit pipelined multistaged architecture with four 1-bit stages followed by four 2-bit
stages, which achieves a high sample rate with low power consumption. The THS12082 distributes the
conversion over several smaller ADC subblocks, refining the conversion with progressively higher accuracy as
the device passes the results from stage to stage. This distributed conversion requires a small fraction of the
number of comparators used in a traditional flash ADC. A sample-and-hold amplifier (SHA) within each of the
stages permits the first stage to operate on a new input sample while the second through the eighth stages
operate on the seven preceding samples.
conversion modes
The conversion can be performed in two different conversion modes. In the single conversion mode, the
conversion is initiated by an external signal (CONVST). An internal oscillator controls the conversion time. In
the continuous conversion mode, an external clock signal is applied to the clock input (CONV_CLK). A new
conversion is started with every falling edge of the applied clock signal.
sampling rate
The maximum possible conversion rate per channel is dependent on the selected analog input channels. Table
1 shows the maximum conversion rate in the continuous conversion mode for different combinations.
Table 1. Maximum Conversion Rate
MAXIMUM CONVERSION
RATE PER CHANNEL
CHANNEL CONFIGURATION
NUMBER OF CHANNELS
1 single-ended channel
2 single-ended channels
1 differential channel
1
2
1
8 MSPS
4 MSPS
8 MSPS
The maximum conversion rate in the continuous conversion mode per channel, fc, is given by:
8 MSPS
fc
# channels
Table 2 shows the maximum conversion rate in the single conversion mode.
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
sampling rate (continued)
Table 2. Maximum Conversion Rate in Single Conversion Mode
NUMBER OF
CHANNELS
MAXIMUM CONVERSION
RATE PER CHANNEL
CHANNEL CONFIGURATION
1 single-ended channel
1
2
1
4 MSPS
2.67 MSPS
4 MSPS
2 single-ended channels
1 differential channel
In single conversion mode, a single conversion of the selected analog input channels is performed. The single
conversion mode is selected by setting bit 1 of control register 0 to 1.
A single conversion is initiated by pulsing the CONVST input. On the falling edge of CONVST, the sample and
hold stages of the selected analog inputs are placed into hold simultaneously, and the conversion sequence
for the selected channels is started.
Theconversionclockinsingleconversionmodeisgeneratedinternallyusingaclockoscillatorcircuit. Thesignal
DATA_AV (data available) becomes active when the trigger level is reached and indicates that the converted
sample(s) is (are) written into the FIFO and can be read out. The trigger level in the single conversion mode
can be selected according to Table 13.
Figure 1 shows the timing of the single conversion mode. In this mode, up to two analog input channels can be
selected to be sampled simultaneously (see Table 2).
t
2
CONVST
AIN
t
t
1
1
t
d(A)
Sample N
t
DATA_AV
DATA_AV,
Trigger Level = 1
Figure 1. Timing of Single Conversion Mode
The time (t ) between consecutive starts of single conversions is dependent on the number of selected analog
2
input channels. The time t
, until DATA_AV becomes active is given by: t
= t
+ n × t . This
DATA_AV
DATA_AV
pipe c
equation is valid for a trigger level which is equivalent to the number of selected analog input channels. For all
other trigger level conditions refer to the timing specifications of single conversion mode.
10
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
continuous conversion mode
The internal clock oscillator used in the single-conversion mode is switched off in continuous conversion mode.
In continuous conversion mode, (bit 1 of control register 0 set to 0) the ADC operates with a free running
external clock signal CONV_CLK. With every rising edge of the CONV_CLK signal a new converted value is
written into the FIFO. The first conversion value is written into the FIFO with a latency of 8 + TL (trigger level)
clock cycles after the FIFO reset.
Figure 2 shows the timing of continuous conversion mode when one analog input channel is selected. The
maximum throughput rate is 8 MSPS in this mode. The timing of the DATA_AV signal is shown here in the case
of a trigger level set to 1 or 4.
Sample N
Channel 1
Sample N+1 Sample N+2 Sample N+3 Sample N+4 Sample N+5 Sample N+6 Sample N+7 Sample N+8
Channel 1
Channel 1
Channel 1
Channel 1
Channel 1
Channel 1
Channel 1
Channel 1
AIN
t
d(A)
t
d(pipe)
w(CONV_CLKL)
50%
t
t
w(CONV_CLKH)
50%
t
CONV_CLK
t
d(O)
c
Data Into
FIFO
Data N–5
Channel 1
Data N–4
Channel 1
Data N–3
Channel 1
Data N–2
Channel 1
Data N–1
Channel 1
Data N
Channel 1
Data N+1
Channel 1
Data N+2
Channel 1
Data N+3
Channel 1
t
d(DATA_AV)
DATA_AV,
Trigger Level = 1
t
d(DATA_AV)
DATA_AV,
Trigger Level = 4
Figure 2. Timing of Continuous Conversion Mode (1-channel operation)
Figure 3 shows the timing of continuous conversion mode when two analog input channels are selected. The
maximum throughput rate per channel is 4 MSPS in this mode. The data flow in the bottom of the figure shows
theordertheconverteddataiswrittenintotheFIFO. ThetimingoftheDATA_AVsignalshownhereisforatrigger
level set to 2 or 4.
Sample N
Channel 1,2
Sample N+1
Channel 1,2
Sample N+2
Channel 1,2
Sample N+3
Channel 1,2
Sample N+4
Channel 1,2
AIN
t
d(A)
t
d(Pipe)
w(CONV_CLKL)
50%
t
t
w(CONV_CLKH)
50%
CONV_CLK
t
c
t
d(O)
Data Into
FIFO
Data N–3
Channel 2
Data N–2
Channel 1
Data N–2
Channel 2
Data N–1
Channel 1
Data N–1
Channel 2
Data N
Channel 1
Data N
Channel 2
Data N+1
Channel 1
Data N+1
Channel 2
t
d(DATA_AV)
DATA_AV,
Trigger Level = 2
t
d(DATA_AV)
DATA_AV,
Trigger Level = 4
Figure 3. Timing of Continuous Conversion Mode (2-channel operation)
11
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
digital output data format
The digital output data format of the THS12082 can be in either binary format or in twos complement format.
The following tables list the digital outputs for the analog input voltages.
Table 3. Binary Output Format for Single-Ended Configuration
SINGLE-ENDED, BINARY OUTPUT
ANALOG INPUT VOLTAGE
AIN = V
DIGITAL OUTPUT CODE
FFFh
800h
000h
REFP
AIN = (V
+ V
)/2
REFM
REFP
AIN = V
REFM
Table 4. Twos Complement Output Format for Single-Ended Configuration
SINGLE-ENDED, TWOS COMPLEMENT
ANALOG INPUT VOLTAGE
AIN = V
DIGITAL OUTPUT CODE
7FFh
000h
800h
REFP
AIN = (V
+ V
)/2
REFM
REFP
REFM
AIN = V
Table 5. Binary Output Format for Differential Configuration
DIFFERENTIAL, BINARY OUTPUT
ANALOG INPUT VOLTAGE
DIGITAL OUTPUT CODE
V
= AINP – AINM
in
V
= V
– V
REFP REFM
REF
V
in
V
in
V
in
= V
= 0
FFFh
800h
000h
REF
= –V
REF
Table 6. Twos Complement Output Format for Differential Configuration
DIFFERENTIAL, BINARY OUTPUT
ANALOG INPUT VOLTAGE
DIGITAL OUTPUT CODE
V
= AINP – AINM
in
V
= V
– V
REFP REFM
REF
V
in
V
in
V
in
= V
= 0
7FFh
000h
800h
REF
= –V
REF
12
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12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
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FIFO description
In order to facilitate an efficient connection to today’s processors, the THS12082 is supplied with a FIFO. This
integrated FIFO enables a problem-free processing of data. The FIFO is provided as a flexible circular buffer.
The circular buffer integrated in the THS12082 can store up to 16 conversion values. Therefore, the number
of interrupts to be served by a processor can be reduced significantly.
16
1
15
2
Read Pointer
14
3
13
12
4
5
Trigger Pointer
6
11
Data in FIFO
Free
7
10
8
9
Write Pointer
Figure 4. Circular Buffer
The converted data of the THS12082 is automatically written into the FIFO. To control the writing and reading
process, a write pointer, a read pointer, and a trigger pointer are used. The read pointer always shows the
location which will be read next. The write pointer indicates the location which contains the last written sample.
With a selection of multiple analog input channels, the converted values are written in a predefined sequence
to the circular buffer (Autoscan Mode). In this way, the channel information for the reading processor is
continually maintained.
The FIFO can be programmed through the control register of the ADC. The user has the ability to select a
specific trigger level from Table 13 in order to choose the configuration which best fits the application. The FIFO
provides the signal DATA_AV, which signals the processor to read the amount of data equal to the trigger level
selected in Table 13. The signal DATA_AV becomes active when the trigger condition is satisfied. The trigger
condition is satisfied when as many values as selected for the trigger level where written into the FIFO.
The signal DATA_AV could be connected to an interrupt input of a processor. In every interrupt service routine
call, theprocessormustreadtheamountofdataequaltothetriggerlevelfromtheADC. Thefirstdatarepresents
the first channel according to the autoscan mode, which is shown in Table 10. The channel information is
therefore always maintained.
13
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12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
reading data from the FIFO
The THS12082 informs the connected processor via the digital output DATA_AV (data available) that a block
of conversion values is ready to be read. The block size to be read is always equal to the setting of the trigger
level. Theselectabletriggerlevelsdependonthenumberofselectedanaloginputchannels. Forexample, when
choosing one analog input, a trigger level of 1, 4, 8, and 14 can be selected. The following figures demonstrate
the principle of reading the data.
In Figure 5, a trigger level of 1 is selected. The control signal DATA_AV is set to an active low pulse. This means
that the connected processor has the task to read 1 value from the ADC after every DATA_AV low pulse.
CONV_CLK
DATA_AV
READ
Figure 5. Trigger Level 1 Selected
In Figure 6, a trigger level of 4 is selected. The control signal DATA_AV is set to an active low pulse. This means
that the connected processor has the task to read 4 values from the ADC after every DATA_AV low pulse.
CONV_CLK
DATA_AV
READ
Figure 6. Trigger Level 4 Selected
In Figure 7, a trigger level of 8 is selected. The control signal DATA_AV is set to an active low pulse. This means
that the connected processor has the task to read 8 values from the ADC after every DATA_AV low pulse.
CONV_CLK
DATA_AV
READ
Figure 7. Trigger Level 8 Selected
14
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12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
reading data from the FIFO (continued)
In Figure 8, a trigger level of 14 is selected. The control signal DATA_AV is set to an active low pulse. This means
that the connected processor has the task to read 14 values from the ADC after every DATA_AV low pulse.
CONV_CLK
DATA_AV
READ
Figure 8. Trigger Level 14 Selected
READ is always the logical combination of CS0, CS1 and RD.
ADC control register
The THS12082 contains two 10-bit wide control registers (CR0, CR1) in order to program the device into the
desired mode. The bit definitions of both control registers are shown in Table 7.
Table 7. Bit Definitions of Control Register CR0 and CR1
BIT
CR0
CR1
BIT 9
TEST1
RBACK
BIT 8
TEST0
OFFSET
BIT 7
SCAN
BIN/2’s
BIT 6
DIFF1
R/W
BIT 5
DIFF0
BIT 4
BIT 3
CHSEL0
TRIG1
BIT 2
PD
BIT 1
MODE
BIT 0
VREF
CHSEL1
DATA_T
DATA_P
TRIG0
OVFL/FRST
RESET
writing to control register 0 and control register 1
The 10-bit wide control register 0 and control register 1 can be programmed by addressing the desired control
register and writing the register value to the ADC. The addressing is performed with the upper data bits D10
and D11, which function in this case as address lines RA0 and RA1. During this write process, the data bits D0
to D9 contain the desired control register value. Table 8 shows the addressing of each control register.
Table 8. Control Register Addressing
D0 – D9
D10/RA0
D11/RA1
Addressed Control Register
Control register 0
Desired register value
Desired register value
Desired register value
Desired register value
0
1
0
1
0
0
1
1
Control register 1
Reserved for future
Reserved for future
15
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12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
initialization of the THS12082
The initialization of the THS12082 should be done according to the configuration flow shown in Figure 9.
Start
No
Use Default
Values?
Yes
Write 0x401 to
Write 0x401 to
THS12082
THS12082
(Set Reset Bit in
(Set Reset Bit in CR1)
CR1)
Clear RESET By
Writing 0x400 to
CR1
Clear RESET By
Writing 0x400 to
CR1
Write the User
Configuration to
CR0
Write the User
Configuration to
CR1 (Can Include
FIFO Reset, Must
Exclude RESET)
Continue
Figure 9. THS12082 Configuration Flow
16
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
ADC control registers
control register 0 (see Table 8)
–
–
BIT 9
BIT 8
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
–
–
TEST1
TEST0
SCAN
DIFF1
DIFF0
CHSEL1 CHSEL0
PD
MODE
VREF
Table 9. Control Register 0 Bit Functions
RESET
VALUE
BITS
NAME
FUNCTION
0
0
VREF
Vref select:
Bit 0 = 0 → The internal reference is selected.
Bit 0 = 1 → The external reference voltage is selected.
1
0
MODE
Continuous conversion mode/single conversion mode
Bit 1 = 0 → Continuous conversion mode is selected.
An external clock signal is applied to the CONV_CLK input in this mode. With every falling edge of the
CONV_CLK signal a new converted value is written into the FIFO.
Bit 1 = 1 → Single conversion mode is selected.
In this mode, the CONV_CLK input functions as a CONVST input. A single conversion is initiated on the
THS12082 by pulsing the CONVST input. On the falling edge of CONVST, the sample and hold stages of
the selected analog inputs are placed into hold simultaneously, and the conversion sequence for the
selected channels is started. The signal DATA_AV (data available) becomes active when the trigger
condition is satisfied.
2
0
PD
Power down.
Bit 2 = 0 → The ADC is active.
Bit 2 = 1 → Power down
The reading and writing to and from the digital outputs is possible during power down. It is also possible to
read out the FIFO.
3, 4
5,6
7
0,0
1,0
0
CHSEL0,
CHSEL1
Channel select
Bit 3 and bit 4 select the analog input channel of the ADC. Refer to Table 10.
DIFF0, DIFF1 Number of differential channels
Bit 5 and bit 6 contain information about the number of selected differential channels. Refer to Table 10.
SCAN
Autoscan enable
Bit 7 enables or disables the autoscan function of the ADC. Refer to Table 10.
8,9
0,0
TEST0,
TEST1
Test input enable
Bit 8 and bit 9 control the test function of the ADC. Three different test voltages can be measured. This
feedback allows the check of all hardware connections and the ADC operation.
Refer to Table 11 for selection of the three different test voltages.
17
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
analog input channel selection
The analog input channels of the THS12082 can be selected via bits 3 to 7 of control register 0. One single
channel (single-ended or differential) is selected via bit 3 and bit 4 of control register 0. Bit 5 controls the
selection between single-ended and differential configuration. Bit 6 and bit 7 select the autoscan mode, if more
than one input channel is selected. Table 10 shows the possible selections.
Table 10. Analog Input Channel Configurations
BIT 7
AS
BIT 6
DF1
BIT 5
DF0
BIT 4
CHS1
BIT 3
CHS0
DESCRIPTION OF THE SELECTED INPUTS
Analog input AINP (single ended)
0
0
0
0
0
0
1
1
1
1
1
1
0
0
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
1
1
0
0
0
0
1
1
1
1
0
1
1
0
0
0
1
1
1
1
0
0
1
1
0
0
0
1
1
0
0
1
1
1
0
0
1
0
1
1
0
0
1
1
0
1
0
1
0
1
1
0
1
1
1
0
0
1
0
0
1
0
0
1
0
1
0
1
Analog input AINM (single ended)
Reserved
Reserved
Differential channel (AINP–AINM)
Reserved
Autoscan two single ended channels: AINP, AINM, AINP, …
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
test mode
The test mode of the ADC is selected via bit 8 and bit 9 of control register 0. The different selections are shown
in Table 11.
Table 11. Test Mode
BIT 9
TEST1 TEST0
BIT 8
OUTPUT RESULT
0
0
1
1
0
1
0
1
Normal mode
V
REFP
)+(V
((V
))/2
REFM
REFP
REFM
V
Three different options can be selected. This feature allows support testing of hardware connections between
the ADC and the processor.
18
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12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
analog input channel selection (continued)
control register 1 (see Table 8)
–
–
BIT 9
BIT 8
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
–
–
RBACK
OFFSET
BIN/2s
R/W
DATA_P DATA_T
TRIG1
TRIG0
OVFL/FRST
RESET
Table 12. Control Register 1 Bit Functions
RESET
VALUE
BITS
NAME
FUNCTION
0
0
RESET
Reset
Writing a 1 into this bit resets the device and sets the control register 0 and control register 1 to the reset
values. In addition the FIFO pointer and offset register is reset. After reset, it takes 5 clock cycles until the first
value is converted and written into the FIFO.
1
0
OVFL
Overflow flag (read only)
(read only) Bit 1 of control register 1 indicates an overflow in the FIFO.
Bit 1 = 0 → no overflow occurred.
Bit 1 = 1 → an overflow occurred. This bit is reset to 0, after this control register is read from the processor.
FRST
(write only)
FRST: FIFO reset (write only)
By writing a 1 into this bit, the FIFO is reset.
2, 3
0,0
1
TRIG0,
TRIG1
FIFO trigger level
Bit 2 and bit 3 of control register 1 are used to set the trigger level for the FIFO. If the trigger level is reached,
the signal DATA_AV (data available) becomes active according to the settings of DATA_T and DATA_P. This
indicates to the processor that the ADC values can be read. Refer to Table 13.
4
DATA_T
DATA_AV type
Bit 4 of control register 1 controls whether the DATA_AV signal is a pulse or static (e.g for edge or level
sensitive interrupt inputs). If it is set to 0, the DATA_AV signal is static. If it is set to 1, the DATA_AV signal is a
pulse. Refer to Table 14.
5
6
1
0
DATA_P
R/W
DATA_AV polarity
Bit 5 of control register 1 controls the polarity ofDATA_AV. Ifitissetto1, DATA_AVisactivehigh. Ifitissetto0,
DATA_AV is active low. Refer to Table 14.
R/W, RD/WR selection
Bit 6 of control register 1 controls the function of the inputs RD and WR. When bit 6 in control register 1 is set
to 1, WR becomes a R/W input and RD is disabled. From now on a read is signalled with R/W high and a write
with R/W as a low signal. If bit 6 in control register 1 is set to 0, the input RDbecomesareadinputandtheinput
WR becomes a write input.
7
8
0
0
BIN/2s
Complement select
If bit 7 of control register 1 is set to 0, the output value of the ADC is in twos complement. If bit 7 of
control register 1 is set to 1, the output value of the ADC is in binary format. Refer to Table 3 through Table 6.
OFFSET
Offset cancellation mode
Bit 8 = 0 → normal conversion mode
Bit 8 = 1 → offset calibration mode
If a 1 is written into bit 8 of control register 1, the device internally sets the inputs to zero and does a con-
version. The conversion result is stored in an offset register and subtracted from all conversions in order
to reduce the offset error.
9
0
RBACK
Debug mode
Bit 9 = 0 → normal conversion mode
Bit 9 = 1 → enable debug mode
When bit 9 of control register 1 is set to 1, debug mode is enabled. In this mode, the contents of control
register 0 and control register 1 can be read back. The first read after bit 9 is set to 1 contains the value of
control register 0. The second read after bit 9 is set to 1 contains the value of control register 1.
19
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
FIFO trigger level
Bit 2 and bit 3 (TRIG1, TRIG0) of control register 1 are used to set the trigger level of the FIFO (see Table 13).
If the trigger level is reached, the DATA_AV (data available) signal becomes active according to the setting of
the signal DATA_AV to indicate to the processor that the ADC values can be read.
Table 13 shows four different programmable trigger levels for each configuration. The FIFO trigger level, which
can be selected, is dependent on the number of input channels. Either a differential or a single-ended input is
considered as one channel. The processor, therefore, always reads the data from the FIFO in the same order
and is able to distinguish between the channels.
Table 13. FIFO Trigger Level
TRIGGER LEVEL
FOR 1 CHANNEL
(ADC values)
TRIGGER LEVEL
FOR 2 CHANNELS
(ADC values)
BIT 3
TRIG1
BIT 2
TRIG0
0
0
1
1
0
1
0
1
01
04
08
14
02
04
8
12
timing and signal description of the THS12082
The reading from the THS12082 and writing to the THS12082 is performed by using the chip select inputs (CS0,
CS1), the write input WR and the read input RD. The write input is configurable to a combined read/write input
(R/W). This is desired in cases where the connected processor consists of a combined read/write output signal
(R/W). The two chip select inputs can be used to interface easily to a processor.
Reading from the THS12082 takes place by an internal RD signal, which is generated from the logical
int
combination of the external signals CS0, CS1 and RD (see Figure 10). This signal is then used to strobe the
words out of the FIFO and to enable the output buffers. The last external signal (either CS0, CS1 or RD) to
becomevalidwillmakeRD activewhilethewriteinput(WR)isinactive. Thefirstofthoseexternalsignalsgoing
int
to its inactive state will then deactivate RD again.
int
WritingtotheTHS12082takesplacebyaninternalWR signal,whichisgeneratedfromthelogicalcombination
int
of the external signals CS0, CS1 and WR
. This signal is then used to strobe the control words into the control registers 0 and 1. The last external signal
(either CS0, CS1 or WR) to become valid will make WR active while the read input (RD) is inactive. The first
int
of those external signals going to its inactive state will then deactivate WR again.
int
Read Enable
Write Enable
CS0
CS1
RD
WR
Control/Data
Registers
Data Bits
Figure 10. Logical Combination of CS0, CS1, RD, and WR
20
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12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
DATA_AV type
Bit 4 and bit 5 (DATA_T, DATA_P) of control register 1 are used to program the signal DATA_AV. Bit 4 of
control register 1 determines whether the DATA_AV signal is static or a pulse. Bit 5 of the control register
determines the polarity of DATA_AV. This is shown in Table 14.
Table 14. DATA_AV Type
BIT 5
DATA_P
BIT 4
DATA_T
DATA_AV TYPE
0
0
1
1
0
1
0
1
Active low level
Active low pulse
Active high level
Active high pulse
The signal DATA_AV is set to active when the trigger condition is satisfied. It is set back inactive independent
of the DATA_T selection (pulse or level).
If level mode is chosen, DATA_AV is set inactive after the first of the TL (TL = trigger level) reads (with the falling
edge of READ). The trigger condition is checked again after TL reads.
If pulse mode is chosen, the signal DATA_AV is a pulse with a width of one half of a CONV_CLK cycle in
continuous conversion mode and one half of a clock cycle of the internal oscillator in single conversion mode.
When the TL values previously written into the FIFO were read out by the processor, the next DATA_AV pulse
(when the trigger condition is satisfied) is sent out first.
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timing and signal description of the THS12082
read timing (using R/W, CS0-controlled)
Figure 11 shows the read-timing behavior when the WR(R/W) input is programmed as a combined read-write
input R/W. The RD input has to be tied to high-level in this configuration. This timing is called CS0-controlled
because CS0 is the last external signal of CS0, CS1, and R/W which becomes valid.
t
w(CS)
90%
CS0
CS1
10%
10%
t
t
su(R/W)
h(R/W)
90%
90%
R/W
RD
t
t
a
h
90%
90%
D(0–11)
t
d(CSDAV)
90%
DATA_AV
Figure 11. Read Timing Diagram Using R/W (CS0-controlled)
†
read timing parameter (CS0-controlled)
PARAMETER
Setup time, R/W high to last CS valid
MIN
0
TYP
MAX
10
UNIT
ns
t
t
t
t
t
t
su(R/W)
Access time, last CS valid to data valid
Delay time, last CS valid to DATA_AV inactive
Hold time, first CS invalid to data invalid
Hold time, first external CS invalid to R/W change
Pulse duration, CS active
0
ns
a
12
ns
d(CSDAV)
h
0
5
5
ns
ns
h(R/W)
10
ns
w(CS)
†
CS = CSO
22
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
timing and signal description of the THS12082 (continued)
write timing (using R/W, CS0-controlled)
Figure 12 shows the write-timing behavior when the WR(R/W) input is programmed as a combined read-write
input R/W. The RD input has to be tied to high-level in this configuration. This timing is called CS0-controlled
because CS0 is the last external signal of CS0, CS1, and R/W which becomes valid.
t
w(CS)
90%
CS0
CS1
10%
10%
t
t
su(R/W)
h(R/W)
WR
RD
t
su
t
h
90%
90%
D(0–11)
DATA_AV
Figure 12. Write Timing Diagram Using R/W (CS0-controlled)
†
write timing parameter (CSO-controlled)
PARAMETER
Setup time, R/W stable to last CS valid
MIN
0
TYP
MAX
UNIT
ns
t
t
t
t
t
su(R/W)
Setup time, data valid to first CS invalid
Hold time, first CS invalid to data invalid
Hold time, first CS invalid to R/W change
Pulse duration, CS active
5
ns
su
2
ns
h
5
ns
h(R/W)
10
ns
w(CS)
†
CS = CSO
23
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
timing and signal description of the THS12082 (continued)
interfacing the THS12082 to the TMS320C30/31/33 DSP
The following application circuit shows an interface of the THS12082 to the TMS320C30/31/33 DSPs. The read
and write timings (using R/W, CS0-controlled) shown before are valid for this specific interface.
THS12082
TMS320C30/31/33
DV
DD
STRB
A23
CS0
CS1
R/W
RD
R/W
DATA_AV
CONV_CLK
DATA
INTX
TOUT
DATA
interfacing the THS12082 to the TMS320C54x using I/O strobe
The following application circuit shows an interface of the THS12082 to the TMS320C54x. The read and write
timings (using R/W, CS0-controlled) shown before are valid for this specific interface.
THS12082
TMS320C54x
DV
DD
I/O STRB
CS0
CS1
A15
R/W
RD
R/W
DATA_AV
CONV_CLK
DATA
INTX
BCLK
DATA
24
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THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
timing and signal description of the THS12082 (continued)
read timing (using RD, RD-controlled)
Figure 13 shows the read-timing behavior when the WR(R/W) input is programmed as a write-input only. The
input RD acts as the read-input in this configuration. This timing is called RD-controlled because RD is the last
external signal of CS0, CS1, and RD that becomes valid.
CS0
CS1
t
t
su(CS)
h(CS)
WR
RD
t
w(RD)
10%
10%
t
t
a
h
90%
90%
D(0–11)
t
d(CSDAV)
90%
DATA_AV
Figure 13. Read Timing Diagram Using RD (RD-controlled)
read timing parameter (RD-controlled)
PARAMETER
Setup time, RD low to last CS valid
MIN
0
TYP
MAX
10
UNIT
ns
t
t
t
t
t
t
su(CS)
Access time, last CS valid to data valid
Delay time, last CS valid to DATA_AV inactive
Hold time, first CS invalid to data invalid
Hold time, RD change to first CS invalid
Pulse duration, RD active
0
ns
a
12
ns
d(CSDAV)
h
0
5
5
ns
ns
h(CS)
w(RD)
10
ns
25
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
timing and signal description of the THS12082 (continued)
write timing (using WR, WR-controlled)
Figure 14 shows the write-timing behavior when the WR(R/W) input is programmed as a write input WR only.
The input RD acts as the read input in this configuration. This timing is called WR-controlled because WR is
the last external signal of CS0, CS1, and WR that becomes valid.
CS0
CS1
t
t
h(CS)
su(CS)
t
w(WR)
WR
RD
10%
10%
t
su
t
h
90%
90%
D(0–11)
DATA_AV
Figure 14. Write Timing Diagram Using WR (WR-controlled)
write timing parameter using WR (WR-controlled)
PARAMETER
MIN
0
TYP
MAX
UNIT
ns
t
t
t
t
t
Setup time, CS stable to last WR valid
Setup time, data valid to first WR invalid
Hold time, WR invalid to data invalid
Hold time, WR invalid to CS change
Pulse duration, WR active
su(CS)
5
ns
su
2
ns
h
5
ns
h(CS)
w(WR)
10
ns
26
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
interfacing the THS12082 to the TMS320C6201 DSP
The following application circuit shows an interface of the THS12082 to the TMS320C6201. The read (using
RD, RD-controlled) and write timings (using WR, WR-controlled) shown before are valid for this specific
interface.
THS12082–1
TMS320C6201
CE1
CS0
CS1
EA20
ARE
RD
AWE
WR
EXT_INT6
DATA
DATA_AV
DATA
TOUT1
TOUT2
EA21
CONV_CLK
THS12082–2
EXT_INT7
CS0
CS1
RD
WR
DATA_AV
DATA
CONV_CLK
analog input configuration and reference voltage
The THS12082 features two analog input channels. These can be configured for either single-ended or
differential operation. Best performance is achieved in differential mode. Figure 15 shows a simplified model,
where a single-ended configuration for channel AINP is selected. The reference voltages for the ADC itself are
V
V
and V
(either internal or external reference voltage). The analog input voltage range goes from
REFP
REFM
REFM
toV
.ThismeansthatV
definestheminimumvoltage,whichcanbeappliedtotheADC.V
REFP
REFM REFP
defines the maximum voltage, which can be applied to the ADC. The internal reference source provides the
voltage V
of 1.5 V and the voltage V
of 3.5 V. The resulting analog input voltage swing of 2 V can be
REFM
REFP
expressed by:
V
AINP
V
REFM
REFP
(1)
V
REFP
12-Bit
ADC
AINP
V
REFM
Figure 15. Single-Ended Input Stage
27
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
analog input configuration and reference voltage (continued)
Adifferentialoperationisdesiredformanyapplications. Figure16showsasimplifiedmodelfortheanaloginputs
AINM and AINP, which are configured for differential operation. This configuration has a few advantages, which
are discussed in the following paragraphs.
V
REFP
AINP
+
V
ADC
12-Bit
ADC
Σ
–
AINM
V
REFM
Figure 16. Differential Input Stage
In comparison to the single-ended configuration it can be seen that the voltage, V
input of the ADC, is the difference between the input AINP and AINM. This means that V
, which is applied at the
ADC
defines the
REFM
minimumvoltage(V
can be applied to the ADC. The voltage V
), whichcanbeappliedtotheADC. V
definesthemaximumvoltage(VADC),which
ADC
REFP
can be calculated as follows:
ADC
( )
ABS AINP–AINM
V
ADC
(2)
(3)
An advantage to single-ended operation is that the common-mode voltage
AINM AINP
V
CM
2
can be rejected in the differential configuration, if the following condition for the analog input voltages is true:
AGND
1 V
AINM, AINP
4 V
AV
DD
(4)
(5)
V
CM
In addition to the common-mode voltage rejection, the differential operation allows a dc-offset rejection, which
is common to both analog inputs. See also Figure 18.
single-ended mode of operation
The THS12082 can be configured for single-ended operation using dc or ac coupling. In either case, the input
of the THS12082 must be driven from an operational amplifier that does not degrade the ADC performance.
Because the THS12082 operates from a 5-V single supply, it is necessary to level-shift ground-based bipolar
signals to comply with its input requirements. This can be achieved with dc- and ac-coupling. An application
example is shown for dc-coupled level shifting in the following section, dc-coupling.
28
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
dc coupling
An operational amplifier can be configured to shift the signal level according to the analog input voltage range
of the THS12082. The analog input voltage range of the THS12082 goes from 1.5 V to 3.5 V. An op-amp
specified for 5-V single supply can be used as shown in Figure 17.
Figure 17 shows an application example where the analog input signal in the range from –1 V up to 1 V is shifted
by an operational amplifier to the analog input range of the THS12082 (1.5 V to 3.5 V). The operational amplifier
is configured as an inverting amplifier with a gain of –1. The required dc voltage of 1.25 V at the noninverting
input is derived from the 2.5-V output reference REFOUT of the THS12082 by using a resistor divider.
Therefore, the op-amp output voltage is centered at 2.5 V. The use of ratio matched, thin-film resistor networks
minimizes gain and offset errors.
R
3.5 V
2.5 V
1.5 V
5 V
1 V
0 V
R
THS12082
AINP
_
R
S
–1 V
+
1.25 V
REFIN
REFOUT
R
R
Figure 17. Level-Shift for DC-Coupled Input
differential mode of operation
For the differential mode of operation, a conversion from single-ended to differential is required. A conversion
to differential signals can be achieved by using an RF-transformer, which provides a center tap. Best
performance is achieved in differential mode.
Mini Circuits
T4–1
THS12082
49.9 Ω
R
AINP
C
C
200 Ω
R
AINM
REFOUT
Figure 18. Transformer Coupled Input
29
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION
SIGNAL-TO-NOISE AND DISTORTION
vs
vs
SAMPLING FREQUENCY (SINGLE-ENDED)
SAMPLING FREQUENCY (SINGLE-ENDED)
80
75
70
65
60
55
50
45
40
70
65
60
55
50
45
40
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
f
IN
f
IN
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
f
– Sampling Frequency – MHz
f
– Sampling Frequency – MHz
s
s
Figure 19
Figure 20
SIGNAL-TO-NOISE
vs
SPURIOUS FREE DYNAMIC RANGE
vs
SAMPLING FREQUENCY (SINGLE-ENDED)
SAMPLING FREQUENCY (SINGLE-ENDED)
70
65
60
55
50
45
40
90
85
80
75
70
65
60
55
50
45
40
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
f
IN
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
f
IN
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
f
– Sampling Frequency – MHz
f
– Sampling Frequency – MHz
s
s
Figure 21
Figure 22
30
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION
SIGNAL-TO-NOISE AND DISTORTION
vs
SAMPLING FREQUENCY (DIFFERENTIAL)
vs
SAMPLING FREQUENCY (DIFFERENTIAL)
85
80
75
70
65
60
55
50
45
40
80
75
70
65
60
55
50
45
40
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
DD
= 500 kHz, AIN = –1 dBFS
f
f
IN
IN
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
f
– Sampling Frequency – MHz
f
– Sampling Frequency – MHz
s
s
Figure 23
Figure 24
SIGNAL-TO-NOISE
vs
SPURIOUS FREE DYNAMIC RANGE
vs
SAMPLING FREQUENCY (DIFFERENTIAL)
SAMPLING FREQUENCY (DIFFERENTIAL)
80
75
70
65
60
55
50
45
40
100
95
90
85
80
75
70
65
60
55
50
45
40
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
f
IN
f
IN
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
f
– Sampling Frequency – MHz
f
– Sampling Frequency – MHz
s
s
Figure 25
Figure 26
31
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION
SIGNAL-TO-NOISE AND DISTORTION
vs
vs
INPUT FREQUENCY (SINGLE-ENDED)
INPUT FREQUENCY (SINGLE-ENDED)
80
80
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
75
70
65
60
55
50
45
40
f
s
75
70
65
60
55
50
45
40
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
f
s
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
f – Input Frequency – MHz
i
f – Input Frequency – MHz
i
Figure 27
Figure 28
SIGNAL-TO-NOISE
vs
INPUT FREQUENCY (SINGLE-ENDED)
SPURIOUS FREE DYNAMIC RANGE
vs
INPUT FREQUENCY (SINGLE-ENDED)
80
75
70
65
60
55
50
45
40
100
95
90
85
80
75
70
65
60
55
50
45
40
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
f
s
f
s
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
f – Input Frequency – MHz
i
f – Input Frequency – MHz
i
Figure 29
Figure 30
32
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
TYPICAL CHARACTERISTICS
SIGNAL-TO-NOISE AND DISTORTION
vs
TOTAL HARMONIC DISTORTION
vs
INPUT FREQUENCY (DIFFERENTIAL)
INPUT FREQUENCY (DIFFERENTIAL)
80.00
75.00
70.00
65.00
60.00
55.00
50.00
45.00
40.00
80.00
75.00
70.00
65.00
60.00
55.00
50.00
45.00
40.00
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
f
s
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
f
s
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
f – Input Frequency – MHz
i
f – Input Frequency – MHz
i
Figure 32
Figure 31
SPURIOUS FREE DYNAMIC RANGE
vs
SIGNAL-TO-NOISE
vs
INPUT FREQUENCY (DIFFERENTIAL)
INPUT FREQUENCY (DIFFERENTIAL)
100.00
95.00
90.00
85.00
80.00
75.00
70.00
65.00
60.00
55.00
50.00
45.00
40.00
80.00
75.00
70.00
65.00
60.00
55.00
50.00
45.00
40.00
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
f
s
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
f
s
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
f – Input Frequency – MHz
i
f – Input Frequency – MHz
i
Figure 33
Figure 34
33
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
TYPICAL CHARACTERISTICS
EFFECTIVE NUMBER OF BITS
EFFECTIVE NUMBER OF BITS
vs
vs
SAMPLING FREQUENCY (SINGLE-ENDED)
SAMPLING FREQUENCY (DIFFERENTIAL)
12
11
10
9
12
11
10
9
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
f
in
8
8
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 500 kHz, AIN = –1 dBFS
7
7
f
in
6
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
f
– Sampling Frequency – MHz
f
– Sampling Frequency – MHz
s
s
Figure 36
Figure 35
EFFECTIVE NUMBER OF BITS
vs
EFFECTIVE NUMBER OF BITS
vs
INPUT FREQUENCY (SINGLE-ENDED)
INPUT FREQUENCY (DIFFERENTIAL)
12
11
10
9
12
11
10
9
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
AV
DD
= 5 V, DV
= BV
= 3 V,
DD
DD
= 8 MSPS, AIN = –1 dBFS
s
DD
= 8 MSPS, AIN = –1 dBFS
f
f
s
8
8
7
7
6
6
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
f – Input Frequency – MHz
i
f – Input Frequency – MHz
i
Figure 38
Figure 37
34
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
TYPICAL CHARACTERISTICS
FAST FOURIER TRANSFORM (4096 POINTS)
(SINGLE-ENDED)
vs
FREQUENCY
0
AV
= 5 V, DV
= BV
= 3 V,
DD
DD
DD
–20
–40
f
s
f
= 8 MSPS, AIN = –1 dBFS
= 1.25 MHz
in
–60
–80
–100
–120
–140
0
1000000.00
2000000.00
3000000.00
4000000.00
f – Frequency – Hz
Figure 39
FAST FOURIER TRANSFORM (4096 POINTS)
(DIFFERENTIAL)
vs
FREQUENCY
0
–20
AV
= 5 V, DV
= BV
= 3 V,
DD
DD
DD
f
s
f
= 8 MSPS, AIN = –1 dBFS
= 1.25 MHz
in
–40
–60
–80
–100
–120
–140
0
1000000.00
2000000.00
3000000.00
4000000.00
f – Frequency – Hz
Figure 40
35
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
definitions of specifications and terminology
integral nonlinearity
Integral nonlinearity refers to the deviation of each individual code from a line drawn from zero through full scale.
The point used as zero occurs 1/2 LSB before the first code transition. The full-scale point is defined as level
1/2 LSB beyond the last code transition. The deviation is measured from the center of each particular code to
the true straight line between these two points.
differential nonlinearity
An ideal ADC exhibits code transitions that are exactly 1 LSB apart. DNL is the deviation from this ideal value.
A differential nonlinearity error of less than ±1 LSB ensures no missing codes.
zero offset
The major carry transition should occur when the analog input is at zero volts. Zero error is defined as the
deviation of the actual transition from that point.
gain error
The first code transition should occur at an analog value 1/2 LSB above negative full scale. The last transition
should occur at an analog value 1 1/2 LSB below the nominal full scale. Gain error is the deviation of the actual
difference between first and last code transitions and the ideal difference between first and last code transitions.
signal-to-noise ratio + distortion (SINAD)
SINAD is the ratio of the rms value of the measured input signal to the rms sum of all other spectral components
below the Nyquist frequency, including harmonics but excluding dc. The value for SINAD is expressed in
decibels.
effective number of bits (ENOB)
For a sine wave, SINAD can be expressed in terms of the number of bits. Using the following formula,
(
)
SINAD 1.76
6.02
N
it is possible to get a measure of performance expressed as N, the effective number of bits. Thus, effective
number of bits for a device for sine wave inputs at a given input frequency can be calculated directly from its
measured SINAD.
total harmonic distortion (THD)
THDistheratioofthermssumofthefirstsixharmoniccomponentstothermsvalueofthemeasuredinputsignal
and is expressed as a percentage or in decibels.
spurious free dynamic range (SFDR)
SFDR is the difference in dB between the rms amplitude of the input signal and the peak spurious signal.
36
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
THS12082
12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS
SLAS271 – MAY 2000
MECHANICAL DATA
DA (R-PDSO-G**)
PLASTIC SMALL-OUTLINE PACKAGE
38 PINS SHOWN
0,30
0,19
M
0,13
0,65
38
20
6,20
8,40
NOM 7,80
0,15 NOM
Gage Plane
1
19
0,25
A
0°–8°
0,75
0,50
Seating Plane
0,10
0,15
0,05
1,20 MAX
PINS **
28
30
32
38
DIM
9,80
9,60
11,10
10,90
11,10
12,60
12,40
A MAX
A MIN
10,90
4040066/D 11/98
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. Body dimensions do not include mold flash or protrusion.
D. Falls within JEDEC MO-153
37
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
IMPORTANT NOTICE
Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
Customers are responsible for their applications using TI components.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. 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 of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright 2000, Texas Instruments Incorporated
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