Texas Instruments | 16-Bit, 1.25MSPS Analog-to-Digital Converter (Rev. D) | Datasheet | Texas Instruments 16-Bit, 1.25MSPS Analog-to-Digital Converter (Rev. D) Datasheet

Texas Instruments 16-Bit, 1.25MSPS Analog-to-Digital Converter (Rev. D) Datasheet
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
16-Bit, 1.25MSPS Analog-to-Digital Converter
Check for Samples: ADS1601
FEATURES
DESCRIPTION
•
The ADS1601 is a high-speed, high-precision,
delta-sigma
analog-to-digital
converter
(ADC)
manufactured on an advanced CMOS process. The
ADS1601 oversampling topology reduces clock jitter
sensitivity during the sampling of high-frequency,
large amplitude signals by a factor of four over that
achieved by Nyquist-rate ADCs. Consequently,
signal-to-noise ratio (SNR) is particularly improved.
Total harmonic distortion (THD) is –103dB, and the
spurious-free dynamic range (SFDR) is 105dB
1
2
•
•
•
High Speed:
– Data Rate: 1.25MSPS
– Bandwidth: 615kHz
Outstanding Performance:
– SNR: 92dB at fIN = 100kHz, –1dBFS
– THD: –103dB at fIN = 100kHz, –6dBFS
– SFDR: 105dB at fIN = 100kHz, –6dBFS
Ease-of-Use:
– High-Speed 3-Wire Serial Interface
– Directly Connects to TMS320 DSPs
– On-Chip Digital Filter Simplifies Anti-Alias
Requirements
– Simple Pin-Driven Control—No On-Chip
Registers to Program
– Selectable On-Chip Voltage Reference
– Simultaneous Sampling with Multiple
ADS1601s
Low Power:
– 330mW at 1.25MSPS
– 145mW at 625kSPS
– Power-Down Mode
APPLICATIONS
•
•
•
Sonar
Vibration Analysis
Data Acquisition
VREFP VREFN VMID
RBIAS VCAP
AVDD
DVDD
IOVDD
CLK
SYNC
Reference and Bias Circuits
FSO
FSO
AINP
AINN
DS
Modulator
Linear Phase
FIR Digital Filter
Serial
Interface
SCLK
SCLK
DOUT
DOUT
OTR
Optimized for power and performance, the ADS1601
dissipates only 330mW while providing a full-scale
differential input range of ±0.94VREF. Having such a
wide input range makes out-of-range signals
uncommon. The OTR pin indicates if an analog input
out-of-range condition does occur. The differential
input signal is measured against the differential
reference, which can be generated internally on the
ADS1601 or supplied externally.
The ADS1601 uses an inherently stable advanced
modulator with an on-chip decimation filter. The filter
stop band extends to 19.3MHz, which greatly
simplifies the anti-aliasing circuitry. The modulator
samples the input signal up to 20MSPS, depending
on fCLK, while the 16x decimation filter uses a series
of four half-band FIR filter stages to provide 75dB of
stop band attenuation and 0.001dB of passband
ripple.
Output data is provided over a simple 3-wire serial
interface at rates up to 1.25MSPS, with a –3dB
bandwidth of 615kHz. The output data or its
complementary format directly connects to DSPs
such as TI’s TMS320 family, FPGAs, or ASICs. A
dedicated synchronization pin enables simultaneous
sampling with multiple ADS1601s in multi-channel
systems. Power dissipation is set by an external
resistor that allows a reduction in dissipation when
operating at slower speeds. All of the ADS1601
features are controlled by dedicated I/O pins, which
simplify operation by eliminating the need for on-chip
registers.
PD
ADS1601
AGND
REFEN
DGND
The high performing, easy-to-use ADS1601 is
especially suitable for demanding measurement
applications in sonar, vibration analysis, and data
acquisition. The ADS1601 is offered in a small, 7mm
× 7mm TQFP-48 package and is specified
from –40°C to +85°C.
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
PACKAGE/ORDERING INFORMATION
For the most current package and ordering information, see the Package Option Addendum at the end of this
document, or visit the device product folder at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range, unless otherwise noted.
ADS1601
UNIT
AVDD to AGND
–0.3 to +6
V
DVDD to DGND
–0.3 to +3.6
V
IOVDD to DGND
–0.3 to +6
V
–0.3 to +0.3
V
Input current
100, momentary
mA
Input current
10, continuous
mA
Analog I/O to AGND
–0.3 to AVDD + 0.3
V
Digital I/O to DGND
–0.3 to IOVDD + 0.3
V
+150
°C
Operating temperature range
–40 to +105
°C
Storage temperature range
–60 to +150
°C
AGND to DGND
Maximum junction temperature
(1)
2
Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may
degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond
those specified is not implied.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
ELECTRICAL CHARACTERISTICS
All specifications at TA = –40°C to +85°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
ADS1601
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Analog Input
Differential input voltage (VIN) (AINP – AINN)
0dBFS
±0.94VREF
V
2.7
V
Common-mode input voltage (VCM) (AINP + AINN) / 2
Differential input voltage (VIN)
(AINP or AINN with respect to AGND)
0dBFS
–0.1
4.6
V
Dynamic Specifications
1.25
Data rate
fIN = 10kHz, –1dBFS
Total harmonic distortion (THD)
92
dB
90
dB
fIN = 10kHz, –6dBFS
84
87
dB
92
dB
fIN = 100kHz, –3dBFS
87
90
dB
fIN = 100kHz, –6dBFS
84
87
dB
fIN = 500kHz, –1dBFS
91
dB
fIN = 500kHz, –3dBFS
89
dB
fIN = 500kHz, –6dBFS
87
dB
fIN = 10kHz, –1dBFS
–91
fIN = 10kHz, –3dBFS
–100
–90
dB
fIN = 10kHz, –6dBFS
–104
–97
dB
fIN = 100kHz, –1dBFS
–88
fIN = 100kHz, –3dBFS
–96
–90
dB
fIN = 100kHz, –6dBFS
–103
–96
dB
fIN = 500kHz, –1dBFS
–115
dB
fIN = 500kHz, –3dBFS
–112
dB
fIN = 500kHz, –6dBFS
–110
dB
Aperture delay
Copyright © 2004–2011, Texas Instruments Incorporated
dB
88
dB
85
89
dB
fIN = 10kHz, –6dBFS
84
87
dB
87
dB
fIN = 100kHz, –3dBFS
85
88
dB
fIN = 100kHz, –6dBFS
84
86
dB
fIN = 500kHz, –1dBFS
91
dB
fIN = 500kHz, –3dBFS
89
dB
fIN = 500kHz, –6dBFS
87
dB
fIN = 10kHz, –1dBFS
92
dB
fIN = 10kHz, –3dBFS
91
100
dB
fIN = 10kHz, –6dBFS
98
109
dB
88
dB
fIN = 100kHz, –1dBFS
Intermodulation distortion (IMD)
dB
fIN = 10kHz, –3dBFS
fIN = 100kHz, –1dBFS
Spurious-free dynamic range (SFDR)
MSPS
87
fIN = 10kHz, –1dBFS
Signal-to-noise + distortion (SINAD)
CLK
fIN = 10kHz, –3dBFS
fIN = 100kHz, –1dBFS
Signal-to-noise ratio (SNR)
f
( 20MHZ
)
fIN = 100kHz, –3dBFS
90
97
dB
fIN = 100kHz, –6dBFS
97
105
dB
fIN = 500kHz, –1dBFS
120
dB
fIN = 500kHz, –3dBFS
118
dB
fIN = 500kHz, –6dBFS
115
dB
f1 = 499kHz, –6dBFS
f2 = 501kHz, –6dBFS
94
dB
4
ns
3
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = –40°C to +85°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
ADS1601
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Digital Filter Characteristics
Passband
550
0
f
( 20MHZ
)
CLK
±0.001
Passband ripple
–0.1dB attenuation
fCLK
575
20MHZ
–3.0dB attentuation
615
(
Passband transition
0.7
Stop band
Stop band attenuation
dB
)
kHz
f
( 20MHZ
)
kHz
CLK
f
f
( 20MHZ
) 19.3 ( 20MHZ
)
CLK
CLK
MHz
75
dB
20MHz
20.8
fCLK
(
Group delay
Settling time
kHz
40.8
Complete settling
)
μs
( 20MHz
)
f
μs
CLK
Static Specifications
Resolution
16
Bits
No missing codes
16
Input-referred noise
0.5
Integral nonlinearity
–0.5dBFS signal
Bits
0.75
LSB, rms
0.75
LSB
Differential nonlinearity
0.25
LSB
Offset error
–0.05
%FSR
0.5
ppmFSR/°C
Offset error drift
0.25 (1)
%
Excluding reference drift
10
ppm/°C
Common-mode rejection
At DC
75
dB
Power-supply rejection
At DC
65
dB
Gain error
Gain error drift
Internal Voltage Reference
REFEN = low
VREF = (VREFP – VREFN)
2.75
3
3.25
V
VREFP
3.5
3.8
4.1
V
VREFN
0.5
0.8
1.1
V
VMID
2.3
2.4
2.6
VREF drift
Startup time
External Voltage Reference
V
50
ppm/°C
15
ms
REFEN = high
VREF = (VREFP – VREFN)
2.0
3
3.25
V
VREFP
3.5
4
4.25
V
VREFN
0.5
1
1.5
V
VMID
2.3
2.5
2.6
V
(1)
4
There is a constant gain error of 2.5% in addition to the variable gain error of ±0.25%. Therefore, the gain error is 2.5 ± 0.25%.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = –40°C to +85°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
ADS1601
PARAMETER
TEST CONDITIONS
MIN
fCLK = 20MHz
45
TYP
MAX
UNIT
20
MHz
55
%
IOVDD
V
Clock Input
Frequency (fCLK)
Duty cycle
Digital Input/Output
VIH
0.7 × IOVDD
VIL
DGND
0.3 × IOVDD
IOVDD – 0.5
V
VOH
IOH = 50μA
VOL
IOL = 50μA
DGND + 0.5
V
DGND < VDIGIN < IOVDD
±10
μA
Input leakage
V
Power-Supply Requirements
AVDD
4.75
5.25
V
DVDD
2.7
3.3
V
2.7
5.25
V
IOVDD
AVDD current (IAVDD)
IOH = 50μA
REFEN = low
65
77
mA
REFEN = high
55
65
mA
DVDD current (IDVDD)
IOVDD = 3V
15
18
mA
IOVDD current (IIOVDD)
IOVDD = 3V
3
8
mA
AVDD = 5V, DVDD = 3V, IOVDD = 3V,
REFEN = high
330
380
mW
PD = low, CLK disabled
10
Power dissipation
mW
Temperature Range
Specified
–40
+85
°C
Operating
–40
+105
°C
Storage
–60
+150
°C
Copyright © 2004–2011, Texas Instruments Incorporated
5
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
DEFINITIONS
Absolute Input Voltage
Intermodulation Distortion (IMD)
Absolute input voltage, given in volts, is the voltage of
each analog input (AINN or AINP) with respect to
AGND.
IMD, given in dB, is measured while applying two
input signals of the same magnitude, but with slightly
different frequencies. It is calculated as the difference
between the rms amplitude of the input signal to the
rms amplitude of the peak spurious signal.
Aperture Delay
Aperture delay is the delay between the rising edge
of CLK and the sampling of the input signal.
Common-Mode Input Voltage
Common-mode input voltage (VCM) is the average
voltage of the analog inputs:
Offset Error
Offset Error, given in % of FSR, is the output reading
when the differential input is zero.
Offset Error Drift
Differential Input Voltage
Offset error drift, given in ppm of FSR/°C, is the drift
over temperature of the offset error. The offset error
is specified as the larger of the drift from ambient
(T = +25°C) to the minimum or maximum operating
temperatures.
Differential input voltage (VIN) is the voltage
difference between the analog inputs (AINP−AINN).
Signal-to-Noise Ratio (SNR)
(AINP + AINN)
2
DNL, given in least-significant bits of the output code
(LSB), is the maximum deviation of the output code
step sizes from the ideal value of 1LSB.
SNR, given in dB, is the ratio of the rms value of the
input signal to the sum of all the frequency
components below fCLK/2 (the Nyquist frequency)
excluding the first six harmonics of the input signal
and the dc component.
Full-Scale Range (FSR)
Signal-to-Noise and Distortion (SINAD)
FSR is the difference between the maximum and
minimum measurable input signals (FSR = 1.88VREF).
SINAD, given in dB, is the ratio of the rms value of
the input signal to the sum of all the frequency
components below fCLK/2 (the Nyquist frequency)
including the harmonics of the input signal but
excluding the dc component.
Differential Nonlinearity (DNL)
Gain Error
Gain error, given in %, is the error of the full-scale
input signal with respect to the ideal value.
Gain Error Drift
Gain error drift, given in ppm/°C, is the drift over
temperature of the gain error. The gain error is
specified as the larger of the drift from ambient
(T = 25°C) to the minimum or maximum operating
temperatures.
Integral Nonlinearity (INL)
Spurious-Free Dynamic Range (SFDR)
SFDR, given in dB, is the difference between the rms
amplitude of the input signal to the rms amplitude of
the peak spurious signal.
Total Harmonic Distortion (THD)
THD, given in dB, is the ratio of the sum of the rms
value of the first six harmonics of the input signal to
the rms value of the input signal.
INL, given in least-significant bits of the output code
(LSB), is the maximum deviation of the output codes
from a best fit line.
6
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
IOVDD
AGND
DGND
CLK
AVDD
48 47 46 45 44 43 42
AGND
VREFN
VCAP
VMID
VREFN
VREFP
VREFP
PIN ASSIGNMENTS
41 40 39 38 37
AGND
1
36
AVDD
2
35
NC
AGND
3
34
DVDD
AINN
4
33
DGND
AINP
5
32
FSO
DGND
AGND
6
AVDD
7
RBIAS
8
29
DOUT
AGND
9
28
SCLK
ADS1601
31
FSO
30
DOUT
SCLK
NC
AVDD 12
25
NC
NC
DVDD
OTR
21 22 23 24
DGND
PD
DVDD
NC
RPULLUP
20
NC
13 14 15 16 17 18 19
SYNC
27
26
DGND
AVDD 10
AGND 11
REFEN
TQFP PACKAGE
(TOP VIEW)
TERMINAL FUNCTIONS
TERMINAL
I/O
DESCRIPTION
1, 3, 6, 9, 11, 39, 41
Analog
Analog ground
2, 7, 10, 12, 42
Analog
Analog supply
AINN
4
Analog input
Negative analog input
AINP
5
Analog input
Positive analog input
RBIAS
8
Analog
REFEN
13
Digital input: active low
14, 16, 24–26, 35
Do not connect
RPULLUP
15
Digital Input
PD
17
Digital input: active low
DVDD
18, 23, 34
Digital
Digital supply
DGND
19, 22, 33, 36, 38
Digital
Digital ground
SYNC
20
Digital input
Synchronization control input
OTR
21
Digital output
Indicates analog input signal is out of range.
SCLK
28
Digital output
Serial clock output
SCLK
27
Digital output
Serial clock output, complementary signal.
DOUT
30
Digital output
Data output
DOUT
29
Digital output
Data output, complementary signal.
FSO
32
Digital output
Frame synchronization output
FSO
31
Digital output
Frame synchronization output, complementary signal.
IOVDD
37
Digital
Digital I/O supply
CLK
40
Digital output
Clock input supply
VCAP
43
Analog
Terminal for external bypass capacitor connection to internal bias voltage.
44, 45
Analog
Negative reference voltage
46
Analog
Midpoint voltage
47, 48
Analog
Positive reference voltage
NAME
NO.
AGND
AVDD
NC
VREFN
VMID
VREFP
Copyright © 2004–2011, Texas Instruments Incorporated
Terminal for external analog bias setting resistor.
Internal reference enable. Internal pull-down resistor of 170kΩ to DGND.
These terminals must be left unconnected.
Pull-up to DVDD with 10kΩ resistor (see Figure 50).
Power-down all circuitry. Internal pull-up resistor of 170kΩ to DGND.
7
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
TIMING DIAGRAMS
tC
CLK
tHSC
tSSC
SYNC
tSYPW
tSTL
FSO
Figure 1. Initialization Timing
TIMING REQUIREMENTS
For TA = –40°C to +85°C, DVDD = 2.7V to 3.6V, and IOVDD = 2.7V to 5.25V.
SYMBOL
tSYPW
tC
DESCRIPTION
MIN
TYP
MAX
UNIT
SYNC positive pulse width
1
CLK period
Clock period (CLK)
50
ns
tSSC
Setup time; SYNC rising edge to CLK rising edge
0.5
CLK period
tHSC
Hold time; CLK rising edge to SYNC falling edge
0.5
CLK period
tSTL
Settling time of the ADS1601; FSO falling edge to next
FSO rising edge
833
CLK periods
tCPW
CLK
tCPW
tCS
SCLK
tCF
tFPW
tDH
FSO
tDS
DOUT
MSB
BIT
14
BIT
1
LSB
New Data
Figure 2. Data Retrieval Timing
TIMING REQUIREMENTS
For TA = –40°C to +85°C, DVDD = 2.7V to 3.6V, and IOVDD = 2.7V to 5.25V.
SYMBOL
8
MAX
UNIT
tCS
DESCRIPTION
Rising edge of CLK to rising edge of SCLK
15
ns
tCF
Rising edge of SCLK to rising edge of FSO
5
ns
tCPW
CLK positive or negative pulse width
tFPW
Frame sync output high pulse width
tDS
SCLK rising edge to new DOUT valid
tDH
SCLK falling edge to DOUT invalid
MIN
TYP
25
ns
1
CLK period
5
20
ns
ns
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
TYPICAL CHARACTERISTICS
All specifications at TA = +25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
SPECTRAL RESPONSE
SPECTRAL RESPONSE
0
0
Amplitude (dB)
-40
-60
-80
-100
fIN = 10kHz, -6dBFS
SNR = 87dB
THD = -108dB
SFDR = 111dB
-20
-40
Amplitude (dB)
fIN = 10kHz, -1dBFS
SNR = 92dB
THD = -91dB
SFDR = 92dB
-20
-60
-80
-100
-120
-120
-140
-140
-160
-160
0
100
200
300
400
Frequency (kHz)
500
600
0
100
200
Figure 3.
SPECTRAL RESPONSE
600
SPECTRAL RESPONSE
0
-40
-60
-80
-100
fIN = 100kHz, -1dBFS
SNR = 92dB
THD = -88dB
SFDR = 88dB
-20
-40
Amplitude (dB)
fIN = 10kHz, -10dBFS
SNR = 83dB
THD = -106dB
SFDR = 111dB
-20
Amplitude (dB)
500
Figure 4.
0
-60
-80
-100
-120
-120
-140
-140
-160
-160
0
100
200
300
400
Frequency (kHz)
500
600
0
100
200
Figure 5.
300
400
Frequency (kHz)
500
600
Figure 6.
SPECTRAL RESPONSE
SPECTRAL RESPONSE
0
0
-40
-60
-80
-100
-40
-60
-80
-100
-120
-120
-140
-140
-160
fIN = 100kHz, -10dBFS
SNR = 83dB
THD = -103dB
SFDR = 105dB
-20
Amplitude (dB)
fIN = 100kHz, -6dBFS
SNR = 87dB
THD = -103dB
SFDR = 105dB
-20
Amplitude (dB)
300
400
Frequency (kHz)
-160
0
100
200
300
400
Frequency (kHz)
Figure 7.
Copyright © 2004–2011, Texas Instruments Incorporated
500
600
0
100
200
300
400
Frequency (kHz)
500
600
Figure 8.
9
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
SPECTRAL RESPONSE
SPECTRAL RESPONSE
0
0
fIN = 504kHz, -1dBFS
SNR = 91dB
THD = -117dB
SFDR = 122dB
Amplitude (dB)
-40
-40
-60
-80
-100
-80
-100
-120
-140
-140
-160
100
200
300
400
Frequency (kHz)
500
0
600
-80
-100
-120
-140
-160
200
300
400
Frequency (kHz)
500
600
100
SFDR
80
THD
SNR
60
40
fIN = 10kHz
20
-70
-60
-50
-40
-30
-20
Figure 12.
SNR, THD, AND SFDR
vs INPUT SIGNAL AMPLITUDE
SNR, THD, AND SFDR
vs INPUT SIGNAL AMPLITUDE
120
SFDR
THD
80
SNR
60
40
fIN = 100kHz
20
-70
-60
-50
-40
-30
-20
Input Signal Amplitude, VIN (dB)
Figure 13.
-10
0
Input Signal Amplitude, VIN (dB)
140
-80
120
Figure 11.
100
600
140
-80
SIGNAL- TO- NOISE RATIO,
TOTAL HARMONIC DISTORTION,
SPURIOUS- FREE DYNAMIC RANGE (dB)
SIGNAL- TO- NOISE RATIO,
TOTAL HARMONIC DISTORTION,
SPURIOUS- FREE DYNAMIC RANGE (dB)
100
500
SNR, THD, AND SFDR
vs INPUT SIGNAL AMPLITUDE
-60
0
300
400
Frequency (kHz)
SPECTRAL RESPONSE
fIN = 504kHz, -10dBFS
SNR = 83dB
THD = -110dB
SFDR = 117dB
-40
200
Figure 10.
0
-20
100
Figure 9.
SIGNAL- TO- NOISE RATIO,
TOTAL HARMONIC DISTORTION,
SPURIOUS- FREE DYNAMIC RANGE (dB)
0
Amplitude (dB)
-60
-120
-160
10
fIN = 504kHz, -6dBFS
SNR = 86dB
THD = -110dB
SFDR = 115dB
-20
Amplitude (dB)
-20
-10
0
140
120
100
SFDR
80
THD
60
SNR
40
fIN = 500kHz
20
-80
-70
-60
-50
-40
-30
-20
-10
0
Input Signal Amplitude, VIN (dB)
Figure 14.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
SIGNAL-TO-NOISE RATIO
vs INPUT FREQUENCY
TOTAL HARMONIC DISTORTION
vs INPUT FREQUENCY
100
-80
VIN = -1dB
95
VIN = -1dB
-90
VIN = -6dB
THD (dB)
SNR (dB)
90
85
VIN = -10dB
80
-100
VIN = -10dB
-110
VIN = -6dB
75
70
10k
100k
-120
1M
10k
100k
1M
Input Frequency, fIN (Hz)
Input Frequency, fIN (Hz)
Figure 15.
Figure 16.
SPURIOUS-FREE DYNAMIC RANGE
vs INPUT FREQUENCY
SIGNAL-TO-NOISE RATIO
vs INPUT COMMON-MODE VOLTAGE
100
120
fIN = 10kHz, VIN = -1dB
95
VIN = -10dB
fIN = 100kHz, VIN = -1dB
110
SNR (dB)
SFDR (dB)
90
VIN = -6dB
100
85
fIN = 10kHz, VIN = -6dB
fIN = 100kHz, VIN = -6dB
80
90
VIN = -1dB
75
70
80
10k
100k
1.0
1M
1.4
1.8
2.2
2.6
3.0
3.4
Input Common-Mode Voltage, VCM (V)
Input Frequency, fIN (Hz)
Figure 17.
Figure 18.
TOTAL HARMONIC DISTORTION
vs INPUT COMMON-MODE VOLTAGE
SPURIOUS-FREE DYNAMIC RANGE
vs INPUT COMMON-MODE VOLTAGE
120
-80
fIN = 100kHz, VIN = -1dB
fIN = 10kHz, VIN = -6dB
110
-90
SFDR (dB)
THD (dB)
fIN = 10kHz, VIN = -1dB
-100
fIN = 10kHz, VIN = -6dB
100
fIN = 10kHz, VIN = -1dB
fIN = 100kHz, VIN = -6dB
90
-110
fIN = 100kHz, VIN = -6dB
fIN = 100kHz, VIN = -1dB
80
-120
1.0
1.4
1.8
2.2
2.6
3.0
Input Common-Mode Voltage, VCM (V)
Figure 19.
Copyright © 2004–2011, Texas Instruments Incorporated
3.4
1.0
1.4
1.8
2.2
2.6
3.0
3.4
Input Common-Mode Voltage, VCM (V)
Figure 20.
11
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
SIGNAL-TO-NOISE RATIO
vs CLOCK FREQUENCY
TOTAL HARMONIC DISTORTION
vs CLOCK FREQUENCY
100
-80
VIN = -6dBFS, fIN = 10kHz
RBIAS = 210kW
95
-90
RBIAS = 60kW
85
THD (dB)
SNR (dB)
90
RBIAS = 140kW
RBIAS = 210kW
RBIAS = 267kW
-100
80
RBIAS = 267kW
-110
75
70
-120
0
5
10
15
0
20
5
10
15
Figure 21.
Figure 22.
SPURIOUS-FREE DYNAMIC RANGE
vs CLOCK FREQUENCY
NOISE
vs DC INPUT VOLTAGE
120
1000
RBIAS = 140kW
RBIAS = 60kW
20
Clock Frequency, fCLK (MHz)
Clock Frequency, fCLK (MHz)
RMS Noise (LSB)
110
SFDR (dB)
RBIAS = 140kW
RBIAS = 60kW
VIN = -6dBFS, fIN = 10kHz
100
RBIAS = 210kW
100
10
1
90
RBIAS = 267kW
VIN = -6dBFS, fIN = 10kHz
0.1
80
0
5
10
15
-3
20
Figure 23.
0
1
2
3
OFFSET DRIFT OVER TIME
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
3
VIN = 0V
2
1
Offset (LSB)
Occurrences
-1
Figure 24.
NOISE HISTOGRAM
0
-1
-2
-3
-4
-4
-3
-2
-1
0
1
Output Code (LSB)
Figure 25.
12
-2
Input DC Voltage (V)
Clock Frequency, fCLK (MHz)
2
3
4
0
100 200 300 400 500
600 700 800 900 1000
Time Interval (s)
Figure 26.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
POWER-SUPPLY CURRENT vs TEMPERATURE
SUPPLY CURRENT vs CLOCK FREQUENCY
80
80
IAVDD (REFEN = low)
70
70
Supply Current (mA)
Current (mA)
60
IAVDD (REFEN = high)
50
40
30
IDVDD + IIOVDD
20
10
IAVDD (REFEN = low)
60
50
IAVDD (REFEN = high)
40
30
20
IIOVDD + IDVDD
10
RBIAS = 60kW, fCLK = 20MHz
0
RBIAS = 60kW
0
-40
10
-15
35
60
85
0
10
15
Clock Frequency, fCLK (MHz)
Figure 27.
Figure 28.
ANALOG SUPPLY CURRENT vs RBIAS
20
25
SIGNAL-TO-NOISE RATIO vs TEMPERATURE
70
100
60
95
50
90
VIN = -1dB
SNR (dB)
Analog Supply Current, IAVDD (mA)
5
Temperature (°C)
40
IAVDD (REFEN = low)
VIN = -6dB
85
VIN = -10dB
80
30
IAVDD (REFEN = high)
75
20
fIN = 100kHz
fCLK = 20MHz
70
10
0
50
100
150
200
250
300
-40
10
-15
35
60
85
Temperature (°C)
RBIAS (kW)
Figure 29.
Figure 30.
TOTAL HARMONIC DISTORTION vs TEMPERATURE
SPURIOUS-FREE DYNAMIC RANGE vs TEMPERATURE
120
-80
VIN = -1dB
110
VIN = -6dB
VIN = -6dB
SFDR (dB)
THD (dB)
-90
-100
VIN = -10dB
100
VIN = -10dB
90
-110
VIN = -1dB
fIN = 100kHz
-40
-15
10
35
Temperature (°C)
Figure 31.
Copyright © 2004–2011, Texas Instruments Incorporated
60
fIN = 100kHz
80
-120
85
-40
-15
10
35
60
85
Temperature (°C)
Figure 32.
13
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, AVDD = 5V, DVDD = IOVDD = 3V, fCLK = 20MHz, VREF = +3V, VCM = +2.7V, and
RBIAS = 60kΩ, unless otherwise noted.
VREF vs TEMPERATURE
INTERMODULATION RESPONSE
3.00
0
2.99
2.98
Amplitude (dB)
2.97
VREF (V)
fIN1 = 499kHz
fIN2 = 501kHz
IMD = -94dB
-20
2.96
2.95
2.94
2.93
-40
-60
-80
-100
2.92
-120
2.91
2.90
-140
-40
-15
10
35
Temperature (°C)
Figure 33.
14
60
85
480
485
490
495
500
505
Frequency (kHz)
510
515
520
Figure 34.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
OVERVIEW
The ADS1601 is a high-performance delta-sigma
ADC. The modulator uses an inherently stable 2-1-1
multi-stage architecture incorporating proprietary
circuitry that allows for very linear high-speed
operation. The modulator samples the input signal at
20MSPS (when fCLK = 20MHz). A low-ripple linear
phase digital filter decimates the modulator output by
16 to provide high resolution 16-bit output data.
Conceptually, the modulator and digital filter measure
the differential input signal, VIN = (AINP – AINN),
against
the
scaled
differential
reference,
VREF = (VREFP – VREFN), as shown in Figure 35.
The voltage reference can either be generated
internally or supplied externally. A three-wire serial
interface, designed for direct connection to DSPs,
outputs the data. A separate power supply for the I/O
allows flexibility for interfacing to different logic
families. Out-of-range conditions are indicated with a
dedicated digital output pin. Analog power dissipation
is controlled using an external resistor. This control
allows reduced dissipation when operating at slower
speeds. When not in use, power consumption can be
dramatically reduced by setting the PD pin low to
enter Power-Down mode.
The ADS1601 supports a very wide range of input
signals. For VREF = 3V, the full-scale input voltage is
±2.82V. Having such a wide input range makes
out-of-range signals unlikely. However, if an
out-of-range signal occurs, the digital output OTR
goes high.
The analog inputs must be driven with a differential
signal to achieve optimum performance. For the input
signal:
VCM = AINP + AINN
2
the recommended common-mode voltage is 2.7V. In
addition to the differential and common-mode input
voltages, the absolute input voltage is also important.
This is the voltage on either input (AINP or AINN)
with respect to AGND. The range for this voltage is:
–0.1V < (AINN or AINP) < 4.6V
If either input is taken below –0.1V, ESD protection
diodes on the inputs will turn on. Exceeding 4.6V on
either input results in degradation in the linearity
performance. ESD protection diodes will also turn on
if the inputs are taken above AVDD (+5V).
ANALOG INPUTS (AINP, AINN)
The recommended absolute input voltage is:
The ADS1601 measures the differential signal,
VIN = (AINP – AINN), against the differential
reference, VREF = (VREFP – VREFN). The most
positive measurable differential input is 0.94VREF,
which produces the most positive digital output code
of 7FFFh. Likewise, the most negative measurable
differential input is –0.94VREF, which produces the
most negative digital output code of 8000h.
–0.1V < (AINN or AINP) < 4.2V
Keeping the inputs within this range provides for
optimum performance.
VREFP VREFN
IOVDD
CLK
S
VREF
AINP
AINN
S
1.06
VIN
SD
Modulator
Digital
Filter
Serial
Interface
FSO
FSO
SCLK
SCLK
DOUT
DOUT
Figure 35. Conceptual Block Diagram
Copyright © 2004–2011, Texas Instruments Incorporated
15
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
INPUT CIRCUITRY
The ADS1601 uses switched-capacitor circuitry to
measure the input voltage. Internal capacitors are
charged by the inputs and then discharged internally
with this cycle repeating at the frequency of CLK.
Figure 36 shows a conceptual diagram of these
circuits. Switches S2 represent the net effect of the
modulator circuitry in discharging the sampling
capacitors; the actual implementation is different. The
timing for switches S1 and S2 is shown in Figure 37.
ADS1601
S1
www.ti.com
drivers close to the inputs and use good capacitor
bypass techniques on their supplies, such as a
smaller high-quality ceramic capacitor in parallel with
a larger capacitor. Keep the resistances used in the
driver circuits low—thermal noise in the driver circuits
degrades the overall noise performance. When the
signal can be ac-coupled to the ADS1601 inputs, a
simple RC filter can set the input common-mode
voltage.
The
ADS1601
is
a
high-speed,
high-performance ADC. Special care must be taken
when selecting the test equipment and setup used
with this device. Pay particular attention to the signal
sources to ensure they do not limit performance when
measuring the ADS1601.
AINP
S2
10pF
392W
8pF
-
VMID
VIN
2
40pF
392W
OPA2822
0.01mF
S1
AINN
VCM
(1)
S2
10pF
392W
+ VCM
AINP
100pF
392W
8pF
49.9W
(2)
1kW
1mF
(2)
392W
(1)
(3)
VCM
VMID
AGND
VIN
2
100pF
40pF
392W
1kW
+ VCM
0.01mF
Figure 36. Conceptual Diagram of Internal
Circuitry Connected to the Analog Inputs
VCM
(1)
ADS1601
(2)
392W
OPA2822
49.9W
AINN
(2)
100pF
392W
1mF
AGND
tSAMPLE = 1/fCLK
On
S1
Off
On
S2
Off
(1) Recommended VCM = 2.7V.
(2) Optional ac-coupling circuit provides common-mode input
voltage.
(3) Increase to 390pF when fIN ≤ 100kHz for improved SNR and
THD.
Figure 38. Recommended Driver Circuit Using
the OPA2822
Figure 37. Timing for the Switches in Figure 36
22pF
24.9W
DRIVING THE INPUTS
The external circuits driving the ADS1601 inputs must
be able to handle the load presented by the switching
capacitors within the ADS1601. The input switches S1
in Figure 36 are closed for approximately one-half of
the sampling period, tSAMPLE, allowing only ≉ 24ns for
the internal capacitors to be charged by the inputs
when fCLK = 20MHz.
Figure 38 and Figure 39 show the recommended
circuits when using single-ended or differential op
amps, respectively. The analog inputs must be driven
differentially to achieve optimum performance. The
external capacitors, between the inputs and from
each input to AGND, improve linearity and should be
placed as close to the pins as possible. Place the
16
AINP
392W
392W
100pF
-VIN
VCM
THS4503
100pF
ADS1601
+VIN
392W
392W
24.9W
AINN
100pF
22pF
Figure 39. Recommended Driver Circuit Using
the THS4503 Differential Amplifier
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
REFERENCE INPUTS (VREFN, VREFP, VMID)
EXTERNAL REFERENCE (REFEN = HIGH)
The ADS1601 can operate from an internal or
external voltage reference. In either case, the
reference voltage VREF is set by the differential
voltage between VREFN and VREFP: VREF =
(VREFP – VREFN). VREFP and VREFN each use
two pins, which should be shorted together. VMID
equals approximately 2.5V and is used by the
modulator. VCAP connects to an internal node and
must also be bypassed with an external capacitor.
To use an external reference, set the REFEN pin
high. This deactivates the internal generators for
VREFP,
VREFN,
and
VMID,
and
saves
approximately 25mA of current on the analog supply
(AVDD). The voltages applied to these pins must be
within the values specified in the Electrical
Characteristics table. Typically, VREFP = 4V, VMID =
2.5V, and VREFN = 1V. The external circuitry must
be capable of providing both a dc and a transient
current. Figure 41 shows a simplified diagram of the
internal circuitry of the reference when the internal
reference is disabled. As with the input circuitry,
switches S1 and S2 open and close as shown by the
timing in Figure 37.
INTERNAL REFERENCE (REFEN = LOW)
To use the internal reference, set the REFEN pin low.
This activates the internal circuitry that generates the
reference voltages. The internal reference voltages
are applied to the pins. Good bypassing of the
reference pins is critical to achieve optimum
performance and is done by placing the bypass
capacitors as close to the pins as possible. Figure 40
shows the recommended bypass capacitor values.
Use high-quality ceramic capacitors for the smaller
values. Avoid loading the internal reference with
external circuitry. If the ADS1601 internal reference is
to be used by other circuitry, buffer the reference
voltages to prevent directly loading the reference
pins.
ADS1601
S1
VREFP
VREFP
S2
300W
VREFN
VREFN
50pF
S1
Figure 41. Conceptual Internal Circuitry for the
Reference When REFEN = High
ADS1601
10mF
0.1mF
VREFP
VREFP
VMID
0.1mF
10mF
0.1mF
VREFN
VREFN
10mF
0.1mF
Figure 42 shows the recommended circuitry for
driving these reference inputs. Keep the resistances
used in the buffer circuits low to prevent excessive
thermal noise from degrading performance. Layout of
these circuits is critical; be sure to follow good
high-speed layout practices. Place the buffers, and
especially the bypass capacitors, as close to the pins
as possible. VCAP is unaffected by the setting on
REFEN and must be bypassed when using the
internal or an external reference.
VCAP
0.1mF
AGND
Figure 40. Reference Bypassing When Using the
Internal Reference
Copyright © 2004–2011, Texas Instruments Incorporated
17
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
Table 1. Maximum Allowable Clock Source Jitter
for Different Input Signal Frequencies and
Amplitude
392W
0.001mF
ADS1601
INPUT SIGNAL
VREFP
OPA2822
VREFP
10mF
4V
0.1mF
392W
0.1mF
0.001mF
VMID
OPA2822
10mF
2.5V
MAXIMUM ALLOWABLE
CLOCK SOURCE JITTER
500kHz
–0.5dB
6ps
500kHz
–20dB
60ps
100kHz
–0.5dB
30ps
100kHz
–20dB
300ps
DATA FORMAT
0.001mF
VREFN
VREFN
OPA2822
10mF
0.1mF
VCAP
0.1mF
AGND
Figure 42. Recommended Buffer Circuit When
Using an External Reference
CLOCK INPUT (CLK)
The ADS1601 requires an external clock signal to be
applied to the CLK input pin. The sampling of the
modulator is controlled by this clock signal. As with
any high-speed data converter, a high quality clock is
essential for optimum performance. Crystal clock
oscillators are the recommended CLK source; other
sources, such as frequency synthesizers, are usually
inadequate. Make sure to avoid excess ringing on the
CLK input; keeping the trace as short as possible
helps.
Measuring high-frequency, large amplitude signals
requires tight control of clock jitter. The uncertainty
during sampling of the input from clock jitter limits the
maximum achievable SNR. This effect becomes more
pronounced with higher frequency and larger
magnitude inputs. Fortunately, the ADS1601
oversampling topology reduces clock jitter sensitivity
over that of Nyquist rate converters such as pipeline
and successive approximation converters by a factor
of √16.
In order to not limit the ADS1601 SNR performance,
keep the jitter on the clock source below the values
shown in Table 1. When measuring lower frequency
and lower amplitude inputs, more CLK jitter can be
tolerated. In determining the allowable clock source
jitter, select the worst-case input (highest frequency,
largest amplitude) that will be seen in the application.
18
MAXIMUM
AMPLITUDE
0.1mF
392W
1V
MAXIMUM
FREQUENCY
The 16-bit output data are in binary two’s
complement format as shown in Table 2. When the
input is positive out-of-range, exceeding the positive
full-scale value of +0.94VREF, the output clips to all
7FFFh and the OTR output goes high.
Likewise, when the input is negative out-of-range by
going below the negative full-scale value
of –0.94VREF, the output clips to 8000h and the OTR
output goes high. The OTR remains high while the
input signal is out-of-range.
Table 2. Output Code versus Input Signal
INPUT SIGNAL (INP –
INN)
IDEAL OUTPUT
CODE(1)
OTR
≥ +0.94VREF (> 0dB)
7FFFh
1
–0.94VREF (0dB)
7FFFh
0
001h
0
0000h
0
FFFFh
0
8000h
0
8000h
1
+0.94VREF
2
15
-1
0
-0.94VREF
2
15
-0.94VREF
-1
2
(
2
£ -0.94VREF
15
15
)
-1
2
(
2
15
15
)
-1
(1) Excludes effects of noise, INL, offset and gain errors.
OUT-OF-RANGE INDICATION (OTR)
If the output code exceeds the positive or negative
full-scale, the out-of-range digital output OTR will go
high on the falling edge of SCLK. When the output
code returns within the full-scale range, OTR returns
low on the falling edge of SCLK.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
DATA RETRIEVAL
STEP RESPONSE
Data retrieval is controlled through a simple serial
interface. The interface operates in a master fashion
by outputting both a frame sync indicator (FSO) and a
serial clock (SCLK). Complementary outputs are
provided for the frame sync output (FSO), serial clock
(SCLK), and data output (DOUT). When not needed,
leave the complementary outputs unconnected.
Figure 44 plots the normalized step response for an
input applied at t = 0. The x-axis units of time are
conversions cycles. It takes 51 cycles to fully settle;
for fCLK = 20MHz, this corresponds to 40.8μs.
1.2
1.0
INITIALIZING THE ADS1601
After the power supplies have stabilized, you must
initialize the ADS1601 by issuing a SYNC pulse as
shown in Figure 1. This operation needs only to be
done once after power-up and does not need to be
performed when exiting the Power-Down mode. Note
that the ADS1601 silicon was revised in June 2006.
The digital interface timing specifications were
modified slightly from the previous revision. This data
sheet reflects behavior of the latest revision. Contact
the factory for more information on the previous
revision.
Step Response
0.8
0.6
0.4
0.2
0
-0.2
0
ADS16011
SYNC
CLK
SYNC
CLK
FSO
FSO1
DOUT
DOUT1
20
30
40
50
Time (Conversion Cycles)
Figure 44. Step Response
SYNCHRONIZING MULTIPLE ADS1601s
The SYNC input can be used to synchronize multiple
ADS1601s to provide simultaneous sampling. All
devices to be synchronized must use a common CLK
input. With the CLK inputs running, pulse SYNC on
the falling edge of CLK, as shown in Figure 43.
Afterwards, the converters will be converting
synchronously with the FSO outputs updating
simultaneously. After synchronization, FSO is held
low until the digital filter has fully settled.
10
FREQUENCY RESPONSE
The linear phase FIR digital filter sets the overall
frequency response. Figure 45 shows the frequency
response from dc to 10MHz for fCLK = 20MHz. The
frequency response of the ADS1601 filter scales
directly with CLK frequency. For example, if the CLK
frequency is decreased by half (to 10MHz), the
values on the X-axis in Figure 45 would need to be
scaled by half, with the span becoming dc to 5MHz.
Figure 46 shows the passband ripple from dc to
600kHz (fCLK = 20MHz). Figure 47 shows a closer
view of the passband transition by plotting the
response from 400kHz to 650kHz (fCLK = 20MHz).
20
fCLK = 20MHz
ADS16012
SYNC
0
FSO2
FSO
DOUT2
DOUT
CLK
Magnitude (dB)
-20
CLK
-40
-60
-80
-100
-120
SYNC
tSTL
FSO1
FSO2
-140
0
1
2
3
4
5
6
7
8
9
10
Frequency (MHz)
Figure 45. Frequency Response
Figure 43. Synchronizing Multiple Converters
Copyright © 2004–2011, Texas Instruments Incorporated
19
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
0.001
20
fCLK = 20MHz
0.0008
0
-20
0.0004
Magnitude (dB)
Magnitude (dB)
0.0006
0.0002
0
-0.0002
-0.0004
-40
-60
-80
-100
-0.0006
-0.0008
-120
fCLK = 20MHz
-0.001
0
100
200
400
300
500
600
-140
0
10
Frequency (kHz)
fCLK = 20MHz
Magnitude (dB)
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
450
500
550
40
50
60
Figure 48. Frequency Response Out to 120MHz
0.5
400
30
Frequency (MHz)
Figure 46. Passband Ripple
0
20
600
650
Frequency (kHz)
Figure 47. Passband Transition
ANALOG POWER DISSIPATION
An external resistor connected between the RBIAS
pin and the analog ground sets the analog current
level, as shown in Figure 49. The current is inversely
proportional to the resistor value. Table 3 shows the
recommended values of RBIAS for different CLK
frequencies. Notice that the analog current can be
reduced when using a slower frequency CLK input
because the modulator has more time to settle. Avoid
adding any capacitance in parallel to RBIAS because
this interferes with the internal circuitry used to set
the biasing. Please note that changing RBIAS changes
internally-generated voltages, including the internal
reference; therefore, it should be understood that the
recommendations of Table 3 are for external
reference only.
ADS1601
ANTI-ALIAS REQUIREMENTS
Higher frequency, out-of-band signals must be
eliminated to prevent aliasing with ADCs. Fortunately,
the ADS1601 on-chip digital filter greatly simplifies
this filtering requirement. Figure 48 shows the
ADS1601 response out to 60MHz (fCLK = 20MHz).
Since the stop band extends out to 19.3MHz, the
anti-alias filter in front of the ADS1601 only needs to
be designed to remove higher frequency signals than
this, which can usually be accomplished with a simple
RC circuit on the input driver.
RBIAS
RBIAS
AGND
Figure 49. External Resistor Used to Set Analog
Power Dissipation
Table 3. Recommended RBIAS Resistor Values for
Different CLK Frequencies
20
fCLK
DATA
RATE
RBIAS
TYPICAL POWER
DISSIPATION
WITH REFEN HIGH
5MHz
315kSPS
267k
100mW
10MHz
625kSPS
210k
145mW
15MHz
940kSPS
140k
200mW
20MHz
1.25MSPS
60k
325mW
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
POWER DOWN (PD)
POWER SUPPLIES
When not in use, the ADS1601 can be powered down
by taking the PD pin low. All circuitry is shut down,
including the voltage reference. To minimize the
digital current during power down, stop the clock
signal supplied to the CLK input. There is an internal
pull-up resistor of 170kΩ on the PD pin, but it is
recommended that this pin be connected to IOVDD if
not used. Make sure to allow time for the reference to
start up after exiting power-down mode. The internal
reference typically requires 15ms. After the reference
has stabilized, allow at least 100 conversions for the
modulator and digital filter to settle before retrieving
data.
Three supplies are used on the ADS1601: analog
(AVDD), digital (DVDD) and digital I/O (IOVDD). Each
supply must be suitably bypassed to achieve the best
performance. It is recommended that a 1μF and
0.1μF ceramic capacitor be placed as close to each
supply pin as possible. Connect each supply-pin
bypass capacitor to the associated ground, as shown
in Figure 50. Each main supply bus should also be
bypassed with a bank of capacitors from 47μF to
0.1μF, as shown. The I/O and digital supplies (IOVDD
and DVDD) can be connected together when using
the same voltage. In this case, only one bank of 47μF
to 0.1μF capacitors is needed on the main supply
bus, though each supply pin must still be bypassed
with a 1μF and 0.1μF ceramic capacitor.
DVDD
47mF
4.7mF
1mF
0.1mF
47mF
4.7mF
1mF
0.1mF
IOVDD
CP
AVDD
2
AVDD
digital ground planes, connect
3
38
37
34
33
DGND
If using separate analog and
55
DVDD
AGND
41
IOVDD
1
42
DGND
0.1mF
AGND
1mF
AGND
4.7mF
CP
AVDD
47mF
CP
DGND 36
CP
together on the ADS1601 PCB.
6
AGND
7
AVDD
9
AGND
CP
DGND
AGND
NOTE: CP = 1mF úú 0.1mF
ADS1601
CP
10 AVDD
19
22
CP
DVDD
18
10kW
DGND
15
DGND
12 AVDD
DVDD
CP
RPULLUP
11 AGND
23
CP
Figure 50. Recommended Power-Supply Bypassing
Copyright © 2004–2011, Texas Instruments Incorporated
21
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
LAYOUT ISSUES AND COMPONENT
SELECTION
The McBSP provides a host of functions including:
• Full-duplex communication
• Double-buffered data registers
• Independent framing and clocking for reception
and transmission of data
The ADS1601 is a very high-speed, high-resolution
data converter. In order to achieve maximum
performance, the user must give very careful
consideration to both the layout of the printed circuit
board (PCB) in addition to the routing of the traces.
Capacitors that are critical to achieve the best
performance from the device should be placed as
close to the pins of the device as possible. These
include capacitors related to the analog inputs, the
reference, and the power supplies.
For critical capacitors, it is recommended that Class II
dielectrics such as Z5U be avoided. These dielectrics
have a narrow operating temperature, a large
tolerance on the capacitance, and lose up to 20% of
the rated capacitance over 10,000 hours. Rather,
select capacitors with a Class I dielectric. C0G (also
known as NP0), for example, has a tight tolerance
less than ±30ppm/°C and is very stable over time.
Should Class II capacitors be chosen because of the
size constraints, select an X7R or X5R dielectric to
minimize the variations of the capacitor’s critical
characteristics.
The resistors used in the circuits to drive the input
and reference should be kept as low as possible to
prevent excess thermal noise from degrading the
system performance.
The digital outputs from the device should always be
buffered. This will have a number of benefits: it
reduces the loading of the internal digital buffers,
which decreases noise generated within the device,
and it also reduces device power consumption.
APPLICATIONS INFORMATION
Interfacing the ADS1601 to the TMS320 DSP
family.
Since the ADS1601 communicates with the host via a
serial interface, the most suitable method to connect
to any of the TMS320 DSPs is via the multi-channel
buffered serial port (McBSP). A typical connection to
the TMS320 DSP is shown in Figure 51.
22
The sequence begins with a one-time synchronization
of the serial port by the microprocessor. The
ADS1601 recognizes the SYNC signal if it is high for
at least one CLK period. Transfers are initiated by the
ADS1601 after the SYNC signal is de-asserted by the
microprocessor.
The FSO signal from the ADS1601 indicates that
data is available to be read, and is connected to the
frame sync receive (FSR) pin of the DSP. The clock
receiver (CLKR) is derived directly from the ADS1601
serial
clock
output
to
ensure
continued
synchronization of data with the clock.
ADS1601
FSO
TMS320
FSR
SCLK
CLKR
DOUT
DR
SYNC
FSX
Figure 51. ADS1601—TMS320 Interface
Connection
An evaluation module (EVM) is available from Texas
Instruments. The module consists of the ADS1601
and supporting circuits, allowing users to quickly
assess the performance and characteristics of the
ADS1601. The EVM easily connects to various
microcontrollers and DSP systems. For more details,
or to download a copy of the ADS1601EVM User’s
Guide, visit the Texas Instruments web site at
www.ti.com.
Copyright © 2004–2011, Texas Instruments Incorporated
ADS1601
SBAS322D – DECEMBER 2004 – REVISED OCTOBER 2011
www.ti.com
REVISION HISTORY
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (September 2010) to Revision D
•
Page
Added footnote 1 to Electrical Characteristics table ............................................................................................................. 4
Changes from Revision B (September 2008) to Revision C
Page
•
Changed the Timing Diagrams section ................................................................................................................................. 8
•
Added note to Initializing the ADS1601 section .................................................................................................................. 19
•
Updated Figure 43 .............................................................................................................................................................. 19
Copyright © 2004–2011, Texas Instruments Incorporated
23
PACKAGE OPTION ADDENDUM
www.ti.com
24-Aug-2018
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
ADS1601IPFBR
ACTIVE
TQFP
PFB
48
1000
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
-40 to 85
ADS1601I
ADS1601IPFBT
ACTIVE
TQFP
PFB
48
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
-40 to 85
ADS1601I
(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/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
24-Aug-2018
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
26-Feb-2019
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
ADS1601IPFBR
TQFP
PFB
48
1000
330.0
16.4
9.6
9.6
1.5
12.0
16.0
Q2
ADS1601IPFBT
TQFP
PFB
48
250
180.0
16.4
9.6
9.6
1.5
12.0
16.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
26-Feb-2019
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
ADS1601IPFBR
TQFP
PFB
48
1000
350.0
350.0
43.0
ADS1601IPFBT
TQFP
PFB
48
250
213.0
191.0
55.0
Pack Materials-Page 2
MECHANICAL DATA
MTQF019A – JANUARY 1995 – REVISED JANUARY 1998
PFB (S-PQFP-G48)
PLASTIC QUAD FLATPACK
0,27
0,17
0,50
36
0,08 M
25
37
24
48
13
0,13 NOM
1
12
5,50 TYP
7,20
SQ
6,80
9,20
SQ
8,80
Gage Plane
0,25
0,05 MIN
0°– 7°
1,05
0,95
Seating Plane
0,75
0,45
0,08
1,20 MAX
4073176 / B 10/96
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. Falls within JEDEC MS-026
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
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