TI1 ADS58B19IRGZT 11-bit, 200msps/9-bit, 250msps, ultralow-power adcs with analog buffer Datasheet

ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009 – REVISED JANUARY 2011
www.ti.com
11-Bit, 200MSPS/9-Bit, 250MSPS,
Ultralow-Power ADCs with Analog Buffer
Check for Samples: ADS58B18, ADS58B19
FEATURES
DESCRIPTION
•
•
•
The ADS58B18/B19 are members of the ultralow
power ADS4xxx analog-to-digital converter (ADC)
family that features integrated analog buffers and
SNRBoost technology. The ADS58B18 and
ADS58B19 are 11-bit and 9-bit ADCs with sampling
rates up to 200MSPS and 250MSPS, respectively.
Innovative design techniques are used to achieve
high dynamic performance while consuming
extremely low power. The analog input pins have
buffers with constant performance and input
impedance across a wide frequency range. This
architecture makes these parts well-suited for
multi-carrier,
wide
bandwidth
communications
applications such as PA linearization.
1
23
•
•
•
•
•
•
•
•
•
ADS58B18: 11-Bit, 200MSPS
ADS58B19: 9-Bit, 250MSPS
Integrated High-Impedance Analog Input
Buffer
Ultralow Power:
– Analog Power: 258mW at 200MSPS
– I/O Power: 69mW (DDR LVDS, low LVDS
swing)
High Dynamic Performance:
– ADS58B18: 66dBFS SNR and 81dBc SFDR
at 150MHz
– ADS58B19: 55.7dBFS SNR and 76dBc
SFDR at 150MHz
Enhanced SNR Using TI-Proprietary SNRBoost
Technology (ADS58B18 Only)
– –77.7dBFS SNR in 20MHz Bandwidth
Dynamic Power Scaling with Sample Rate
Output Interface:
– Double Data Rate (DDR) LVDS with
Programmable Swing and Strength
– Standard Swing: 350mV
– Low Swing: 200mV
– Default Strength: 100Ω Termination
– 2x Strength: 50Ω Termination
– 1.8V Parallel CMOS Interface Also
Supported
Programmable Gain for SNR/SFDR Trade-Off
DC Offset Correction
Supports Low Input Clock Amplitude
Package: QFN-48 (7mm × 7mm)
The ADS58B18 uses TI-proprietary SNRBoost
technology that can be used to overcome SNR
limitation as a result of quantization noise for
bandwidths less than Nyquist (fS/2).
Both devices have gain options that can be used to
improve SFDR performance at lower full-scale input
ranges, especially at very high input frequencies.
They also include a dc offset correction loop that can
be used to cancel the ADC offset. At lower sampling
rates, the ADC automatically operates at scaled-down
power with no loss in performance.
These devices support both double data rate (DDR)
low-voltage differential signaling (LVDS) and parallel
CMOS digital output interfaces. The low data rate of
the DDR LVDS interface (maximum 500Mbps) makes
it possible to use low-cost field-programmable gate
array (FPGA)-based receivers. They have a
low-swing LVDS mode that can be used to further
reduce the power consumption. The strength of the
LVDS output buffers can also be increased to support
50Ω differential termination.
The ADS58B18/B19 are both available in a compact
QFN-48 package and specified over the industrial
temperature range (–40°C to +85°C).
1
2
3
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PowerPAD is a trademark of Texas Instruments Incorporated.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
© 2009–2011, Texas Instruments Incorporated
ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009 – REVISED JANUARY 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.
ORDERING INFORMATION (1)
PRODUCT
PACKAGELEAD
PACKAGE
DESIGNATOR
SPECIFIED
TEMPERATURE
RANGE
ADS58B18
QFN-48
RGZ
ADS58B19
(1)
(2)
QFN-48
RGZ
ECO PLAN (2)
LEAD/BALL
FINISH
PACKAGE
MARKING
–40°C to +85°C
GREEN (RoHS,
no Sb/Br)
Cu/NiPdAu
AZ58B18
–40°C to +85°C
GREEN (RoHS,
no Sb/Br)
Cu/NiPdAu
AZ58B19
ORDERING
NUMBER
TRANSPORT
MEDIA
ADS58B18IRGZR
Tape and reel
ADS58B18IRGZT
Tape and reel
ADS58B19IRGZR
Tape and reel
ADS58B19IRGZT
Tape and reel
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.
Eco Plan is the planned eco-friendly classification. Green (RoHS, no Sb/Br): TI defines Green to mean Pb-Free (RoHS compatible) and
free of Bromine- (Br) and Antimony- (Sb) based flame retardants. Refer to the Quality and Lead-Free (Pb-Free) Data web site for more
information.
ABSOLUTE MAXIMUM RATINGS (1)
ADS58B18, ADS58B19
MIN
MAX
UNIT
Supply voltage range, AVDD
–0.3
2.1
V
Supply voltage range, AVDD_BUF
–0.3
3.9
V
Supply voltage range, DRVDD
–0.3
2.1
V
Voltage between AGND and DRGND
–0.3
0.3
V
Voltage between AVDD to DRVDD (when AVDD leads DRVDD)
–2.4
2.4
V
Voltage between DRVDD to AVDD (when DRVDD leads AVDD)
–2.4
2.4
V
Voltage between AVDD_BUF to DRVDD/AVDD
–4.2
4.2
V
–0.3
minimum
(1.9, AVDD + 0.3)
V
–0.3
AVDD + 0.3
V
INP, INM
Voltage applied to input pins
(2)
CLKP, CLKM , RESET, SCLK,
SDATA, SEN, DFS, SNRBoost_En
–40
Operating free-air temperature range, TA
Operating junction temperature range, TJ
–65
Storage temperature range, Tstg
ESD, human body model (HBM)
(1)
(2)
+85
°C
+125
°C
+150
°C
2
kV
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.
When AVDD is turned off, it is recommended to switch off the input clock (or ensure the voltage on CLKP, CLKM is less than |0.3V|.
Doing so prevents the ESD protection diodes at the clock input pins from turning on.
THERMAL INFORMATION
ADS58B18
THERMAL METRIC (1)
RGZ
UNITS
48 PINS
θJA
Junction-to-ambient thermal resistance
29
θJCtop
Junction-to-case (top) thermal resistance
n/a
θJB
Junction-to-board thermal resistance
10
ψJT
Junction-to-top characterization parameter
0.3
ψJB
Junction-to-board characterization parameter
9
θJCbot
Junction-to-case (bottom) thermal resistance
1.13
(1)
2
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
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ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009 – REVISED JANUARY 2011
www.ti.com
RECOMMENDED OPERATING CONDITIONS
ADS58B18, ADS58B19
MIN
TYP
MAX
UNIT
1.7
1.8
1.9
V
3
3.3
3.6
V
1.7
1.8
1.9
V
SUPPLIES
AVDD
Analog supply voltage
AVDD_BUF
Analog buffer supply voltage
DRVDD
Digital supply voltage
ANALOG INPUTS
Differential input voltage range
1.5
VPP
1.7 ± 0.05
V
Maximum analog input frequency with 1.5VPP input amplitude (1)
400
MHz
Maximum analog input frequency with 1VPP input amplitude (1)
600
MHz
Input common-mode voltage
CLOCK INPUT
Input clock sample rate: ADS58B18
Enable low speed mode (2)
Low speed mode disabled (default mode after reset)
30
80
MSPS
> 80
200
MSPS
30
80
MSPS
> 80
250
MSPS
Input clock sample rate: ADS58B19
Enable low speed mode (2)
Low speed mode disabled (default mode after reset)
Input clock amplitude differential (VCLKP – VCLKM)
Sine wave, ac-coupled
0.2
1.5
VPP
LVPECL, ac-coupled
1.6
VPP
LVDS, ac-coupled
0.7
VPP
LVCMOS, single-ended, ac-coupled
1.8
Input clock duty cycle
35
50
V
65
%
DIGITAL OUTPUTS
CLOAD
Maximum external load capacitance from each output pin to
DRGND
5
pF
RLOAD
Differential load resistance between the LVDS output pairs
(LVDS mode)
100
Ω
TA
Operating free-air temperature
(1)
(2)
–40
+85
°C
See the Theory of Operation section in the Application Information.
See the Serial Interface section for details on the low-speed mode.
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3
ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009 – REVISED JANUARY 2011
www.ti.com
ELECTRICAL CHARACTERISTICS: ADS58B18/ADS58B19
Typical values are at +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, 50% clock duty cycle, –1dBFS differential
analog input, and DDR LVDS interface, unless otherwise noted. Minimum and maximum values are across the full
temperature range:
TMIN = –40°C to TMAX = +85°C, AVDD = 1.8V, and DRVDD = 1.8V.
ADS58B18
PARAMETER
TEST CONDITIONS
MIN
TYP
ADS58B19
MAX
Resolution
SINAD (signal-to-noise and distortion ratio),
LVDS
HD2
fIN = 70MHz
66.2
55.8
dBFS
fIN = 100MHz
66.1
55.8
dBFS
55.8
dBFS
fIN = 300MHz
65.3
55.8
dBFS
fIN = 10MHz
66.2
55.8
dBFS
fIN = 70MHz
66.1
55.8
dBFS
fIN = 100MHz
66
55.8
dBFS
55.8
HD3
dBFS
IMD
Input overload recovery
dBFS
76.5
dBc
fIN = 70MHz
87
76.2
dBc
fIN = 100MHz
87
76.1
dBc
76
dBc
71
81
68.5
fIN = 300MHz
75
75.7
dBc
fIN = 10MHz
86.5
85
dBc
fIN = 70MHz
85
80
dBc
fIN = 100MHz
84
79
dBc
80.5
dBc
70
81
67.5
fIN = 300MHz
74.5
71.5
dBc
fIN = 10MHz
90
88
dBc
fIN = 70MHz
91
89
dBc
fIN = 100MHz
92
85
dBc
85
dBc
fIN = 300MHz
79
75
dBc
fIN = 10MHz
87.5
89
dBc
fIN = 70MHz
87
90
dBc
fIN = 100MHz
87
82
dBc
85
71
dBc
76
87
68.5
81
68.5
fIN = 300MHz
75
75
dBc
fIN = 10MHz
91
76.5
dBc
fIN = 70MHz
91
76.2
dBc
fIN = 100MHz
90
76.1
dBc
76
dBc
76
89
68.5
fIN = 300MHz
88
76
dBc
f1 = 185MHz, f2 = 190MHz,
each tone at –7dBFS
–86
–86
dBFS
Recovery to within 1% (of final
value) for 6dB overload with
sine-wave input
1
1
Clock
cycles
> 30
> 30
dB
For 100mVPP signal on AVDD
supply, up to 10MHz
Effective number of bits
ENOB
fIN = 170MHz
DNL
fIN = 170MHz
INL
fIN = 170MHz
4
54.2
87.5
PSRR
Integral nonlinearity
65.8
fIN = 10MHz
AC power-supply rejection ratio
Differential nonlinearity
54.7
55.7
fIN = 170MHz
Two-tone intermodulation
distortion
64
66
64.8
fIN = 170MHz
Worst spur
(other than second and third harmonics)
64.5
fIN = 300MHz
fIN = 170MHz
Third-harmonic distortion
Bits
dBFS
fIN = 170MHz
Second-harmonic distortion
UNIT
55.8
fIN = 170MHz
THD
9
66.3
fIN = 170MHz
SFDR
MAX
fIN = 10MHz
fIN = 170MHz
Total harmonic distortion
TYP
11
SNR (signal-to-noise ratio), LVDS
Spurious-free dynamic range
MIN
10.6
–0.7
9
±0.25
2
±0.5
±2.5
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–0.6
LSBs
±0.15
0.85
LSBs
±0.25
±1.2
LSBs
© 2009–2011, Texas Instruments Incorporated
Product Folder Link(s): ADS58B18 ADS58B19
ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009 – REVISED JANUARY 2011
www.ti.com
ELECTRICAL CHARACTERISTICS: GENERAL
Typical values are at +25°C, AVDD = 1.8V, DRVDD = 1.8V, 50% clock duty cycle, and 0dB gain, unless otherwise noted.
Minimum and maximum values are across the full temperature range: TMIN = –40°C to TMAX = +85°C, AVDD = 1.8V, and
DRVDD = 1.8V.
ADS58B18
PARAMETER
MIN
TYP
ADS58B19
MAX
MIN
TYP
MAX
UNIT
ANALOG INPUTS
Differential input voltage range
1.5
1.5
VPP
4
4
kΩ
Differential input capacitance; see Figure 60
2.1
2.1
pF
Analog input bandwidth
550
550
MHz
<2
<2
µA
1.7
1.7
V
4
4
mA
Differential input resistance (at dc); see Figure 59
Analog input common-mode current (per input pin)
Common-mode output voltage
VCM
VCM output current capability
DC ACCURACY
–15
Offset error
Temperature coefficient of offset error
Gain error as a result of internal reference
inaccuracy alone
Gain error of channel alone
Temperature coefficient of EGCHAN
2
15
–15
0.003
EGREF
EGCHAN
–2
2
–0.2
2
15
0.003
–1
0.001
–2
2
–0.2
mV
mV/°C
–1
%FS
%FS
Δ%/°C
0.001
POWER SUPPLY
IAVDD
Analog supply current
88
105
103
113
mA
IAVDD_BUF
Input buffer supply current
30
40
31
42
mA
IDRVDD (1)
Output buffer supply current
LVDS interface with 100Ω external termination
Low LVDS swing (200mV)
38
IDRVDD
Output buffer supply current
LVDS interface with 100Ω external termination
Standard LVDS swing (350mV)
62
IDRVDD output buffer supply current (1) (2)
CMOS interface (2)
8pF external load capacitance
fIN = 2.5MHz
26
35
mA
Analog power:
AVDD + AVDD_BUF supplies
260
287
mW
Digital power:
LVDS interface, low LVDS swing
68.7
84.6
mW
47
63
mW
Digital power:
CMOS interface (2)
8pF external load capacitance
fIN = 2.5MHz
Global power-down
10
Standby
185
(1)
(2)
47
75
35
64
10
mA
82
35
185
mA
mW
mW
The maximum DRVDD current with CMOS interface depends on the actual load capacitance on the digital output lines. Note that the
maximum recommended load capacitance on each digital output line is 10pF.
In CMOS mode, the DRVDD current scales with the sampling frequency, the load capacitance on output pins, input frequency, and the
supply voltage (see the CMOS Interface Power Dissipation section in the Application Information).
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5
ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009 – REVISED JANUARY 2011
www.ti.com
DIGITAL CHARACTERISTICS
The dc specifications refer to the condition where the digital outputs are not switching but are permanently at a valid logic
level '0' or '1'. AVDD = 1.8V and DRVDD = 1.8V.
ADS58B18, ADS58B19
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DIGITAL INPUTS (RESET, SCLK, SDATA, SEN, OE, SNRBoost_En)
High-level input voltage
Low-level input voltage
High-level input voltage
Low-level input voltage
RESET, SCLK, SDATA,
SNRBoost_En, and SEN
support 1.8V and 3.3V CMOS
logic levels
1.3
OE only supports 1.8V CMOS
logic levels
1.3
V
0.4
V
V
0.4
V
High-level input current: SDATA, SCLK (1)
VHIGH = 1.8V
10
µA
High-level input current: SEN (2)
VHIGH = 1.8V
0
µA
Low-level input current: SDATA, SCLK
VLOW = 0V
0
µA
Low-level input current: SEN
VLOW = 0V
–10
µA
DIGITAL OUTPUTS (CMOS INTERFACE: D0 TO D13, OVR_SDOUT)
DRVDD – 0.1
High-level output voltage
Low-level output voltage
DRVDD
0
V
0.1
V
DIGITAL OUTPUTS (LVDS INTERFACE: D0P/M TO D9_10_P/M, CLKOUTP/M)
High-level output voltage (3)
VODH
Standard swing LVDS
270
+350
430
mV
Low-level output voltage (3)
VODL
Standard swing LVDS
–430
–350
–270
mV
High-level output voltage
(3)
VODH
Low swing LVDS
+200
Low-level output voltage (3)
VODL
Low swing LVDS
–200
Output common-mode voltage
VOCM
(1)
(2)
(3)
6
0.85
1.05
mV
mV
1.25
V
SDATA and SCLK have an internal 180kΩ pull-down resistor.
SEN has an internal 180kΩ pull-up resistor to AVDD.
With an external 100Ω termination.
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SBAS487D – NOVEMBER 2009 – REVISED JANUARY 2011
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PIN CONFIGURATION (LVDS MODE)
D9_D10_P
D9_D10_M
D7_D8_P
D7_D8_M
D5_D6_P
D5_D6_M
D3_D4_P
D3_D4_M
D1_D2_P
D1_D2_M
D0_P
D0_M
RGZ PACKAGE(3)
QFN-48
(TOP VIEW)
48
47
46
45
44
43
42
41
40
39
38
37
NC
CLKOUTP
5
32
NC
DFS
6
31
NC
OE
7
30
RESET
AVDD
8
29
SCLK
AGND
9
28
SDATA
CLKP 10
27
SEN
CLKM 11
26
AVDD
AGND 12
25
AGND
13
14
15
16
17
18
19
20
21
22
23
24
AVDD
NC
33
SNRBoost_En
34
4
AVDD
3
CLKOUTM
AVDD
OVR_SDOUT
AVDD_BUF
DRVDD
AVDD
35
AGND
2
AGND
DRVDD
INP
DRGND
INM
36
AGND
1
VCM
DRGND
(1) The PowerPAD™ is connected to DRGND.
Figure 1. ADS58B18 LVDS Pinout
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SBAS487D – NOVEMBER 2009 – REVISED JANUARY 2011
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42
41
40
NC
43
D0_M
D0_P
44
NC
D1_D2_M
45
D1_D2_P
46
D3_D4_P
D5_D6_M
47
D3_D4_M
D7_D8_M
48
D5_D6_P
D7_D8_P
RGZ PACKAGE(4)
QFN-48
(TOP VIEW)
39
38
37
NC
CLKOUTP
5
32
NC
DFS
6
31
NC
OE
7
30
RESET
AVDD
8
29
SCLK
AGND
9
28
SDATA
CLKP 10
27
SEN
CLKM 11
26
AVDD
AGND 12
25
AGND
13
14
15
16
17
18
19
20
21
22
23
24
AVDD
NC
33
UNUSED
34
4
AVDD
3
CLKOUTM
AVDD
OVR_SDOUT
AVDD_BUF
DRVDD
AVDD
35
AGND
2
AGND
DRVDD
INP
DRGND
INM
36
AGND
1
VCM
DRGND
(2) The PowerPAD is connected to DRGND.
Figure 2. ADS58B19 LVDS Pinout
ADS58B18, ADS58B19 Pin Assignments (LVDS Mode)
8
PIN NAME
PIN NUMBER
# OF
PINS
FUNCTION
AVDD
8, 18, 20, 22, 24, 26
6
I
1.8V analog power supply
AVDD_BUF
21
1
I
3.3V input buffer supply
AGND
9, 12, 14, 17, 19, 25
6
I
Analog ground
CLKP
10
1
I
Differential clock input, positive
CLKM
11
1
I
Differential clock input, negative
INP
15
1
I
Differential analog input, positive
INM
16
1
I
Differential analog input, negative
VCM
13
1
O
Outputs the common-mode voltage that can be used externally to bias the analog input
pins.
DESCRIPTION
RESET
30
1
I
Serial interface RESET input.
When using the serial interface mode, the internal registers must initialize through
hardware RESET by applying a high pulse on this pin or by using the software reset
option; refer to the Serial Interface section.
When RESET is tied high, the internal registers are reset to the default values. In this
condition, SEN can be used as an analog control pin.
RESET has an internal 180kΩ pull-down resistor.
SCLK
29
1
I
This pin functions as a serial interface clock input when RESET is low. When RESET is
high, SCLK has no function and should be tied to ground. This pin has an internal
180kΩ pull-down resistor.
SDATA
28
1
I
This pin functions as a serial interface data input when RESET is low. When RESET is
high, SDATA functions as a STANDBY control pin (see Table 7). This pin has an
internal 180kΩ pull-down resistor.
SEN
27
1
I
This pin functions as a serial interface enable input when RESET is low. When RESET
is high, SEN has no function and should be tied to AVDD. This pin has an internal
180kΩ pull-up resistor to AVDD.
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ADS58B18, ADS58B19 Pin Assignments (LVDS Mode) (continued)
PIN NAME
PIN NUMBER
# OF
PINS
FUNCTION
DESCRIPTION
OE
7
1
I
Output buffer enable input, active high; this pin has an internal 180kΩ pull-up resistor to
DRVDD.
DFS
6
1
I
Data format select input. This pin sets the DATA FORMAT (twos compliment or offset
binary) and the LVDS/CMOS output interface type. See Table 4 for detailed information.
SNRBoost_En
23
1
I
ADS58B18: Digital control pin for SNRBoost mode, active high.
ADS58B19: Unused.
CLKOUTP
5
1
O
Differential output clock, true
CLKOUTM
4
1
O
Differential output clock, complement
D0_P
Refer to Figure 1 and
Figure 2
1
O
Differential output data D0 and logic low multiplexed, true
D0_M
Refer to Figure 1 and
Figure 2
1
O
Differential output data D0 and logic low multiplexed, complement
D1_D2_P
Refer to Figure 1 and
Figure 2
1
O
Differential output data D1 and D2 multiplexed, true
D1_D2_M
Refer to Figure 1 and
Figure 2
1
O
Differential output data D1 and D2 multiplexed, complement
D3_D4_P
Refer to Figure 1 and
Figure 2
1
O
Differential output data D3 and D4 multiplexed, true
D3_D4_M
Refer to Figure 1 and
Figure 2
1
O
Differential output data D3 and D4 multiplexed, complement
D5_D6_P
Refer to Figure 1 and
Figure 2
1
O
Differential output data D5 and D6 multiplexed, true
D5_D6_M
Refer to Figure 1 and
Figure 2
1
O
Differential output data D5 and D6 multiplexed, complement
D7_D8_P
Refer to Figure 1 and
Figure 2
1
O
Differential output data D7 and D8 multiplexed, true
D7_D8_M
Refer to Figure 1 and
Figure 2
1
O
Differential output data D7 and D8 multiplexed, complement
D9_D10_P
Refer to Figure 1 and
Figure 2
1
O
Differential output data D9 and D10 multiplexed, true
D9_D10_M
Refer to Figure 1 and
Figure 2
1
O
Differential output data D9 and D10 multiplexed, complement
OVR_SDOUT
3
1
O
This pin functions as an out-of-range indicator after reset, when register bit
SERIAL READOUT = 0, and functions as a serial register readout pin when SERIAL
READOUT = 1.
This pin is a CMOS output level that runs off DRVDD supply.
DRVDD
2, 35
2
I
1.8V digital and output buffer supply
DRGND
1, 36, PAD
2
I
Digital and output buffer ground
NC
Refer to Figure 1 and
Figure 2
—
—
Do not connect
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PIN CONFIGURATION (CMOS MODE)
D0
NC
42
D1
43
D3
44
D2
45
D4
46
D6
D7
47
D5
D9
48
D8
D10
RGZ PACKAGE(5)
QFN-48
(TOP VIEW)
41
40
39
38
37
DRGND
1
36
DRGND
DRVDD
2
35
DRVDD
OVR_SDOUT
3
34
NC
UNUSED
4
33
NC
CLKOUT
5
32
NC
DFS
6
31
NC
OE
7
30
RESET
AVDD
8
29
SCLK
AGND
9
28
SDATA
15
16
17
18
19
20
21
22
23
24
AVDD
AVDD_BUF
AVDD
SNRBoost_En
AVDD
14
AVDD
13
AGND
AGND
AGND
25
INP
AVDD
AGND 12
INM
SEN
26
AGND
27
VCM
CLKP 10
CLKM 11
(3) The PowerPAD is connected to DRGND.
Figure 3. ADS58B18 CMOS Pinout
10
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NC
NC
42
NC
43
D1
44
D0
D2
45
D4
46
D3
47
D6
D7
48
D5
D8
RGZ PACKAGE(6)
QFN-48
(TOP VIEW)
41
40
39
38
37
DRGND
1
36
DRGND
DRVDD
2
35
DRVDD
OVR_SDOUT
3
34
NC
UNUSED
4
33
NC
CLKOUT
5
32
NC
DFS
6
31
NC
OE
7
30
RESET
AVDD
8
29
SCLK
AGND
15
16
17
18
19
20
21
22
23
24
AVDD
14
UNUSED
13
AVDD
AGND
AVDD
25
AVDD_BUF
AGND 12
AVDD
AVDD
AGND
26
AGND
CLKM 11
INP
SEN
INM
SDATA
27
AGND
28
VCM
9
CLKP 10
(4) The PowerPAD is connected to DRGND.
Figure 4. ADS58B19 CMOS Pinout
ADS58B18, ADS58B19 Pin Assignments (CMOS Mode)
PIN NAME
PIN NUMBER
# OF
PINS
FUNCTION
AVDD
8, 18, 20, 22, 24, 26
6
I
1.8V analog power supply
AVDD_BUF
21
1
I
3.3V input buffer supply
AGND
9, 12, 14, 17, 19, 25
6
I
Analog ground
CLKP
10
1
I
Differential clock input, positive
CLKM
11
1
I
Differential clock input, negative
INP
15
1
I
Differential analog input, positive
INM
16
1
I
Differential analog input, negative
VCM
13
1
O
Outputs the common-mode voltage that can be used externally to bias the analog input
pins.
DESCRIPTION
RESET
30
1
I
Serial interface RESET input.
When using the serial interface mode, the internal registers must initialize through
hardware RESET by applying a high pulse on this pin or by using the software reset
option; refer to the Serial Interface section.
When RESET is tied high, the internal registers are reset to the default values. In this
condition, SEN can be used as an analog control pin.
RESET has an internal 180kΩ pull-down resistor.
SCLK
29
1
I
This pin functions as a serial interface clock input when RESET is low. When RESET is
high, SCLK has no function and should be tied to ground. This pin has an internal
180kΩ pull-down resistor.
SDATA
28
1
I
This pin functions as a serial interface data input when RESET is low. When RESET is
high, SDATA functions as a STANDBY control pin (see Table 7). This pin has an
internal 180kΩ pull-down resistor.
SEN
27
1
I
This pin functions as a serial interface enable input when RESET is low. When RESET
is high, SEN has no function and should be tied to AVDD. This pin has an internal
180kΩ pull-up resistor to AVDD.
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ADS58B18, ADS58B19 Pin Assignments (CMOS Mode) (continued)
PIN NAME
PIN NUMBER
# OF
PINS
FUNCTION
DESCRIPTION
DFS
6
1
I
Data format select input. This pin sets the DATA FORMAT (twos compliment or offset
binary) and the LVDS/CMOS output interface type. See Table 4 for detailed information.
SNRBoost_En
23
1
I
ADS58B18: Digital control pin for SNRBoost mode, active high.
ADS58B19: Unused.
CLKOUT
5
1
O
Differential output clock, true
OE
7
1
I
Output buffer enable input, active high; this pin has an internal 180kΩ pull-up resistor to
DRVDD.
D0
Refer to Figure 1 and
Figure 2
1
O
Differential output data D0 and logic low multiplexed, true
D1
Refer to Figure 1 and
Figure 2
1
O
Differential output data D1 and D2 multiplexed, true
D2
Refer to Figure 1 and
Figure 2
1
O
Differential output data D1 and D2 multiplexed, complement
D3
Refer to Figure 1 and
Figure 2
1
O
Differential output data D3 and D4 multiplexed, true
D4
Refer to Figure 1 and
Figure 2
1
O
Differential output data D3 and D4 multiplexed, complement
D5
Refer to Figure 1 and
Figure 2
1
O
Differential output data D5 and D6 multiplexed, true
D6
Refer to Figure 1 and
Figure 2
1
O
Differential output data D5 and D6 multiplexed, complement
D7
Refer to Figure 1 and
Figure 2
1
O
Differential output data D7 and D8 multiplexed, true
D8
Refer to Figure 1 and
Figure 2
1
O
Differential output data D7 and D8 multiplexed, complement
D9
Refer to Figure 1 and
Figure 2
1
O
Differential output data D9 and D10 multiplexed, true
D10
Refer to Figure 1 and
Figure 2
1
O
Differential output data D9 and D10 multiplexed, complement
OVR_SDOUT
3
1
O
This pin functions as an out-of-range indicator after reset, when register bit
SERIAL READOUT = 0, and functions as a serial register readout pin when SERIAL
READOUT = 1.
This pin is a CMOS output level that runs off DRVDD supply.
12
DRVDD
2, 35
2
I
1.8V digital and output buffer supply
DRGND
1, 36, PAD
2
I
Digital and output buffer ground
UNUSED
4
1
—
Not used in CMOS mode
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FUNCTIONAL BLOCK DIAGRAMS
AVDD
AGND
DRVDD
DDR LVDS
Interface
DRGND
CLKP
CLKOUTP
CLOCKGEN
CLKOUTM
CLKM
D0_P
D0_M
D1_D2_P
AVDD_BUF
D1_D2_M
D3_D4_P
INP
14-Bit
ADC
Sampling
Circuit
Digital
Functions
SNRBoost
DDR
Serializer
D3_D4_M
D5_D6_P
INM
D5_D6_M
D7_D8_P
Analog Buffers
D7_D8_M
Control
Interface
Reference
VCM
D9_D10_P
D9_D10_M
OVR_SDOUT
OE
SNRBoost_En
DFS
SEN
SDATA
SCLK
RESET
ADS58B18
Figure 5. ADS58B18 Block Diagram
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AGND
DRVDD
DDR LVDS
Interface
DRGND
CLKP
CLKOUTP
CLOCKGEN
CLKOUTM
CLKM
D0_P
AVDD_BUF
D0_M
D1_D2_P
INP
D1_D2_M
9-Bit
ADC
Sampling
Circuit
DDR
Serializer
Digital
Functions
INM
D3_D4_P
D3_D4_M
D5_D6_P
Analog Buffers
D5_D6_M
Control
Interface
Reference
VCM
D7_D8_P
D7_D8_M
OVR_SDOUT
OE
DFS
SEN
SDATA
SCLK
RESET
ADS58B19
Figure 6. ADS58B19 Block Diagram
14
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TIMING CHARACTERISTICS
Dn_Dn + 1_P
Logic 0
VOD = -350mV
Logic 1
VOD = +350mV
Dn_Dn + 1_M
VOCM
GND
(1) With external 100Ω termination.
Figure 7. LVDS Output Voltage Levels
TIMING REQUIREMENTS: LVDS and CMOS Modes (1)
Typical values are at +25°C, AVDD = 1.8V, DRVDD = 1.8V, sampling frequency = 250 MSPS, sine wave input clock,
CLOAD = 5pF (2), and RLOAD = 100Ω (3), unless otherwise noted. Minimum and maximum values are across the full temperature
range: TMIN = –40°C to TMAX = +85°C, AVDD = 1.8V, and DRVDD = 1.7V to 1.9V.
PARAMETER
tA
CONDITIONS
(4)
Aperture delay
Variation of aperture
delay
tJ
MIN
TYP
MAX
UNIT
0.6
0.8
1.2
ns
Between two devices at the same temperature and
DRVDD supply
Aperture jitter
Wakeup time
ADC latency
±100
ps
100
fS rms
Time to valid data after coming out of STANDBY
mode
5
25
µs
Time to valid data after coming out of PDN GLOBAL
mode
100
500
µs
After reset, gain enabled and offset correction
disabled
16
Clock
cycles
Gain and offset correction enabled
17
Clock
cycles
(5)
DDR LVDS MODE (6)
tSU
tH
tPDI
Data setup time (7)
Data hold time
(7)
Clock propagation
delay
Variation of tPDI
(1)
(2)
(3)
(4)
(5)
(6)
(7)
Data valid to zero-crossing of CLKOUTP
0.75
1.1
ns
Zero-crossing of CLKOUTP to data becoming invalid
0.35
0.6
ns
Input clock rising edge cross-over to output clock
rising edge cross-over
1MSPS ≤ sampling frequency ≤ 250MSPS
3
4.2
Between two devices at the same temperature and
DRVDD supply
5.4
±0.6
ns
ns
Timing parameters are ensured by design and characterization but are not production tested.
CLOAD is the effective external single-ended load capacitance between each output pin and ground.
RLOAD is the differential load resistance between the LVDS output pair.
This parameter is specified by design.
At higher frequencies, tPDI is greater than one clock period and overall latency = ADC latency + 1.
Measurements are done with a transmission line of 100Ω characteristic impedance between the device and the load. Setup and hold
time specifications take into account the effect of jitter on the output data and clock.
Data valid refers to a logic high of +100mV and a logic low of –100mV.
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TIMING REQUIREMENTS: LVDS and CMOS Modes(1) (continued)
Typical values are at +25°C, AVDD = 1.8V, DRVDD = 1.8V, sampling frequency = 250 MSPS, sine wave input clock,
CLOAD = 5pF(2), and RLOAD = 100Ω(3), unless otherwise noted. Minimum and maximum values are across the full temperature
range: TMIN = –40°C to TMAX = +85°C, AVDD = 1.8V, and DRVDD = 1.7V to 1.9V.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
Duty cycle of differential clock, (CLKOUTP –
CLKOUTM)
1MSPS ≤ sampling frequency ≤ 250MSPS
42
48
54
%
DDR LVDS MODE (continued)
LVDS bit clock duty
cycle
tRISE, tFALL
Data rise time,
Data fall time
Rise time measured from –100mV to +100mV
Fall time measured from +100mV to –100mV
1MSPS ≤ sampling frequency ≤ 250MSPS
0.14
ns
tCLKRISE,
tCLKFALL
Output clock rise
time,
Output clock fall time
Rise time measured from –100mV to +100mV
Fall time measured from +100mV to –100mV
1MSPS ≤ sampling frequency ≤ 250MSPS
0.14
ns
tOE
Output enable (OE) to
data delay
Time to valid data after OE becomes active
50
PARALLEL CMOS MODE
Input clock to data
delay
tSTART
tDV
Input clock rising edge cross-over to start of data
valid (9)
Data valid time
tPDI
100
ns
1.1
ns
(8)
Time interval of valid data
(9)
2.5
3.2
4
5.5
ns
Clock propagation
delay
Input clock rising edge cross-over to output clock
rising edge cross-over
1MSPS ≤ sampling frequency ≤ 200MSPS
Output clock duty
cycle
Duty cycle of output clock, CLKOUT
1MSPS ≤ sampling frequency ≤ 200MSPS
47
%
7
ns
tRISE, tFALL
Data rise time,
Data fall time
Rise time measured from 20% to 80% of DRVDD
Fall time measured from 80% to 20% of DRVDD
1 ≤ sampling frequency ≤ 250MSPS
0.35
ns
tCLKRISE,
tCLKFALL
Output clock rise
time,
Output clock fall time
Rise time measured from 20% to 80% of DRVDD
Fall time measured from 80% to 20% of DRVDD
1 ≤ sampling frequency ≤ 200MSPS
0.35
ns
tOE
Output enable (OE) to
data delay
Time to valid data after OE becomes active
20
(8)
(9)
16
40
ns
For fS > 200MSPS, it is recommended to use an external clock for data capture instead of the device output clock signal (CLKOUT).
Data valid refers to a logic high of 1.26V and a logic low of 0.54V.
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Table 1. LVDS Timing Across Sampling Frequencies
SAMPLING
FREQUENCY
(MSPS)
SETUP TIME (ns)
MIN
TYP
230
0.85
200
1.05
185
HOLD TIME (ns)
MAX
MIN
TYP
1.25
0.35
0.6
1.55
0.35
0.6
1.1
1.7
0.35
0.6
160
1.6
2.1
0.35
0.6
125
2.3
3
0.35
0.6
80
4.5
5.2
0.35
0.6
MAX
Table 2. CMOS Timing Across Sampling Frequencies (Default, After Reset)
TIMING SPECIFIED WITH RESPECT TO OUTPUT CLOCK
SAMPLING
FREQUENCY
(MSPS)
MIN
TYP
200
1
185
160
tSETUP (ns)
tHOLD (ns)
MAX
MIN
TYP
1.6
2
1.3
2
1.8
2.5
125
2.5
80
4.8
tPDI (ns)
MAX
MIN
TYP
MAX
2.8
4
5.5
7
2.2
3
4
5.5
7
2.5
3.3
4
5.5
7
3.2
3.5
4.3
4
5.5
7
5.5
5.7
6.5
4
5.5
7
Table 3. CMOS Timing Across Sampling Frequencies (Default, After Reset)
TIMING SPECIFIED WITH RESPECT TO INPUT CLOCK
SAMPLING FREQUENCY
(MSPS)
tSTART (ns)
MIN
TYP
tDV (ns)
MAX
MIN
TYP
250
1.6
2.5
3.2
230
1.1
2.9
3.5
200
0.3
3.5
4.2
185
0
3.9
4.5
170
–1.3
4.3
5
MAX
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N+3
N+2
N+1
Sample N
N+4
N + 18
N + 17
N + 16
Input Signal
tA
CLKP
Input Clock
CLKM
CLKOUTM
CLKOUTP
tPDI
tH
16 Clock Cycles
DDR LVDS
(1)
tSU
(2)
Output Data
(DXP, DXM)
E
O
N - 16
E
O
N - 15
E
O
E
N - 14
O
N - 13
O
E
E
N - 12
O
O
E
E
O
N+1
N
E
O
E
O
N+2
tPDI
CLKOUT
tSU
Parallel CMOS
16 Clock Cycles
Output Data
N - 16
N - 15
N - 14
(1)
N - 13
tH
N-1
N
N+1
(1) At higher sampling frequencies, tDPI is greater than one clock cycle, which then makes the overall latency = ADC latency + 1.
(2) E = Even bits (D0, D2, D4, etc). O = Odd bits (D1, D3, D5, etc).
Figure 8. Latency Diagram
18
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CLKM
Input
Clock
CLKP
tPDI
CLKOUTP
Output
Clock
CLKOUTM
tSU
Output Dn_Dn + 1_P
Data Pair Dn_Dn + 1_M
tSU
tH
Dn
(1)
Dn + 1
tH
(1)
(1) Dn = bits D0, D2, D4, etc. Dn + 1 = Bits D1, D3, D5, etc.
Figure 9. LVDS Mode Timing
CLKM
Input
Clock
CLKP
tPDI
Output
Clock
CLKOUT
tSU
Output
Data
Dn
tH
Dn
(1)
CLKM
Input
Clock
CLKP
tSTART
tDV
Output
Data
Dn
Dn
(1)
Dn = bits D0, D1, D2, etc.
Figure 10. CMOS Mode Timing
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DEVICE CONFIGURATION
The ADS58B18/9 have several modes that can be configured using a serial programming interface, as described
in Table 4 through Table 7. In addition, the devices have three dedicated parallel pins for quickly configuring
commonly-used functions. The parallel pins are DFS (analog 4-level control pin), OE (digital control pin), and
SNRBoost_En (digital control pin). The analog control pin can be easily configured using a simple resistor divider
(with 10% tolerance resistors).
Table 4. DFS: Analog Control Pin
DESCRIPTION
(Data Format/Output Interface)
VOLTAGE APPLIED ON DFS
0, +100mV/–0mV
Twos complement/DDR LVDS
(3/8) AVDD ± 100mV
Twos complement/parallel CMOS
(5/8) AVDD ± 100mV
Straight binary/parallel CMOS
AVDD, +0mV/–100mV
Straight binary/DDR LVDS
Table 5. OE: Digital Control Pin
VOLTAGE APPLIED ON OE
DESCRIPTION
0
Output data buffers disabled
AVDD
Output data buffers enabled
Table 6. SNRBoost_En: Digital Control Pin (ADS58B18 Only)
VOLTAGE APPLIED ON SNRBoost_En
DESCRIPTION
0
SNRBoost disabled
Logic high
SNRBoost enabled
When the serial interface is not used, the SDATA pin can also be used as a standby control pin. To enable this,
the RESET pin must be tied high.
Table 7. SDATA: Digital Control Pin
VOLTAGE APPLIED ON SDATA
DESCRIPTION
0
Normal operation
Logic high
Device enters standby
AVDD
(5/8) AVDD
3R
(5/8) AVDD
GND
AVDD
2R
(3/8) AVDD
3R
(3/8) AVDD
To Parallel Pin
Figure 11. Simplified Diagram to Configure DFS Pin
20
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SERIAL INTERFACE
The analog-to-digital converter (ADC) has a set of internal registers that can be accessed by the serial interface
formed by the SEN (serial interface enable), SCLK (serial interface clock), and SDATA (serial interface data)
pins. When SEN is low, the serial shift of bits into the device is enabled, the serial data (on SDATA) are latched
at every falling edge of SCLK, and the serial data are loaded into the register at every 16th SCLK falling edge.
In case the word length exceeds a multiple of 16 bits, the excess bits are ignored. Data can be loaded in
multiples of 16-bit words within a single active SEN pulse. The first eight bits form the register address and the
remaining eight bits are the register data. The interface can work with SCLK frequency from 20MHz down to very
low speeds (a few hertz) and also with non-50% SCLK duty cycle.
Register Initialization
After power-up, the internal registers must be initialized to the default values. This initialization can be
accomplished in one of two ways:
1. Either through hardware reset by applying a high pulse on the RESET pin (of width greater than 10ns), as
shown in Figure 12; or
2. By applying a software reset. When using the serial interface, set the RESET bit (D7 in register 00h) high.
This setting initializes the internal registers to the default values and then self-resets the RESET bit low. In
this case, the RESET pin is held low.
Register Address
SDATA
A7
A6
A5
A4
A3
Register Data
A2
A1
A0
D7
D6
D5
tSCLK
D4
tDSU
D3
D2
D1
D0
tDH
SCLK
tSLOADS
tSLOADH
SEN
RESET
Figure 12. Serial Interface Timing
SERIAL INTERFACE TIMING CHARACTERISTICS
Typical values at +25°C, minimum and maximum values across the full temperature range: TMIN = –40°C to TMAX = +85°C,
AVDD = 1.8V, and DRVDD = 1.8V, unless otherwise noted.
PARAMETER
MIN
> DC
TYP
MAX
UNIT
20
MHz
fSCLK
SCLK frequency (equal to 1/tSCLK)
tSLOADS
SEN to SCLK setup time
25
ns
tSLOADH
SCLK to SEN hold time
25
ns
tDSU
SDATA setup time
25
ns
tDH
SDATA hold time
25
ns
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Serial Register Readout
The device includes a mode where the contents of the internal registers can be read back on the OVR_SDOUT
pin. This readback may be useful as a diagnostic check to verify the serial interface communication between the
external controller and the ADC.
After power-up and device reset, the OVR_SDOUT pin functions as an over-range indicator pin by default. When
the readout mode is enabled, OVR_SDOUT outputs the contents of the selected register serially. OVR_SDOUT
is a CMOS logic output buffer that runs off the DRVDD supply.
1. Set the READOUT register bit to '1'. This setting puts the device in serial readout mode and disables any
further writes to the internal registers except the register at address 0. Note that the READOUT bit itself is
also located in register 0. The device can exit readout mode by writing READOUT to 0. Only the contents of
the register at address 0 cannot be read in the register readout mode.
2. Initiate a serial interface cycle specifying the address of the register (A7 to A0) whose content must be read.
3. The device serially outputs the contents (D7 to D0) of the selected register on the OVR_SDOUT pin.
4. The external controller can latch the contents at the falling edge of SCLK.
5. To exit the serial readout mode, the reset register bit READOUT = 0 enables writes into all registers of the
device. At this point, the OVR_SDOUT pin becomes an over-range indicator pin.
Register Address A[7:0] = 0x00
SDATA
0
0
0
0
0
0
Register Data D[7:0] = 0x01
0
0
0
0
0
0
0
0
0
1
SCLK
SEN
OVR_SDOUT
The OVR_SDOUT pin functions as OVR (READOUT = 0).
a) Enable serial readout (READOUT = 1)
Register Address A[7:0] = 0x43
SDATA
A7
A6
A5
A4
A3
A2
Register Data D[7:0] = XX (don’t care)
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
0
1
0
0
0
0
0
0
SCLK
SEN
OVR_SDOUT
The OVR_SDOUT pin functions as a serial readout (READOUT = 1).
b) Read contents of register 0x43.
This register has been initialized with 0x40 (device is put in global power-down mode).
(1) The OVR_SDOUT pin finctions as OVR (READOUT = 0).
(2) The OVR_SDOUT pin finctions as a serial readout (READOUT = 1).
Figure 13. Serial Readout Timing Diagram
22
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SERIAL REGISTER MAP
Table 8 summarizes the functions supported by the serial interface.
Table 8. Serial Interface Register Map (1)
(1)
REGISTER
ADDRESS
DEFAULT VALUE
AFTER RESET
A[7:0] (Hex)
D[7:0] (Hex)
D7
D6
D5
D4
D3
D2
D1
D0
00
00
0
0
0
0
0
0
RESET
READOUT
01
00
0
0
25
00
26
00
0
3D
00
DATA FORMAT
3E
00
3F
00
40
00
REGISTER DATA
LVDS SWING
GAIN
0
0
0
0
ENABLE
OFFSET
CORR
SNRBoost
Enable
TEST PATTERNS
0
0
LVDS
LVDS DATA
CLKOUT
STRENGTH
STRENGTH
SNRBoost Coeff1
SNRBoost Coeff2
0
0
0
0
0
0
CUSTOM PATTERN HIGH D[10:3]
CUSTOM PATTERN D[2:0]
0
0
CMOS CLKOUT
STRENGTH
ENABLE
CLKOUT
RISE
CLKOUT FALL POSN
0
0
DIS LOW
LATENCY
STBY
PDN
GLOBAL
0
PDN OBUF
0
0
0
0
0
41
00
LVDS CMOS
42
00
43
00
BF
00
0
OFFSET PEDESTAL
CF
00
FREEZE
OFFSET
CORR
EA
00
OVERRIDE
SNRBoost_
EN PIN
0
DF
00
0
0
0
CLKOUT RISE POSN
OFFSET CORR TIME CONSTANT
0
0
LOW SPEED
0
0
ENABLE
CLKOUT
FALL
BYTE-WISE
En
EN LVDS SWING
0
0
0
0
0
0
0
0
0
0
0
0
Multiple functions in a register can be programmed in a single write operation.
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DESCRIPTION OF SERIAL REGISTERS
Register Address 00h (Default = 00h)
7
6
5
4
3
2
1
0
0
0
0
0
0
0
RESET
READOUT
Bits[7:2]
Always write '0'
Bit 1
RESET: Software reset applied
This bit resets all internal registers to the default values and self-clears to 0 (default = 1).
Bit 0
READOUT: Serial readout
This bit sets the serial readout of the registers.
0 = Serial readout of registers disabled; the OVR_SDOUT pin functions as an over-voltage
indicator.
1 = Serial readout enabled; the OVR_SDOUT pin functions as a serial data readout. See the Serial
Register Readout section.
Register Address 01h (Default = 00h)
7
6
5
4
3
2
LVDS SWING
Bits[7:2]
1
0
0
0
LVDS SWING: LVDS swing programmability (1)
000000 = Default LVDS swing; ±350mV with external 100Ω termination
011011 = LVDS swing increases to ±410mV
110010 = LVDS swing increases to ±465mV
010100 = LVDS swing increases to ±570mV
111110 = LVDS swing decreases to ±200mV
001111 = LVDS swing decreases to ±125mV
Bits[1:0]
(1)
24
Always write '0'
The EN LVDS SWING register bits must be set to enable LVDS swing control.
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Register Address 25h (Default = 00h)
7
6
5
4
GAIN
Bits[7:4]
3
2
1
0
0
TEST PATTERNS
GAIN: Gain programmability
These bits set the gain programmability in 0.5dB steps.
0000
0110
0111
1000
1001
1010
1011
1100
=
=
=
=
=
=
=
=
0dB gain (default after reset)
0.5dB gain
1dB gain
1.5dB gain
2dB gain
2.5dB gain
3dB gain
3.5dB gain
Bit 3
Always write '0'
Bits[2:0]
TEST PATTERNS: Data capture
These bits can be used to verify data capture.
000 = Normal operation
001 = Outputs all 0s
010 = Outputs all 1s
011 = Outputs toggle pattern
In the ADS58B18, output data D[10:0] are an alternating sequence of 01010101010 and
10101010101.
In the ADS58B19, output data D[8:0] are an alternating sequence of 010101010 and 101010101.
100 = Outputs digital ramp
Output data increments by one LSB (11-bit) every eighth clock cycle from code 0 to code 2047
101 = Output custom pattern (use registers 3Fh and 40h for setting the custom pattern)
110 = Unused
111 = Unused
Register Address 26h (Default = 00h)
7
0
6
0
5
0
4
0
3
0
2
1
0
0
LVDS CLKOUT
STRENGTH
LVDS DATA
STRENGTH
Bits[7:2]
Always write '0'
Bit 1
LVDS CLKOUT STRENGTH: LVDS output clock buffer strength
This bit determines the external termination to be used with the LVDS output clock buffer.
0 = 100Ω external termination (default strength)
1 = 50Ω external termination (2x strength)
Bit 0
LVDS DATA STRENGTH: LVDS data buffer strength
This bit determines the external termination to be used with all of the LVDS data buffers.
0 = 100Ω external termination (default strength)
1 = 50Ω external termination (2x strength)
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Register Address 3Dh (Default = 00h)
7
6
DATA FORMAT
Bits[7:6]
5
4
ENABLE
OFFSET
CORR
SNRBoost
Enable
3
2
1
0
SNRBoost Coeff1
DATA FORMAT: Data format selection
These bits select the data format.
00 = The DFS pin controls data format selection
10 = Twos complement
11 = Offset binary
Bit 5
ENABLE OFFSET CORR: Offset correction setting
This bit sets the offset correction.
0 = Offset correction disabled
1 = Offset correction enabled
Bit 4
SNRBoost Enable: SNRBoost setting
This bit enables the SNRBoost.
0 = SNRBoost disabled
1 = SNRBoost enabled
Bits[3:0]
SNRBoost Coeff1: SNRBoost coefficient 1
See the SNR Enhancement Using SNRBoost section.
Register Address 3Eh (Default = 00h)
7
6
5
4
SNRBoost Coeff2
Bits[7:4]
3
2
1
0
0
0
0
0
SNRBoost Coeff2: SNRBoost coefficient 2
See the SNR Enhancement Using SNRBoost section.
Bits[3:0]
Always write '0'
Register Address 3Fh (Default = 00h)
7
6
5
4
3
2
1
0
CUSTOM
PATTERN D10
CUSTOM
PATTERN D9
CUSTOM
PATTERN D8
CUSTOM
PATTERN D7
CUSTOM
PATTERN D6
CUSTOM
PATTERN D5
CUSTOM
PATTERN D4
CUSTOM
PATTERN D3
Bits[7:0]
CUSTOM PATTERN
These bits set the custom pattern.
Register Address 40h (Default = 00h)
7
6
5
4
3
2
1
0
CUSTOM
PATTERN D2
CUSTOM
PATTERN D1
CUSTOM
PATTERN D0
0
0
0
0
0
Bits[7:5]
CUSTOM PATTERN
These bits set the custom pattern.
Bits[4:0]
26
Always write '0'
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Register Address 41h (Default = 00h)
7
6
LVDS CMOS
Bits[7:6]
5
4
CMOS CLKOUT STRENGTH
3
ENABLE
CLKOUT RISE
2
1
CLKOUT RISE POSN
0
ENABLE
CLKOUT FALL
LVDS CMOS: Interface selection
These bits select the interface.
00 = The DFS pin controls the selection of either LVDS or CMOS interface
01 = DDR LVDS interface
11 = Parallel CMOS interface
Bits[5:4]
CMOS CLKOUT STRENGTH
Controls strength of CMOS output clock only.
00 = Maximum strength (recommended and used for specified timings)
01 = Medium strength
10 = Low strength
11 = Very low strength
Bit 3
ENABLE CLKOUT RISE
0 = Disables control of output clock rising edge
1 = Enables control of output clock rising edge
Bits[2:1]
CLKOUT RISE POSN: CLKOUT rise control
Controls position of output clock rising edge
LVDS interface:
00 = Default position (timings are specified in this condition)
01 = Setup reduces by 500ps, hold increases by 500ps
10 = Data transition is aligned with rising edge
11 = Setup reduces by 200ps, hold increases by 200ps
CMOS interface:
00 = Default position (timings are specified in this condition)
01 = Setup reduces by 100ps, hold increases by 100ps
10 = Setup reduces by 200ps, hold increases by 200ps
11 = Setup reduces by 1.5ns, hold increases by 1.5ns
Bit 0
ENABLE CLKOUT FALL
0 = Disables control of output clock fall edge
1 = Enables control of output clock fall edge
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Register Address 42h (Default = 00h)
7
6
CLKOUT FALL POSN
Bits[7:6]
5
0
4
3
2
1
0
0
DIS LOW
LATENCY
STBY
0
BYTE-WISE En
CLKOUT FALL POSN
These bits control the position of the output clock falling edge.
LVDS interface:
00 = Default position (timings are specified in this condition)
01 = Setup reduces by 400ps, hold increases by 400ps
10 = Data transition is aligned with rising edge
11 = Setup reduces by 200ps, hold increases by 200ps
CMOS interface:
00 = Default position (timings are specified in this condition)
01 = Falling edge is advanced by 100ps
10 = Falling edge is advanced by 200ps
11 = Falling edge is advanced by 1.5ns
Bits[5:4]
Always write '0'
Bit 3
DIS LOW LATENCY: Disable low latency
This bit controls the low-latency mode.
0 = Recommended not to use this mode.
1 = After reset, the low-latency mode is disabled and 0dB gain is enabled.
Bit 2
STBY: Standby mode
This bit sets the standby mode.
0 = Normal operation
1 = Only the ADC and output buffers are powered down; internal reference is active; wake-up time
from standby is fast
Bit 1
Always write '0'
Bit 0
BYTE-WISE En: Output data enable
0 = The output data bit sequence is bit-wise (see Figure 22).
1 = The output data bit sequence is byte-wise (see Figure 23 and Figure 24).
28
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Register Address 43h (Default = 00h)
7
6
5
4
3
2
1
0
PDN GLOBAL
0
PDN OBUF
0
0
EN LVDS SWING
Bit 7
Always write '0'
Bit 6
PDN GLOBAL: Power-down
0
This bit sets the state of operation.
0 = Normal operation
1 = Total power down; the ADC, internal references, and output buffers are powered down; slow
wake-up time.
Bit 5
Always write '0'
Bit 4
PDN OBUF: Power-down output buffer
This bit set the output buffer.
0 = Output buffer enabled
1 = Output buffer powered down
Bits[3:2]
Always write '0'
Bits[1:0]
EN LVDS SWING: LVDS swing control
00
01
10
11
=
=
=
=
LVDS swing control using LVDS SWING register bits is disabled
Do not use
Do not use
LVDS swing control using LVDS SWING register bits is enabled
Register Address BFh (Default = 00h)
7
6
OFFSET PEDESTAL
Bits[7:5]
5
4
3
2
1
0
0
0
0
0
0
OFFSET PEDESTAL
These bits set the offset pedestal.
When the offset correction is enabled, the final converged value after the offset is corrected is the
ADC mid-code value. A pedestal can be added to the final converged value by programming these
bits.
011 = +3 LSB
010 = +2 LSB
001 = +1 LSB
000 = 0 LSB
111 = –1 LSB
110 = –2 LSB
101 = –3 LSB
100 = –4 LSB
Bits[4:0]
Always write '0'
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Register Address CFh (Default = 00h)
7
6
FREEZE
OFFSET
CORR
0
Bit 7
5
4
3
2
OFFSET CORR TIME CONSTANT
1
0
0
0
FREEZE OFFSET CORR
This bit sets the freeze offset correction.
0 = Estimation of offset correction is not frozen (bit ENABLE OFFSET CORR must be set).
1 = Estimation of offset correction is frozen (bit EN OFFSET CORR must be set). When frozen, the
last estimated value is used for offset correction every clock cycle; see Offset Correction section.
Bit 6
Always write '0'
Bit[5:2]
OFFSET CORR TIME CONSTANT
These bits set the offset correction time constant for the correction loop time constant in number of
clock cycles.
Bits[1:0]
VALUE
TIME CONSTANT
(Number of Clock Cycles)
0000
1M
0001
2M
0010
3M
0011
4M
0100
16M
0101
32M
0110
64M
0111
128M
1000
256M
1001
512M
1010
1G
1011
2G
Always write '0'
Register Address EAh (Default = 00h)
7
6
5
4
3
2
1
0
OVERRIDE
SNBoost_EN
PIN
0
0
0
0
0
0
0
Bit 7
OVERRIDE SNBoost_EN PIN: SNBoost_EN pin override
After reset, the SNRBoost_En pin controls the turning on and off of the SNRBoost function,
independent of the state of register bit SNRBoost Enable. By setting the OVER-RIDE bit to '1', the
register bit can control the SNRBoost function.
0 = SNRBoost_En pin controls SNRBoost function, independent of register bit.
1 = Register bit SNRBoost Enable controls the SNRBoost function, independent of SNRBoost_En
pin.
Bits[6:0]
30
Always write '0'
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Register Address DFh (Default = 00h)
7
6
0
0
5
4
LOW SPEED
Bits[7:6]
Always write '0'
Bits[5:4]
LOW SPEED: Low-speed mode
3
2
1
0
0
0
0
0
00, 01, 10 = Low-speed mode disabled (default state after reset); this setting is recommended for
sampling rates greater than 80MSPS.
11 = Low-speed mode enabled; this setting is recommended for sampling rates lower than or equal
to 80MSPS.
Bits[3:0]
Always write '0'
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TYPICAL CHARACTERISTICS: ADS58B18
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
FFT FOR 20MHz INPUT SIGNAL
FFT FOR 170MHz INPUT SIGNAL
0
0
SFDR = 92.8dBc
SNR = 66.1dBFS
SINAD = 66.1dBFS
THD = 89.5dBc
−10
−20
−30
−30
−40
−40
Amplitude (dB)
Amplitude (dB)
−20
−50
−60
−70
−50
−60
−70
−80
−80
−90
−90
−100
−100
−110
−110
−120
0
20
40
60
80
SFDR = 81.8dBc
SNR = 65.8dBFS
SINAD = 65.7dBFS
THD = 80.6dBc
−10
−120
100
0
Frequency (MHz)
Figure 15.
80
100
FFT FOR TWO-TONE INPUT SIGNAL
0
Each Tone at −7dBFS Amplitude
SFDR = 99.83dBFS
fIN1 = 185MHz
fIN2 = 190MHz
Two-Tone IMD = 86.81dBFS
−10
−20
−30
Each Tone at −36dBFS Amplitude
SFDR = 98.38dBFS
fIN1 = 185MHz
fIN2 = 190MHz
Two-Tone IMD = 96.95dBFS
−10
−20
−30
−40
Amplitude (dB)
−40
Amplitude (dB)
60
Figure 14.
FFT FOR TWO-TONE INPUT SIGNAL
32
40
Frequency (MHz)
0
−50
−60
−70
−50
−60
−70
−80
−80
−90
−90
−100
−100
−110
−110
−120
20
0
20
40
60
80
100
−120
0
20
40
60
Frequency (MHz)
Frequency (MHz)
Figure 16.
Figure 17.
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TYPICAL CHARACTERISTICS: ADS58B18 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
FFT FOR 150MHz INPUT SIGNAL
(SNRBoost Enabled, 5MHz Bandwidth)
FFT FOR 150MHz INPUT SIGNAL
(SNRBoost Enabled, 5MHz Bandwidth)
0
0
AIN = −1dBFS
SFDR = 88.5dBc
SNR = 78.2dBFS
SINAD = 77.6dBFS
THD = 85.3dBc
Coeff1 = 0x0
Coeff2 = 0x0
BW = 47.5MHz to 52.5MHz
−10
−20
−30
−20
−30
−40
Amplitude (dB)
Amplitude (dB)
−40
−50
−60
−70
−60
−70
−80
−90
−90
−100
−100
−110
−110
0
20
40
60
80
−120
100
20
40
60
80
Frequency (MHz)
Figure 18.
Figure 19.
FFT FOR 150MHz INPUT SIGNAL
(SNRBoost Enabled, 20MHz Bandwidth)
FFT FOR 150MHz INPUT SIGNAL
(SNRBoost Enabled, 20MHz Bandwidth)
100
0
AIN = −1dBFS
SFDR = 86.2dBc
SNR = 73.7dBFS
SINAD = 73.5dBFS
THD = 85.1dBc
Coeff1 = 0xf
Coeff2 = 0x1
BW = 40MHz to 60MHz
−10
−20
−30
−20
−30
−40
−50
−60
−70
−50
−60
−70
−80
−80
−90
−90
−100
−100
−110
−110
0
20
40
AIN = −40dBFS
SFDR = 55dBc
SNR = 77.7dBFS
SINAD = 77.5dBFS
THD = 52.3dBc
Coeff1 = 0xf
Coeff2 = 0x1
BW = 40MHz to 60MHz
−10
Amplitude (dB)
−40
−120
0
Frequency (MHz)
0
Amplitude (dB)
−50
−80
−120
AIN = −40dBFS
SFDR = 56.9dBc
SNR = 83.8dBFS
SINAD = 83.5dBFS
THD = 55.4dBc
Coeff1 = 0x0
Coeff2 = 0x0
BW = 47.5MHz to 52.5MHz
−10
60
80
100
−120
0
20
40
60
Frequency (MHz)
Frequency (MHz)
Figure 20.
Figure 21.
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TYPICAL CHARACTERISTICS: ADS58B18 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
FFT FOR 150MHz INPUT SIGNAL
(SNRBoost Enabled, 30MHz Bandwidth)
FFT FOR 150MHz INPUT SIGNAL
(SNRBoost Enabled, 30MHz Bandwidth)
0
0
AIN = −1dBFS
SFDR = 89.5dBc
SNR = 72.2dBFS
SINAD = 72dBFS
THD = 85.9dBc
Coeff1 = 0xd
Coeff2 = 0x3
BW = 35MHz to 65MHz
−10
−20
−30
−20
−30
−40
Amplitude (dB)
Amplitude (dB)
−40
−50
−60
−70
−50
−60
−70
−80
−80
−90
−90
−100
−100
−110
−110
−120
0
20
AIN = −40dBFS
SFDR = 57.3dBc
SNR = 75.6dBFS
SINAD = 75.6dBFS
THD = 55.2dBc
Coeff1 = 0xd
Coeff2 = 0x3
BW = 35MHz to 65MHz
−10
40
60
80
−120
100
0
20
40
60
Frequency (MHz)
Frequency (MHz)
Figure 22.
Figure 23.
SFDR ACROSS INPUT FREQUENCY
80
100
SNR ACROSS INPUT FREQUENCY
67
95
90
66
85
SNR (dBFS)
SFDR (dBc)
80
75
65
70
65
64
60
55
0
50
100
150
200
250
300
350
400
450
500
63
0
50
100
Input Frequency (MHz)
Figure 24.
34
150
200
250
300
350
400
450
500
Input Frequency (MHz)
Figure 25.
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TYPICAL CHARACTERISTICS: ADS58B18 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
SFDR ACROSS GAIN
SINAD ACROSS GAIN
68
96
150MHz
170MHz
220MHz
300MHz
400MHz
500MHz
92
88
66
64
SINAD (dBFS)
SFDR (dBc)
84
80
76
72
68
62
60
58
150MHz
170MHz
220MHz
300MHz
400MHz
500MHz
64
56
60
56
0
0.5
1
1.5
2
2.5
3
54
3.5
0
0.5
1
1.5
Gain (dB)
2
2.5
3
3.5
Gain (dB)
Figure 26.
Figure 27.
SFDR ACROSS AVDD SUPPLY vs TEMPERATURE
SNR ACROSS AVDD SUPPLY vs TEMPERATURE
88
66.8
− 40°C
− 25°C
25°C
55°C
85°C
86
84
66.4
− 40°C
− 25°C
25°C
55°C
85°C
66
SNR (dBFS)
SFDR (dBc)
82
80
65.6
65.2
78
64.8
76
64.4
74
Input Frequency = 170MHz
72
1.65
1.70
1.75
1.80
Input Frequency = 170MHz
1.85
1.90
1.95
64
1.65
1.70
1.75
1.80
1.85
AVDD Supply (V)
AVDD Supply (V)
Figure 28.
Figure 29.
1.90
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TYPICAL CHARACTERISTICS: ADS58B18 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
PERFORMANCE ACROSS INPUT AMPLITUDE
66
84
SFDR
SNR
65.4
78
SFDR (dBc, dBFS)
65.2
76
68
110
67
100
66
90
65
80
64
70
63
60
62
50
61
60
40
SFDR (dBc)
SFDR (dBFS)
SNR
30
Input Frequency = 170MHz
74
1.65
1.70
1.75
1.80
1.85
1.90
Input Frequency = 170.1MHz
65
1.95
20
−45
−40
−35
−30
DRVDD Supply (V)
−20
−10
−5
0
58
Figure 31.
PERFORMANCE ACROSS INPUT COMMON-MODE
VOLTAGE
PERFORMANCE ACROSS INPUT CLOCK AMPLITUDE
70
99
SFDR
SNR
68
90
SFDR
SNR
86
66
90
68.5
84
65
87
68
82
64
84
67.5
80
63
81
67
78
62
78
66.5
76
61
75
66
74
60
72
65.5
72
59
69
65
70
58
64.5
68
66
SFDR (dBc)
88
69
SNR (dBFS)
69.5
93
96
67
57
Input Frequency = 170MHz
63
1.55
1.60
1.65
1.70
1.75
1.80
Input Common-Mode Voltage (V)
64
1.85
Input Frequency = 170MHz
66
0
0.5
1
1.5
2
2.5
3
56
Differential Clock Amplitude (VPP)
Figure 32.
36
−15
Amplitude (dBFS)
Figure 30.
SFDR (dBc)
−25
59
SNR (dBFS)
SFDR (dBc)
65.6
80
SNR (dBFS)
65.8
82
120
SNR (dBFS)
PERFORMANCE ACROSS DRVDD SUPPLY
Figure 33.
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TYPICAL CHARACTERISTICS: ADS58B18 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
PERFORMANCE ACROSS INPUT CLOCK DUTY CYCLE
ANALOG POWER vs SAMPLING FREQUENCY
67
95
260
THD
SNR
Includes AVDD and AVDD_BUF Power
250
240
230
66.5
90
66
85
Analog Power (mW)
SNR (dBFS)
THD (dBc)
220
210
200
190
180
170
65.5
80
160
150
140
Input Frequency = 10MHz
75
35
40
45
50
55
60
65
65
130
120
Input Clock Duty Cycle (%)
0
20
40
60
80
100
120
140
160
180
200
Sampling Speed (MSPS)
Figure 34.
Figure 35.
DRVDD POWER vs SAMPLING FREQUENCY
110
100
DRVDD Power (mW)
90
80
70
60
50
Default
With SNRBoost Enable
40
0
20
40
60
80
100
120
140
160
180
200
Sampling Speed (MSPS)
Figure 36.
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TYPICAL CHARACTERISTICS: ADS58B19
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
FFT FOR 20MHz INPUT SIGNAL
FFT FOR 170MHz INPUT SIGNAL
0
0
SFDR = 75.8dBc
SNR = 55.7dBFS
SINAD = 55.7dBFS
THD = 84.5dBc
−10
−20
−20
−30
Amplitude (dB)
Amplitude (dB)
−30
−40
−50
−60
−40
−50
−60
−70
−70
−80
−80
−90
−90
−100
SFDR = 76.2dBc
SNR = 55.7dBFS
SINAD = 55.7dBFS
THD = 78.6dBc
−10
0
25
50
75
100
−100
125
0
Frequency (MHz)
Figure 38.
100
125
FFT FOR TWO-TONE INPUT SIGNAL
0
Each Tone at
−7dBFS Amplitude
SFDR = 88.68dBc
fIN1 = 185MHz
fIN2 = 190MHz
Two-Tone IMD = 86.8dBc
−10
−20
Each Tone at
−36dBFS Amplitude
SFDR = 96.75dBFS
fIN1 = 185MHz
fIN2 = 190MHz
Two-Tone IMD = 89.4dBFS
−10
−20
−30
Amplitude (dB)
−30
Amplitude (dB)
75
Figure 37.
FFT FOR TWO-TONE INPUT SIGNAL
38
50
Frequency (MHz)
0
−40
−50
−60
−40
−50
−60
−70
−70
−80
−80
−90
−90
−100
25
0
25
50
75
100
125
−100
0
25
50
75
Frequency (MHz)
Frequency (MHz)
Figure 39.
Figure 40.
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125
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TYPICAL CHARACTERISTICS: ADS58B19 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
SNR ACROSS INPUT FREQUENCY
80
57
75
56.5
70
56
SNR (dBFS)
SFDR (dBc)
SFDR ACROSS INPUT FREQUENCY
65
55.5
60
55
55
54.5
50
0
50
100
150
200
250
300
350
400
450
54
500
0
50
100
150
Input Frequency (MHz)
250
300
350
Figure 41.
Figure 42.
SFDR ACROSS GAIN
SINAD ACROSS GAIN
84
400
450
500
58
40MHz
150MHz
170MHz
220MHz
300MHz
400MHz
500MHz
80
57
76
SINAD (dBFS)
72
SFDR (dBc)
200
Input Frequency (MHz)
68
64
56
55
60
150MHz
170MHz
220MHz
300MHz
400MHz
500MHz
56
52
48
0
0.5
1
1.5
2
2.5
3
3.5
54
53
0
0.5
Gain (dB)
1
1.5
2
2.5
3
3.5
Gain (dB)
Figure 43.
Figure 44.
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TYPICAL CHARACTERISTICS: ADS58B19 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
SFDR ACROSS AVDD SUPPLY vs TEMPERATURE
85
58
− 40°C
− 25°C
25°C
55°C
85°C
83
81
− 40°C
− 25°C
25°C
55°C
85°C
57.5
57
79
56.5
77
56
SNR (dBFS)
75
73
55.5
55
71
54.5
69
54
67
53.5
Input Frequency = 170MHz
65
1.65
1.70
1.75
1.80
1.85
1.90
Input Frequency = 170MHz
53
1.65
1.95
1.75
1.90
1.95
Figure 46.
PERFORMANCE ACROSS DRVDD SUPPLY
PERFORMANCE ACROSS INPUT AMPLITUDE
58
100
57
90
SFDR (dBc)
SFDR (dBFS)
SNR
57
56
74
55.5
SFDR (dBc, dBFS)
76
SNR (dBFS)
56.5
78
80
56
70
55
60
54
50
53
40
52
55
72
Input Frequency = 170MHz
1.70
1.75
1.80
1.85
1.90
54.5
1.95
Input Frequency = 170.1MHz
30
−30
−25
DRVDD Supply (V)
−20
−15
−10
−5
0
51
Amplitude (dBFS)
Figure 47.
40
1.85
Figure 45.
SFDR
SNR
70
1.65
1.80
AVDD Supply (V)
80
SFDR (dBc)
1.70
AVDD Supply (V)
SNR (dBFS)
SFDR (dBc)
SNR ACROSS AVDD SUPPLY vs TEMPERATURE
Figure 48.
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TYPICAL CHARACTERISTICS: ADS58B19 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
PERFORMANCE ACROSS INPUT COMMON-MODE
VOLTAGE
58
SFDR
SNR
57
74
56.5
72
56
70
55.5
68
55
66
54.5
64
54
62
53.5
SFDR (dBc)
76
SNR (dBFS)
57.5
78
57
76
56
74
55
72
54
70
53
Input Frequency = 170MHz
60
1.55
1.60
1.65
1.70
1.75
1.80
Input Frequency = 170MHz
53
1.85
68
0
0.5
Input Common-Mode Voltage (V)
1
1.5
2
2.5
52
3.5
3
Differential Clock Amplitude (VPP)
Figure 49.
Figure 50.
PERFORMANCE ACROSS INPUT CLOCK DUTY CYCLE
ANALOG POWER vs SAMPLING FREQUENCY
57
90
280
THD
SNR
Includes AVDD and AVDD_BUF Power
260
240
55.5
75
Analog Power (mW)
56
80
SNR (dBFS)
56.5
85
THD (dBc)
SNR (dBFS)
SFDR
SNR
78
SFDR (dBc)
PERFORMANCE ACROSS INPUT CLOCK AMPLITUDE
80
58
80
220
200
180
160
140
Input Frequency = 10MHz
70
35
40
45
50
55
Input Clock Duty Cycle (%)
60
65
120
55
100
0
20
40
60
80
100
120
140
160
180
200
Sampling Speed (MSPS)
Figure 51.
Figure 52.
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TYPICAL CHARACTERISTICS: ADS58B19 (continued)
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
DRVDD POWER vs SAMPLING FREQUENCY
120
110
DRVDD Power (mW)
100
90
80
70
60
50
40
0
20
40
60
80
100
120
140
160
180
200
Sampling Speed (MSPS)
Figure 53.
42
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TYPICAL CHARACTERISTICS: GENERAL
At +25°C, AVDD = 1.8V, AVDD_BUF = 3.3V, DRVDD = 1.8V, maximum rated sampling frequency, sine wave input clock,
1.5VPP differential clock amplitude, 50% clock duty cycle, –1dBFS differential analog input, DDR LVDS output interface, and
32k-point FFT, unless otherwise noted.
PSRR ACROSS FREQUENCY
ZOOMED VIEW OF SPECTRUM WITH PSRR SIGNAL
0
0
PSRR on AVDD Supply 50mVPP
PSRR on AVDD 3V Supply 100mVPP
fIN = 10MHz
fPSRR = 1MHz, 50mVPP
Amplitude (fIN) = -1dBFS
Amplitude (fPSRR) = -64.5
Amplitude (fIN + fP) = -67.4
Amplitude (fIN - fP) = -68.5
fIN
−10
-20
−20
-40
Amplitude (dB)
PSRR (dB)
−30
−40
−50
-60
fPSRR
fIN - fPSRR
fIN + fPSRR
-80
−60
-100
−70
−80
0
10
20
30
40
50
60
70
80
90
-120
100
0
10
5
15
Frequency of Signal on Supply (MHz)
20
25
Figure 54.
35
40
45
50
Figure 55.
CMRR ACROSS FREQUENCY
SPECTRUM WITH CMRR SIGNAL
0
0
Input Frequency = 170MHz
50mVPP Signal Superimposed
on Input Common-Mode Voltage (1.7V)
fIN = 170MHz
fCM = 10MHz, 50mVPP
SFDR = 79.36
Amplitude (fIN) = -1dBFS
Amplitude (fCM) = -99.7
Amplitude (fIN + fCM) = -78.1
Amplitude (fIN - fCM) = -80.8
-10
−10
-20
-30
Amplitude (dB)
−20
CMRR (dB)
30
Frequency (MHz)
−30
-40
-50
fIN (10MHz)
-60
fIN + fCM
(180MHz)
-70
−40
fIN - fCM (160MHz)
-80
−50
fCM
(10MHz)
-90
-100
−60
0
50
100
150
200
250
300
-110
0
10
20
Frequency of Input Common-Mode Signal (MHz)
Figure 56.
30
40
50
60
70
80
90
100
Frequency (MHz)
Figure 57.
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APPLICATION INFORMATION
THEORY OF OPERATION
The ADS58B18 and ADS58B19 are members of the ultralow power ADS4xxx analog-to-digital converter (ADC)
family with integrated analog buffers and SNRBoost technology. The analog-to-digital conversion process is
initiated by a rising edge of the external input clock when the analog input signal is sampled. The sampled signal
is sequentially converted by a series of small resolution stages with the outputs combined in a digital correction
logic block. At every clock edge the sample propagates through the pipeline, resulting in a data latency of 10
clock cycles. The output is available as 11-bit data (ADS58B18) or 9-bit data (ADS58B19), in DDR LVDS or
CMOS, and coded in either offset binary or binary twos complement format.
ANALOG INPUT
The analog inputs include an analog buffer (powered by the AVDD_BUF supply) that internally drives the
differential sampling circuit. As a result of the analog buffer, the input pins present high input impedance to the
external driving source (10kΩ dc resistance and 2pF input capacitance).
The buffer helps to isolate the external driving source from the switching currents of the sampling circuit. With a
constant input impedance, the ADC is easier to drive and to reproduce data sheet measurements. For wideband
applications (such as power amplifier linearization) the signal gain across frequency is more consistent. Spectral
performance variation across the sampling frequency is also reduced.
The input common-mode is set internally using a 5kΩ resistor from each input pin to 1.7V, so the input signal can
be ac-coupled to the pins. For a full-scale differential input, each input pin (INP, INM) must swing symmetrically
between VCM + 0.375V and VCM – 0.375V, resulting in a 1.5VPP differential input swing. The input sampling circuit
has a high 3dB bandwidth that extends up to 550MHz (measured from the input pins to the sampled voltage).
Figure 58 shows an equivalent circuit for the analog input.
LPKG
1nH
INP
Buffer
5W
CBOND
1pF
CEQ
Buffer
5kW
RESR
100W
REQ
Buffer
Sampling
Circuit
1.7V
REQ
Buffer
LPKG
1nH
INM
5W
CBOND
1pF
5kW
CEQ
Buffer
Buffer
RESR
100W
Figure 58. Analog Input Equivalent Circuit
44
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Drive Circuit Requirements
The primary advantage of the buffered analog inputs is the isolation of the external drive source from the
switching currents of the sampling circuit. The filtering of the glitches with an external R-C-R filter, as suggested
for the ADS4149 family, is not required. Using a simple drive circuit, it is possible to obtain uniform performance
over a wide frequency range.
For optimum performance, the analog inputs must be driven differentially. This configuration improves the
common-mode noise immunity and even-order harmonic rejection. A small resistor (5Ω to 10Ω) in series with
each input pin is recommended to damp out ringing caused by package parasitics.
Figure 59 and Figure 60 show the differential impedance (ZIN = RIN || CIN) seen by looking into the ADC input
pins. The presence of the analog input buffer results in an almost constant input capacitance up to 1GHz.
Differential Input Resistance (kW)
100
10
1
0.1
0.01
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Input Frequency (GHz)
Figure 59. ADC Analog Input Resistance (RIN) Across Frequency
2.5
Differential Input Capacitance (pF)
2.25
2
1.75
1.5
1.25
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Input Frequency (GHz)
Figure 60. ADC Analog Input Capacitance (CIN) Across Frequency
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Driving Circuit
Two example driving circuit configurations are shown in Figure 61 and Figure 62—one optimized for low input
frequencies and the other optimized for high input frequencies. Notice in both cases that the board circuitry is
simplified compared to the non-buffered ADS4149.
In Figure 61, a single transformer is used and is suited for low input frequencies. To optimize even-harmonic
performance at high input frequencies (greater than the first Nyquist), the use of back-to-back transformers is
recommended (see Figure 62). Note that both drive circuits have been terminated by 50Ω near the ADC side.
The ac-coupling capacitors allow the analog inputs to self-bias around the required common-mode voltage.
5W
T1
INP
0.1mF
25W
0.1mF
25W
INM
1:1
5W
Figure 61. Drive Circuit for Low Input Frequencies
5W
T2
T1
INP
0.1mF
50W
0.1mF
50W
50W
50W
INM
1:1
1:1
5W
Figure 62. Drive Circuit for High Input Frequencies
The mismatch in the transformer parasitic capacitance (between the windings) results in degraded even-order
harmonic performance. Connecting two identical RF transformers back-to-back helps minimize this mismatch and
good performance is obtained for high-frequency input signals. An additional termination resistor pair may be
required between the two transformers, as shown in Figure 61 and Figure 62. The center point of this termination
is connected to ground to improve the balance between the P (positive) and M (negative) sides. The values of
the terminations between the transformers and on the secondary side must be chosen to obtain an effective 50Ω
(for a 50Ω source impedance).
46
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CLOCK INPUT
The ADS58B18/19 clock inputs can be driven differentially (sine, LVPECL, or LVDS) or single-ended (LVCMOS),
with little or no difference in performance. The common-mode voltage of the clock inputs is set to VCM using
internal 5kΩ resistors. This setting allows the use of transformer-coupled drive circuits for sine-wave clock or
ac-coupling for LVPECL and LVDS clock sources. Figure 63 shows a circuit for the internal clock buffer.
Clock Buffer
LPKG
1nH
20W
CLKP
CBOND
1pF
RESR
100W
LPKG
1nH
5kW
2pF
20W
CEQ
CEQ
0.95V
5kW
CLKM
CBOND
1pF
RESR
100W
NOTE: CEQ is 1pF to 3pF and is the equivalent input capacitance of the clock buffer.
Figure 63. Internal Clock Buffer
A single-ended CMOS clock can be ac-coupled to the CLKP input, with CLKM connected to ground with a 0.1μF
capacitor, as shown in Figure 64. For best performance, the clock inputs must be driven differentially, reducing
susceptibility to common-mode noise. For high input frequency sampling, it is recommended to use a clock
source with very low jitter. Band-pass filtering of the clock source can help reduce the effects of jitter. There is no
change in performance with a non-50% duty cycle clock input (see Figure 34). Figure 65 shows a differential
circuit.
CMOS
Clock Input
0.1mF
0.1mF
CLKP
CLKP
Differential Sine-Wave,
PECL, or LVDS
Clock Input
VCM
0.1mF
0.1mF
CLKM
CLKM
Figure 64. Single-Ended Clock Driving Circuit
Figure 65. Differential Clock Driving Circuit
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SNR ENHANCEMENT USING SNRBoost (ADS58B18 ONLY)
SNRBoost technology makes it possible to overcome SNR limitations resulting from quantization noise. Using
SNRBoost, enhanced SNR can be obtained for any bandwidth (less than Nyquist or fS/2; see Table 4). SNR
improvement is achieved without affecting the default harmonic performance.
SNRBoost can be enabled using the SNRBoost_EN pin or via register bits. When SNRBoost is enabled, the
noise floor in the spectrum acquires a typical bathtub shape; see Figure 66. The bathtub is centered around a
specific frequency (called center frequency). The center frequency is located midway between two corner
frequencies that are specified by the SNRBoost coefficients (register bits SNRBoost Coeff1 and SNRBoost
Coeff2).
0
AIN = −1dBFS
SFDR = 88.5dBc
SNR = 78.2dBFS
SINAD = 77.6dBFS
THD = 85.3dBc
Coeff1 = 0x0
Coeff2 = 0x0
BW = 47.5MHz to 52.5MHz
−10
−20
−30
Amplitude (dB)
−40
−50
−60
−70
−80
−90
−100
−110
−120
0
20
40
60
80
100
Frequency (MHz)
Figure 66. Spectrum with SNRBoost Enabled
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Table 9 shows the relation between each coefficient and its corner frequency. By choosing appropriate
coefficients, the bathtub can be positioned over the frequency range of 0 to fS/2 (Table 10 shows some
examples). By positioning the bathtub within the desired signal band, SNR improvement can be achieved (see
Table 4). Note that as the bandwidth is increased, the amount of SNR improvement reduces.
After a reset, the device is in low-latency disabled mode. To use the SNRBoost:
• For the required bathtub position, write the appropriate coefficients in the SNRBoost Coeff1 and SNRBoost
Coeff2 registers
• SNRBoost can be enabled or disabled using the SNRBoost_EN digital input pin. This pin has higher priority
over the SNRBoost Enable1 and SNRBoost Enable2 register bits
• To use the enable register bits, set the override bit (OVER_RIDE SNRBoost pin).
Table 9. Setting the Corner Frequency
SNRBoost COEFFICIENT
VALUE
NORMALIZED CORNER
FREQUENCY (f/fS)
SNRBoost COEFFICIENT
VALUE
NORMALIZED CORNER
FREQUENCY (f/fS)
7
0.42
F
0.23
6
0.385
E
0.21
5
0.357
D
0.189
4
0.333
C
0.167
3
0.311
B
0.143
2
0.29
A
0.115
1
0.27
9
0.08
0
0.25
8
0
Table 10. Positioning the Corner Frequency
SNRBoost
COEFFICIENT1
(SNRBoost Coeff1)
NORMALIZED CORNER
FREQUENCY1 (f/fS)
SNRBoost
COEFFICIENT1
(SNRBoost Coeff2)
NORMALIZED CORNER
FREQUENCY2 (f/fS)
CENTER FREQUENCY
0
0.25
0
0.25
fS × 0.25
F
0.23
1
0.27
fS × 0.25
6
0.385
2
0.29
fS × 0.3375
D
0.189
B
0.143
fS × 0.166
9
0.08
7
0.42
fS × 0.25
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GAIN FOR SFDR/SNR TRADE-OFF
The ADS58B18/19 include gain settings that can be used to get improved SFDR performance. The gain is
programmable from 0dB to 3.5dB (in 0.5dB steps) using the GAIN register bits. For each gain setting, the analog
input full-scale range scales proportionally, as shown in Table 11.
The SFDR improvement is achieved at the expense of SNR; for each gain setting, the SNR degrades
approximately between 0.5dB and 1dB. The SNR degradation is reduced at high input frequencies. As a result,
the gain is very useful at high input frequencies because the SFDR improvement is significant with marginal
degradation in SNR. Therefore, the gain can be used to trade-off between SFDR and SNR.
After a reset, the device is in low-latency disabled mode and gain is enabled with 0dB gain. For other gain
settings, program the GAIN bits.
Table 11. Full-Scale Range Across Gains
GAIN (dB)
TYPE
FULL-SCALE (VPP)
0
Default after reset
1.5
0.5
1.41
1
1.33
1.5
2
50
1.26
Programmable gain
1.19
2.5
1.12
3
1.06
3.5
1
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OFFSET CORRECTION
The ADS58B18/19 has an internal offset corretion algorithm that estimates and corrects dc offset up to ±10mV.
The correction can be enabled using the ENABLE OFFSET CORR serial register bit. Once enabled, the
algorithm estimates the channel offset and applies the correction every clock cycle. The time constant of the
correction loop is a function of the sampling clock frequency. The time constant can be controlled using the
OFFSET CORR TIME CONSTANT register bits, as described in Table 12.
Table 12. Time Constant of Offset Correction Loop
(1)
OFFSET CORR TIME CONSTANT
TIME CONSTANT, TCCLK
(Number of Clock Cycles)
TIME CONSTANT, TCCLK × 1/fS (sec) (1)
0000
1M
5ms
0001
2M
10.5ms
0010
4M
21ms
0011
8M
42ms
0100
16M
84ms
0101
32M
168ms
0110
64M
336ms
0111
128M
671ms
1000
256M
1.34s
1001
512M
2.68s
1010
1G
5.37s
1011
2G
10.7s
1100
Reserved
—
1101
Reserved
—
1110
Reserved
—
1111
Reserved
—
Sampling frequency, fS = 250MSPS.
After the offset is estimated, the correction can be frozen by setting FREEZE OFFSET CORR = 1. Once frozen,
the last estimated value is used for the offset correction of every clock cycle. Note that offset correction is
disabled by default after reset.
After a reset, the device is in low-latency disabled mode. To use offset correction, set ENABLE OFFSET CORR
to '1' and program the required time constant.
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POWER DOWN
The ADS58B18/19 has three power-down modes: power-down global, standby, and output buffer disable.
Power-Down Global
In this mode, the entire chip (including the ADC, internal reference, and the output buffers) are powered down,
resulting in reduced total power dissipation of about 10mW. The output buffers are in a high-impedance state.
The wake-up time from the global power-down to data becoming valid in normal mode is typically 100µs. To
enter the global power-down mode, set the PDN GLOBAL register bit.
Standby
In this mode, only the ADC is powered down and the internal references are active, resulting in a fast wake-up
time of 5µs. The total power dissipation in standby mode is approximately 185mW. To enter the standby mode,
set the STANDBY register bit.
Output Buffer Disable
The output buffers can be disabled and put in a high-impedance state; wakeup time from this mode is fast,
approximately 100ns. This can be controlled using the PDN OBUF register bit or using the OE pin.
Input Clock Stop
In addition, the converter enters a low-power mode when the input clock frequency falls below 1MSPS. The
power dissipation is approximately 80mW.
POWER-SUPPLY SEQUENCE
During power-up, the AVDD and DRVDD supplies can come up in any sequence. The two supplies are
separated in the device. Externally, they can be driven from separate supplies or from a single supply.
DIGITAL OUTPUT INFORMATION
The ADS58B18/19 provide either 11-bit or 9-bit data and an output clock synchronized with the data.
Output Interface
Two output interface options are available: double data rate (DDR) LVDS and parallel CMOS. The output can be
selected using the LVDS CMOS serial interface register bit or using the DFS pin. The DFS pin has higher priority
for deciding the type of interface, unless the LVDS CMOS override bit is set.
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DDR LVDS Outputs
In this mode, the data bits and clock are output using low voltage differential signal (LVDS) levels. Two data bits
are multiplexed and output on each LVDS differential pair, as shown in Figure 67 and Figure 68. Two bit order
options are available: bit-wise sequence (default) and byte-wise sequence. Byte-wise sequence can be
programmed with the BYTE-WISE En Register bit.
Figure 67. ADS58B18 LVDS Outputs
Pins
CLKOUTP
Pins
Output Clock
CLKOUTM
CLKOUTP
Output Clock
CLKOUTM
D0_P
Data Bits D0
D0_P
Data Bits D0
D1_D2_P
LVDS Buffers
LVDS Buffers
D0_M
Data Bits D1, D2
D1_D2_M
D3_D4_P
11-Bit
ADC Data
Data Bits D3, D4
D3_D4_M
D0_M
D1_D2_P
Data Bits D1, D2
D1_D2_M
D3_D4_P
D5_D6_P
Data Bits D5, D6
9-Bit
ADC Data
Data Bits D3, D4
D3_D4_M
D5_D6_M
D5_D6_P
Data Bits D5, D6
D7_D8_P
D5_D6_M
Data Bits D7, D8
D7_D8_M
D7_D8_P
Data Bits D7, D8
D9_D10_P
D7_D8_M
Data Bits D9, D10
D9_D10_M
ADS58B19
ADS58B18
Figure 68. ADS58B19 LVDS Outputs
Bit-Wise Sequence
Even data bits (D0, D2, D4, etc) are output at the rising edge of CLKOUTP and the odd data bits (D1, D3, D5,
etc) are output at the falling edge of CLKOUTP. Both the rising and falling edges of CLKOUTP must be used to
capture all the data bits; see Figure 69.
Byte-Wise Sequence
In the ADS58B18, data bits D[0:4] are output at the falling edge of CLKOUTP and data bits D[5:10] are output at
the rising edge of CLKOUTP. Both the rising and falling edges of CLKOUTP must be used to capture all the data
bits; see Figure 70.
In the ADS58B19, data bits D[0:3] are output at the falling edge of CLKOUTP and data bits D[4:8] are output at
the rising edge of CLKOUTP. Both the rising and falling edges of CLKOUTP must be used to capture all the data
bits; see Figure 71.
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CLKOUTP
CLKOUTM
D0_P,
D0_M
0
D0
0
D0
D1_D2_P,
D1_D2_M
D1
D2
D1
D2
D3_D4_P,
D3_D4_M
D3
D4
D3
D4
D5_D6_P,
D5_D6_M
D5
D6
D5
D6
D7_D8_P,
D7_D8_M
D7
D8
D7
D8
D9_D10_P,
D9_D10_M
D9
D10
D9
D10
Sample N
Sample N + 1
(1) Bits D9 and D10 are only available in the ADS58B18.
Figure 69. Bit-Wise Sequence (Only with DDR LVDS Interface)
CLKOUTP
CLKOUTM
D0_P,
D0_M
0
D5
0
D5
D1_D2_P,
D1_D2_M
D0
D6
D0
D6
D3_D4_P,
D3_D4_M
D1
D7
D1
D7
D5_D6_P,
D5_D6_M
D2
D8
D2
D8
D7_D8_P,
D7_D8_M
D3
D9
D3
D9
D9_D10_P,
D9_D10_M
D4
D10
D4
D10
Sample N
Sample N + 1
Figure 70. ADS58B18 Byte-Wise Sequence (Only with DDR LVDS Interface)
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CLKOUTP
CLKOUTM
D0_P,
D0_M
0
D4
0
D4
D1_D2_P,
D1_D2_M
D0
D5
D0
D5
D3_D4_P,
D3_D4_M
D1
D6
D1
D6
D5_D6_P,
D5_D6_M
D2
D7
D2
D7
D7_D8_P,
D7_D8_M
D3
D8
D3
D8
Sample N
Sample N + 1
Figure 71. ADS58B19 Byte-Wise Sequence (Only with DDR LVDS Interface)
LVDS Output Data and Clock Buffers
The equivalent circuit of each LVDS output buffer is shown in Figure 72. After reset, the buffer presents an
output impedance of 100Ω to match with the external 100Ω termination.
Additionally, a mode exists to double the strength of the LVDS buffer to support 50Ω differential termination. This
mode can be used when the output LVDS signal is routed to two separate receiver chips, each using a 100Ω
termination. The mode can be enabled using the LVDS DATA STRENGTH and LVDS CLKOUT STRENGTH
register bits for data and output clock buffers, respectively.
The buffer output impedance behaves in the same way as a source-side series termination. By absorbing
reflections from the receiver end, it helps to improve signal integrity.
VDIFF
High
Low
OUTP
External
100W Load
OUTM
1.1V
ROUT
VDIFF
Low
High
Figure 72. LVDS Buffer Equivalent Circuit
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Parallel CMOS Interface
In CMOS mode, each data bit is output on a separate pin as the CMOS voltage level, for every clock cycle. The
rising edge of the output clock CLKOUT can be used to latch data in the receiver. Figure 73 depicts the CMOS
output interface.
Switching noise (caused by CMOS output data transitions) can couple into the analog inputs and degrade SNR.
The coupling and SNR degradation increases as the output buffer drive is made stronger. To minimize this
degradation, the CMOS output buffers are designed with controlled drive strength. The default drive strength
ensures a wide data stable window (even at 250MSPS) is provided so the data outputs have minimal load
capacitance. It is recommended to use short traces (1 to 2 inches, or 2,54cm to 5,08cm) terminated with less
than 5pF load capacitance, as shown in Figure 74.
For sampling frequencies greater than 200MSPS, it is recommended to use an external clock to capture data.
The delay from input clock to output data and the data valid times are specified for higher sampling frequencies.
These timings can be used to delay the input clock appropriately and use it to capture data.
Pins
OVR_SDOUT
CLKOUT
CMOS Output Buffers
D0
D1
D2
D3
¼
¼
11-Bit
ADC Data
D8
D9
D10
ADS58B18
Figure 73. CMOS Output Interface
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Use External Clock Buffer
(> 200MSPS)
Input Clock
Receiver (FPGA, ASIC, etc.)
Flip-Flops
CLKOUT
CMOS Output Buffers
D0
D1
D2
CLKIN
D0_In
D1_In
D2_In
9-/11-Bit ADC Data
ADS58B1x
Use short traces between
ADC output and receiver pins (1 to 2 inches).
Figure 74. CMOS Capture Example
CMOS Interface Power Dissipation
With CMOS outputs, the DRVDD current scales with the sampling frequency and the load capacitance on every
output pin. The maximum DRVDD current occurs when each output bit toggles between '0' and '1' every clock
cycle. In actual applications, this condition is unlikely to occur. The actual DRVDD current would be determined
by the average number of output bits switching, which is a function of the sampling frequency and the nature of
the analog input signal.
Digital Current as a Result of CMOS Output Switching = CL × DRVDD × (N × fAVG)
where:
CL = load capacitance,
N × FAVG = average number of output bits switching.
(1)
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Input Over-Voltage Indication (OVR_SDOUT Pin)
The device has an OVR_SDOUT pin that provides information about analog input overload (as long as the
READOUT register bit is '0'). When the READOUT bit is '1', it functions as a serial readout pin.
At any clock cycle, if the sampled input voltage exceeds the positive or negative full-scale range, the OVR pin
goes high. The OVR remains high as long as the overload condition persists. The OVR pin is a CMOS output
buffer (running off DRVDD supply), independent of the type of output data interface (DDR LVDS or CMOS).
For a positive overload, the D[10:0] output data bits are 7FFh in offset binary output format and 3FFh in twos
complement output format. For a negative input overload, the output code is 000h in offset binary output format
and 400h in twos complement output format.
Output Data Format
Two output data formats are supported: twos complement and offset binary. They can be selected using the
DATA FORMAT serial interface register bit or using the DFS pin.
BOARD DESIGN CONSIDERATIONS
Grounding
A single ground plane is sufficient to give good performance, provided the analog, digital, and clock sections of
the board are cleanly partitioned. See the ADS414x, ADS412x EVM User Guide (SLWU067) for details on layout
and grounding.
Supply Decoupling
Because the ADS58B18/19 already include internal decoupling, minimal external decoupling can be used without
loss in performance. Note that decoupling capacitors can help filter external power-supply noise, so the optimum
number of capacitors depends on the actual application. The decoupling capacitors should be placed very close
to the converter supply pins.
Exposed Pad
In addition to providing a path for heat dissipation, the PowerPAD is also electrically internally connected to the
digital ground. Therefore, it is necessary to solder the exposed pad to the ground plane for best thermal and
electrical performance. For detailed information, see application notes QFN Layout Guidelines (SLOA122) and
QFN/SON PCB Attachment (SLUA271), both available for download at the TI web site (www.ti.com).
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DEFINITION OF SPECIFICATIONS
Analog Bandwidth – The analog input frequency at which the power of the fundamental is reduced by 3dB with
respect to the low-frequency value.
Aperture Delay – The delay in time between the rising edge of the input sampling clock and the actual time at
which the sampling occurs. This delay is different across channels. The maximum variation is specified as
aperture delay variation (channel-to-channel).
Aperture Uncertainty (Jitter) – The sample-to-sample variation in aperture delay.
Clock Pulse Width/Duty Cycle – The duty cycle of a clock signal is the ratio of the time the clock signal remains
at a logic high (clock pulse width) to the period of the clock signal. Duty cycle is typically expressed as a
percentage. A perfect differential sine-wave clock results in a 50% duty cycle.
Maximum Conversion Rate – The maximum sampling rate at which specified operation is given. All parametric
testing is performed at this sampling rate unless otherwise noted.
Minimum Conversion Rate – The minimum sampling rate at which the ADC functions.
Differential Nonlinearity (DNL) – An ideal ADC exhibits code transitions at analog input values spaced exactly
1LSB apart. The DNL is the deviation of any single step from this ideal value, measured in units of LSBs.
Integral Nonlinearity (INL) – The INL is the deviation of the ADC transfer function from a best fit line determined
by a least squares curve fit of that transfer function, measured in units of LSBs.
Gain Error – Gain error is the deviation of the ADC actual input full-scale range from its ideal value. The gain
error is given as a percentage of the ideal input full-scale range. Gain error has two components: error as a
result of reference inaccuracy and error as a result of the channel. Both errors are specified independently as
EGREF and EGCHAN.
To a first-order approximation, the total gain error is ETOTAL ~ EGREF + EGCHAN.
For example, if ETOTAL = ±0.5%, the full-scale input varies from (1 – 0.5/100) x FSideal to (1 + 0.5/100) x FSideal.
Offset Error – The offset error is the difference, given in number of LSBs, between the ADC actual average idle
channel output code and the ideal average idle channel output code. This quantity is often mapped into millivolts.
Temperature Drift – The temperature drift coefficient (with respect to gain error and offset error) specifies the
change per degree Celsius of the parameter from TMIN to TMAX. It is calculated by dividing the maximum deviation
of the parameter across the TMIN to TMAX range by the difference TMAX – TMIN.
Signal-to-Noise Ratio – SNR is the ratio of the power of the fundamental (PS) to the noise floor power (PN),
excluding the power at dc and the first nine harmonics.
SNR = 10Log10
PS
PN
(2)
SNR is either given in units of dBc (dB to carrier) when the absolute power of the fundamental is used as the
reference, or dBFS (dB to full-scale) when the power of the fundamental is extrapolated to the converter
full-scale range.
Signal-to-Noise and Distortion (SINAD) – SINAD is the ratio of the power of the fundamental (PS) to the power
of all the other spectral components including noise (PN) and distortion (PD), but excluding dc.
SINAD = 10Log10
PS
PN + PD
(3)
SINAD is either given in units of dBc (dB to carrier) when the absolute power of the fundamental is used as the
reference, or dBFS (dB to full-scale) when the power of the fundamental is extrapolated to the converter
full-scale range.
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Effective Number of Bits (ENOB) – ENOB is a measure of the converter performance as compared to the
theoretical limit based on quantization noise.
ENOB =
SINAD - 1.76
6.02
(4)
Total Harmonic Distortion (THD) – THD is the ratio of the power of the fundamental (PS) to the power of the
first nine harmonics (PD).
THD = 10Log10
PS
PN
(5)
THD is typically given in units of dBc (dB to carrier).
Spurious-Free Dynamic Range (SFDR) – The ratio of the power of the fundamental to the highest other
spectral component (either spur or harmonic). SFDR is typically given in units of dBc (dB to carrier).
Two-Tone Intermodulation Distortion – IMD3 is the ratio of the power of the fundamental (at frequencies f1
and f2) to the power of the worst spectral component at either frequency 2f1 – f2 or 2f2 – f1. IMD3 is either given
in units of dBc (dB to carrier) when the absolute power of the fundamental is used as the reference, or dBFS (dB
to full-scale) when the power of the fundamental is extrapolated to the converter full-scale range.
DC Power-Supply Rejection Ratio (DC PSRR) – DC PSSR is the ratio of the change in offset error to a change
in analog supply voltage. The dc PSRR is typically given in units of mV/V.
AC Power-Supply Rejection Ratio (AC PSRR) – AC PSRR is the measure of rejection of variations in the
supply voltage by the ADC. If ΔVSUP is the change in supply voltage and ΔVOUT is the resultant change of the
ADC output code (referred to the input), then:
DVOUT
PSRR = 20Log 10
(Expressed in dBc)
DVSUP
(6)
Voltage Overload Recovery – The number of clock cycles taken to recover to less than 1% error after an
overload on the analog inputs. This is tested by separately applying a sine wave signal with 6dB positive and
negative overload. The deviation of the first few samples after the overload (from the expected values) is noted.
Common-Mode Rejection Ratio (CMRR) – CMRR is the measure of rejection of variation in the analog input
common-mode by the ADC. If ΔVCM_IN is the change in the common-mode voltage of the input pins and ΔVOUT is
the resulting change of the ADC output code (referred to the input), then:
DVOUT
CMRR = 20Log10
(Expressed in dBc)
DVCM
(7)
Crosstalk (only for multi-channel ADCs) – This is a measure of the internal coupling of a signal from an
adjacent channel into the channel of interest. It is specified separately for coupling from the immediate
neighboring channel (near-channel) and for coupling from channel across the package (far-channel). It is usually
measured by applying a full-scale signal in the adjacent channel. Crosstalk is the ratio of the power of the
coupling signal (as measured at the output of the channel of interest) to the power of the signal applied at the
adjacent channel input. It is typically expressed in dBc.
60
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© 2009–2011, Texas Instruments Incorporated
Product Folder Link(s): ADS58B18 ADS58B19
ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009 – REVISED JANUARY 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 (August 2010) to Revision D
Page
•
Changed documet status to production data ........................................................................................................................ 1
•
Updated status of ADS58B19 to production data throughout document .............................................................................. 1
•
Updated document format to current standards ................................................................................................................... 1
•
Changed Clock Input, Input clock sample rate parameters for both ADS58B18 and ADS58B19 in Recommended
Operating Conditions table ................................................................................................................................................... 3
•
Added footnote 3 to Recommended Operating Conditions table ......................................................................................... 3
•
Changed conditions of ADC latency parameter in Timing Requirements table ................................................................. 15
•
Deleted footnote 7 from Timing Requirements table .......................................................................................................... 15
•
Deleted footnote 10 in Timing Requirements tableα .......................................................................................................... 16
•
Deleted table 2 (CMOS Timing Across Sampling Frequencies, withe respect to output clock) and table 4 (CMOS
Timing Across Sampling Frequencies, withe respect to input clock) ................................................................................. 17
•
Changed titles of Table 2 and Table 3 ............................................................................................................................... 17
•
Updated Figure 8 ................................................................................................................................................................ 18
•
Changed description of logic high in Table 6 ..................................................................................................................... 20
•
Updated bit D3 of registers 25 and 42 and added register DF to Table 8 ......................................................................... 23
•
Changed bit 3 and description of bits 2 to 0 in Register Address 25h ............................................................................... 25
•
Changed description of bit 4 in Register Address 3Dh ....................................................................................................... 26
•
Changed bit 3 of register address 42h ............................................................................................................................... 28
•
Added Register Address DFh to Description of Serial Registers section ........................................................................... 31
•
Updated conditions of Typical Characteristics: ADS58B18 ................................................................................................ 32
•
Updated Figure 36 .............................................................................................................................................................. 37
•
Updated conditions of Typical Characteristics: ADS58B19 ................................................................................................ 38
•
Updated Figure 53 .............................................................................................................................................................. 42
•
Updated conditions of Typical Characteristics: General ..................................................................................................... 43
•
Deleted Digital Functions and Low-Latency Mode section ................................................................................................. 48
•
Changed SNRBoost enable description in SNR Enhancement Using SNRBoost section ................................................. 49
•
Changed reset description in Gain for SFDR/SNR Trade-Off section ................................................................................ 50
•
Changed reset description in Offset Correction section ..................................................................................................... 51
Changes from Revision B (July 2010) to Revision C
Page
•
Changed Analog Inputs, Input common-mode voltage typical specification in Recommended Operating Conditions
table ...................................................................................................................................................................................... 3
•
Added Clock Input, Input clock duty cycle minimum and maximum specifiations to Recommended Operating
Conditions table .................................................................................................................................................................... 3
•
Updated format of Typical Characteristics graphs .............................................................................................................. 32
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© 2009–2011, Texas Instruments Incorporated
Product Folder Link(s): ADS58B18 ADS58B19
61
PACKAGE OPTION ADDENDUM
www.ti.com
3-Mar-2011
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package
Drawing
Pins
Package Qty
Eco Plan
(2)
Lead/
Ball Finish
MSL Peak Temp
(3)
ADS58B18IRGZR
ACTIVE
VQFN
RGZ
48
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-3-260C-168 HR
ADS58B18IRGZT
ACTIVE
VQFN
RGZ
48
250
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-3-260C-168 HR
ADS58B19IRGZR
ACTIVE
VQFN
RGZ
48
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-3-260C-168 HR
ADS58B19IRGZT
ACTIVE
VQFN
RGZ
48
250
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-3-260C-168 HR
Samples
(Requires Login)
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
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
PACKAGE MATERIALS INFORMATION
www.ti.com
1-Mar-2011
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
ADS58B18IRGZR
VQFN
RGZ
48
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
2500
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
ADS58B18IRGZT
VQFN
RGZ
48
250
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
ADS58B19IRGZR
VQFN
RGZ
48
2500
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
ADS58B19IRGZT
VQFN
RGZ
48
250
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
1-Mar-2011
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
ADS58B18IRGZR
VQFN
RGZ
48
2500
333.2
345.9
28.6
ADS58B18IRGZT
VQFN
RGZ
48
250
333.2
345.9
28.6
ADS58B19IRGZR
VQFN
RGZ
48
2500
333.2
345.9
28.6
ADS58B19IRGZT
VQFN
RGZ
48
250
333.2
345.9
28.6
Pack Materials-Page 2
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