Maxim MAX19505 Dual-channel, 8-bit, 65msps adc Datasheet

19-4314; Rev 0; 10/08
Dual-Channel, 8-Bit, 65Msps ADC
The MAX19505 dual-channel, analog-to-digital converter (ADC) provides 8-bit resolution and a maximum sample rate of 65Msps.
The MAX19505 analog input accepts a wide 0.4V to
1.4V input common-mode voltage range, allowing DCcoupled inputs for a wide range of RF, IF, and baseband front-end components. The MAX19505 provides
excellent dynamic performance from baseband to high
input frequencies beyond 400MHz, making the device
ideal for zero-intermediate frequency (ZIF) and highintermediate frequency (IF) sampling applications. The
typical signal-to-noise ratio (SNR) performance is
49.8dBFS and typical spurious-free dynamic range
(SFDR) is 69dBc at fIN = 70MHz and fCLK = 65MHz.
The MAX19505 operates from a 1.8V supply.
Additionally, an integrated, self-sensing voltage regulator allows operation from a 2.5V to 3.3V supply (AVDD).
The digital output drivers operate on an independent
supply voltage (OVDD) over the 1.8V to 3.5V range.
The analog power consumption is only 43mW per channel at V AVDD = 1.8V. In addition to low operating
power, the MAX19505 consumes only 1mW in powerdown mode and 15mW in standby mode.
Various adjustments and feature selections are available through programmable registers that are
accessed through the 3-wire serial-port interface.
Alternatively, the serial-port interface can be disabled,
with the three pins available to select output mode,
data format, and clock-divider mode. Data outputs are
available through a dual parallel CMOS-compatible output data bus that can also be configured as a single
multiplexed parallel CMOS bus.
The MAX19505 is available in a small 7mm x 7mm
48-pin thin QFN package and is specified over the
-40°C to +85°C extended temperature range.
Refer to the MAX19515, MAX19516, and MAX19517
data sheets for pin- and feature-compatible 10-bit,
65Msps, 100Msps, and 130Msps versions, respectively.
Refer to the MAX19506 and MAX19507 data sheets for
pin- and feature-compatible 8-bit, 100Msps and
130Msps versions, respectively.
Applications
IF and Baseband Communications, Including
Cellular Base Stations and Point-to-Point
Microwave Receivers
Ultrasound and Medical Imaging
Portable Instrumentation and Low-Power Data
Acquisition
Digital Set-Top Boxes
Features
o Very-Low-Power Operation (43mW/Channel at
65Msps)
o 1.8V or 2.5V to 3.3V Analog Supply
o Excellent Dynamic Performance
49.8dBFS SNR at 70MHz
69dBc SFDR at 70MHz
o User-Programmable Adjustments and Feature
Selection through an SPI™ Interface
o Selectable Data Bus (Dual CMOS or Single
Multiplexed CMOS)
o DCLK Output and Programmable Data Output
Timing Simplifies High-Speed Digital Interface
o Very Wide Input Common-Mode Voltage Range
(0.4V to 1.4V)
o Very High Analog Input Bandwidth (> 850MHz)
o Single-Ended or Differential Analog Inputs
o Single-Ended or Differential Clock Input
o Divide-by-One (DIV1), Divide-by-Two (DIV2), and
Divide-by-Four (DIV4) Clock Modes
o Two’s Complement, Gray Code, and Offset Binary
Output Data Format
o Out-of-Range Indicator (DOR)
o CMOS Output Internal Termination Options
(Programmable)
o Reversible Bit Order (Programmable)
o Data Output Test Patterns
o Small, 7mm x 7mm 48-Pin Thin QFN Package with
Exposed Pad
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX19505ETM+
-40°C to +85°C
48 TQFN-EP*
+Denotes a lead-free/RoHS-compliant package.
*EP = Exposed pad.
Pin Configuration appears at end of data sheet.
SPI is a trademark of Motorola, Inc.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX19505
General Description
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
ABSOLUTE MAXIMUM RATINGS
OVDD, AVDD to GND............................................-0.3V to +3.6V
CMA, CMB, REFIO, INA+, INA-, INB+,
INB- to GND ......................................................-0.3V to +2.1V
CLK+, CLK-, SYNC, SPEN, CS, SCLK, SDIN
to GND ..........-0.3V to the lower of (VAVDD + 0.3V) and +3.6V
DCLKA, DCLKB, D7A–D0A, D7B–D0B, DORA, DORB
to GND..........-0.3V to the lower of (VOVDD + 0.3V) and +3.6V
Continuous Power Dissipation (TA = +70°C)
48-Pin Thin QFN, 7mm x 7mm x 0.8mm
(derate 40mW/°C above +70°C) ................................3200mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC ACCURACY
Resolution
8
Bits
Integral Nonlinearity
INL
fIN = 3MHz
-0.3
±0.0
+0.3
Differential Nonlinearity
DNL
fIN = 3MHz
-0.3
±0.1
+0.3
LSB
LSB
Offset Error
OE
Internal reference
-0.4
±0.1
+0.4
%FS
Gain Error
GE
External reference = 1.25V
-1.5
±0.3
+1.5
%FS
ANALOG INPUTS (INA+, INA-, INB+, INB-) (Figure 3)
Differential Input-Voltage Range
VDIFF
Differential or single-ended inputs
Common-Mode Input-Voltage
Range
VCM
(Note 2)
Input Resistance
Input Current
Input Capacitance
RIN
IIN
CPAR
CSAMPLE
1.5
0.4
Fixed resistance, common mode, and
differential mode
VP-P
1.4
V
> 100
kΩ
Differential input resistance, common mode
connected to inputs
4
Switched capacitance common-mode input
current, each input
35
Fixed capacitance to ground, each input
0.7
Switched capacitance, each input
1.2
µA
pF
CONVERSION RATE
Maximum Clock Frequency
fCLK
Minimum Clock Frequency
fCLK
Data Latency
2
65
MHz
30
Figures 9, 10
9
_______________________________________________________________________________________
MHz
Cycles
Dual-Channel, 8-Bit, 65Msps ADC
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC PERFORMANCE
Small-Signal Noise Floor
Signal-to-Noise Ratio
Signal-to-Noise Plus Distortion
Ratio
Spurious-Free Dynamic Range
(2nd and 3rd Harmonic)
Spurious-Free Dynamic Range
(4th and Higher Harmonics)
Second Harmonic
SSNF
SNR
SINAD
SFDR1
SFDR2
HD2
Third Harmonic
HD3
Total Harmonic Distortion
Third-Order Intermodulation
Full-Power Bandwidth
THD
IM3
FPBW
fIN = 70MHz, < -35dBFS
-49.8
fIN = 3MHz
49.8
fIN = 70MHz
49.0
49.8
fIN = 3MHz
49.3
48.5
49.3
fIN = 3MHz
77.0
65.0
77.0
fIN = 3MHz
69.0
64.4
dBc
77.0
fIN = 175MHz
fIN = 70MHz
dB
49.3
fIN = 175MHz
fIN = 70MHz
dBFS
49.8
fIN = 175MHz
fIN = 70MHz
dBFS
dBc
69.0
fIN = 175MHz
69.0
fIN = 3MHz
-78.0
fIN = 70MHz
-78.0
fIN = 175MHz
-78.0
fIN = 3MHz
-82.0
fIN = 70MHz
-82.0
fIN = 175MHz
-80.0
fIN = 3MHz
-72.0
fIN = 70MHz
-72.0
fIN = 175MHz
-72.0
fIN = 70MHz ± 1.5MHz, -7dBFS
-80
fIN = 175MHz ± 2.5MHz, -7dBFS
-75
RSOURCE = 50Ω differential, -3dB rolloff
850
-65.0
dBc
-65.0
dBc
-63.0
dBc
dBc
MHz
Aperture Delay
tAD
850
ps
Aperture Jitter
tAJ
0.3
psRMS
1
Cycles
Overdrive Recovery Time
±10% beyond full scale
_______________________________________________________________________________________
3
MAX19505
ELECTRICAL CHARACTERISTICS (continued)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
ELECTRICAL CHARACTERISTICS (continued)
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
INTERCHANNEL CHARACTERISTICS
Crosstalk
fINA or fINB = 70MHz at -1dBFS
95
fINA or fINB = 175MHz at -1dBFS
85
dBc
Gain Match
fIN = 70MHz
±0.05
dB
Offset Match
fIN = 70MHz
±0.1
%FSR
Phase Match
fIN = 70MHz
±0.5
Degrees
ANALOG OUTPUTS (CMA, CMB)
CMA, CMB Output Voltage
VCOM
Default programmable setting
0.85
0.9
0.95
1.25
1.27
V
INTERNAL REFERENCE
REFIO Output Voltage
REFIO Temperature Coefficient
VREFOUT
1.23
V
TCREF
< ±60
ppm/°C
REFIO Input-Voltage Range
VREFIN
1.25 +5/
-10%
V
REFIO Input Resistance
RREFIN
10
±20%
kΩ
0.4 to 2.0
VP-P
EXTERNAL REFERENCE
CLOCK INPUTS (CLK+, CLK-)—DIFFERENTIAL MODE
Differential Clock Input Voltage
Self-biased
Differential Input Common-Mode
Voltage
1.20
DC-coupled clock signal
Input Resistance
RCLK
Input Capacitance
CCLK
V
1.0 to 1.4
Differential, default
10
kΩ
Differential, programmable internal
termination selected
100
Ω
Common mode
9
kΩ
DC-coupled clock signal
3
pF
CLOCK INPUTS (CLK+, CLK-)—SINGLE-ENDED MODE (VCLK- < 0.1V)
Single-Ended Mode Selection
Threshold (VCLK-)
0.1
Allowable Logic Swing (VCLK+)
0 - VAVDD
Single-Ended Clock Input High
Threshold (VCLK+)
Input Leakage (CLK-)
Input Capacitance (CLK+)
4
V
1.5
V
Single-Ended Clock Input Low
Threshold (VCLK+)
Input Leakage (CLK+)
0.3
VCLK+ = VAVDD = 1.8V or 3.3V
+0.5
VCLK+ = 0
-0.5
VCLK- = 0
-150
V
-50
3
_______________________________________________________________________________________
V
µA
µA
pF
Dual-Channel, 8-Bit, 65Msps ADC
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CLOCK INPUTS (SYNC)
Allowable Logic Swing
0 - VAVDD
Sync Clock Input High Threshold
V
1.5
V
Sync Clock Input Low Threshold
0.3
VSYNC = VAVDD = 1.8V or 3.3V
Input Leakage
VSYNC = 0
+0.5
-0.5
Input Capacitance
V
µA
4.5
pF
0 - VAVDD
V
DIGITAL INPUTS (SHDN, SPEN)
Allowable Logic Swing
Input High Threshold
1.5
V
Input Low Threshold
0.3
VSHDN/VSPEN = VAVDD = 1.8V or 3.3V
Input Leakage
VSHDN/VSPEN = 0
Input Capacitance
+0.5
-0.5
CDIN
V
µA
3
pF
0 - VAVDD
V
SERIAL-PORT INPUTS (SCLK, SDIN, CS, where SPEN = 0V)—SERIAL-PORT CONTROL MODE
Allowable Logic Swing
Input High Threshold
1.5
V
Input Low Threshold
0.3
VSCLK/VSDIN/VCS = VAVDD = 1.8V or 3.3V
Input Leakage
VSCLK/VSDIN/VCS = 0
Input Capacitance
+0.5
-0.5
CDIN
3
V
µA
pF
SERIAL-PORT INPUTS (SCLK, SDIN, CS, where SPEN = VAVDD)—PARALLEL CONTROL MODE (Figure 5)
Input Pullup Current
Input Pulldown Current
Open-Circuit Voltage
VOC
VSCLK/VSDIN/VCS = VAVDD = 1.8V
7
12
17
VSCLK/VSDIN/VCS = VAVDD = 3.3V
16
21
26
VSCLK/VSDIN/VCS = 0, VAVDD = 1.8V
-65
-50
-35
VSCLK/VSDIN/VCS = 0, VAVDD = 3.3V
-105
-90
-75
I = 0V, VAVDD = 1.8V
1.35
1.45
1.55
I = 0V, VAVDD = 3.3V
2.58
2.68
2.78
µA
µA
V
DIGITAL OUTPUTS (CMOS MODE, 75Ω, D0–D7 (A and B Channel), DCLKA, DCLKB, DORA, DORB)
Output-Voltage Low
VOL
Output-Voltage High
VOH
Three-State Leakage Current
ILEAK
ISINK = 200µA
ISOURCE = 200µA
0.2
VOVDD
- 0.2
VOVDD applied
GND applied
V
+0.5
-0.5
V
µA
_______________________________________________________________________________________
5
MAX19505
ELECTRICAL CHARACTERISTICS (continued)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
ELECTRICAL CHARACTERISTICS (continued)
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER-MANAGEMENT CHARACTERISTICS
Wake-Up Time from Shutdown
tWAKE
Internal reference, CREFIO = 0.1µF (10τ)
5
ms
Wake-Up Time from Standby
tWAKE
Internal reference
15
µs
SERIAL-PORT INTERFACE TIMING (Note 2) (Figure 7)
SCLK Period
tSCLK
50
ns
SCLK to CS Setup Time
tCSS
10
ns
SCLK to CS Hold Time
tCSH
10
ns
SDIN to SCLK Setup Time
tSDS
Serial-data write
10
ns
SDIN to SCLK Hold Time
tSDH
Serial-data write
0
ns
SCLK to SDIN Output Data Delay
tSDD
Serial-data read
10
ns
TIMING CHARACTERISTICS—DUAL BUS PARALLEL MODE (Figure 9) (Default Timing, see Table 5)
Clock Pulse-Width High
Clock Pulse-Width Low
Clock Duty Cycle
Data Delay After Rising Edge of
CLK+
tCH
7.69
ns
tCL
7.69
ns
tCH/tCLK
30 to 70
tDD
CL = 10pF, VOVDD = 1.8V (Note 2)
4.2
CL = 10pF, VOVDD = 3.3V
6.1
%
7.9
4.9
ns
Data to DCLK Setup Time
tSETUP
CL = 10pF, VOVDD = 1.8V (Note 2)
12.7
13.3
ns
Data to DCLK Hold Time
tHOLD
CL = 10pF, VOVDD = 1.8V (Note 2)
1.6
2.1
ns
TIMING CHARACTERISTICS—MULTIPLEXED BUS PARALLEL MODE (Figure 10) (Default Timing, see Table 5)
Clock Pulse-Width High
tCH
7.69
ns
Clock Pulse-Width Low
tCL
7.69
ns
Clock Duty Cycle
Data Delay After Rising Edge of
CLK+
tCH/tCLK
tDD
30 to 70
CL = 10pF, VOVDD = 1.8V (Note 2)
3.2
CL = 10pF, VOVDD = 3.3V
5.7
%
8.2
4.8
ns
Data to DCLK Setup Time
tSETUP
CL = 10pF, VOVDD = 1.8V (Note 2)
4.3
5.9
ns
Data to DCLK Hold Time
tHOLD
CL = 10pF, VOVDD = 1.8V (Note 2)
0.5
1.7
ns
DCLK Duty Cycle
tDCH/tCLK
CL = 10pF, VOVDD = 1.8V (Note 2)
45
50
54
%
MUX Data Duty Cycle
tCHA/tCLK
CL = 10pF, VOVDD = 1.8V (Note 2)
40
50
61
%
TIMING CHARACTERISTICS—SYNCHRONIZATION (Figure 12)
Setup Time for Valid Clock Edge
tSUV
Edge mode (Note 2)
0.7
ns
Hold-Off Time for Invalid Clock
Edge
tSDH
Edge mode (Note 2)
0.5
ns
Minimum Synchronization Pulse
Width
6
Relative to input clock period
2
_______________________________________________________________________________________
Cycles
Dual-Channel, 8-Bit, 65Msps ADC
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER REQUIREMENTS
Analog Supply Voltage
VAVDD
Digital Output Supply Voltage
VOVDD
Analog Supply Current
Analog Power Dissipation
Digital Output Supply Current
IAVDD
PDA
IOVDD
Low-level VAVDD
1.7
1.9
High-level VAVDD (regulator mode, invoked
automatically)
2.3
3.5
1.7
3.5
Dual channel
47
Single channel active
28
8.5
12
Power-down mode
0.65
0.9
Power-down mode, VAVDD = 3.3V
1.6
Dual channel
85
Dual channel, VAVDD = 3.3V
155
Single channel active
50
Standby mode
15
22
Power-down mode
1.2
1.6
Power-down mode, VAVDD = 3.3V
2.9
Power-down mode
11
< 0.1
V
55
Standby mode
Dual-channel mode, CL = 10pF
V
mA
99
mW
mA
Note 1: Specifications ≥ +25°C guaranteed by production test, specifications < +25°C guaranteed by design and characterization.
Note 2: Guaranteed by design and characterization.
_______________________________________________________________________________________
7
MAX19505
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = +25°C, unless otherwise noted.)
-60
-40
-60
-40
-60
-70
-80
-80
-80
-90
-90
10
15
20
25
FREQUENCY (MHz)
-90
0
30
175MHz INPUT FFT PLOT
-50
-60
-20
-30
-40
-50
-60
-70
-40
-50
-60
-70
-90
-90
-100
-100
20
25
30
-80
0
FREQUENCY (MHz)
30
0
0.08
0.04
0.02
0.02
DNL (LSB)
0.04
0
-0.02
0
-0.02
-0.04
-0.04
-0.06
-0.06
-0.08
-0.10
0
64
128
192
DIGITAL OUTPUT CODE
256
30
80
-THD
SFDR1
75
70
65
SFDR2
60
55
SNR
SINAD
50
-0.08
-0.10
10
15
20
25
FREQUENCY (MHz)
PERFORMANCE vs. INPUT FREQUENCY
PERFORMANCE (dBFS)
0.06
5
85
MAX19505 toc08
0.06
10
15
20
25
FREQUENCY (MHz)
0.10
MAX19505 toc07
0.08
5
DIFFERENTIAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
0.10
30
-30
-90
15
25
-20
-80
10
20
fIN1 = 172.50202MHz
fIN2 = 177.49286MHz
-10
-80
5
15
175MHz TWO-TONE IMD PLOT
-70
0
10
0
AMPLITUDE (dBFS)
-40
5
FREQUENCY (MHz)
fIN1 = 71.496925MHz
fIN2 = 68.504600MHz
-10
AMPLITUDE (dBFS)
-30
0
30
0
MAX19505 toc04
-20
10
15
20
25
FREQUENCY (MHz)
70MHz TWO-TONE FFT PLOT
fIN = 175.096626MHz
AIN = - 0.457dBFS
SNR = 48.939dB
SINAD = 48.936dB
THD = -80.024dBc
SFDR1 = 83.676dBc
SFDR2 = 69.175dBc
-10
5
MAX19505 toc05
5
MAX19505 toc03
-50
-70
0
AMPLITUDE (dBFS)
MAX19505 toc02
-50
-30
-70
0
8
-20
MAX19505 toc06
-50
-30
fIN = 70.1014328MHz
AIN = -0.497dBFS
SNR = 49.243dB
SINAD = 49.241dB
THD = -83.453dBc
SFDR1 = 90.072dBc
SFDR2 = 68.395dBc
-10
MAX19505 toc09
-40
-20
0
AMPLITUDE (dBFS)
-30
fIN = 3.05034637MHz
AIN = -0.517dBFS
SNR = 49.130dB
SINAD = 49.092dB
THD = -69.749dBc
SFDR1 = 72.278dBc
SFDR2 = 68.102dBc
-10
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
-20
0
MAX19505 toc01
fIN = 2.99877166MHz
AIN = -0.493dBFS
SNR = 49.285dB
SINAD = 49.282dB
THD = -80.871dBc
SFDR1 = 87.801dBc
SFDR2 = 68.102dBc
-10
70MHz INPUT FFT PLOT
3MHz SINGLE-ENDED INPUT FFT PLOT
3MHz INPUT FFT PLOT
0
INL (LSB)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
45
0
64
128
192
DIGITAL OUTPUT CODE
256
0
100
200
300
INPUT FREQUENCY (MHz)
_______________________________________________________________________________________
400
Dual-Channel, 8-Bit, 65Msps ADC
70
65
-THD
SNR
60
-THD
55
45
45
60
SFDR1
75
-THD
70
SFDR2
60
80
SNR
-THD
75
70
65
SFDR2
60
SNR
55
SINAD
SFDR1
80
-THD
75
70
SFDR2
65
60
55
SNR
1.70 1.75 1.80 1.85 1.90
ANALOG SUPPLY VOLTAGE (V)
2.3
1.95
36
34
48
47
46
45
44
43
42
32
41
30
40
20 25 30 35 40 45 50 55 60 65 70
SAMPLING FREQUENCY (MHz)
MAX19505 toc17
49
50
49
ANALOG SUPPLY CURRENT (mA)
38
50
ANALOG SUPPLY CURRENT (mA)
40
2.5
2.7
2.9
3.1
3.3
ANALOG SUPPLY VOLTAGE (V)
3.5
ANALOG SUPPLY CURRENT
vs. SUPPLY VOLTAGE
ANALOG SUPPLY CURRENT
vs. TEMPERATURE
42
SINAD
45
1.65
44
70
50
45
0.55
0.75
0.95
1.15
1.35
COMMON-MODE VOLTAGE (V)
30
40
50
60
SAMPLING FREQUENCY (Msps)
85
50
MAX19505 toc16
ANALOG SUPPLY CURRENT (mA)
20
PERFORMANCE
vs. ANALOG SUPPLY VOLTAGE
SFDR1
ANALOG SUPPLY CURRENT
vs. SAMPLING FREQUENCY
46
0
85
50
48
SINAD
45
-50
-40
-30
-20
-10
ANALOG INPUT AMPLITUDE (dBFS)
PERFORMANCE
vs. ANALOG SUPPLY VOLTAGE
PERFORMANCE (dBFS)
PERFORMANCE (dBFS)
80
50
SNR
55
50
-60
MAX19505 toc13
85
45
0.35
60
MAX19505 toc18
20
40
INPUT FREQUENCY (MHz)
SINAD
SFDR2
65
SINAD
PERFORMANCE
vs. COMMON-MODE VOLTAGE
55
-THD
70
MAX19505 toc15
50
65
75
SNR
50
0
SFDR1
65
PERFORMANCE (dBFS)
55
SINAD
70
MAX19505 toc14
60
SFDR2
75
SFDR1
80
PERFORMANCE (dBFS)
SFDR2
75
80
PERFORMANCE (dBFS)
PERFORMANCE (dBFS)
SFDR1
85
MAX19505 toc11
80
PERFORMANCE
vs. SAMPLING FREQUENCY
85
MAX19505 toc10
85
PERFORMANCE
vs. ANALOG INPUT AMPLITUDE
MAX19505 toc12
SINGLE-ENDED PERFORMANCE
vs. INPUT FREQUENCY
48
47
46
45
44
43
42
41
40
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
1.65
1.70
1.75 1.80 1.85
SUPPLY VOLTAGE (V)
1.90
_______________________________________________________________________________________
1.95
9
MAX19505
Typical Operating Characteristics (continued)
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = +25°C, unless otherwise noted.)
45
44
43
42
41
8
7
6
5
4
3
2
16
14
12
10
8
6
4
2
0
0
2.7
2.9
3.1
SUPPLY VOLTAGE (V)
3.3
3.5
20
30
40
50
60
SAMPLING FREQUENCY (Msps)
DIGITAL SUPPLY CURRENT
vs. TEMPERATURE
15
OVDD = 3.6V
OVDD = 1.8V
9
DUAL BUS
16
7
30
40
50
60
SAMPLING FREQUENCY (Msps)
70
DIGITAL SUPPLY CURRENT
vs. SUPPLY VOLTAGE
18
DIGITAL SUPPLY CURRENT (mA)
MAX19505 toc22
17
11
20
DIGITAL SUPPLY CURRENT
vs. SUPPLY VOLTAGE
19
13
70
14
12
10
8
6
4
25
MULTIPLEXED BUS
DIGITAL SUPPLY CURRENT (mA)
2.5
MAX19505 toc23
2.3
OVDD = 3.6V
18
1
40
20
15
10
5
2
5
0
0
-20
0
20
40
60
80
1.8
2.0
2.2
TEMPERATURE (°C)
PERFORMANCE
vs. CLOCK DUTY CYCLE
-THD
70
SFDR2
60
SFDR1
80
PERFORMANCE (dBFS)
80
65
SNR
55
-THD
70
65
SFDR2
60
35
40
45
50
55
CLOCK DUTY CYCLE (%)
65
0.03
0.02
0.01
0
-0.01
-0.03
-0.04
-0.05
45
60
0.04
-0.02
SNR
55
SINAD
SINAD
30
GAIN ERROR vs. TEMPERATURE
0.05
75
50
50
45
1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5
SUPPLY VOLTAGE (V)
3.4
85
MAX19505 toc25
SFDR1
75
3.2
PERFORMANCE vs. TEMPERATURE
90
85
2.4 2.6 2.8 3.0
SUPPLY VOLTAGE (V)
MAX19505 toc27
-40
GAIN ERROR (%)
DIGITAL SUPPLY CURRENT (mA)
20
MAX19505 toc24
46
OVDD = 1.8V
9
DIGITAL SUPPLY CURRENT (mA)
47
MAX19505 toc20
48
10
MAX19505 toc26
ANALOG SUPPLY CURRENT (mA)
49
DIGITAL SUPPLY CURRENT (mA)
MAX19505 toc19
50
10
DIGITAL SUPPLY CURRENT
vs. SAMPLING FREQUENCY
DIGITAL SUPPLY CURRENT
vs. SAMPLING FREQUENCY
MAX19505 toc21
ANALOG SUPPLY CURRENT
vs. SUPPLY VOLTAGE
PERFORMANCE (dBFS)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
-40
-20
0
20
40
TEMPERATURE (°C)
______________________________________________________________________________________
60
80
Dual-Channel, 8-Bit, 65Msps ADC
REFERENCE VOLTAGE
vs. TEMPERATURE
REFERENCE VOLTAGE (V)
-0.1
-0.2
-0.3
-0.4
-0.5
1.2495
1.2474
1.2453
-0.6
-0.7
1.2432
60
80
VCM = 1.35V
1.4
VCM = 1.2V
1.2
VCM = 1.05V
1.0
VCM = 0.9V
0.8
VCM = 0.75V
VCM = 0.6V
0.6
VCM = 0.45V
0.4
0.2
0
-40
-20
0
20
40
TEMPERATURE (°C)
0.06
80
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
INPUT CURRENT
vs. COMMON-MODE VOLTAGE
GAIN ERROR vs. SUPPLY VOLTAGE
0.08
60
60
55
0.02
0
-0.02
REGULATOR MODE
INPUT CURRENT (µA)
0.04
50
45
40
35
-0.04
30
-0.06
25
-0.08
MAX19505 toc32
0
20
40
TEMPERATURE (°C)
MAX19505 toc31
-20
GAIN ERROR (%)
-40
1.6
MAX19505 toc30
0
MAX19505 toc29
0.1
OFFSET ERROR (mV)
1.2516
MAX19505 toc28
0.2
COMMON-MODE REFERENCE VOLTAGE
vs. TEMPERATURE
COMMON-MODE REFERENCE VOLTAGE (V)
OFFSET ERROR vs. TEMPERATURE
20
1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
SUPPLY VOLTAGE (V)
0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4
COMMON-MODE VOLTAGE (V)
______________________________________________________________________________________
11
MAX19505
Typical Operating Characteristics (continued)
(VAVDD = VOVDD = 1.8V, internal reference, differential clock, VCLK = 1.5VP-P, fCLK = 65MHz, AIN = -0.5dBFS, data output termination
= 50Ω, TA = +25°C, unless otherwise noted.)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
Pin Description
PIN
NAME
1, 12, 13, 48
AVDD
Analog Supply Voltage. Bypass each AVDD input pair (1, 48) and (12, 13) to GND with 0.1µF.
2
CMA
Channel A Common-Mode Input-Voltage Reference
3
INA+
Channel A Positive Analog Input
4
INA-
Channel A Negative Analog Input
5
SPEN
Active-Low SPI Enable. Drive high to enable parallel programming mode.
6
REFIO
Reference Input/Output. To use internal reference, bypass to GND with a > 0.1µF capacitor. See
the Reference Input/Output (REFIO) section for external reference adjustment.
7
SHDN
Active-High Power-Down. If SPEN is high (parallel programming mode), a register reset is initiated
on the falling edge of SHDN.
12
FUNCTION
8
I.C.
9
INB+
Internally Connected. Leave unconnected.
Channel B Positive Analog Input
10
INB-
Channel B Negative Analog Input
11
CMB
Channel B Common-Mode Input-Voltage Reference
14
SYNC
Clock-Divider Mode Synchronization Input
15
CLK+
Clock Positive Input
16
CLK-
Clock Negative Input. If CLK- is connected to ground, CLK+ is a single-ended logic-level clock
input. Otherwise, CLK+/CLK- are self-biased differential clock inputs.
17, 18
GND
Ground. Connect all ground inputs and EP (exposed pad) together.
19
DORB
Channel B Data Over Range
20
DCLKB
Channel B Data Clock
21
I.C.
Internally Connected. Leave unconnected.
22
I.C.
Internally Connected. Leave unconnected.
23
D0B
Channel B Three-State Digital Output, Bit 0 (LSB)
24
D1B
Channel B Three-State Digital Output, Bit 1
25, 36
OVDD
26
D2B
Channel B Three-State Digital Output, Bit 2
27
D3B
Channel B Three-State Digital Output, Bit 3
28
D4B
Channel B Three-State Digital Output, Bit 4
29
D5B
Channel B Three-State Digital Output, Bit 5
30
D6B
Channel B Three-State Digital Output, Bit 6
Digital Supply Voltage. Bypass each OVDD input to GND with 0.1µF capacitor.
31
D7B
Channel B Three-State Digital Output, Bit 7 (MSB)
32, 33
I.C.
Internally Connected. Leave unconnected.
34
D0A
Channel A Three-State Digital Output, Bit 0 (LSB)
35
D1A
Channel A Three-State Digital Output, Bit 1
37
D2A
Channel A Three-State Digital Output, Bit 2
38
D3A
Channel A Three-State Digital Output, Bit 3
39
D4A
Channel A Three-State Digital Output, Bit 4
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
PIN
NAME
FUNCTION
40
D5A
Channel A Three-State Digital Output, Bit 5
41
D6A
Channel A Three-State Digital Output, Bit 6
42
D7A
Channel A Three-State Digital Output, Bit 7 (MSB)
43
DORA
Channel A Data Over Range
44
DCLKA
Channel A Data Clock
45
SDIN/FORMAT
46
SCLK/DIV
Serial Clock/Clock Divider. Serial clock when SPEN is low. Clock divider when SPEN is high.
47
CS/OUTSEL
Serial-Port Select/Data Output Mode. Serial-port select when SPEN is low. Data output mode
selection when SPEN is high.
—
EP
SPI Data Input/Format. Serial-data input when SPEN is low. Output data format when SPEN is high.
Exposed Pad. Internally connected to GND. Connect to a large ground plane to maximize thermal
performance.
Detailed Description
The MAX19505 uses a 10-stage, fully differential,
pipelined architecture (Figure 1) that allows for highspeed conversion while minimizing power consumption. Samples taken at the inputs move progressively
through the pipeline stages every half clock cycle.
From input to output, the total latency is 9 clock cycles.
Each pipeline converter stage converts its input voltage
to a digital output code. At every stage, except the last,
the error between the input voltage and the digital output code is multiplied and passed on to the next
pipeline stage. Digital error correction compensates for
ADC comparator offsets in each pipeline stage and
ensures no missing codes. Figure 2 shows the
MAX19505 functional diagram.
current is supplied by the common-mode input voltage.
For example, the input current can be supplied through
the center tap of a transformer secondary winding.
Alternatively, program the appropriate internal register
through the serial-port interface to supply the input DC
current through internal 2kΩ resistors (Figure 3). When
the input current is supplied through the internal resistors, the input common-mode potential is reduced by
the voltage drop across the resistors. The commonmode input reference voltage can be adjusted through
programmable register settings from 0.45V to 1.35V in
0.15V increments. The default setting is 0.90V. Use this
feature to provide a common-mode output reference to
a DC-coupled driving circuit.
Analog Inputs
and Common-Mode Reference
Apply the analog input signal to the analog inputs
(INA+/INA- or INB+/INB-), which are connected to the
input sampling switch (Figure 3). When the input sampling switch is closed, the input signal is applied to the
sampling capacitors through the input switch resistance.
The input signal is sampled at the instant the input
switch opens. The pipeline ADC processes the sampled
voltage and the digital output result is available 9 clock
cycles later. Before the input switch is closed to begin
the next sampling cycle, the sampling capacitors are
reset to the input common-mode potential.
Common-mode bias can be provided externally or
internally through 2kΩ resistors. In DC-coupled applications, the signal source provides the external bias and
the bias current. In AC-coupled applications, the input
+
MAX19505
Σ
x2
−
FLASH
ADC
DAC
IN_+
STAGE 1
STAGE 2
STAGE 9
IN_-
STAGE 10
END OF PIPELINE
DIGITAL ERROR CORRECTION
D0_ THROUGH D7_
Figure 1. Pipeline Architecture—Stage Blocks
______________________________________________________________________________________
13
MAX19505
Pin Description (continued)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
CLOCK
MAX19505
INA+
T/H
INA-
PIPELINE
ADC
DIGITAL
ERROR
CORRECTION
D0A–D7A
DORA
DCLKA
CMA
REFIO
CMB
REFERENCE
AND BIAS
SYSTEM
INTERNAL
REFERENCE
GENERATOR
PIPELINE
ADC
DIGITAL
ERROR
CORRECTION
DATA
AND
OUTPUT
FORMAT
OUTPUT
DRIVERS
OVDD
(1.8V TO 3.3V)
D0B–D7B
INB+
T/H
INB-
DORB
DCLKB
CLOCK
CLK+
CLOCK
DIVIDER
CLK-
DUTYCYCLE
EQUALIZER
SYNC
AVDD
(1.8V OR
2.5V TO 3.3V)
REGULATOR
AND
POWER CONTROL
1.8V INTERNAL
CS
SERIAL PORT
AND
CONTROL REGISTERS
SCLK
SDIN
SHDN
INTERNAL CONTROL
GND
SPEN
Figure 2. Functional Diagram
AVDD
CMA
RSWITCH
120Ω
INA+
CSAMPLE
1.2pF
CPAR
0.7pF
2kΩ
*VCOM
AVDD
2kΩ
RSWITCH
120Ω
INACPAR
0.7pF
CSAMPLE
1.2pF
SAMPLING CLOCK
MAX19505
*VCOM PROGRAMMABLE FROM 0.45V TO 1.35V. SEE COMMON-MODE REGISTER (08h).
Figure 3. Internal Track-and-Hold (T/H) Circuit
14
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
1.250V
10kΩ
BUFFER
DECODER
AVDD
36kΩ
0.1µF
EXTERNAL BYPASS
REFIO
BANDGAP
REFERENCE
MAX19505
29/32 AVDD
INTERNAL GAIN—BYPASS REFIO
EXTERNAL GAIN CONTROL—DRIVE REFIO
CS
SCLK
SDIN
23/32 AVDD
TO
CONTROL
LOGIC
156kΩ
SCALE AND
INTERNAL REFERENCE
LEVEL SHIFT
(CONTROLS ADC GAIN)
3/32 AVDD
Figure 4. Simplified Reference Schematic
Figure 5. Simplified Parallel-Interface Input Schematic
Table 1. Parallel-Interface Pin Functionality
SPEN
SDIN/FORMAT
SCLK/DIV
CS/OUTSEL
DESCRIPTION
0
SDIN
SCLK
CS
SPI interface active. Features are programmed through the
serial port (see the Serial Programming Interface section).
1
0
X
X
Two’s complement
1
AVDD
X
X
Offset binary
1
Unconnected
X
X
Gray code
1
X
0
X
Clock divide-by-1
1
X
AVDD
X
Clock divide-by-2
1
X
Unconnected
X
Clock divide-by-4
1
X
X
0
CMOS (dual bus)
1
X
X
AVDD
MUX CMOS (channel A data bus)
1
X
X
Unconnected
MUX CMOS (channel B data bus)
X = Don’t care.
Reference Input/Output (REFIO)
Programming and Interface
REFIO adjusts the reference potential, which, in turn,
adjusts the full-scale range of the ADC. Figure 4 shows
a simplified schematic of the reference system. An
internal bandgap voltage generator provides an internal
reference voltage. The bandgap potential is buffered
and applied to REFIO through a 10kΩ resistor. Bypass
REFIO with a 0.1µF capacitor to AGND. The bandgap
voltage is applied to a scaling and level-shift circuit,
which creates internal reference potentials that establish the full-scale range of the ADC. Apply an external
voltage on REFIO to trim the ADC full scale. The allowable adjustment range is +5/-15%. The REFIO-to-ADC
gain transfer function is:
VFS = 1.5 x [VREFIO/1.25] Volts
There are two ways to control the MAX19505 operating
modes. Full feature selection is available using the SPI
interface, while the parallel interface offers a limited set
of commonly used features. The programming mode is
selected using the SPEN input. Drive SPEN low for SPI
interface; drive SPEN high for parallel interface.
Parallel Interface
The parallel interface offers a pin-programmable interface with a limited feature set. Connect SPEN to AVDD
to enable the parallel interface. See Table 1 for pin
functionality; see Figure 5 for a simplified parallel-interface input schematic.
______________________________________________________________________________________
15
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
CS
SCLK
SDIN
R/W
A6
A5
A4
A3
R/W
A2
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
DATA
WRITE OR READ
ADDRESS
0 = WRITE
1 = READ
Figure 6. Serial-Interface Communication Cycle
tCSH
tCSS
CS
tSCLK
SCLK
tSDS
tSDH
tSDD
SDIN
WRITE
READ
Figure 7. Serial-Interface Timing Diagram
Serial Programming Interface
A serial interface programs the MAX19505 control registers through the CS, SDIN, and SCLK inputs. Serial
data is shifted into SDIN on the rising edge of SCLK
when CS is low. The MAX19505 ignores the data presented at SDIN and SCLK when CS is high. CS must
transition high after each read/write operation. SDIN
also serves as the serial-data output for reading control
registers. The serial interface supports two-byte transfer
in a communication cycle. The first byte is a control
byte, containing the address and read/write instruction,
written to the MAX19505. The second byte is a data
byte and can be written to or read from the MAX19505.
Figure 6 shows a serial-interface communication
cycle. The first SDIN bit clocked in establishes the
16
communication cycle as either a write or read transaction (0 for write operation and 1 for read operation). The
following 7 bits specify the address of the register to be
written or read. The final 8 SDIN bits are the register
data. All address and data bits are clocked in or out
MSB first. During a read operation, the MAX19505 serial
port drives read data (D7) into SDIN after the falling
edge of SCLK following the 8th rising edge of SCLK.
Since the minimum hold time on SDIN input is zero, the
master can stop driving SDIN any time after the 8th rising edge of SCLK. Subsequent data bits are driven into
SDIN on the falling edge of SCLK. Output data in a read
operation is latched on the rising edge of SCLK. Figure
7 shows the detailed serial-interface timing diagram.
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
are reset to default values. A read operation of register
0Ah returns a status byte with information described in
Table 2.
Table 2. Register 0Ah Status Byte
BIT NO.
VALUE
7
0
Reserved
DESCRIPTION
6
0
Reserved
5
0 or 1
1 = ROM read in progress
4
0 or 1
1 = ROM read completed and register data is valid (checksum is OK)
3
0
Reserved
2
1
Reserved
1
0 or 1
Reserved
0
0 or 1
1 = Duty-cycle equalizer DLL is locked
User-Programmable Registers
Table 3. User-Programmable Registers
ADDRESS
POR DEFAULT
00h
00000011
FUNCTION
Power management
01h
00000000
Output format
02h
00000000
Digital output power management
03h
10000000
Data/DCLK timing
04h
00000000
CHA data output termination control
05h
00000000
CHB data output termination control
06h
00000000
Clock divide/data format/test pattern
07h
Reserved
Reserved—do not use
08h
00000000
Common mode
0Ah
—
Software reset
Power Management (00h)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
HPS_SHDN1 STBY_SHDN1 CHB_ON_SHDN1 CHA_ON_SHDN1 HPS_SHDN0 STBY_SHDN0 CHB_ON_SHDN0 CHA_ON_SHDN0
The SHDN input (pin 7) toggles between any two
power-management states. The Power Management
register defines each power-management state. In the
default state, SHDN = 1 shuts down the MAX19505 and
SHDN = 0 returns to full power.
______________________________________________________________________________________
17
MAX19505
Register address 0Ah is a special-function register.
Writing data 5Ah to register 0Ah initiates a register
reset. When this operation is executed, all control registers
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
In addition to power management, the HPS_SHDN1
and HPS_SHDN0 activate an A+B adder mode. In this
mode, the results from both channels are averaged.
The MUX_CH bit selects which bus the (A+B)/2 data is
presented.
Control Bits:
HPS_SHDN0
STBY_SHDN0
CHA_ON_SHDN0
CHB_ON_SHDN0
SHDN INPUT = 0*
HPS_SHDN1
STBY_SHDN1
CHA_ON_SHDN1
CHB_ON_SHDN1
SHDN INPUT = 1**
X
0
0
0
Complete power-down
0
0
0
1
Channel B active, channel A full power-down
0
0
1
0
Channel A active, channel B full power-down
0
X
1
1
Channels A and B active
0
1
0
0
Channels A and B in standby mode
0
1
0
1
Channel B active, channel A standby
0
1
1
0
Channel A active, channel B standby
1
1
0
0
Channels A and B in standby mode
1
X
X
1
Channels A and B active, output is averaged
1
X
1
X
Channels A and B active, output is averaged
*HPS_SHDN0, STBY_SHDN0, CHA_ON_SHDN0, and CHB_ON_SHDN0 are active when SHDN = 0.
**HPS_SHDN1, STBY_SHDN1, CHA_ON_SHDN1, and CHB_ON_SHDN1 are active when SHDN = 1.
X = Don’t care.
Note: When HPS_SHDN_ = 1 (A+B adder mode), CHA_ON and CHB_ON must BOTH equal 0 for power-down or standby.
Output Format (01h)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
0
0
0
BIT_ORDER_B
BIT_ORDER_A
MUX_CH
MUX
0
Bit 7, 6, 5
Set to 0 for proper operation
Bit 4
BIT_ORDER_B: Reverse CHB output bit order
0 = Defined data bus pin order (default)
1 = Reverse data bus pin order
Bit 3
BIT_ORDER_A: Reverse CHA output bit order
0 = Defined data bus pin order (default)
1 = Reverse data bus pin order
Bit 2
MUX_CH: Multiplexed data bus selection
0 = Multiplexed data output on CHA (CHA data presented first, followed by CHB data) (default)
1 = Multiplexed data output on CHB (CHB data presented first, followed by CHA data)
Bit 1
MUX: Digital output mode
0 = Dual data bus output mode (default)
1 = Single multiplexed data bus output mode
MUX_CH selects the output bus
Bit 0
18
Set to 0 for proper operation
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
X
X
X
X
PD_DOUT_1
PD_DOUT_0
DIS_DOR
DIS_DCLK
Bit 7–4
Don’t care
Bit 3, 2
PD_DOUT_1, PD_DOUT_0: Power-down digital output state control
00 = Digital output three state (default)
01 = Digital output low
10 = Digital output three state
11 = Digital output high
Bit 1
DIS_DOR: DOR driver disable
0 = DOR active (default)
1 = DOR disabled (three state)
Bit 0
DIS_DCLK: DCLK driver disable
0 = DCLK active (default)
1 = DCLK disabled (three state)
______________________________________________________________________________________
19
MAX19505
Digital Output Power Management (02h)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
Data/DCLK Timing (03h)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
DA_BYPASS
DLY_HALF_T
DCLKTIME_2
DCLKTIME_1
DCLKTIME_0
DTIME_2
DTIME_1
DTIME_0
Bit 7
DA_BYPASS: Data aligner bypass
0 = Nominal
1 = Bypasses data aligner delay line to minimize output data latency with respect to the input clock.
Rising clock to data transition is approximately 6ns with DTIME = 000b settings (default)
Bit 6
DLY_HALF_T: Data and DCLK delayed by T/2
0 = Normal, no delay (default)
1 = Delays data and DCLK outputs by T/2
Disabled in MUX data bus mode
Bit 5, 4, 3
DCLKTIME_2, DCLKTIME_1, DCLKTIME_0: DCLK timing adjust (controls both channels)
000 = Nominal (default)
001 = +T/16
010 = +2T/16
011 = +3T/16
100 = Reserved, do not use
101 = -1T/16
110 = -2T/16
111 = -3T/16
Bit 2, 1, 0
DTIME_2, DTIME_1, DTIME_0: Data timing adjust (controls both channels)
000 = Nominal (default)
001 = +T/16
010 = +2T/16
011 = +3T/16
100 = Reserved, do not use
101 = -1T/16
110 = -2T/16
111 = -3T/16
20
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
BIT 7
X
Bit 7, 6
Bit 5, 4, 3
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
X
CT_DCLK_2_A
CT_DCLK_1_A
CT_DCLK_0_A
CT_DATA_2_A
CT_DATA_1_A
CT_DATA_0_A
Don’t care
CT_DCLK_2_A, CT_DCLK_1_A, CT_DCLK_0_A: CHA DCLK termination control
000 = 50Ω (default)
001 = 75Ω
010 = 100Ω
011 = 150Ω
1xx = 300Ω
Bit 2, 1, 0
CT_DATA_2_A, CT_DATA_1_A, CT_DATA_0_A: CHA data output termination control
000 = 50Ω (default)
001 = 75Ω
010 = 100Ω
011 = 150Ω
1xx = 300Ω
CHB Data Output Termination Control (05h)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
X
X
CT_DCLK_2_B
CT_DCLK_1_B
CT_DCLK_0_B
CT_DATA_2_B
CT_DATA_1_B
CT_DATA_0_B
Bit 7, 6
Don’t care
Bit 5, 4, 3
CT_DCLK_2_B, CT_DCLK_1_B, CT_DCLK_0_B: CHB DCLK termination control
000 = 50Ω (default)
001 = 75Ω
010 = 100Ω
011 = 150Ω
1xx = 300Ω
Bit 2, 1, 0
CT_DATA_2_B, CT_DATA_1_B, CT_DATA_0_B: CHB data output termination control
000 = 50Ω (default)
001 = 75Ω
010 = 100Ω
011 = 150Ω
1xx = 300Ω
______________________________________________________________________________________
21
MAX19505
CHA Data Output Termination Control (04h)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
Clock Divide/Data Format/Test Pattern (06h)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
TEST_PATTERN
TEST_DATA
FORMAT_1
FORMAT_0
TERM_100
SYNC_MODE
DIV1
DIV0
Bit 7
TEST_PATTERN: Test pattern selection
0 = Ramps from 0 to 255 (offset binary) and repeats (subsequent formatting applied) (default)
1 = Data alternates between D[7:0] = 01010101, DOR = 1, and D[7:0] = 10101010,
DOR = 0 on both channels
Bit 6
TEST_DATA: Data test mode
0 = Normal data output (default)
1 = Outputs test data pattern
Bit 5, 4
FORMAT_1, FORMAT_0: Data numerical format
00 = Two’s complement (default)
01 = Offset binary
10 = Gray code
11 = Two’s complement
Bit 3
TERM_100: Select 100Ω clock input termination
0 = No termination (default)
1 = 100Ω termination across differential clock inputs
Bit 2
SYNC_MODE: Divider synchronization mode select
0 = Slip mode (Figure 11) (default)
1 = Edge mode (Figure 12)
Bit 1, 0
DIV1, DIV0: Input clock-divider select
00 = No divider (default)
01 = Divide-by-2
10 = Divide-by-4
11 = No divider
Reserved (07h)—Do not write to this register
22
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
CMI_SELF_B
CMI_ADJ_2_B
CMI_ADJ_1_B
CMI_ADJ_0_B
CMI_SELF_A
CMI_ADJ_2_A
CMI_ADJ_1_A
CMI_ADJ_0_A
Bit 7
CMI_SELF_B: CHB connect input common-mode to analog inputs
0 = Internal common-mode voltage is NOT applied to inputs (default)
1 = Internal common-mode voltage applied to analog inputs through 2kΩ resistors
Bit 6, 5, 4
CMI_ADJ_2_B, CMI_ADJ_1_B, CMI_ADJ_0_B: CHB input common-mode voltage adjustment
000 = 0.900V (default)
001 = 1.050V
010 = 1.200V
011 = 1.350V
100 = 0.900V
101 = 0.750V
110 = 0.600V
111 = 0.450V
Bit 3
CMI_SELF_A: CHA connect input common-mode to analog inputs
0 = Internal common-mode voltage is NOT applied to inputs (default)
1 = Internal common-mode voltage applied to analog inputs through 2kΩ resistors
Bit 2, 1, 0
CMI_ADJ_2_A, CMI_ADJ_1_A, CMI_ADJ_0_A: CHA input common-mode adjustment
000 = 0.900V (default)
001 = 1.050V
010 = 1.200V
011 = 1.350V
100 = 0.900V
101 = 0.750V
110 = 0.600V
111 = 0.450V
Software Reset (0Ah)
Bit 7–0
SWRESET: Write 5Ah to initiate software reset
______________________________________________________________________________________
23
MAX19505
Common Mode (08h)
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
Clock Inputs
100Ω
TERMINATION
(PROGRAMMABLE)
CLK+
The input clock interface provides for flexibility in the
requirements of the clock driver. The MAX19505
accepts a fully differential clock or single-ended logiclevel clock. For differential clock operation, connect a
differential clock to the CLK+ and CLK- inputs. In this
mode, the input common mode is established internally
to allow for AC-coupling. The differential clock signal
can also be DC-coupled if the common mode is constrained to the specified 1V to 1.4V clock input common-mode range. For single-ended operation, connect
CLK- to GND and drive the CLK+ input with a logiclevel signal. When the CLK- input is grounded (or
pulled below the threshold of the clock mode detection
comparator) the differential-to-single-ended conversion
stage is disabled and the logic-level inverter path is
activated.
2:1 MUX
AVDD
5kΩ
50Ω
10kΩ
20kΩ
50Ω
SELECT
THRESHOLD
5kΩ
GND
CLK-
SELF-BIAS TURNED OFF FOR
SINGLE-ENDED CLOCK
OR POWER-DOWN.
Clock Divider
The MAX19505 offers a clock-divider option. Enable
clock division either by setting DIV0 and DIV1 through
the serial interface; see the Clock Divide/Data
Figure 8. Simplified Clock Input Schematic
DUAL-BUS OUTPUT MODE
SAMPLING
INSTANT
SAMPLING
INSTANT
SAMPLING
INSTANT
tAD
SAMPLING
INSTANT
SAMPLING
INSTANT
IN_
SAMPLING
INSTANT
tCLK
SAMPLE ON RISING EDGE
n
tCL
tCH
n+1
n+2
n+4
n+3
n+5
SAMPLE CLOCK
tDD
DATA, DOR
n-10
n-9
tDC
n-8
n-7
n-6
n-5
tHOLD
tSETUP
DCLK
SAMPLE CLOCK IS THE DERIVED CLOCK FROM (CLK+ - CLK-)/CLOCK DIVIDER, IN_ = IN_+ - IN_-.
Figure 9. Dual-Bus Output Mode Timing
24
______________________________________________________________________________________
n-4
Dual-Channel, 8-Bit, 65Msps ADC
MAX19505
MUX OUTPUT MODE
SAMPLING
INSTANT
tAD
SAMPLING
INSTANT
SAMPLING
INSTANT
SAMPLING
INSTANT
SAMPLING
INSTANT
SAMPLING
INSTANT
IN_
tCLK
n
tCL
tCH
SAMPLE ON RISING EDGE
n+1
n+2
n+3
n+4
n+5
SAMPLE CLOCK
tCHA
tDD
DATA, DOR
tCHB
CHB
CHA
CHB
CHA
CHB
CHA
CHB
CHA
CHB
CHA
CHB
CHA
CHB
n-10
n-9
n-9
n-8
n-8
n-7
n-7
n-6
n-6
n-5
n-5
n-4
n-4
tDC
tHOLD
tDCH
tDCL
tSETUP
tHOLD
tSETUP
DCLK
SAMPLE CLOCK IS THE DERIVED CLOCK FROM (CLK+ - CLK-)/CLOCK DIVIDER, IN_ = IN_+ - IN_-.
MUX_CH (BIT 2, OUTPUT FORMAT 01h) DETERMINES THE OUTPUT BUS AND WHICH CHANNEL DATA IS PRESENTED.
Figure 10. Multiplexed Output Mode Timing
Format/Test Pattern register (06h) for clock-divider
options, or in parallel programming configuration (SPEN
= 1) by using the DIV input.
System Timing Requirements
Figures 9 and 10 depict the relationship between the
clock input and output, analog input, sampling event,
and data output. The MAX19505 samples on the rising
edge of the sampling clock. Output data is valid on the
next rising edge of DCLK after a nine-clock internal
latency. For applications where the clock is divided, the
sample clock is the divided internal clock derived from:
[(CLK+ - CLK-)/DIVIDER]
Synchronization
When using the clock divider, the phase of the internal
clock can be different than that of the FPGA, microcontroller, or other MAX19505s in the system. There are
two mechanisms to synchronize the internal clock: slip
synchronization and edge synchronization. Select the
synchronization mode using SYNC_MODE (bit 2) in the
Clock Divide/Data Format/Test Pattern register (06h)
and drive the SYNCIN input high to synchronize.
Slip Synchronization Mode, SYNC_MODE = 0
(default): On the third rising edge of the input clock
(CLK) after the rising edge of SYNC (provided set-up
and hold times are met), the divided output is forced to
skip a state transition (Figure 11).
Edge Synchronization Mode, SYNC_MODE = 1: On
the third rising edge of the input clock (CLK) after the
rising edge of SYNC (provided set-up and hold times
are met), the divided output is forced to state 0. A divided clock rising edge occurs on the fourth (/2 mode) or
fifth (/4 mode) rising edge of CLK, after a valid rising
edge of SYNC (Figure 12).
______________________________________________________________________________________
25
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
tHO
DIVIDE-BY-2 SLIP SYNCRONIZATION
tSUV
tSUV = SET-UP TIME FOR VALID CLOCK EDGE.
tHO = HOLD-OFF TIME FOR INVALID CLOCK EDGE.
SYNCIN
1
2
3
4
2x INPUT CLK
SLIP
(0)
(1)
(0)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
1x DIVIDED CLK
(STATE)
tHO
tSUV
DIVIDE-BY-4 SLIP SYNCHRONIZATION
SYNCIN
1
2
3
5
4
4x INPUT CLK
SLIP
(0)
(1)
(2)
(3)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(1)
(2)
(3)
(0)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(2)
(3)
(0)
(1)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(3)
(0)
(1)
(2)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
1x DIVIDED CLK
(STATE)
Figure 11. Slip Synchronization Mode
26
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
MAX19505
tHO
DIVIDE-BY-2 EDGE SYNCRONIZATION
tSUV
tSUV = SET-UP TIME FOR VALID CLOCK EDGE.
tHO = HOLD-OFF TIME FOR INVALID CLOCK EDGE.
SYNCIN
1
2
3
4
2x INPUT CLK
FORCE TO 0
(0)
(1)
(0)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
(0)
(1)
1x DIVIDED CLK
(STATE)
tHO
tSUV
DIVIDE-BY-4 EDGE SYNCHRONIZATION
SYNCIN
1
2
3
4
5
4x INPUT CLK
FORCE TO 0
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(1)
(2)
(3)
(0)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
(3)
(0)
(1)
(2)
(0)
(1)
(2)
(3)
(0)
(1)
(2)
(3)
(0)
(1)
1x DIVIDED CLK
(STATE)
Figure 12. Edge Synchronization Mode
______________________________________________________________________________________
27
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
Table 4. Data Timing Controls
DATA TIMING CONTROL
DESCRIPTION
DA_BYPASS
Data aligner bypass. When this control is active (high), data and DCLK delay is reduced by
approximately 2.6ns (relative to DA_BYPASS = 0).
DLY_HALF_T
When this control is active, data output is delayed by half clock period (T/2). This control does not
delay data output if MUX mode is active.
DTIME<2:0>
Allows adjustment of data output delay in T/16 increments, where T is the sample clock period.
Provides adjustment of DCLK delay in T/16 increments, where T is the sample clock period. When
DTIME and DCLKTIME are adjusted to the same setting, the rising edge of DCLK occurs T/8 prior
to data transitions.
DCLKTIME<2:0>
Table 5. Data Timing Control Default
Settings
DATA TIMING
CONTROL
DEFAULT
DESCRIPTION
DA_BYPASS
1
Data aligner disabled
DLY_HALF_T
0
No delay
DTIME<2:0>
000
No delay
DCLKTIME<2:0>
000
No delay
Digital Outputs
The MAX19505 features a dual CMOS, multiplexable,
reversible data bus. In parallel programming mode,
configure the data outputs (D0_–D7_) for offset binary,
two’s complement, or gray code using the FORMAT
input. Select multiplexed or dual-bus operation using the
OUTSEL input. See the Output Format register (01h) for
details on output formatting using the SPI interface. The
SPI interface offers additional flexibility where D0_–D7_
are reversed, so the LSB appears at D7_ and the MSB
at D0_. OVDD sets the output voltage; set OVDD
between 1.8V and 3.3V. The digital outputs feature programmable output impedance from 50Ω to 300Ω. Set
the output impedance for each bus using the CH_ Data
Output Termination Control registers (04h and 05h).
Programmable Data Timing
The MAX19505 provides programmable data timing control to allow for optimization of timing characteristics to
meet the system timing requirements. The timing adjustment feature also allows for ADC performance improvements by shifting the data output transition away from
the sampling instant. The data timing control signals are
summarized in Table 4. The default settings for timing
adjustment controls are given in Table 5. Many applications do not require adjustment from the default settings.
The effects of the data timing adjustment settings are
illustrated in Figures 13 and 14. The x axis is sampling
rate and the y axis is data delay in units of clock period.
28
The solid lines are the nominal data timing characteristics for the 14 available states of DTIME and
DLY_HALF_T. The heavy line represents the nominal
data timing characteristics for the default settings. Note
that the default timing adjustment setting for the
MAX19505 65Msps ADC results in an additional period
of data latency.
Tables 6 and 7 show the recommended timing control
settings versus sampling rate.
The nominal data timing characteristics versus sampling rate for these recommended timing adjustment
settings are shown in Figures 15 and 16.
When DA_BYPASS = 1, the DCLKTIME delay setting
must be equal to or less than the DTIME delay setting,
as shown in Table 8.
Power Management
The SHDN input (pin 7) toggles between any two powermanagement states. The Power Management register
(00h) defines each power-management state. In default
state, SHDN = 1 shuts down the MAX19505 and SHDN
= 0 returns to full power. Use of the SHDN input is not
required for power management. For either state of
SHDN, complete power-management flexibility is provided, including individual ADC channel power-management control, through the Power Management register
(00h). The available reduced-power modes are shutdown and standby. In standby mode, the reference and
duty-cycle equalizer circuits remain active for rapid
wake-up time. In standby mode, the externally applied
clock signal must remain active for the duty-cycle equalizer to remain locked. Typical wake-up time from standby mode is 15µs. In shutdown mode, all circuits are
turned off except for the reference circuit required for the
integrated self-sensing voltage regulator. If the regulator
is active, there is additional supply current associated
with the regulator circuit when the device is in shutdown.
Typical wake-up time from shutdown mode is 5ms,
which is dominated by the RC time constant on REFIO.
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
RECOMMENDED DATA TIMING
vs. SAMPLING RATE
2.0
2.0
DATA DELAY (T FRACTIONAL PERIOD)
DATA DELAY (T FRACTIONAL PERIOD)
OVDD = 1.8V
DA_BYPASS = 1
1.5
+11/16
+9/16
+7/16
+5/16
+3/16
+1/16
-1/16
-3/16
1.0
0.5
+10/16
+8/16
+6/16
+2/16
0
-2/16
0
OVDD = 1.8V
DA_BYPASS = 1
1.5
40
50
60
+11/16
+9/16
+7/16
+5/16
+3/16
+1/16
-1/16
-3/16
1.0
0.5
0
30
65
30
40
Figure 13. Default Data Timing (VOVDD = 1.8V)
2.0
OVDD = 3.3V
DA_BYPASS = 1
DATA DELAY (T FRACTIONAL PERIOD)
DATA DELAY (T FRACTIONAL PERIOD)
65
RECOMMENDED DATA TIMING
vs. SAMPLING RATE
2.0
1.5
1.0
+11/16
+9/16
+7/16
+5/16
+3/16
+1/16
-1/16
-3/16
0.5
40
60
+2/16
0
-2/16
Figure 15. Recommended Data Timing (VOVDD = 1.8V)
FACTORY DEFAULT NOMINAL DATA
TIMING vs. SAMPLING RATE
30
50
+10/16
+8/16
+6/16
SAMPLING RATE (Msps)
SAMPLING RATE (Msps)
0
MAX19505
FACTORY DEFAULT NOMINAL DATA
TIMING vs. SAMPLING RATE
50
60
+10/16
+8/16
+6/16
+2/16
0
-2/16
OVDD = 3.3V
DA_BYPASS = 1
1.5
1.0
0.5
0
65
+11/16
+9/16
+7/16
+5/16
+3/16
+1/16
-1/16
-3/16
30
40
50
60
+10/16
+8/16
+6/16
+2/16
0
-2/16
65
SAMPLING RATE (Msps)
SAMPLING RATE (Msps)
Figure 14. Default Data Timing (VOVDD = 3.3V)
Figure 16. Recommended Data Timing (VOVDD = 3.3V)
Table 6. Recommended Timing Adjustments (VOVDD = 1.8V)
SAMPLING RATE (Msps)
VOVDD = 1.8V
FROM
TO
DA_BYPASS
DLY_HALF_T
DTIME<2:0>
DCLKTIME<2:0>
30
45
1
0
000
000
45
55
1
0
101
101
55
65
1
0
110
010
______________________________________________________________________________________
29
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
Table 7. Recommended Timing Adjustments (VOVDD = 3.3V)
SAMPLING RATE (Msps)
VOVDD = 3.3V
FROM
TO
DA_BYPASS
DLY_HALF_T
DTIME<2:0>
DCLKTIME<2:0>
30
63
1
0
000
000
63
65
1
0
101
101
Table 8. Allowed Settings of DCLKTIME and DTIME for DA_BYPASS = 1
DTIME<2:0>
ALLOWED DCLKTIME<2:0> SETTINGS
111 (-3T/16)
111 (-3T/16)
110 (-2T/16)
110 (-2T/16); 111 (-3T/16)
101 (-1T/16)
101 (-1T/16); 110 (-2T/16); 111 (-3T/16)
000 (nominal)
000 (nominal); 101 (-1T/16); 110 (-2T/16); 111 (-3T/16)
001 (+1T/16)
001 (+1T/16); 000 (nominal); 101 (-1T/16); 110 (-2T/16); 111 (-3T/16)
010 (+2T/16)
010 (+2T/16); 001 (+1T/16); 000 (nominal); 101 (-1T/16); 110 (-2T/16); 111 (-3T/16)
011 (+3T/16)
011 (+3T/16); 010 (+2T/16); 001 (+1T/16); 000 (nominal); 101 (-1T/16); 110 (-2T/16); 111 (-3T/16)
Table 9. Reset Methods
RESET MODE
DESCRIPTION
Power-On Reset
Upon power-up (AVDD supply voltage and clock signal applied), the POR (power-on-reset) circuit initiates a
register reset.
Software Reset
Write data 5Ah to address 0Ah to initiate register reset.
Hardware Reset A register reset is initiated by the falling edge on the SHDN pin when SPEN is high.
Integrated Voltage Regulator
Power-On and Reset
The MAX19505 includes an integrated self-sensing linear voltage regulator on the analog supply (AVDD). See
Figure 17. When the applied voltage on AVDD is below
2V, the voltage regulator is bypassed, and the core
analog circuitry operates from the externally applied
voltage. If the applied voltage on AVDD is higher than
2V, the regulator bypass switches off, and voltage regulator mode is enabled. When in voltage regulation
mode, the internal-core analog circuitry operates from a
stable 1.8V supply voltage provided by the regulator.
The regulator provides an output voltage of 1.8V over a
2.3V to 3.5V AVDD input-voltage range. Since the
power-supply current is constant over this voltage
range, analog power dissipation is proportional to the
applied voltage.
The user-programmable register default settings and
other factory-programmed settings are stored in nonvolatile memory. Upon device power-up, these values are
loaded into the control registers. This operation occurs
after application of supply voltage to AVDD and application of an input clock signal. The register values are
retained as long as AVDD is applied. While AVDD is
applied, the registers can be reset, which overwrites all
user-programmed registers with the default values. This
reset operation can be initiated by software command
through the serial-port interface or by hardware control
using the SPEN and SHDN inputs. The reset time is proportional to the ADC clock period and requires 130µs at
65Msps. Table 9 summarizes the reset methods.
30
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
MAX19505
AVDD
(PINS 1, 12, 13, 48)
REGULATOR
IN
2.3V TO 3.5V
OUT
1.8V
ENABLE
INTERNAL
ANALOG
CIRCUITS
REFERENCE
GND
Figure 17. Integrated Voltage Regulator
Applications Information
Analog Inputs
IN_+
0.1µF
1
VIN
6
36.5Ω
0.5%
MAX19505
T1
N.C.
5
2
Transformer-Coupled Differential Analog Input
The MAX19505 provides better SFDR and THD with
fully differential input signals than a single-ended input
drive. In differential input mode, even-order harmonics
are lower as both inputs are balanced, and each of the
ADC inputs only require half the signal swing compared
to single-ended input mode.
An RF transformer (Figure 18) provides an excellent
solution for converting a single-ended signal to a fully
differential signal. Connecting the center tap of the
transformer to CM_ provides a common-mode voltage.
The transformer shown has an impedance ratio of 1:1.4.
Alternatively, a different step-up transformer can be
selected to reduce the drive requirements. A reduced
signal swing from the input driver can also improve the
overall distortion. The configuration of Figure 18 is good
for frequencies up to Nyquist (fCLK/2).
CM_
N.C.
0.1µF
3
4
MINI-CIRCUITS 36.5Ω
0.5%
ADT1-1WT
IN_-
Figure 18. Transformer-Coupled Input Drive for Input
Frequencies Up to Nyquist
IN_+
0.1µF
1
VIN
N.C.
5
T1
6
2
1
75Ω
0.5%
N.C.
N.C.
5
T2
110Ω
0.5%
6
MAX19505
2
CM_
N.C.
0.1µF
3
4
MINI-CIRCUITS
ADT1-1WT
75Ω
0.5%
3
4
MINI-CIRCUITS
ADT1-1WT
110Ω
0.5%
IN_-
Figure 19. Transformer-Coupled Input Drive for Input Frequencies Beyond Nyquist
______________________________________________________________________________________
31
MAX19505
Dual-Channel, 8-Bit, 65Msps ADC
VIN
0.1µF
0.01µF
IN_+
MAX4108
CLK+
0.1µF
CLKIN
100Ω
49.9Ω
MAX19505
MAX19505
CM_
100Ω
0.1µF
49.9Ω
0.01µF
CLK-
IN_0.1µF
Figure 20. Single-Ended, AC-Coupled Input Drive
Figure 21. Single-Ended-to-Differential Clock Input
The circuit of Figure 19 also converts a single-ended
input signal to a fully differential signal. Figure 19 utilizes an additional transformer to improve the commonmode rejection, allowing high-frequency signals
beyond the Nyquist frequency. A set of 75Ω and 110Ω
termination resistors provide an equivalent 50Ω termination to the signal source. The second set of termination resistors connect to CM_ providing the correct
input common-mode voltage.
produce the highest level of signal integrity. Route highspeed digital signal traces away from the sensitive analog traces of either channel. Make sure to isolate the
analog input lines to each respective converter to minimize channel-to-channel crosstalk. Keep all signal lines
short and free of 90° turns.
Single-Ended AC-Coupled Input Signal
Figure 20 shows a single-ended, AC-coupled input
application. The MAX4108 provides high speed, high
bandwidth, low noise, and low distortion to maintain the
input signal integrity. Bias voltage is applied to the
inputs through internal 2kΩ resistors. See Common
Mode register 08h for further details.
INL is the deviation of the measured transfer function
from a best-fit straight line. Worst-case deviation is
defined as INL.
DC-Coupled Input
The MAX19505’s wide common-mode voltage range
(0.4V to 1.4V) allows DC-coupled signals. Ensure that the
common-mode voltage remains between 0.4V and 1.4V.
Definitions
Integral Nonlinearity (INL)
Differential Nonlinearity (DNL)
DNL is the difference between the measured transfer
function step width and the ideal value of 1 LSB. A DNL
error specification of less than 1 LSB guarantees no
missing codes and a monotonic transfer function. DNL
deviations are measured at each step of the transfer
function and the worst-case deviation is defined as DNL.
Offset Error
Grounding, Bypassing, and
Board-Layout Considerations
Offset error is a parameter that indicates how well the
actual transfer function matches the ideal transfer function at midscale. Ideally, the midscale transition occurs
at 0.5 LSB above midscale. The offset error is the
amount of deviation between the measured midscale
transition point and the ideal midscale transition point.
The MAX19505 requires high-speed board-layout
design techniques. Locate all bypass capacitors as
close as possible to the device, preferably on the same
side as the ADC, using surface-mount devices for minimum inductance. Bypass AVDD, OVDD, REFIO, CMA,
and CMB with 0.1µF ceramic capacitors to GND.
Multilayer boards with ground and power planes
Gain error is a figure of merit that indicates how well the
slope of the measured transfer function matches the
slope of the ideal transfer function based on the specified full-scale input-voltage range. The gain error is
defined as the relative error of the measured transfer
function and is expressed as a percentage.
Clock Input
Figure 21 shows a single-ended-to-differential clock
input converting circuit.
32
Gain Error
______________________________________________________________________________________
Dual-Channel, 8-Bit, 65Msps ADC
Single-Tone Spurious-Free Dynamic Range
(SFDR1 and SFDR2)
SFDR is the ratio expressed in decibels of the RMS
amplitude of the fundamental (maximum signal component) to the RMS amplitude of the next largest spurious
component, excluding DC offset. SFDR1 reflects the
spurious performance based on worst 2nd-order or
3rd-order harmonic distortion. SFDR2 is defined by the
worst spurious component excluding 2nd- and 3rdorder harmonics and DC offset.
Signal-to-Noise Ratio (SNR)
Total Harmonic Distortion (THD)
For a waveform perfectly reconstructed from digital
samples, the theoretical maximum SNR is the ratio of
the full-scale analog input (RMS value) to the RMS
quantization error (residual error). The ideal, theoretical
minimum analog-to-digital noise is caused by quantization error only and results directly from the ADC’s resolution (N bits):
SNR[max] = 6.02 x N + 1.76
In reality, there are other noise sources besides quantization noise (e.g., thermal noise, reference noise, clock
jitter, etc.). SNR is computed by taking the ratio of the
RMS signal to the RMS noise. RMS noise includes all
spectral components to the Nyquist frequency excluding the fundamental, the first six harmonics (HD2–HD7),
and the DC offset.
THD is the ratio of the RMS of the first six harmonics of
the input signal to the fundamental itself. This is
expressed as:
⎛ SIGNALRMS ⎞
SNR = 20 × log ⎜
⎟
⎝ NOISERMS ⎠
⎞
⎟
⎟
⎠
where V1 is the fundamental amplitude and V2–V7 are
the amplitudes of the 2nd-order through 7th-order harmonics (HD2–HD7).
Third-Order Intermodulation (IM3)
IM3 is the total power of the third-order intermodulation
products to the Nyquist frequency relative to the total
input power of the two input tones fIN1 and fIN2. The
individual input tone levels are at -7dBFS. The thirdorder intermodulation products are: 2 x fIN1 - fIN2, 2 x
fIN2 - fIN1, 2 x fIN1 + fIN2, 2 x fIN2 + fIN1.
Aperture Delay
Signal-to-Noise and Distortion (SINAD)
SINAD is computed by taking the ratio of the RMS signal to the RMS noise plus the RMS distortion. RMS
noise includes all spectral components to the Nyquist
frequency excluding the fundamental, the first six harmonics (HD2–HD7), and the DC offset. RMS distortion
includes the first six harmonics (HD2–HD7).
⎛
SIGNALRMS
SINAD = 20 × log ⎜
⎜
2
2
⎝ NOISERMS + DISTORTIONRMS
⎛
V22 + V32 + V4 2 + V52 + V62 + V72
THD = 20 × log ⎜
⎜
V1
⎝
⎞
⎟
⎟
⎠
The input signal is sampled on the rising edge of the
sampling clock. There is a small delay between the rising edge of the sampling clock and the actual sampling
instant, which is defined as aperture delay (tAD).
Aperture Jitter
Aperture jitter (tAJ) is defined as the sample-to-sample
time variation in the aperture delay.
Overdrive Recovery Time
Overdrive recovery time is the time required for the
ADC to recover from an input transient that exceeds the
full-scale limits. The specified overdrive recovery time is
measured with an input transient that exceeds the fullscale limits by ±10%.
Process Information
PROCESS: CMOS
______________________________________________________________________________________
33
MAX19505
Small-Signal Noise Floor (SSNF)
SSNF is the integrated noise and distortion power in the
Nyquist band for small-signal inputs. The DC offset is
excluded from this noise calculation. For this converter, a
small signal is defined as a single tone with an amplitude
less than -35dBFS. This parameter captures the thermal
and quantization noise characteristics of the converter
and can be used to help calculate the overall noise figure
of a receive channel. Refer to www.maxim-ic.com for
application notes on Thermal + Quantization Noise Floor.
Dual-Channel, 8-Bit, 65Msps ADC
OVDD
D2B
D3B
D4B
D5B
D6B
D7B
I.C.
I.C.
D0A
OVDD
TOP VIEW
D1A
MAX19505
Pin Configuration
36 35 34 33 32 31 30 29 28 27 26 25
D2A
37
24
D1B
D3A
38
23
D0B
D4A
39
22
I.C.
D5A
40
21
I.C.
D6A
41
20
DCLKB
D7A
42
19
DORB
MAX19505
DORA
43
18
GND
DCLKA
44
17
GND
SDIN/FORMAT
45
16
CLK-
15
CLK+
14
SYNC
13
AVDD
3
4
5
6
7
8
9
10 11 12
SPEN
REFIO
SHDN
I.C.
INB+
INB-
AVDD
2
CMB
1
INA-
AVDD
48
*EP
+
INA+
47
CMA
46
AVDD
SCLK/DIV
CS/OUTSEL
*EXPOSED PAD
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYGREAT PE
PACKAGE CODE
DOCUMENT NO.
48 TQFN-EP
T4877-4
21-0144
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.