Maxim MAX11047 4-/6-/8-channel, 16-bit, simultaneous-sampling adc Datasheet

19-5106; Rev 0; 12/09
KIT
ATION
EVALU
E
L
B
A
AVAIL
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
4
6
MAX11049ETN+
56 TQFN-EP*
8
Note: All devices are specified over the -40°C to +85°C operating
temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
DB4
DB3
DB0
CH1
RD
DVDD 51
20 DVDD
CS
WR 52
19 SHDN
CONVST
CS 53
18 CONVST
SHDN
RD 54
RDC
DB14 56
DGND
17 EOC
*EP
+
16 DB0
15 DB1
1
2
3
4
5
6
7
8
9
10 11 12 13 14
DB2
DB15 55
DB3
EOC
DB4
EXT REF
21 DGND
DGND 50
DB8
REFIO
REF
BUF
22 RDC
WR
DB9
BANDGAP
REFERENCE
23 AGNDS
MAX11047
MAX11048
MAX11049
DB10
INT REF
AVDD
24 AVDD
AGNDS 48
DB11
INTERFACE
AND
CONTROL
AGND
25 AGND
AVDD 47
DB12
AGND
MAX11047
MAX11048
MAX11049
CH2
26 CH0
AGND 46
DB13
AGNDS
AGNDS
27 AGNDS
CH7 45
RDC 49
CONFIGURATION
REGISTERS
CH3
28 RDC
AGNDS 44
DB5
16-BIT ADC
42 41 40 39 38 37 36 35 34 33 32 31 30 29
RDC 43
DB6
S/H
16-BIT ADC
DB7
CLAMP
S/H
RDC
TOP VIEW
REFIO
Pin Configuration
DVDD
CLAMP
BIDIRECTIONAL DRIVERS
CH7
56 TQFN-EP*
56 TQFN-EP*
DB15
8 x 16-BIT REGISTERS
CH0
DVDD
MAX11047ETN+
DGND
AVDD
CHANNELS
MAX11048ETN+
CH4
Functional Diagram
PIN-PACKAGE
AGNDS
Power-Grid Protection
Multiphase Motor Control
Vibration and Waveform Analysis
PART
CH5
Automatic Test Equipment
Power-Factor Monitoring and Correction
Ordering Information
AGND
Applications
AVDD
The MAX11047/MAX11048/MAX11049 operate with a
4.75V to 5.25V analog supply and a separate flexible 2.7V
to 5.25V digital supply for interfacing with the host without a
level shifter. The MAX11047/MAX11048/MAX11049
are available in a 56-pin TQFN package and operate over
the extended -40°C to +85°C temperature range.
4-/6-/8-Channel 16-Bit ADC
Single Analog and Digital Supply
High-Impedance Inputs Up to 1GΩ
On-Chip T/H Circuit for Each Channel
Fast 3µs Conversion Time
High Throughput: 250ksps for All 8 Channels
16-Bit, High-Speed, Parallel Interface
Internal Clocked Conversions
10ns Aperture Delay
100ps Channel-to-Channel T/H Matching
Low Drift, Accurate 4.096V Internal Reference
Providing an Input Range of 0 to 5V
o External Reference Range of 3.0V to 4.25V,
Allowing Full-Scale Input Ranges of +3.7V to
+5.2V
o 56-Pin TQFN Package (8mm x 8mm)
o Evaluation Kit Available
CH6
The MAX11047/MAX11048/MAX11049 16-bit ADCs
offer 4, 6, or 8 independent input channels. Featuring
independent track and hold (T/H) and SAR circuitry,
these parts provide simultaneous sampling at 250ksps
for each channel.
The MAX11047/MAX11048/MAX11049 accept a 0 to
+5V input. All inputs are overrange protected with internal ±20mA input clamps providing overrange protection with a simple external resistor. Other features
include a 4MHz T/H input bandwidth, internal clock,
and internal or external reference. A 20MHz, 16-bit,
bidirectional, parallel interface provides the conversion
results and accepts digital configuration inputs.
Features
o
o
o
o
o
o
o
o
o
o
o
TQFN
____________________________ 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
MAX11047/MAX11048/MAX11049
General Description
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
ABSOLUTE MAXIMUM RATINGS
AVDD to AGND ........................................................-0.3V to +6V
DVDD to AGND and DGND .....................................-0.3V to +6V
DGND to AGND.....................................................-0.3V to +0.3V
AGNDS to AGND...................................................-0.3V to +0.3V
CH0–CH7 to AGND ...............................................-2.5V to +7.5V
REFIO, RDC to AGND ..................................-0.3V to the lower of
(AVDD + 0.3V) and +6V
EOC, WR, RD, CS, CONVST to AGND.........-0.3V to the lower of
(DVDD + 0.3V) and +6V
DB0–DB15 to AGND ....................................-0.3V to the lower of
(DVDD + 0.3V) and +6V
Maximum Current into Any Pin Except AVDD, DVDD, AGND,
DGND ...........................................................................±50mA
Continuous Power Dissipation (TA = +70°C)
56-Pin TQFN (derated 36mW/°C above +70°C) ........2222mW
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
(AVDD = 4.75V to 5.25V, DVDD = +2.7V to 5.25V, VAGNDS = VAGND = VDGND = 0V, VREFIO = internal reference, CRDC = 4 x 33μF,
CREFIO = 0.1μF, CAVDD = 4 x 0.1μF || 10μF, CDVDD = 3 x 0.1μF || 10μF; all digital inputs at DVDD or DGND, unless otherwise noted.
TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
-2
±0.6
+2
LSB
> -1
±0.6
< +1.3
LSB
STATIC PERFORMANCE (Note 1)
Resolution
Integral Nonlinearity
N
INL
16
(Note 2)
Integral Nonlinearity
INL
(Note 3)
Differential Nonlinearity
DNL
(Note 2)
Differential Nonlinearity
DNL
(Note 3)
No Missing Codes
Bits
±0.8
LSB
±0.7
LSB
16
Bits
±0.002
Offset Error
Offset Temperature Coefficient
±0.01
±2.4
%FSR
μV/°C
Channel Offset Matching
±0.01
%FSR
Gain Error
±0.03
%FSR
Positive Full-Scale Error
±0.02
%FSR
Positive Full-Scale Error Matching
Channel Gain-Error Matching
Between all channels
Gain Temperature Coefficient
±0.02
%FSR
±0.03
%FSR
±0.8
ppm/°C
DYNAMIC PERFORMANCE (Note 4)
Signal-to-Noise Ratio
SNR
fIN = 10kHz, full-scale input
91
92.3
dB
Signal-to-Noise and Distortion Ratio
SINAD
fIN = 10kHz, full-scale input
90.5
92
dB
Spurious-Free Dynamic Range
SFDR
fIN = 10kHz, full-scale input
95
Total Harmonic Distortion
THD
fIN = 10kHz, full-scale input
-105
-95
dB
fIN = 60Hz, full scale and ground on
adjacent channel (Note 5)
-126
-100
dB
0
1.22 x
VREFIO
V
-1
+1
μA
Channel-to-Channel Crosstalk
106
dB
ANALOG INPUTS (CH0–CH7)
Input Voltage Range
Input Leakage Current
2
(Note 6)
_______________________________________________________________________________________
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
(AVDD = 4.75V to 5.25V, DVDD = +2.7V to 5.25V, VAGNDS = VAGND = VDGND = 0V, VREFIO = internal reference, CRDC = 4 x 33μF,
CREFIO = 0.1μF, CAVDD = 4 x 0.1μF || 10μF, CDVDD = 3 x 0.1μF || 10μF; all digital inputs at DVDD or DGND, unless otherwise noted.
TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
Input Capacitance
TYP
MAX
UNITS
+20
mA
250
ksps
15
Input-Clamp Protection Current
Each input simultaneously
-20
pF
TRACK AND HOLD
Throughput Rate
Per channel, 8 channels in 4μs
Acquisition Time
tACQ
1
-3dB point
Full-Power Bandwidth
μs
4
-0.1dB point
MHz
> 0.2
Aperture Delay
10
ns
Aperture-Delay Matching
100
ps
Aperture Jitter
50
psRMS
INTERNAL REFERENCE
REFIO Voltage
VREF
4.073
REFIO Temperature Coefficient
4.096
4.119
±5
V
ppm/°C
EXTERNAL REFERENCE
Input Current
REF Voltage Input Range
VREF
-10
+10
μA
3.00
4.25
V
REF Input Capacitance
15
pF
DIGITAL INPUTS (DB0–DB15, RD, WR, CS, CONVST)
Input-Voltage High
VIH
VDVDD = 2.7V to 5.25V
Input-Voltage Low
VIL
VDVDD = 2.7V to 5.25V
Input Capacitance
CIN
Input Current
IIN
VIN = 0 or VDVDD
Output-Voltage High
VOH
ISOURCE = 1.2mA
Output-Voltage Low
VOL
2
V
0.8
10
V
pF
±10
μA
DIGITAL OUTPUTS (DB0–DB15, EOC)
VDVDD 0.4
V
ISINK = 1mA
0.4
V
Three-State Leakage Current
DB0–DB15, VRD ≥ VIH or VCS ≥ VIH
10
μA
Three-State Output Capacitance
DB0–DB15, VRD ≥ VIH or VCS ≥ VIH
15
pF
POWER SUPPLIES (MAX11047)
Analog Supply Voltage
AVDD
4.75
5.25
V
Digital Supply Voltage
DVDD
2.70
5.25
V
Analog Supply Current
IAVDD
Digital Supply Current
IDVDD
Shutdown Current
Shutdown Current
32
mA
VDVDD = 3.3V (Note 7)
5.7
mA
For DVDD
10
μA
For AVDD
Power-Supply Rejection Ratio
PSRR
VAVDD = 4.9V to 5.1V (Note 8)
12
±0.5
μA
LSB
_______________________________________________________________________________________
3
MAX11047/MAX11048/MAX11049
ELECTRICAL CHARACTERISTICS (continued)
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = 4.75V to 5.25V, DVDD = +2.7V to 5.25V, VAGNDS = VAGND = VDGND = 0V, VREFIO = internal reference, CRDC = 4 x 33μF,
CREFIO = 0.1μF, CAVDD = 4 x 0.1μF || 10μF, CDVDD = 3 x 0.1μF || 10μF; all digital inputs at DVDD or DGND, unless otherwise noted.
TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
POWER SUPPLIES (MAX11048)
Analog Supply Voltage
AVDD
4.75
5.25
Digital Supply Voltage
DVDD
2.70
5.25
V
Analog Supply Current
IAVDD
36
mA
Digital Supply Current
IDVDD
VDVDD = 3.3V (Note 7)
6.5
mA
Shutdown Current
For DVDD
10
μA
Shutdown Current
For AVDD
12
Power-Supply Rejection Ratio
PSRR
±0.5
VAVDD = 4.9V to 5.1V (Note 8)
μA
LSB
POWER SUPPLIES (MAX11049)
Analog Supply Voltage
AVDD
4.75
5.25
Digital Supply Voltage
DVDD
2.70
5.25
V
Analog Supply Current
IAVDD
40
mA
Digital Supply Current
IDVDD
VDVDD = 3.3V (Note 7)
7.3
mA
Shutdown Current
For DVDD
10
μA
Shutdown Current
For AVDD
12
Power-Supply Rejection Ratio
PSRR
VAVDD = 4.9V to 5.1V (Note 8)
CONVST Rise to EOC Fall
tCON
Conversion time (Note 9)
Acquisition Time
tACQ
±0.5
V
μA
LSB
TIMING CHARACTERISTICS (Note 7)
3
1
μs
μs
CS Rise to CONVST Rise
tQ
CONVST Rise to EOC Rise
t0
EOC Fall to CONVST Fall
t1
CONVST mode B0 = 0 only (Note 10)
0
ns
CONVST Low Time
t2
CONVST mode B0 = 1 only
20
ns
ns
Sample quiet time (Note 9)
500
ns
65
140
ns
CS Fall to WR Fall
t3
0
WR Low Time
t4
20
ns
CS Rise to WR Rise
t5
0
ns
Input Data Setup Time
t6
10
ns
Input Data Hold Time
t7
0
ns
CS Fall to RD Fall
t8
0
ns
RD Low Time
t9
30
ns
RD Rise to CS Rise
t10
0
ns
RD High Time
t11
10
ns
RD Fall to Data Valid
t12
RD Rise to Data Hold Time
t13
4
35
(Note 10)
5
_______________________________________________________________________________________
ns
ns
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
(AVDD = 4.75V to 5.25V, DVDD = +2.7V to 5.25V, VAGNDS = VAGND = VDGND = 0V, VREFIO = internal reference, CRDC = 4 x 33μF,
CREFIO = 0.1μF, CAVDD = 4 x 0.1μF || 10μF, CDVDD = 3 x 0.1μF || 10μF; all digital inputs at DVDD or DGND, unless otherwise noted.
TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
Note 1: See the Definitions section at the end of the data sheet.
Note 2: Guaranteed at 5V ≤ VAVDD ≤ 5.25V for+25°C ≤ TA ≤ +85°C. See the Input Range and Protection section and Typical
Operating Characteristics.
Note 3: TA = -40°C.
Note 4: Dynamic performance is guaranteed at AVDD = 5.0V to 5.25V. See the Input Range and Protection section and the Typical
Operating Characteristics.
Note 5: Tested with alternating channels modulated at full scale and ground.
Note 6: See the Input Range and Protection section.
Note 7: CLOAD= 30pF on DB0–DB15 and EOC. Inputs (CH0–CH7) alternate between full scale and zero scale. fCONV = 250ksps. All
data is read out.
Note 8: Defined as the change in positive full scale caused by a ±2% variation in the nominal supply voltage.
Note 9: It is recommended that RD, WR, and CS are kept high for the quiet time (tQ) and conversion time (tCON).
Note 10: Guaranteed by design.
Typical Operating Characteristics
(AVDD = 5V, DVDD = 3.3V, TA = +25°C, fSAMPLE = 250ksps, internal reference, unless otherwise noted.)
DIFFERENTIAL NONLINEARITY (DNL)
vs. CODE
0.2
0.2
DNL (LSB)
0.4
0.4
0
-0.4
-0.6
MAX DNL
0
-1.5
65536
57344
49152
40960
24576
32768
MIN INL
4.75
4.85
5.05
5.15
5.25
VAVDD (V)
TA = +25°C
fSAMPLE = 250ksps
35
33
VAVDD = 5.0V
VDVDD = 3.3V
fSAMPLE = 250ksps
VRDC = 4.096V
31
29
-0.5
MIN INL
4.95
MAX11049
STATIC
MAX11049
CONVERTING
MAX11048
STATIC
MAX11048
CONVERTING
MAX11047 CONVERTING
27
MIN DNL
MAX11047 toc05
37
IAVDD (mA)
0.5
VDVDD = 3.3V
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
ANALOG SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX11047 toc04
1.0
MAX11047 toc03
MIN DNL
-0.5
OUTPUT CODE (DECIMAL)
MAX INL
-1.0
MAX DNL
0
-1.0
INL AND DNL vs. TEMPERATURE
1.5
0.5
-0.8
-1.0
65536
57344
32768
24576
8192
-0.2
OUTPUT CODE (DECIMAL)
INL AND DNL (LSB)
0
16384
-0.8
-1.0
49152
-0.6
40960
VAVDD = 5.0V
VDVDD = 3.3V
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
-0.4
MAX INL
1.0
0
16384
-0.2
1.5
INL AND DNL (LSB)
0.6
8192
0.6
VAVDD = 5.0V, VDVDD = 3.3V, fSAMPLE = 250ksps
TA = +25°C, VRDC = 4.096V
0.8
0
0.8
INL (LSB)
1.0
MAX11047 toc01
1.0
INL AND DNL
vs. ANALOG SUPPLY VOLTAGE
MAX11047 toc02
INTEGRAL NONLINEARITY (INL)
vs. CODE
MAX11047 STATIC
25
-1.5
-40
-15
10
35
TEMPERATURE (°C)
60
85
4.75
4.85
4.95
5.05
5.15
5.25
VAVDD (V)
_______________________________________________________________________________________
5
MAX11047/MAX11048/MAX11049
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics (continued)
(AVDD = 5V, DVDD = 3.3V, TA = +25°C, fSAMPLE = 250ksps, internal reference, unless otherwise noted.)
DIGITAL SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX11047 CONVERTING
2
10
60
MAX11047/MAX11048/
MAX11049 STATIC
0
2.75
85
VDVDD = 3.3V
fSAMPLE = 250ksps
CDBxx = 15pF
1.2
3.25
3.75
4.25
4.75
5.25
-40
-15
10
35
60
VDVDD (V)
TEMPERATURE (°C)
ANALOG AND DIGITAL SHUTDOWN
CURRENT vs. TEMPERATURE
ANALOG AND DIGITAL SHUTDOWN
CURRENT vs. SUPPLY VOLTAGE
INTERNAL REFERENCE VOLTAGES
vs. SUPPLY VOLTAGE
4
3
2
VAVDD = 5.0V
VDVDD = 3.3V
IDVDD
5
10
4
35
60
VRDC
4.09505
2
4.09500
IDVDD
VREFIO
4.09495
0
85
TA = +25°C
4.09515
4.09510
3
1
0
-15
IAVDD
TA = +25°C
85
4.09520
MAX11047 toc9a
IAVDD
2.75
3.25
3.75
4.25
4.75
5.25
4.09490
4.75
4.85
4.95
5.05
5.15
5.25
TEMPERATURE (°C)
AVDD OR VDVDD (V)
VAVDD (V)
INTERNAL REFERENCE VOLTAGE
vs. TEMPERATURE
OFFSET ERROR AND OFFSET ERROR
MATCHING vs. SUPPLY VOLTAGE
OFFSET ERROR AND OFFSET ERROR
MATCHING vs. TEMPERATURE
VAVDD = 5.0V
4.108
4.104
0.010
0.006
ERRORS (%FS)
UPPER TYPICAL LIMIT
TA = +25°C
4.100
4.096
4.092
OFFSET ERROR MATCHING
0.002
-0.002
VAVDD = 5.0V
VREFIO = 4.096V
0.006
OFFSET ERROR MATCHING
0.002
-0.002
OFFSET ERROR
OFFSET ERROR
LOWER TYPICAL LIMIT
4.088
0.010
ERRORS (%FS)
4.112
MAX11047 toc11
-40
MAX11047/MAX11048/
MAX11049 STATIC
MAX11047
CONVERTING
TEMPERATURE (°C)
5
1
2.4
0
35
MAX11048
CONVERTING
MAX11047
CONVERTING
3.6
MAX11047 toc13
-15
SHUTDOWN CURRENT (µA)
-40
MAX11048
CONVERTING
MAX11047 toc10
4
MAX11047 STATIC
23
4.8
6
MAX11048 STATIC
MAX11049
CONVERTING
6.0
VREF (V)
27
SHUTDOWN CURRENT (µA)
IDVDD (mA)
MAX11048 CONVERTING
MAX11047 toc09
IAVDD (mA)
8
MAX11049 STATIC
31
MAX11047 toc08
TA = +25°C
fSAMPLE = 250ksps
CDBxx = 15pF
10
7.2
IDVDD (mA)
MAX11049 CONVERTING
MAX11049
CONVERTING
MAX11047 toc12
35
12
MAX11047 toc06
VAVDD = 5.0V
fSAMPLE = 250ksps
DIGITAL SUPPLY CURRENT
vs. TEMPERATURE
MAX11047 toc07
ANALOG SUPPLY CURRENT
vs. TEMPERATURE
VREFIO (V)
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
-0.006
-0.006
4.084
4.080
-0.010
-40
-15
10
35
TEMPERATURE (°C)
6
60
85
4.75
4.85
4.95
5.05
VAVDD (V)
5.15
5.25
-0.010
-40
-15
10
35
TEMPERATURE (°C)
_______________________________________________________________________________________
60
85
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
GAIN ERROR AND GAIN ERROR
MATCHING vs. TEMPERATURE
ERRORS (%FS)
0.002
-0.002
GAIN-ERROR MATCHING
GAIN ERROR
0.002
GAIN-ERROR MATCHING
-0.002
fIN = 10kHz
fSAMPLE = 250ksps
TA = +25°C
VAVDD = 5.0V
-20
-40
MAX11047 toc16
VAVDD = 5.0V
0.006
ERRORS (%FS)
GAIN ERROR
FFT PLOT
0
MAGNITUDE (dB)
TA = +25°C
0.006
0.010
MAX11047 toc14
0.010
MAX11047 toc15
GAIN ERROR AND GAIN ERROR
MATCHING vs. SUPPLY VOLTAGE
-60
-80
-100
-0.006
-0.006
4.85
4.95
5.05
5.15
5.25
60
85
0
25
50
75
100
TWO-TONE IMD PLOT
TOTAL HARMONIC DISTORTION
vs. TEMPERATURE
SNR
SNR AND SINAD (dB)
92.5
9.2
10.0
10.8
-106.0
91.5
VAVDD = 5.0V
fIN = 10kHz
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
VIN = -0.025dB FROM FS
91.0
90.0
12.4
11.6
-40
FREQUENCY (kHz)
-15
10
SINAD
-106.5
-107.0
-107.5
35
60
-108.0
85
-40
-15
60
85
THD vs. ANALOG SUPPLY VOLTAGE
MAX11047 toc21
SNR
92.5
35
-105.0
MAX11047 toc20
93.0
10
TEMPERATURE (°C)
TEMPERATURE (°C)
SNR AND SINAD
vs. ANALOG SUPPLY VOLTAGE
-105.5
-106.0
91.5
THD (dB)
92.0
SINAD
91.0
4.75
4.85
4.95
-106.5
-107.0
fIN = 10kHz
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
VIN = -0.025dB FROM FS
90.5
90.0
VAVDD = 5.0V
fIN = 10kHz
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
VIN = -0.025dB FROM FS
-105.5
92.0
90.5
8.4
-105.0
125
MAX11047 toc19
MAX11047 toc17
93.0
-120
7.6
35
SIGNAL-TO-NOISE RATIO (SNR) AND
SIGNAL-TO-NOISE AND DISTORTION
RATIO (SINAD) vs. TEMPERATURE
-100
-140
10
FREQUENCY (kHz)
-80
SNR AND SINAD (dB)
MAGNITUDE (dB)
-60
-15
TEMPERATURE (°C)
fIN1 = 9834Hz
fIN2 = 10384Hz
fSAMPLE = 250ksps
TA = +25°C
VAVDD = 5.0V
VRDC = 4.096V
VIN = -0.01dBFS
-40
-140
-40
VAVDD (V)
0
-20
-0.010
THD (dB)
4.75
MAX11047 toc18
-0.010
-120
fIN = 10kHz
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
VIN = -0.025dB FROM FS
-107.5
-108.0
5.05
VAVDD (V)
5.15
5.25
4.75
4.85
4.95
5.05
5.15
5.25
VAVDD (V)
_______________________________________________________________________________________
7
MAX11047/MAX11048/MAX11049
Typical Operating Characteristics (continued)
(AVDD = 5V, DVDD = 3.3V, TA = +25°C, fSAMPLE = 250ksps, internal reference, unless otherwise noted.)
Typical Operating Characteristics (continued)
(AVDD = 5V, DVDD = 3.3V, TA = +25°C, fSAMPLE = 250ksps, internal reference, unless otherwise noted.)
SIGNAL-TO-NOISE AND DISTORTION
RATIO (SINAD) vs. FREQUENCY
-95
THD (dB)
92
91
VAVDD = 5.0V
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
VIN = -0.025dB FROM FS
89
0.1
-95
-110
-120
1.0
100.0
10.0
0.1
1.0
10.0
100.0
FREQUENCY (kHz)
FREQUENCY (kHz)
CROSSTALK vs. FREQUENCY
OUTPUT NOISE HISTOGRAM WITH
INPUT CONNECTED TO 2.5V
-115
24,000
VCHX = 2.500270V
VAVDD = 5.0V
fSAMPLE = 250ksps
TA = +25°C
20,000
16,000
12,000
-120
8000
32774
32773
FREQUENCY (kHz)
32772
0
100.0
10.0
32771
1.0
32770
0.1
32769
4000
32768
-125
MAX11047 toc23
-115
NUMBER OF OCCURENCES
-105
-105
-110
VAVDD = 5.0V
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
VIN = -0.025dB FROM FS
INACTIVE CHANNEL
AT GND
-100
-100
MAX11047 toc25
90
88
VAVDD = 5.0V
fSAMPLE = 250ksps
TA = +25°C
VRDC = 4.096V
VIN = -0.025dB FROM FS
-90
MAX11047 toc24
SINAD (dB)
93
CROSSTALK (dB)
THD vs. INPUT FREQUENCY
-85
MAX11047 toc22
94
OUTPUT CODE (DECIMAL)
CONVERSION TIME
vs. ANALOG SUPPLY VOLTAGE
CONVERSION TIME vs. TEMPERATURE
2.99
CONVERSION TIME (µs)
2.98
2.97
2.96
2.95
2.94
2.93
MAX11047 toc27
2.99
2.98
2.97
2.96
2.95
2.94
2.93
2.92
2.92
4.75
4.85
4.95
5.05
VAVDD (V)
8
3.00
MAX11047 toc26
3.00
CONVERSION TIME (µs)
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
5.15
5.25
-40
-15
10
35
TEMPERATURE (°C)
_______________________________________________________________________________________
60
85
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
PIN
NAME
1
DB13
16-Bit Parallel Data Bus Digital Output Bit 13
FUNCTION
2
DB12
16-Bit Parallel Data Bus Digital Output Bit 12
3
DB11
16-Bit Parallel Data Bus Digital Output Bit 11
4
DB10
16-Bit Parallel Data Bus Digital Output Bit 10
5
DB9
16-Bit Parallel Data Bus Digital Output Bit 9
6
DB8
7, 21, 50
DGND
Digital Ground
16-Bit Parallel Data Bus Digital Output Bit 8
8, 20, 51
DVDD
Digital Supply. Bypass to DGND with a 0.1μF capacitor at each DVDD input.
9
DB7
16-Bit Parallel Data Bus Digital Output Bit 7
10
DB6
16-Bit Parallel Data Bus Digital Output Bit 6
11
DB5
16-Bit Parallel Data Bus Digital Output Bit 5
12
DB4
16-Bit Parallel Data Bus Digital Output Bit 4
13
DB3
16-Bit Parallel Data Bus Digital I/O Bit 3
14
DB2
16-Bit Parallel Data Bus Digital I/O Bit 2
15
DB1
16-Bit Parallel Data Bus Digital I/O Bit 1
16
DB0
16-Bit Parallel Data Bus Digital I/O Bit 0
17
EOC
Active-Low, End-of-Conversion Output. EOC goes low when a conversion is completed. EOC goes high
when a conversion is initiated.
18
CONVST
19
SHDN
22, 28,
35, 43, 49
RDC
23, 27, 33,
38, 44, 48
AGNDS
24, 30,
41, 47
AVDD
Analog Supply Input. Bypass AVDD to AGND with a 0.1μF capacitor at each AVDD input.
25, 31,
40, 46
AGND
Analog Ground. Connect all AGND inputs together.
26
CH0
Channel 0 Analog Input for the MAX11049
29
CH1
Channel 1 Analog Input for the MAX11049. Channel 0 for the MAX11048.
32
CH2
Channel 2 Analog Input for MAX11049. Channel 1 for the MAX11048, Channel 0 for the MAX11047.
34
CH3
Channel 3 Analog Input for MAX11049. Channel 2 for the MAX11048, Channel 1 for the MAX11047.
36
REFIO
External Reference Input/Internal Reference Output. Place a 0.1μF capacitor from REFIO to AGND.
37
CH4
Channel 4 Analog Input for the MAX11049. Channel 3 for the MAX11048, Channel 2 for the MAX11047.
39
CH5
Channel 5 Analog Input for the MAX11049. Channel 4 for the MAX11048, Channel 3 for the MAX11047.
Convert Start Input. The rising edge of CONVST ends sample and starts a conversion on the captured
sample. The ADC is in acquisition mode when CONVST is low and CONVST mode is zero.
Active-High Shutdown Input. Drive the SHDN high to place the device into a low-current state. In
shutdown mode, the contents of the configuration register are not lost.
Reference Buffer Decoupling. Bypass to AGND with at least a 22μF capacitor each at pins 22, 28, 43,
and 49. Connect all RDC outputs together and bypass with 80μF total capacitance. See the Layout,
Grounding, and Bypassing section.
Signal Ground. Connect all AGND and AGNDS inputs together.
_______________________________________________________________________________________
9
MAX11047/MAX11048/MAX11049
Pin Description
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
Pin Description (continued)
PIN
NAME
42
CH6
Channel 6 Analog Input for MAX11049. Channel 5 for MAX11048.
45
CH7
Channel 7 Analog Input for MAX11049
52
WR
Active-Low Write Input. Drive WR low to write to the ADC. Configuration registers are loaded on the
rising edge of WR.
53
CS
Active-Low Chip-Select Input. Drive CS low when reading from or writing to the ADC.
54
RD
Active-Low Read Input. Drive RD low to read from the ADC. Each rising edge of RD advances the
channel output on the data bus.
55
DB15
56
DB14
—
EP
FUNCTION
16-Bit Parallel Data Bus Digital Out Bit 15
16-Bit Parallel Data Bus Digital Out Bit 14
Exposed Pad. Internally connected to AGND. Connect to a large ground plane to maximize thermal
performance. Not intended as an electrical connection point.
Detailed Description
The MAX11047/MAX11048/MAX11049 are fast, lowpower ADCs that combine 4, 6, or 8 independent ADC
channels in a single IC. Each channel includes simultaneously sampling independent T/H circuitry that preserves relative phase information between inputs
making the MAX11047/MAX11048/MAX11049 ideal for
motor control and power monitoring. The MAX11047/
MAX11048/MAX11049 are available with a 0 to 5V input
range that features ±20mA overrange, fault-tolerant
inputs. The MAX11047/MAX11048/MAX11049 operate
with a single 4.75V to 5.25V supply. A separate 2.7V to
5.25V supply for digital circuitry makes the devices
compatible with low-voltage processors.
The MAX11047/MAX11048/MAX11049 perform conversions for all channels in parallel by activating independent ADCs. Results are available through a high-speed,
20MHz, parallel data bus after a conversion time of 3μs
following the end of a sample. The data bus is bidirectional and allows for easy programming of the configuration register. The MAX11047/MAX11048/MAX11049
feature a reference buffer, which is driven by an internal
bandgap reference circuit (VREFIO = 4.096V). Drive
REFIO with an external reference or bypass with a 0.1μF
capacitor to ground when using the internal reference.
Analog Inputs
Track and Hold (T/H)
To preserve phase information across all channels,
each input includes a dedicated T/H circuitry. The input
tracking circuitry provides a 4MHz small-signal bandwidth, enabling the device to digitize high-speed transient events and measure periodic signals with
bandwidths exceeding the ADC’s sampling rate by
10
using undersampling techniques. Use anti-alias filtering
to avoid high-frequency signals being aliased into the
frequency band of interest.
Input Range and Protection
The full-scale analog input voltage is a product of the
reference voltage. For MAX11047/MAX11048/
MAX11049, the input is unipolar in the range of:
0 to + VREFIO x
5.0
4.096
In external reference mode, drive VREFIO with a 3.0V to
4.25V source, resulting in a full-scale input range of
3.662V to 5.188V, respectively.
All analog inputs are fault-protected up to ±20mA. The
MAX11047/MAX11048/MAX11049 include an input
clamping circuit that activates when the input voltage at
the analog input is above (VAVDD + 300mV) or below
-300mV. The clamp circuit remains high impedance
while the input signal is within the range of 0V to
+VAVDD and draws little to no current. However, when
the input signal exceeds the range of 0V to +VAVDD,
the clamps begin to turn on. Consequently, to obtain
the highest accuracy, ensure that the input voltage
does not exceed the range of 0V to +VAVDD.
To make use of the input clamps, connect a resistor
(RS) between the analog input and the voltage source
to limit the voltage at the analog input so that the fault
current into the MAX11047/MAX11048/MAX11049 does
not exceed ±20mA. Note that the voltage at the analog
input pin limits to approximately 7V during a fault condition so the following equation can be used to calculate
the value of RS:
______________________________________________________________________________________
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
Applications Information
VFAULT _ MAX − 7V
Digital Interface
20mA
where VFAULT_MAX is the maximum voltage that the
source produces during a fault condition.
Figures 2 and 3 illustrate the clamp circuit voltage-current characteristics for a source impedance R S =
1280Ω. While the input voltage is within the range of
-300mV to +(VAVDD + 300mV), no current flows in the
input clamps. Once the input voltage goes beyond this
voltage range, the clamps turn on and limit the voltage
at the input pin.
INPUT
SIGNAL
The bidirectional, parallel, digital interface, DB0–DB3,
sets the 4-bit configuration register. This interface
configures the following control signals: chip select
(CS), read (RD), write (WR), end of conversion (EOC),
and convert start (CONVST). Figures 6 and 7 and the
Timing Characteristics in the Electrical Characteristics
table show the operation of the interface. DB0–DB3,
together with the output-only DB4–DB15, also output
the 16-bit conversion result. All bits are high impedance when RD = 1 or CS = 1.
PIN
VOLTAGE
AVDD
DVDD
DB15
CLAMP
S/H
16-BIT ADC
8 x 16-BIT REGISTERS
CH0
SOURCE
CH7
CLAMP
S/H
BIDIRECTIONAL DRIVERS
RS
DB4
DB3
DB0
16-BIT ADC
CONFIGURATION
REGISTERS
AGNDs
MAX11047
MAX11048
MAX11049
WR
RD
CS
INTERFACE
AND
CONTROL
AGND
CONVST
SHDN
EOC
INT REF
BANDGAP
REFERENCE
RDC
REF
BUF
DGND
EXT REF
REFIO
Figure 1. Required Setup for Clamp Circuit
25
15
15
ICLAMP (mA)
AT SOURCE
-5
0
-5
-10
-15
-15
-20
-20
-30
-20
-10
0
10
20
30
40
SIGNAL VOLTAGE AT SOURCE AND CH_ INPUT (V)
Figure 2. Input Clamp Characteristics
AT SOURCE
5
-10
-25
AT CH_ INPUT
10
5
0
RS = 1170I
VAVDD = 5.0V
20
AT CH_ INPUT
10
ICLAMP (mA)
25
RS = 1170I
VAVDD = 5.0V
20
-25
-4
-2
0
2
4
6
8
SIGNAL VOLTAGE AT SOURCE AND CH_ INPUT (V)
Figure 3. Input Clamp Characteristics (Zoom In)
______________________________________________________________________________________
11
MAX11047/MAX11048/MAX11049
RS =
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
DB3 (Int/Ext Reference)
DB3 selects the internal or external reference. The POR
default = 0.
0 = internal reference, REFIO internally driven through a
10kΩ resistor, bypass with 0.1μF capacitor to AGND.
1 = external reference, drive REFIO with a high quality
reference.
DB2 (Output Data Format)
DB2 selects the output data format. The POR default = 0.
0 = offset binary.
1 = two’s complement.
DB1 (Reserved)
Set to 0 for normal operation.
0 = normal operation.
1 = reserved; do not use.
DB0 (CONVST Mode)
DB0 selects the acquisition mode. The POR default = 0.
0 = CONVST controls the acquisition and conversion.
Drive CONVST low to start acquisition. The rising edge
of CONVST begins the conversion.
1 = acquisition mode starts as soon as previous conversion is complete. The rising edge of CONVST begins
the conversion.
Programming the Configuration Register
To program the configuration register, bring the CS and
WR low and apply the required configuration data on
DB3–DB0 of the bus and then raise WR once to save
changes.
Starting a Conversion
CONVST initiates conversions. The MAX11047/
MAX11048/MAX11049 provide two acquisition modes
set through the configuration register. Allow a quiet time
(tQ) of 500ns prior to the start of conversion to avoid
any noise interference during readout or write operations from corrupting a sample.
In default mode (DB0 = 0), drive CONVST low to place
the MAX11047/MAX11048/MAX11049 into acquisition
mode. All the input switches are closed and the internal
T/H circuits track the respective input voltage. Keep the
CONVST signal low for at least 1μs (tACQ) to enable
proper settling of the sampled voltages. On the rising
edge of CONVST, the switches are opened and the
MAX11047/MAX11048/MAX11049 begin the conversion
on all the samples in parallel. EOC remains high until
the conversion is completed.
12
Table 1. Configuration Register
DB3
DB2
DB1
DB0
Int/Ext
Reference
Output
Data Format
Reserved
CONVST
Mode
In the second mode (DB0 = 1), the MAX11047/
MAX11048/MAX11049 enter acquisition mode as soon
as the previous conversion is completed. CONVST rising
edge initiates the next sample and conversion sequence.
Drive CONVST low for at least 20ns to be valid.
Provide adequate time for acquisition and the requisite
quiet time in both modes to achieve accurate sampling
and maximum performance of the MAX11047/
MAX11048/MAX11049.
Reading Conversion Results
The CS and RD are active-low, digital inputs that control the readout through the 16-bit, parallel, 20MHz data
bus (D0–D15). After EOC transitions low, read the conversion data by driving CS and RD low. Each low period of RD presents the next channel’s result. When CS
and RD are high, the data bus is high impedance. CS
may be driven high between individual channel readouts or left low during the entire 8-channel readout.
Reference
Internal Reference
The MAX11047/MAX11048/MAX11049 feature a precision, low-drift, internal bandgap reference. Bypass REFIO
with a 0.1μF capacitor to AGND to reduce noise. The
REFIO output voltage may be used as a reference for
other circuits. The output impedance of REFIO is 10kΩ.
Drive only high-impedance circuits or buffer externally
when using REFIO to drive external circuitry.
External Reference
Set the configuration register to disable the internal reference and drive REFIO with a high-quality external reference. To avoid signal degradation, ensure that the
integrated reference noise applied to REFIO is less
than 10μV in the bandwidth of up to 50kHz.
Reference Buffer
The MAX11047/MAX11048/MAX11049 have a built- in
reference buffer to provide a low-impedance reference
source to the SAR converters. This buffer is used in
both internal and external reference modes. The internal reference buffer output feeds five RDC outputs.
Connect all RDC outputs together. The reference buffer
is externally compensated and requires at least 10μF
on the RDC node for stability. For best performance,
provide a total of at least 80μF on the RDC outputs.
______________________________________________________________________________________
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
Layout, Grounding, and Bypassing
For best performance, use PCBs with ground planes.
Ensure that digital and analog signal lines are separated
from each other. Do not run analog and digital lines parallel to one another (especially clock lines), and avoid running digital lines underneath the ADC package. A single
solid GND plane configuration with digital signals routed
from one direction and analog signals from the other provides the best performance. Connect DGND, AGND, and
AGNDS pins on the MAX11047/MAX11048/MAX11049 to
this ground plane. Keep the ground return to the power
supply for this ground low impedance and as short as
possible for noise-free operation.
To achieve the highest performance, connect all the
RDC outputs to a local RDC plane on the PCB. Bypass
the RDC outputs with a total of at least 80μF of capacitance. For example, if two capacitors are used, place
two 47μF, 10V X5R capacitors in 1210 case size as
close as possible to pins 22 and 49. Alternatively, if four
capacitors are used, place four 22μF, 10V X5R capacitors in 1210 case size as close as possible to pins 22,
28, 43, and 49. Ensure that each capacitor is connected directly into the GND plane with an independent via.
In cases where Y5U or Z5U ceramics are used, select
higher voltage rating capacitors to compensate for the
high-voltage coefficient of these ceramic capacitors,
thus ensuring that at least 80μF of capacitance is on
the RDC plane when the plane is driven to 4.096V by
the internal reference buffer. For example, at 4.096V, a
22μF X5R ceramic capacitor with a 10V rating diminishes to only 20μF, whereas the same capacitor in Y5U
ceramic at 4.096V decreases to about 13μF. However,
a 22μF Y5U ceramic capacitor with a 25V rating capacitor is approximately 20μF at 4.096V.
Bypass AVDD and DVDD to the ground plane with
0.1μF ceramic chip capacitors on each pin as close as
possible to the device to minimize parasitic inductance.
Add at least one bulk 10μF decoupling capacitor to
AVDD and DVDD per PCB. Interconnect all of the
AVDD inputs and DVDD inputs using two solid power
planes. For best performance, bring the AVDD power
plane in on the analog interface side of the MAX11047/
MAX11048/MAX11049 and the DVDD power plane from
the digital interface side of the device.
For sampling periods near minimum (1μs) use a 1nF
C0G ceramic chip capacitor between each of the channel inputs to the ground plane as close as possible to the
MAX11047/MAX11048/MAX11049. This capacitor
reduces the inductance seen by the sampling circuitry
and reduces the voltage transient seen by the input
source circuit.
CS
(USER SUPPLIED)
t5
t3
CS
(USER SUPPLIED)
t4
WR
(USER SUPPLIED)
t10
t9
t8
t11
RD
(USER SUPPLIED)
t7
t13
t12
t6
D0–D15
D0–D15
(USER SUPPLIED)
Sn
Sn + 1
CONFIGURATION
REGISTER
Figure 4. Programming Configuration-Register Timing
Requirements
Figure 5. Readout Timing Requirements
______________________________________________________________________________________
13
MAX11047/MAX11048/MAX11049
Transfer Functions
Figures 8 and 9 show the transfer functions for all the
formats and devices. Code transitions occur halfway
between successive-integer LSB values.
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
SAMPLE
tCON
tACQ
CONVST
t1
EOC
tO
tQ
CS
RD
D0–D15
S0
S1
S6
S7
Figure 6. Conversion Timing Diagram (DB0 = 0)
SAMPLE
tCON
tACQ
CONVST
t2
EOC
tO
tQ
CS
RD
D0–D15
S0
S1
S6
S7
Figure 7. Conversion Timing Diagram (DB0 = 1)
14
______________________________________________________________________________________
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
LSB =
FS
65536
FFFF
FULL-SCALE
TRANSITION
OUTPUT CODE (hex)
OUTPUT CODE (hex)
FS
65536
0001
0000
FFFF
8001
8000
7FFF
FFFE
7FFE
8001
0001
8000
0000
FS/2
+FS
0
FS/2
VIN x 65536
- 32768,
5
VRDC x
4.096
FS =
+FS
INPUT VOLTAGE (LSB)
INPUT VOLTAGE (LSB)
CODE =
FULL-SCALE
TRANSITION
FFFE
7FFE
0
LSB =
5 x VRDC
4.096
Figure 8. Two’s Complement Transfer Function
Typical Application Circuits
Power-Grid Protection
Figure 10 shows a typical power-grid protection application.
DSP Motor Control
Figure 11 shows a typical DSP motor control application.
Definitions
Integral Nonlinearity (INL)
INL is the deviation of the values on an actual transfer
function from a straight line. For these devices, this
straight line is a line drawn between the end points of
the transfer function, once offset and gain errors have
been nullified.
Differential Nonlinearity (DNL)
DNL is the difference between an actual step width and
the ideal value of 1 LSB. For these devices, the DNL of
each digital output code is measured and the worstcase value is reported in the Electrical Characteristics
table. A DNL error specification of greater than -1 LSB
guarantees no missing codes and a monotonic transfer
function for an SAR ADC. For example, -0.9 LSB guarantees no missing code while -1.1 LSB results in missing
code.
CODE =
5 x VRDC
VIN x 65536
, FS =
4.096
5
4.096
VRDC x
Figure 9. Offset-Binary Transfer Function
Offset Error
For the MAX11047/MAX11048/MAX11049, the offset
error is defined at code transition 0x0000 to 0x0001 in
offset binary encoding and 0x8000 to 0x8001 for two’s
complement encoding. The offset code transitions
should occur with an analog input voltage of exactly 0.5
x (5/4.096) x VREF/65,536 above GND. The offset error
is defined as the deviation between the actual analog
input voltage required to produce the offset code transition and the ideal analog input of 0.5 x (5/4.096) x
VREF/65,536 above GND, expressed in LSBs.
Gain Error
Gain error is defined as the difference between the
change in analog input voltage required to produce a
top code transition minus a bottom code transition, subtracted from the ideal change in analog input voltage
on (5/4.096) x V REF x (65,534/65,536). For the
MAX11047/MAX11048/MAX11049, top code transition
is 0x7FFE to 0x7FFF in two’s complement mode and
0xFFFE to 0xFFFF in offset binary mode. The bottom
code transition is 0x8000 and 0x8001 in two’s complement mode and 0x0000 and 0x0001 in offset binary
mode. For the MAX11047/MAX11048/MAX11049, the
analog input voltage to produce these code transitions
is measured and the gain error is computed by subtracting (5/4.096) x VREF x (65,534/65,536) from this
measurement.
______________________________________________________________________________________
15
MAX11047/MAX11048/MAX11049
7FFF
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
VOLTAGE
TRANSFORMER
PHASE 1
OPT
2.5V
ADC
OPT
CURRENT
TRANSFORMER
ADC
2.5V
VN
NEUTRAL
ADC
IN
ADC
LOAD 1
MAX11049
LOAD 2
LOAD 3
I3
V3
I2
ADC
ADC
PHASE 2
V2
ADC
ADC
PHASE 3
Figure 10. Power-Grid Protection
16
______________________________________________________________________________________
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
MAX11047/MAX11048/MAX11049
DSP-BASED DIGITAL
PROCESSING ENGINE
MAX11048
16-BIT
ADC
IGBT CURRENT DRIVERS
16-BIT
ADC
16-BIT
ADC
16-BIT
ADC
16-BIT
ADC
IPHASE1
IPHASE3
IPHASE2
3-PHASE ELECTRIC MOTOR
POSITION
ENCODER
Figure 11. DSP Motor Control
______________________________________________________________________________________
17
MAX11047/MAX11048/MAX11049
4-/6-/8-Channel, 16-Bit,
Simultaneous-Sampling ADCs
Signal-to-Noise Ratio (SNR)
For a waveform perfectly reconstructed from digital
samples, 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 noise error only and
results directly from the ADC’s resolution (N bits):
SNR = (6.02 x N + 1.76)dB
where N = 16 bits. In reality, there are other noise
sources besides quantization noise: thermal noise, reference noise, clock jitter, etc. SNR is computed by taking the ratio of the RMS signal to the RMS noise, which
includes all spectral components not including the fundamental, the first five harmonics, and the DC offset.
Signal-to-Noise Plus Distortion (SINAD)
SINAD is the ratio of the fundamental input frequency’s
RMS amplitude to the RMS equivalent of all the other
ADC output signals:
⎡
⎤
Signal RMS
SINAD(dB) = 10 × log ⎢
⎥
⎣ (Noise + Distortion) RMS ⎦
Effective Number of Bits (ENOB)
The ENOB indicates the global accuracy of an ADC at
a specific input frequency and sampling rate. An ideal
ADC’s error consists of quantization noise only. With an
input range equal to the full-scale range of the ADC,
calculate the ENOB as follows:
ENOB =
SINAD − 1. 76
6. 02
Total Harmonic Distortion (THD)
THD is the ratio of the RMS of the first five harmonics of
the input signal to the fundamental itself. This is
expressed as:
Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio of the RMS amplitude of the fundamental (maximum signal component) to the RMS value
of the next-largest frequency component.
Aperture Delay
Aperture delay (tAD) is the time delay from the sampling
clock edge to the instant when an actual sample is
taken.
Aperture Jitter
Aperture Jitter (tAJ) is the sample-to-sample variation in
aperture delay.
Channel-to-Channel Isolation
Channel-to-channel isolation indicates how well each
analog input is isolated from the other channels.
Channel-to-channel isolation is measured by applying
DC to channels 1 to 7, while a -0.4dBFS sine wave at
60Hz is applied to channel 0. A 10ksps FFT is taken for
channel 0 and channel 1. Channel-to-channel isolation
is expressed in dB as the power ratio of the two 60Hz
magnitudes.
Small-Signal Bandwidth
A small -20dBFS analog input signal is applied to an
ADC in a manner that ensures that the signal’s slew
rate does not limit the ADC’s performance. The input
frequency is then swept up to the point where the
amplitude of the digitized conversion result has
decreased 3dB.
Full-Power Bandwidth
A large -0.5dBFS analog input signal is applied to an
ADC, and the input frequency is swept up to the point
where the amplitude of the digitized conversion result
has decreased by 3dB. This point is defined as fullpower input bandwidth frequency.
Chip Information
PROCESS: BiCMOS
⎡ V2 2 + V3 2 + V4 2 + V 5 2
THD = 20 × log ⎢
V1
⎢
⎣
⎤
⎥
⎥
⎦
where V1 is the fundamental amplitude and V2 through
V5 are the 2nd- through 5th-order harmonics.
Package Information
For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
56 TQFN-EP
T5688+2
21-0135
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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