Synchronous Demodulator
and Configurable Analog Filter
ADA2200
Data Sheet
FEATURES
FUNCTIONAL BLOCK DIAGRAM
VDD
ADA2200
INP
8
INN
LPF
OUTP
PROGRAM
FILTER
OUTN
fM
CLKIN
XOUT
÷2m
fSI
÷8
VOCM
90°
fSO
÷2n+1
CLOCK
GEN
CONTROL
REGISTERS
SYNCO
GND
RCLK/SDO
SPI/I2C
MASTER
RST
VCM
SCLK/SCL
SDIO/SDA
CS/A0
BOOT
12295-001
Demodulates signal input bandwidths to 30 kHz
Programmable filter enables variable bandwidths
Filter tracks input carrier frequency
Programmable reference clock frequency
Flexible system interface
Single-ended/differential signal inputs and outputs
Rail-to-rail outputs directly drive analog-to-digital
converters (ADCs)
Phase detection sensitivity of 9.3m°θREL rms
Configurable with 3-wire and 4-wire serial port interface (SPI) or
seamless boot from I2C EEPROMs
Very low power operation
395 μA at fCLKIN = 500 kHz
Single supply: 2.7 V to 3.6 V
Specified temperature range: −40°C to +85°C
16-lead TSSOP package
Figure 1.
APPLICATIONS
Synchronous demodulation
Sensor signal conditioning
Lock-in amplifiers
Phase detectors
Precision tunable filters
Signal recovery
Control systems
GENERAL DESCRIPTION
The ADA2200 is a sampled analog technology1 synchronous
demodulator for signal conditioning in industrial, medical, and
communications applications. The ADA2200 is an analog input,
sampled analog output device. The signal processing is performed
entirely in the analog domain by charge sharing among capacitors,
which eliminates the effects of quantization noise and rounding
errors. The ADA2200 includes an analog domain, low-pass
decimation filter, a programmable infinite impulse response
(IIR) filter, and a mixer. This combination of features reduces
ADC sample rates and lowers the downstream digital signal
processing requirements.
The ADA2200 acts as a precision filter when the demodulation
function is disabled. The filter has a programmable bandwidth
and tunable center frequency. The filter characteristics are highly
stable over temperature, supply, and process variation.
Single-ended and differential signal interfaces are possible on both
input and output terminals, simplifying the connection to other
1
components of the signal chain. The low power consumption and
rail-to-rail operation is ideal for battery-powered and low
voltage systems.
The ADA2200 can be programmed over its SPI-compatible
serial port or can automatically boot from the EEPROM
through its I2C interface. On-chip clock generation produces a
mixing signal with a programmable frequency and phase. In
addition, the ADA2200 synchronization output signal eases
interfacing to other sampled systems, such as data converters
and multiplexers.
The ADA2200 is available in a 16-lead TSSOP package. Its
performance is specified over the industrial temperature range
of −40°C to +85°C. Note that throughout this data sheet,
multifunction pins, such as SCLK/SCL, are referred to either by
the entire pin name or by a single function of the pin, for
example, SCLK, when only that function is relevant.
Patent pending.
Rev. 0
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• MS-2698: Use Synchronous Detection to Make Precision,
Low Level Measurements
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ADA2200
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Input and Output Amplifiers .................................................... 15
Applications ....................................................................................... 1
Applications Information .............................................................. 16
Functional Block Diagram .............................................................. 1
Amplitude Measurements ......................................................... 16
General Description ......................................................................... 1
Phase Measurements.................................................................. 16
Revision History ............................................................................... 2
Amplitude and Phase Measurements ...................................... 16
Specifications..................................................................................... 3
Analog Output Systems ............................................................. 17
SPI Timing Characteristics ......................................................... 4
Interfacing to ADCs ................................................................... 17
Absolute Maximum Ratings ............................................................ 7
Lock-In Amplifier Application ................................................. 17
Thermal Resistance ...................................................................... 7
Interfacing to Microcontrollers ................................................ 18
ESD Caution .................................................................................. 7
EEPROM Boot Configuration .................................................. 18
Pin Configuration and Function Descriptions ............................. 8
Power Dissipation....................................................................... 18
Typical Performance Characteristics ............................................. 9
Device Configuration .................................................................... 19
Terminology .................................................................................... 10
Serial Port Operation ................................................................. 19
Theory of Operation ...................................................................... 11
Data Format ................................................................................ 19
Synchronous Demodulation Basics ......................................... 11
Serial Port Pin Descriptions ...................................................... 19
ADA2200 Architecture .............................................................. 12
Serial Port Options ..................................................................... 19
Decimation Filter........................................................................ 12
Booting from EEPROM ............................................................ 20
IIR Filter....................................................................................... 13
Device Configuration Register Map and Descriptions ............. 21
Mixer ............................................................................................ 13
Outline Dimensions ....................................................................... 24
Clocking Options ....................................................................... 14
Ordering Guide............................................................................... 24
REVISION HISTORY
8/14—Revision 0: Initial Version
Rev. 0 | Page 2 of 24
Data Sheet
ADA2200
SPECIFICATIONS
VDD = 3.3 V, VOCM = VDD/2, fCLKIN = fSI = 500 kHz, default register configuration, differential input/output, RL = 1 MΩ to GND, TA = 25°C,
unless otherwise noted.
Table 1.
Parameter
SYNCHRONOUS DEMODULATION
Conversion Gain1
Average Temperature Drift
Output Offset, Shorted Inputs
Average Temperature Drift
Power Supply Sensitivity
Measurement Noise
Phase Delay (°θDELAY)1
Average Temperature Drift
Phase Measurement Noise
Shorted Input Noise
Common-Mode Rejection2
Demodulation Signal Bandwidth
INPUT CHARACTERISTICS
Input Voltage Range
Common-Mode Input Voltage Range
Single-Ended Input Voltage Range
Reference Input
Signal Input
Input Impedance3
Input Signal Bandwidth (−3 dB)
OUTPUT CHARACTERISTICS
Output Voltage Range
Short-Circuit Current
Common-Mode Output (VOCM)
Voltage
Average Temperature Drift
Output Settling Time, to 0.1% of Final
Value
DEFAULT FILTER CHARACTERISTICS
Center Frequency (fC)
Quality Factor (Q)
Pass Band Gain
TOTAL HARMONIC DISTORTION (THD)
Second Through Fifth Harmonics
CLOCKING CHARACTERISTICS
CLKIN Frequency Range (fCLKIN)
Maximum CLKIN Frequency
Test Conditions/Comments
Measurements are cycle mean values,1
4 V p-p differential, fIN = 7.8125 kHz
Min
Typ
Max
Unit
1.02
1.055
5
1.09
V/V rms
ppm/°C
mV
μV/°C
mV/V
μV rms
−39
Change in output over change in VDD
Input signal at 83°θREL1
Input signal relative to RCLK
Input signal at 83°θREL
0.1 Hz to 10 Hz
0 kHz to 1 kHz offset from fMOD
fCLKIN = 1 MHz
INP or INN to GND
4 V p-p differential input
+39
6.5
0.5
240
83
70
9.3
300
75
30
0.3
VOCM − 0.2
VDD − 0.3
VOCM + 0.2
V
V
VOCM − 0.2
VOCM − 1.0
VOCM + 0.2
VOCM + 1.0
V
V
kΩ
MHz
VDD − 0.3
V
mA
1.67
V
μV/°C
μs
INP to INN
Input sample and hold circuit
Each output, RL = 10 kΩ to GND
80
4
0.3
OUTP or OUTN to GND
15
1.63
3.7 V output step, RLOAD = 10 kΩ||10 pF,
fCLKIN = 125 kHz
Mixing disabled, VIN = 4 V p-p differential
fC = fSO/8
fC/(filter 3 dB bandwidth)
fIN = 7.8125 kHz
Filter configuration = LPF at fNYQ/6, fIN =
850 Hz, VIN = 4 V p-p differential input
TA = −40°C to +85°C
CLKIN DIV[2:0] = 256
CLKIN DIV[2:0] = 64
CLKIN DIV[2:0] = 16
CLKIN DIV[2:0] = 1
While booting from EEPROM
Rev. 0 | Page 3 of 24
°θREL
μ°θREL/°C
m°θREL rms
μV p-p
dB
kHz
2.56
0.64
0.16
0.01
1.65
9
15
7.8125
1.9
1.05
kHz
Hz/ΔHz
V/V
−80
dBc
20
20
16
1
12.8
MHz
MHz
MHz
MHz
MHz
ADA2200
Data Sheet
Parameter
DIGITAL I/O
Logic Thresholds
Input Voltage
Low
High
Output Voltage
Low
High
Maximum Output Current
Input Leakage
Internal Pull-Up Resistance
Test Conditions/Comments
Min
Typ
Max
Unit
0.8
V
V
0.4
40
V
V
mA
µA
kΩ
500
2
2
kΩ
pF
pF
All inputs/outputs
2.0
While sinking 200 µA
While sourcing 200 µA
Sink or source
VDD − 0.4
8
1
BOOT and RST only
CRYSTAL OSCILLATOR
Internal Feedback Resistor
CLKIN Capacitance
XOUT Capacitance
POWER REQUIREMENTS
Power Supply Voltage Range
Total Supply Current Consumption
2.7
395
3.6
485
V
µA
See the Terminology section.
Common-mode signal swept from fMOD − 1 kHz to fMOD + 1 kHz. Output measured at frequency offset from fMOD. For example, a common-mode signal at fMOD − 500 Hz is
measured at 500 Hz.
3
The input impedance is equal to a 4 pF capacitor switched at fCLKIN. Therefore, the input impedance = 1012/(2πfCLKIN × 4).
1
2
SPI TIMING CHARACTERISTICS
VDD = 2.7 V to 3.6 V, default register configuration, TA = −40 to +85°C, unless otherwise noted.
Table 2. SPI Timing
Parameter
fSCLK
tCS
Test Conditions/Comments
50% ± 5% duty cycle
CS to SCLK edge
tSL
tSH
tDAV
tDSU
tDHD
tDF
tDR
tSR
tSF
tDOCS
tSFS
SCLK low pulse width
SCLK high pulse width
Data output valid after SCLK edge
Data input setup time before SCLK edge
Data input hold time after SCLK edge
Data output fall time
Data output rise time
SCLK rise time
SCLK fall time
Data output valid after CS edge
CS high after SCLK edge
Min
Typ
Max
20
2
10
10
20
2
2
1
1
10
10
1
2
Rev. 0 | Page 4 of 24
Unit
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Data Sheet
ADA2200
CS
tCS
tSFS
tSL
SCLK
tSH
tSF
tDAV
tDF
SDO
(MISO)
MSB
SDIO
(MOSI)
tSR
tDR
DATA BITS
MSB IN
LSB
DATA BITS
LSB IN
12295-003
tDSU
tDHD
Figure 2. SPI Read Timing Diagram (SPI Master Read from the ADA2200)
CS
tSFS
tCS
SCLK
tSL
tSH
tSF
SDIO
(MOSI)
MSB IN
DATA BITS
tSR
LSB IN
12295-004
tDSU
tDHD
Figure 3. SPI Write Timing Diagram (SPI Master Write to the ADA2200)
Table 3. EEPROM Master I2C Boot Timing
Parameter1
BOOT
Load from BOOT Complete
RST to BOOT Setup Time
BOOT Pulse Width
t2
t3
RESET
Minimum RST Pulse Width
t1
START CONDITION
BOOT Low Transition to Start Condition
t4
1
Symbol
CLKIN cycles with CLKIN DIV[2:0] set to 000.
Rev. 0 | Page 5 of 24
Min
Typical
Max
Unit
9600
2
1
CLKIN cycles
CLKIN cycles
CLKIN cycles
25
ns
3
CLKIN cycles
ADA2200
Data Sheet
t1
RST
t2
BOOT
t3
t4
SDA
START
ADDR
[1:0] R/W ACK
b10001
REGISTER ADDR
ACK
DATA
ACK
STOP
12295-005
SCL
Figure 4. Load from EEPROM Timing Diagram
OUTPUT
PHASE90 = 0
OUTPUT
PHASE90 = 1
HOLD SAMPLES
SAMPLE 0
SAMPLE 0
SAMPLE 1
SAMPLE 1
SAMPLE 2
SAMPLE 2
SAMPLE 3 + 4 HOLD SAMPLES
SAMPLE 3 + 4 HOLD SAMPLES
SAMPLE 0
SAMPLE 1
CLKIN
SYNCO
30
40
50
60
70
80
90
100
Figure 5. CLKIN to RCLK, SYNCO, and OUTP/OUTN Sample Timing
Table 4. Output, SYNCO, and RCLK Timing, Default Register Settings
Test Conditions/Comments
CLKIN to OUTx sample update delay
CLKIN to SYNCO delay, rising or falling edge to rising edge
SYNCO pulse width
CLKIN to RCLK delay, rising edge to rising or falling edge
Min
Typ
50
Max
40
1/fSI
70
INN/INP
t1
INx, OUTx
OUTN/OUTP
t2
SYNCO
t3
t4
RCLK
CLKIN
6
7
0
1
2
3
Figure 6. Input, Output, SYNCO, and RCLK Timing Relative to CLKIN
Rev. 0 | Page 6 of 24
4
12295-007
Parameter
t1
t2
t3
t4
Unit
ns
ns
ns
ns
12295-006
RCLK
Data Sheet
ADA2200
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 5.
Parameter
Supply Voltage
Output Short-Circuit Current Duration
Maximum Voltage at Any Input
Minimum Voltage at Any Input
Operational Temperature Range
Storage Temperature Range
Package Glass Transition Temperature
ESD Ratings
Human Body Model (HBM)
Device Model (FICDM)
Machine Model (MM)
θJA is specified for a device in a natural convection environment,
soldered on a 4-layer JEDEC printed circuit board (PCB).
Rating
3.9 V
Indefinite
VDD + 0.3 V
GND − 0.3 V
−40°C to +125°C
−65°C to +150°C
150°C
Table 6.
Package
16-Lead TSSOP
ESD CAUTION
1000 V
500 V
50 V
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
Rev. 0 | Page 7 of 24
θJA
100
θJC
14.8
Unit
°C/W
ADA2200
Data Sheet
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
CLKIN 1
15
SCLK/SCL
CS/A0 3
14
SDIO/SDA
13
RCLK/SDO
12
VDD
BOOT 4
ADA2200
TOP VIEW
(Not to Scale)
GND
5
INP
6
11
OUTP
INN
7
10
OUTN
VOCM
8
9
RST
12295-008
16 XOUT
2
SYNCO
Figure 7. Pin Configuration
Table 7. Pin Function Descriptions
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Mnemonic
CLKIN
SYNCO
CS/A0
BOOT
GND
INP
INN
VOCM
RST
OUTN
OUTP
VDD
RCLK/SDO
SDIO/SDA
SCLK/SCL
XOUT
Description
System Clock Input.
Synchronization Signal Output.
Serial Interface Chip Select Input/Boot EEPROM Address 0 Input.
Boot from EEPROM Control Input.
Power Supply Ground.
Noninverting Signal Input.
Inverting Signal Input.
Common-Mode Voltage Output.
Reset Control Input.
Inverting Output.
Noninverting Output.
Positive Supply Input.
Reference Clock Output/Serial Interface Data Output (in 4-Wire SPI Mode).
Bidirectional Serial Data (Input Only in 4-Wire SPI Mode)/I2C Bidirectional Data.
Serial Interface Clock Input/I2C Clock Output.
Crystal Driver Output. Place a crystal between this pin and CLKIN, or leave this pin disconnected.
Rev. 0 | Page 8 of 24
200
35
150
25
20
15
50
0
–50
10
–100
5
–150
0
78
79
80
81
82
83
84
RELATIVE PHASE (Degrees)
–200
0
1
2
3
4
5
6
7
8
9
10
TIME (Seconds)
12295-112
OUTPUT NOISE (µV)
100
12295-109
NUMBER OF HITS
30
0
–0.05
–0.10
–0.15
0
10
20
30
40
50
60
TIME (µs)
PHASE MEASUREMENT ERROR (Degrees)
25
20
15
10
5
0
–10
–270 –240 –210 –180 –150 –120 –90 –60 –30
RELATIVE PHASE (Degrees)
0
30
60
90
12295-114
MAGNITUDE ERROR
MAGNITUDE ERROR, OFFSET REMOVED
10
100
1k
10k
100k
FREQUENCY (Hz)
1.0
30
MAGNITUDE ERROR (mV)
CLKIN = 500kHz
1
35
–5
1k
100
12295-110
–0.20
10k
0.8
12295-113
SETTLING ERROR (%)
0.05
PHASE ERROR
PHASE ERROR, OFFSET REMOVED
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–270 –240 –210 –180 –150 –120 –90 –60 –30
RELATIVE PHASE (Degrees)
0
30
60
90
12295-111
NOISE SPECTRAL DENSITY (nV/√Hz)
0.10
ADA2200
Data Sheet
TERMINOLOGY
Cycle Mean
The cycle mean is the average of all the output samples
(OUTP/OUTN) over one RCLK period. In the default
configuration, there are eight output samples per RCLK cycle;
thus, the cycle mean is the average of eight consecutive output
samples. If the device is reconfigured such that the frequency of
RCLK is fSO/4, then the cycle mean is the average of four
consecutive output samples.
Conversion Gain
Conversion gain is calculated as follows:
2
Phase Measurement Transfer Function
Figure 15 shows the cycle mean value of the output for a
1 V rms input sine wave as θREL is swept from 0° to 360°.
1.2
1.0
+Q2
0.8
0.6
CYCLE MEAN VALUE
V IN
where:
I is the offset corrected cycle mean, PHASE90 bit = 0.
Q is the offset corrected cycle mean, PHASE90 bit = 1.
VIN is the rms value of the input voltage.
The offset corrected cycle mean = cycle mean − output offset.
100
150
200
250
–0.4
–1.0
–1.2
0
45
90
135
180
225
RELATIVE PHASE (θREL )
270
315
360
Figure 15. Phase Transfer Function with Phase Delay of 83°, 1 V rms Input
300
350
INP/INN
12295-009
PHASE (Degrees)
RELATIVE
PHASE = 37°
0
–0.2
–0.6
RCLK
50
83°
0.2
–0.8
Relative Phase (θREL)
Relative phase is the phase difference between the rising
positive zero crossing of a sine wave at the INN/INP inputs
relative to the next rising edge of RCLK.
0
0.4
12295-010
Conversion Gain =
I
Phase Delay (°θDELAY)
The phase delay is the relative phase (θREL) that produces a zero
cycle mean output value for a sine wave input with a frequency
equal to fRCLK. The phase delay is the relative phase value that
corresponds to the positive zero crossing of the phase measurement
transfer function.
Figure 14. Example Showing Relative Phase, θREL, of 37°
Rev. 0 | Page 10 of 24
Data Sheet
ADA2200
THEORY OF OPERATION
A carrier signal (fMOD) excites the sensor. This shifts the signal
generated by the physical parameter being measured by the
sensor to the carrier frequency. This shift allows the desired signal
to be placed in a frequency band with lower noise, improving
the accuracy of the measurement. A band-pass filter (BPF)
removes some of the out of band noise. A synchronous
demodulator (or mixer) shifts the signal frequency back to dc.
The last stage low-pass filter removes much of the remaining
noise. Figure 17 and Figure 18 show the frequency spectrum of
the signal at different points in the synchronous demodulator.
SAT works on the principle of charge sharing. A sampled
analog signal is a stepwise continuous signal without amplitude
quantization. This contrasts with a signal sampled by an ADC,
which becomes a discrete time signal with quantized amplitude.
NOISE AT A
With SAT, the input signal is sampled by holding the voltage on
a capacitor at the sampling instant. Basic signal processing can
then be performed in the analog domain by charge sharing among
capacitors. The ADA2200 includes an analog domain low-pass
decimation filter, a programmable IIR filter, and a mixer. This
combination of features enables reduced ADC sample rates and
lowers the downstream digital signal processing requirements if
the signal is digitized.
NOISE AT B
SENSOR
SIGNAL AT A, B
PHYSICAL
PARAMETER
12295-018
The ADA2200 is a synchronous demodulator and tunable
filter implemented with sampled analog technology (SAT).
Synchronous demodulators, also known as lock-in amplifiers,
enable accurate measurement of small ac signals in the presence
of noise interference orders of magnitude greater than the signal
amplitude. Synchronous demodulators use phase sensitive
detection to isolate the component of the signal at a specific
reference frequency and phase. Noise at frequencies that are
offset from the reference frequency are easily rejected and do
not significantly impair the measurement.
fREF
The output of the ADA2200 can also be used in an all analog
signal path. In these applications, add a reconstruction filter
following the ADA2200 in the signal path.
Figure 17. Output Spectrum of Synchronous Demodulator
Before Demodulation
SYNCHRONOUS DEMODULATION BASICS
Employing synchronous demodulation as a sensor signaling
conditioning technique can result in improved sensitivity when
compared to other methods. Synchronous demodulation adds
two key benefits for recovering small sensor output signals in
the presence of noise. The first benefit being the addition of an
excitation signal, which enables the sensor output signal to be
moved to a lower noise frequency band. The second benefit is
that synchronous demodulation enables a simple low-pass filter
to remove most of the remaining undesired noise components.
SENSOR
SIGNAL AT C, D
NOISE AT C
Figure 16 shows a basic synchronous demodulation system used
for measuring the output of a sensor.
fREF
Figure 18. Output Spectrum of Synchronous Demodulator
After Demodulation
fMOD
A
BPF
B
C
Phase Sensitive Detection
D
SENSOR
fREF
LPF
NOISE
Figure 16. Basic Synchronous Demodulator Block Diagram
12295-017
PHYSICAL
PARAMETER
12295-019
NOISE AT D
Synchronous demodulation uses the principle of phase sensitive
detection to separate the signal of interest from unwanted signals.
In Figure 16, the mixer performs the phase sensitive detection.
The signal at the mixer output (C) is the product of the reference
signal and a filtered version of the sensor output (B). If the
reference signal is a sine wave, the physical parameter is a
constant and there is no noise in the system. The signal at the
output of the BPF is a sine wave that can be expressed as
VBsin(ωREFt + ϕB)
Rev. 0 | Page 11 of 24
ADA2200
Data Sheet
DECIMATION FILTER
The output of the mixer (if implemented as a multiplier) is then
½VBVREFcos(ϕB − ϕREF) − ½VBVREFcos(2ωREFt + ϕB + ϕREF)
The clock signal divider (after CLKIN) determines the input
sampling frequency, fSI, of the decimation filter. The decimation
filter produces one filtered sample for every eight input samples.
Figure 20 shows the wideband frequency response of the
decimation filter. Because the filter operates on sampled data,
images of the filter appear at multiples of the input sample rate,
fSI. The stop band of the decimation filter begins around ½ of the
output data rate, fSO. Because an image pass band exists around
fSI, any undesired signals in the pass band around fSI alias to dc
and are indistinguishable from the low frequency input signal.
This signal is a dc signal and an ac signal at twice the reference
frequency. If the LPF is sufficient to remove the ac signal, the
signal at the LPF output (D) is
½VBVREFcos(ϕB − ϕREF)
The LPF output is a dc signal that is proportional to both the
magnitude and phase of the signal at the BPF output (B). When
the input amplitude is held constant, the LPF output enables can
be used to measure the phase. When the input phase is held
constant, the LPF can be used to measure amplitude.
To preserve the full dynamic range of the ADA2200, use an
input antialiasing filter if noise at frequencies above 7.5 fSI is not
lower than the noise floor of the frequencies of interest. A firstorder low-pass filter is usually sufficient for the antialiasing filter.
Note that the reference signal is not required to be a pure sine
wave. The excitation signal and demodulation signal must only
share a common frequency and phase to employ phase sensitive
detection. In some applications, it may be possible to use the
square wave output from the ADA2200 RCLK output directly.
Internal to the ADA2200, the demodulation is performed not
by multiplying the REFCLK signal with the input signal, but by
holding the output constant for ½ the sample output periods.
This operation is similar to a half wave demodulation of the
input signal. For more information on signal detection using
this function, see the Applications Information section.
f 0.5fSO
10
VDD
0
ADA2200
–10
PROGRAM
FILTER
fMOD
÷8
÷2n+1
fSO
VOCM
90°
VCM
RCLK/SDO
CLOCK
GEN
CONTROL
REGISTERS
SYNCO
GND
SPI
BOOT FROM
EEPROM (I2C)
RST
BOOT
–30
–40
–50
–60
SCLK/SCL
SDIO/SDA
CS/A0
–70
12295-020
XOUT
fSI
–20
OUTN
Figure 19. ADA2200 Architecture
–80
–90
0
fSO/4
fSO/2
3fSO/4
FREQUENCY
Figure 21. Decimation Filter Transfer Function, fSI = 800 kHz
Rev. 0 | Page 12 of 24
fSO
12295-022
8
LPF
OUTP
GAIN (dB)
INP
÷2m
7.5fSO
8.5fSO
8fSO = fSI
Figure 21 shows a more narrow bandwidth view of the
decimation transfer function. The stop band of the decimation
filter starts at ½ of the output sample rate. The stop band rejection
of the decimator low-pass filter is approximately 55 dB. The
pass band of the decimation filter extends to 1/4th of the output
sample rate or 1/32nd of the decimator input sample rate.
The signal path for the ADA2200 consists of a high impedance input
buffer followed by a fixed low-pass filter (FIR decimation filter),
a programmable IIR filter, a mixer function, and a differential pin
driver. Figure 19 shows a detailed block diagram of the ADA2200.
The signal processing blocks are all implemented using a charge
sharing technique.
CLKIN
2fSO
Figure 20. Decimation Filter Frequency Response
ADA2200 ARCHITECTURE
INN
fSO
12295-021
fSI – f fSI + f
Data Sheet
ADA2200
IIR FILTER
Table 8. IIR Coefficients for the All Pass Filter
The IIR block operates at the output sample rate, fSO, which is at
1/8th of the input sample rate (fSI). By default, the IIR filter is
configured as a band-pass filter with a center frequency at fSO/8
(fSI/64). This frequency corresponds to the default mixing
frequency and assures that input signals in the center of the pass
band mix down to dc.
Register
0x0011
0x0012
0x0013
0x0014
0x0015
0x0016
0x0017
0x0018
0x0019
0x001A
0x001B
0x001C
0x001D
0x001E
0x001F
0x0020
0x0021
0x0022
0x0023
0x0024
0x0025
0x0026
0x0027
Figure 22 shows the default frequency response of the IIR filter.
10
0
GAIN (dB)
–10
–20
–30
–50
0
0.25
0.50
0.75
1.00
NORMALIZED FREQUENCY (Hz/Nyquist)
12295-023
–40
Figure 22. Default IIR Filter Frequency Response (fSO/8 BPF)
If a different frequency response is required, the IIR can be
programmed for a different response. Register 0x0011 through
Register 0x0027 contain coefficient values that program the
filter response. To program the filter, first load the configuration
registers (Register 0x0011 through Register 0x0027) with the
desired coefficients. The coefficients can then be loaded into the
filter by writing 0x03 to Register 0x0010.
The IIR filter can be configured for all pass operation by
loading the coefficients listed in Table 8.
Value
0xC0
0x0F
0x1D
0xD7
0xC0
0x0F
0xC0
0x0F
0x1D
0x97
0x7E
0x88
0xC0
0x0F
0xC0
0x0F
0xC0
0x0F
0x00
0x0E
0x23
0x02
0x24
MIXER
The ADA2200 performs the mixing function by holding the
output samples constant for ½ of the RCLK period. This is
similar to a half-wave rectification function except that the
output does not return to zero for ½ the output period, but
retains the value of the previous sample.
In the default configuration, there are eight output sample periods
during each RCLK cycle. There are four updated output samples
while the RCLK signal is high. While RCLK is low, the fourth
updated sample is held constant for four additional output
sample periods. The timing of the output samples in the default
configuration is shown in Table 4.
The RCLK divider, RCLK DIV[1:0], can be set to divide fSO by 4.
When this mode is selected, four output sample periods occur
during each RCLK cycle. Two output samples occur while the
RCLK signal is high. While RCLK is low, the second updated
sample is held constant for two additional output sample periods.
The mixer can be bypassed. When the mixer is bypassed, the output
produces an updated sample value every output sample period.
Rev. 0 | Page 13 of 24
ADA2200
Data Sheet
Phase Shifter
CLOCKING OPTIONS
It is possible to change the timing of the output samples with
respect to RCLK by writing to the PHASE90 bit in Register
0x002A. When the alternative timing option is selected, two
output samples are updated while RCLK is low, and two are
updated while RCLK is high. The second sample, which is taken
while RCLK is high, is held four additional output sample
periods. The timing is shown in Figure 5.
The ADA2200 has several clocking options to make system
integration easier.
Clock Dividers
The ADA2200 has a pair of on-chip clock dividers to generate
the system clocks. The input clock divider, CLKIN DIV[2:0], sets
the input sample rate of the decimator (fSI) by dividing the CLKIN
signal. The value of CLKIN DIV[2:0] can be set to 1, 16, 64, or 256.
Applying a 90° phase shift can be useful in a number of instances. It
enables a pair of ADA2200 devices to perform in phase and
quadrature demodulation. A 90° phase shift can also be useful in
control systems for selecting an appropriate error signal output.
The output sample rate (fSO) is always 1/8th of the decimator
input sample rate.
The RCLK divider, RCLK DIV[1:0], sets the frequency of the
mixer frequency, fM (which is also the frequency of RCLK) by
dividing fSO by either 4 or 8.
Synchronization Pulse Output
The ADA2200 generates an output pulse (SYNCO), which can
be used by a microprocessor or directly by an ADC to initiate
an analog to digital conversion of the ADA2200 output. The
SYNCO signal ensures that the ADC sampling occurs at an
optimal time during the ADA2200 output sample window.
One output sample of the ADA2200 is 8 fSI clock cycles long.
The SYNCO pulse is 1 fSI clock cycle in duration. As shown in
Figure 24, the SYNCO pulse can be programmed to occur at 1
of 16 different timing offsets. The timing offsets are spaced at ½
fSI clock cycle intervals and span the full output sample window.
(A)
The SYNCO pulse can be inverted, or the SYNCO output can
be disabled. The operation of the SYNCO timing generation
configuration settings are contained in Register 0x0029.
INx, OUTx
SYNCO (0)
Figure 23. Output Sample Timing Relative to RCLK,
(A) PHASE90 = 0, (B) PHASE90 = 1
SYNCO (13)
SYNCO (14)
SYNCO (15)
CLKIN
0
2
4
6
8
10
12
Figure 24. SYNCO Output Timing Relative to OUTP/OUTN, INP/INN,
and CLKIN
Rev. 0 | Page 14 of 24
12295-025
(B)
12295-024
SYNCO (1)
Data Sheet
ADA2200
INPUT AND OUTPUT AMPLIFIERS
For single-ended outputs, either OUTP or OUTN can be used.
Leave the unused output floating.
Single-Ended Configurations
If a single-ended input configuration is desired, the input signal
must have a common-mode voltage near midsupply. Decouple the
other inputs to the common-mode voltage of the input signal.
Note that differences between the common-mode levels
between the INP and INN inputs result in an offset voltage
inside the device. Even though the BPF removes the offset,
minimize the offset to avoid reducing the available signal swing
internal to the device.
Differential Configurations
Using the ADA2200 in differential mode utilizes the full
dynamic range of the device and provides the best noise
performance and common-mode rejection.
Rev. 0 | Page 15 of 24
ADA2200
Data Sheet
APPLICATIONS INFORMATION
The signal present at the output of the ADA2200 depends on
the amplitude and relative phase of the signal applied at it inputs.
When the amplitude or phase is known and constant, any
output variations can be attributed to the modulated parameter.
Therefore, when the relative phase of the input is constant, the
ADA2200 performs amplitude demodulation. When the amplitude
is constant, the ADA2200 performs phase demodulation.
The sampling and demodulation processes introduce additional
frequency components onto the output signal. If the output
signal of the ADA2200 is used in the analog domain or if it is
sampled asynchronously to the ADA2200 sample clock, these high
frequency components can be removed by following the
ADA2200 with a reconstruction filter.
If the ADA2200 output is sampled synchronously to the
ADA2200 output sample rate, an analog reconstruction filter is
not required because the ADC inherently rejects sampling
artifacts. The frequency artifacts introduced by the
demodulation process can be removed by digital filtering.
AMPLITUDE MEASUREMENTS
If the relative phase of the input signal to the ADA2200 remains
constant, the output amplitude is directly proportional to the
amplitude of the input signal. Note that the signal gain is a
function of the relative phase of the input signal. Figure 15 shows
the relationship between the cycle mean output and the relative
phase. The cycle mean output voltage is
The phase sensitivity also varies with relative phase. The
sensitivity is at a maximum when θREL = 83°. For this reason, the
optimal measurement range is for input signals with a relative
phase equal to the phase delay of ±45°. This range provides the
highest gain and thus the largest signal-to-noise ratio
measurement. This range is also the operating point with the
lowest sensitivity to changes in the relative phase. Operating at a
relative phase equal to the phase delay of −135° to −225° offers
the same gain and measurement accuracy, but with a sign
inversion.
The phase sensitivity with a 4 V p-p differential input operating
with a relative phase that is equal to the phase delay results in a
phase sensitivity of 36.6 mV/°θREL.
AMPLITUDE AND PHASE MEASUREMENTS
When both the amplitude and relative phase of the input signals
are unknown, it is necessary to obtain two orthogonal
components of the signal to determine its amplitude, relative
phase, or both. These two signal components are referred to as
the in-phase (I) and quadrature (Q) components of the signal.
A signal with two known rectangular components is represented as
a vector or phasor with an associated amplitude and phase (see
Figure 25).
II
I
A
Q
VCYCLEMEAN = Conversion Gain × VIN(RMS) × sin(θREL − θDEL) =
θ
I
Therefore, the highest gain, and thus the largest signal-to-noise
ratio measurement, is obtained when operating the ADA2200
with θREL = θDEL + 90° = 173°. This value of θREL is also the
operating point with the lowest sensitivity to changes in the
relative phase. Operating with θREL = θDEL − 90° = −7° offers the
same gain and measurement accuracy, but with a sign inversion.
PHASE MEASUREMENTS
If the amplitude of the input signal to the ADA2200 remains
constant, the output amplitude is a function of the relative
phase of the input signal. The relative phase can be measured as
θREL = sin−1(VCYCLEMEAN/(Conversion Gain × VIN(RMS))) + θDEL =
sin−1(VCYCLEMEAN/(1.05 × VIN(RMS))) + θDEL
Note that the output voltage scales directly with the input signal
amplitude. A full-scale input signal provides the greatest phase
sensitivity (V/°θREL) and thus the largest signal-to-noise ratio
measurement.
III
IV
12295-026
1.05 ×VIN(RMS) × sin(θREL − θDEL)
Figure 25. Rectangular and Polar Representation of a Signal
If the signal amplitude remains nearly constant for the duration
of the measurement, it is possible to measure both the I and the
Q components of the signal by toggling the PHASE90 bit
between two consecutive measurements. To measure the I
component, set the PHASE90 bit to 0. To measure the Q
component, set the PHASE90 bit to 1.
After both the I and Q components have been obtained, it is
possible to separate the effects of the amplitude and phase
variations. Then, calculate the magnitude and relative phase
using the following formulas:
A=
I 2 + Q2
θ REL = cos –1 Q A + θ DEL
Or alternatively
θ REL = sin –1 I A + θ DEL
Rev. 0 | Page 16 of 24
Data Sheet
ADA2200
Figure 26 shows an 8-channel system with a 1 MHz aggregate
throughput rate. The ADA2200 samples each channel at 1 MSPS
and produces filtered samples at an output sample rate of 125 kHz
each. The AD7091R-8 is an 8-channel, 1 MHz ADC with
multiplexed inputs, which cycle through the eight channels at
125 kHz, producing an aggregate output sample rate of 1 MHz.
1MHz
SAMPLE
CLOCK
CLKIN
AD7091R-8
Similar to a digital-to-analog converter (DAC), the output of
the ADA2200 is a stepwise continuous output. This waveform
contains positive and negative images of the desired signal at
multiples of fSO. In most cases, the images are undesired noise
components that must be attenuated.
The lowest frequency image to appear in the output spectrum
appears at a frequency of fSO − fIN. The image amplitude is
reduced by the sin(x)/x roll-off. System accuracy requirements
may dictate that additional low-pass filtering is required to remove
the output sample images.
INTERFACING TO ADCS
Settling Time Considerations
If the ADC is coherently sampling the ADA2200 outputs,
design the output filter to ensure that the output samples settle
prior to ADC sampling. The output filter does not need to
remove the sampling images generated by the ADA2200. The
images are inherently rejected by the ADC sampling process.
Clock Synchronization
In multichannel systems that require simultaneous sampling,
the ADA2200 can provide per channel programmable filtering
and simultaneous sampling.
12-BIT
ADC
CS
SCLK
DOUT
DIN
CS
SCLK
MISO
MOSI
MICROCONTROLLER
SEQUENCER
8 CHANNELS
SIMULTANEOUSLY
SAMPLED
AT 125kHz EACH
SIMULTANEOUS
SAMPLING AND
FILTERING
Figure 26. ADA2200 in an 8-Channel Simultaneous Sampling Application
LOCK-IN AMPLIFIER APPLICATION
Figure 27 shows the ADA2200 in a lock-in amplifier
application. The 80 kHz master clock signal sets the input
sample rate of the decimation filter, fSI. The output sample rate
is 10 kHz. In the default configuration, the excitation signal
generated by RCLK is 1.25 kHz. This is also the center
frequency of the on-chip IIR filter.
In many cases, the RCLK signal is buffered to provide a square
wave excitation signal to the sensor. It may also be desirable to
provide further signal conditioning to provide a sine wave
excitation signal to the sensor.
A low noise instrumentation amplifier provides sufficient gain
to amplify the signal so that the noise floor of the signal into the
ADA2200 is above the combined noise floor of the ADA2200
and the ADC referred to the ADA2200 inputs.
3.3V
MASTER
CLOCK
VDD
CLKIN SYNCO
RCLK/SDO
ADA2200
SENSOR
EXCITATION
CONDITIONING
AD8227
The SYNCO output can trigger the ADC sampling process
directly, or a microcontroller can use SYNCO to adjust the
ADC sampling time. Adjusting the SYNCO pulse timing can
maximize the available time for the ADA2200 outputs to settle
prior to ADC sampling.
Multichannel ADCs
ADA2200
CH8
8:1
MUX
12295-028
The bandwidth of the analog reconstruction filter sets the
demodulation bandwidth of the analog output. There is a direct
trade-off between the noise and demodulation bandwidth.
Therefore, it is recommended to ensure that the reconstruction
filter cutoff frequency is as low as possible while minimizing the
attenuation of the demodulated signal of interest.
ADA2200
CH2
Reconstruction Filters
IRQ
ADA2200
CH1
ANALOG OUTPUT SYSTEMS
When the output signal of the ADA2200 is used in the analog
domain or if it is sampled asynchronously to the ADA2200 sample
clock, it is likely that a reconstruction filter is required.
CLK0
SYNCO
DUT
OR
SENSOR
INP
INN
VOCM
OUTP
AD7170
OUTN
GND
REF
AD8613
Figure 27. Lock-In Amplifier Application
In default mode, the ADA2200 produces eight output samples
for every cycle of the excitation (RCLK) signal. There are four
unique output sample values. The fourth value appears on the
output for five consecutive output sample periods.
Rev. 0 | Page 17 of 24
12295-029
The inverse sine or inverse cosine functions linearize the
relationship between the relative phase of the signal and the
measured angle. Because the inverse sine and inverse cosine are
only defined in two quadrants, the sign of I and Q must be
considered to map the result over the entire 360° range of
possible relative phase values. The use of the inverse tangent
function is not recommended because the phase measurements
become extremely sensitive to noise as the calculated phase
approaches ±90°.
ADA2200
Data Sheet
There are several ways of digitally processing the output samples to
optimize measurement accuracy, bandwidth, and throughput
rate. One method is to take the sum of eight samples to return a
value. A moving average filter lowers the noise floor of the
returned values. The length of the moving average filter is
determined by the noise floor and settling time requirements.
INTERFACING TO MICROCONTROLLERS
The ADA2200 current draw is composed of two main
components, the amplifier bias currents and the switched
capacitor currents. The amplifier currents are independent of
clock frequency; the switched capacitor currents scale in direct
proportion to fSI.
Figure 30 shows the ADA2200 measured typical current draw at
supply voltages of 2.7 V and 3.3 V, as the input clock varies from
1 kHz to 1 MHz, with CLKIN DIV[2:0] = 1. With a 3.3 V supply
voltage, the current draw can be estimated with the following
equation:
The diagram in Figure 28 shows basic circuit configuration
driven by a low power microcontroller (the ADuCM361). In
this case, the ADA2200 reduces the ADC sampling rate by a
factor of 8, and reduces the subsequent signal processing
required by the microcontroller.
IDD = 290 × 0.2 × fCLKIN µA
3.3V
where fCLKIN is specified in kHz.
AIN0
INN
OUTN
AIN1
P1.2
P0.6/IRQ2
RST
BOOT
P1.1
P1.0
475
VREF–
AGND
ADA2200
VOCM CLKIN
XOUT SYNCO
450
425
DVDD_REG
AVDD_REG
0.47µF
×2
P1.7/CS0
P0.3/CS1
P1.6/MOSI0 P0.0/MISO1
P1.4/MISO0 P0.2/MOSI1
P1.5/SCLK0 P0.1/SCLK1
CS/A0
SDIO/SDA
RCLK/SDO
SCLK/SCL
500
TO HOST,
MEMORY
OR
INTERFACE
350
275
250
0
EEPROM BOOT CONFIGURATION
VDD
OUTPUT
EXCITATION
3.3V
RST
EEPROM*
SCL A0
SDA A1
A2
*AT24C02 OR EQUIVALENT
12295-031
CS/A0
BOOT
CLKIN SCLK/SCL
SDIO/SDA
XOUT
GND
400
600
800
1000
Figure 30. Typical Current Draw vs. CLKIN Frequency at VDD = 2.7 V and 3.3 V
3.3V
3.3V
200
CLKIN FREQUENCY (kHz)
The diagram in Figure 29 shows a standalone configuration
with an EEPROM boot for the ADA2200. The standard
oscillator circuit between CLKIN and XOUT generates the
clock signal. Holding BOOT low during a power-on reset
(POR) forces the ADA2200 to load its configuration from a
preprogrammed EEPROM. An EEPROM boot is also initiated
by bringing the BOOT pin low while the device in not in reset.
OUTP
INP
OUTN
INN
VOCM RCLK/SDO
2.7V
300
Figure 28. Fully Programmable Configuration:
Interface to Low Power Microcontroller
INPUT
375
325
NOTES
1. SOME PIN NAMES OF THE ADuCM361 HAVE BEEN SIMPLIFIED FOR CLARITY.
ADA2200
3.3V
400
IDD (µA)
VDD
OUTP
12295-030
INP
+VS
0.47µF
VREF+
AVDD
IOVDD
12295-032
ADuCM361
GND
POWER DISSIPATION
Figure 29. Standalone Configuration
Rev. 0 | Page 18 of 24
Data Sheet
ADA2200
DEVICE CONFIGURATION
The ADA2200 has several registers that can be programmed to
customize the device operation. There are two methods for
programming the registers: the device can be programmed over
the serial port interface, or the I2C master can be used to read
the configuration from a serial EEPROM.
SERIAL PORT OPERATION
The serial port is a flexible, synchronous serial communications
port that allows easy interfacing to many industry-standard microcontrollers and microprocessors. The serial I/O is compatible
with most synchronous transfer formats, including both the
Motorola SPI and Intel® SSR protocols. The interface allows
read/write access to all registers that configure the ADA2200.
Single-byte or multiple-byte transfers are supported, as well as
MSB first or LSB first transfer formats. The serial port interface can
be configured as a single-pin I/O (SDIO) or as two unidirectional
pins for input and output (SDIO and SDO).
A communication cycle with the ADA2200 has two phases.
Phase 1 is the instruction cycle (the writing of an instruction
byte into the device), coincident with the first 16 SCLK rising
edges. The instruction byte provides the serial port controller with
information regarding the data transfer cycle—Phase 2 of the
communication cycle. The Phase 1 instruction byte defines
whether the upcoming data transfer is a read or write, along with
the starting register address for the first byte of the data transfer.
The first 16 SCLK rising edges of each communication cycle are
used to write the instruction byte into the device.
A logic high on the CS/A0 pin followed by a logic low resets the
serial port timing to the initial state of the instruction cycle.
From this state, the next 16 rising SCLK edges represent the
instruction bits of the current I/O operation.
The remaining SCLK edges are for Phase 2 of the communication
cycle. Phase 2 is the actual data transfer between the device and
the system controller. Phase 2 of the communication cycle is a
transfer of one or more data bytes. Registers change immediately
upon writing to the last bit of each transfer byte.
DATA FORMAT
The instruction byte contains the information shown in Table 9.
Table 9. Serial Port Instruction Byte
MSB
I15
R/W
I14
A14
I13
A13
I12
A12
…
…
I2
A2
I1
A1
LSB
I0
A0
R/W, Bit 15 of the instruction byte, determines whether a read or a
write data transfer occurs after the instruction byte write. Logic 1
indicates a read operation, and Logic 0 indicates a write operation.
A14 to A0, Bit 14 to Bit 0 of the instruction byte, determine the
register that is accessed during the data transfer portion of the
communication cycle. For multibyte transfers, A14 is the starting
byte address. The remaining register addresses are generated by
the device based on the LSB first bit (Register 0x0000, Bit 6).
SERIAL PORT PIN DESCRIPTIONS
Serial Clock (SCLK/SCL)
The serial clock pin synchronizes data to and from the device
and runs the internal state machines. The maximum frequency
of SCLK is 20 MHz. All data input is registered on the rising edge
of the SCLK signal. All data is driven out on the falling edge of
the SCLK signal
Chip Select (CS/A0)
An active low input starts and gates a communication cycle.
It allows more than one device to be used on the same serial
communications lines. When the CS/A0 pin is high, the SDO
and SDIO signals go to a high impedance state. Keep the CS/A0
pin low throughout the entire communication cycle.
Serial Data I/O (SDIO/SDA)
Data is always written into the device on this pin. However, this
pin can be used as a bidirectional data line. The configuration
of this pin is controlled by Register 0x0000, Bit 3 and Bit 4. The
default is Logic 0, configuring the SDIO/SDA pin as unidirectional.
Serial Data Output (RCLK/SDO)
If the ADA2200 is configured for 4-wire SPI operation, this pin
can be used as the serial data output pin. If the device is configured
for 3-wire SPI operation, this pin can be used as an output for
the reference clock (RCLK) signal. Setting the RCLK select bit
(Register 0x002A, Bit 3) high activates the RCLK signal.
SERIAL PORT OPTIONS
The serial port can support both MSB first and LSB first data
formats. This functionality is controlled by the LSB first bit
(Register 0x0000, Bit 6). The default is MSB first (LSB first = 0).
When the LSB first bit = 0 (MSB first), the instruction and data
bits must be written from MSB to LSB. Multibyte data transfers
in MSB first format start with an instruction byte that includes the
register address of the most significant data byte. Subsequent data
bytes follow from high address to low address. In MSB first
mode, the serial port internal byte address generator decrements
for each data byte of the multibyte communication cycle.
When the LSB first bit = 1, the instruction and data bits must be
written from LSB to MSB. Multibyte data transfers in LSB first
format start with an instruction byte that includes the register
address of the least significant data byte. Subsequent data bytes
follow from the low address to the high address. In LSB first
mode, the serial port internal byte address generator increments
for each data byte of the multibyte communication cycle.
If the MSB first mode is active, the data address is decremented
for each successive read or write operation performed in a
multibyte register access. If the LSB first mode is active, the data
address increments for each successive read or write operation
performed in a multibyte register access.
Rev. 0 | Page 19 of 24
ADA2200
Data Sheet
INSTRUCTION CYCLE
DATA TRANSFER CYCLE
CS
SDIO
R/W A14 A13
A3
A2 A1
A0 D7N D6N D5N
D30 D20 D10 D00
12295-033
SCLK
Figure 31. Serial Port Interface Timing, MSB First
INSTRUCTION CYCLE
DATA TRANSFER CYCLE
The load cycle completes within 10,000 clock cycles of CLKIN
(or CLKIN divided by the current value of CLKIN DIV[2:0] if
the load cycle is being initiated by the BOOT pin).
CS
A0
A1
A2
A12 A13 A14 R/W D00 D10 D20
D4N D5N D6N D7N
12295-034
SCLK
SDIO
In addition, the LSB of the EEPROM status register indicates
whether the load cycle is complete. Logic 1 represents successful
completion of the load cycle. Logic 0 represents the occurrence of
a timeout violation during the loading cycle. In the event of a timeout or the successful completion of the load from a memory cycle,
the ADA2200 I2C master interface disables, and the ADA2200
SPI interface reenables, allowing the user communication access to
the device.
Figure 32. Serial Port Interface Timing, LSB First
BOOTING FROM EEPROM
The device can load the internal registers from the EEPROM using
the internal I2C master to customize the operation of the ADA2200.
To enable this feature, the user must control either the RST pin
or the BOOT pin. In either case, the device boots from the
EEPROM only when it is out of reset and the master clock is active.
Enabling Load from Memory
A boot from the EEPROM is initiated by two methods.
To initiate loading via the BOOT pin, the device must be out of
reset, and the BOOT pin is brought low for a minimum of two
clock cycles of the master clock. After it is initiated, the boot
completes irrespective of the state of the BOOT pin. To initiate
subsequent boots, the BOOT pin must be brought high and
then low for a minimum of two clock cycles of the master clock.
To initiate loading via the RST pin, the BOOT pin must be low.
The RST pin can be tied high and the ADA2200 loads from the
EEPROM when the device is powered up and the internal POR
cycle completes. To initiate subsequent boots, the ADA2200 can
be power cycled or the RST pin can be brought low and then high.
Dual Configuration/Dual Device Memory Load
The CS/A0 pin allows a single EEPROM device to support a dual
configuration for a single ADA2200 device or different
configurations for two different ADA2200 devices. To ensure
reliable operation, set the CS/A0 pin to the desired state before
initiating a boot, and then hold the state for the entire duration
of the boot.
To configure a single ADA2200 device, the EEPROM must have a
word page size that supports a minimum of 32 words, each of 8 bits
per word. To support two devices, or a dual configuration for a
single device, the EEPROM must have at least two word pages.
The ADA2200 configuration data for each device must be
allocated to the EEPROM memory within a single word page.
Using SPI Master with EEPROM Loading
The load from a memory cycle requires an I2C communication
bus between the ADA2200 and the EEPROM device; however,
the ADA2200 can still be controlled by the SPI interface after the
load from the memory cycle is complete. It is recommended that
the CS/A0 pin return to logic high after the load from the memory
cycle and before the first SPI read or write command. This allows
the user to ensure that the proper setup time elapses before the
initiation of a SPI read/write command (see Table 2).
The SPI interface is disabled while the ADA2200 is loading the
EEPROM.
Load from Memory Cycle
The ADA2200 reads the first 28 bytes of the EEPROM. The first
27 bytes represent the contents to be loaded into Register 0x0011 to
Register 0x0027. Byte 28 contains the checksum stored in the
EEPROM.
The ADA2200 calculates the checksum for the first 27 bytes that
it reads back and compares it to the checksum in the EEPROM.
The ADA2200 calculated checksum is accessible by reading the
EEPROM checksum register (Register 0x002E). If the ADA2200
checksum matches the checksum stored in the EEPROM, the
load from the EEPROM was successful. The load from the
EEPROM pass or fail status is recorded in the EEPROM status
register (Register 0x002F).
Rev. 0 | Page 20 of 24
Data Sheet
ADA2200
DEVICE CONFIGURATION REGISTER MAP AND DESCRIPTIONS
Table 10. Device Configuration Register Map1
Addr.
(Hex)
0x0000
0x0006
0x0010
0x0011 to
0x0027
0x0028
Register
Name
Serial
interface
Chip type
Filter strobe
Filter
configuration
Analog pin
configuration
Bit 7
Reset
Bit 6
LSB first
0
Bit 5
Address
increment
0
Bit 4
SDO
active
0
0
0
0
0
0
X
X
X
X
SYNCO
invert
Mixer
enable
Bit 3
SDO
active
0
Coefficient[7:0]
X
Bit 2
Bit 1
Address
LSB first
increment
Die revision[3:0]
0
X
INP gain
Sync control
X
X
0x002A
Demod
control
Clock
configuration
Digital pin
configuration
X
PHASE90
SYNCO output
enable
X
X
X
X
X
X
X
X
X
X
X
Core reset
Checksum
X
X
X
X
X
X
Checksum value[7:0]
X
EEPROM
status
X
X
X
X
X
0x002C
0x002D
0x002E
0x002F
1
2
Default2
0x00
0x00
(read
only)
0x00
See
Table 11
0x00
Load coefficients[1:0]
0x0029
0x002B
Bit 0
Reset
Clock
source
select
SYNCO edge select[3:0]
RCLK
select
CLKIN DIV[2:0]
Checksum
failed
0x2D
VOCM select[2:0]
0x18
RCLK DIV[1:0]
Checksum
passed
0x02
RCLK/SDO
output
enable
Core reset
0x01
0x00
N/A
(read
only)
N/A
(read
only)
Boot from
EEPROM
complete
X means don’t care.
N/A means not applicable.
Table 11. Device Configuration Register Descriptions
Name
Serial
Interface
Chip Type
Address
(Hex)
0x0000
0x0006
Bits
7
Bit Name
Reset
Description
Writing a 1 to this bit places the device in reset. The device
remains in reset until a 0 is written to this bit. All of the
configuration registers return to their default values.
Default1
0
6
LSB first
0
5
Address increment
4
SDO active
3
2
1
0
[3:0]
SDO active
Address increment
LSB first
Reset
Die revision[3:0]
Serial port communication, LSB or MSB first.
0 = MSB first.
1 = LSB first.
Controls address increment mode for multibyte register access.
0 = address decrement.
1 = address increment.
4-wire SPI select.
0 = SDIO operates as a bidirectional input/output. The SDO signal
is disabled.
1 = SDIO operates as an input only. The SDO signal is active.
This bit is a mirror of Bit 4 in Register 0x0000.
This bit is a mirror of Bit 5 in Register 0x0000.
This bit is a mirror of Bit 6 in Register 0x0000.
This bit is a mirror of Bit 7 in Register 0x0000.
Die revision number.
Rev. 0 | Page 21 of 24
0
0
0
0
0
0
0000
ADA2200
Name
Filter Strobe
Filter
Configuration
Analog Pin
Configuration
Data Sheet
Address
(Hex)
0x0010
Bits
[7:0]
Bit Name
Load coefficients[1:0]
0x0011
0x0012
0x0013
0x0014
0x0015
0x0016
0x0017
0x0018
0x0019
0x001A
0x001B
0x001C
0x001D
0x001E
0x001F
0x0020
0x0021
0x0022
0x0023
0x0024
0x0025
0x0026
0x0027
0x0028
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
[7:0]
1
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
Coefficient[7:0]
INP gain
0
Clock source select
Sync Control
0x0029
5
4
[3:0]
SYNCO output enable
SYNCO invert
SYNCO edge select
Demod
Control
0x002A
6
PHASE90
4
Mixer enable
3
RCLK select
[2:0]
VOCM select
Description
When toggled from 0 to 1, the filter coefficients in configuration
Register 0x0011 through Register 0x0027 are loaded into the IIR filter.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
Programmable filter coefficients.
1 = only the INP input signal is sampled. An additional 6 dB of
gain is applied to the signal path.
Default1
00
0 = device is configured to generate a clock if a crystal or
resonator is placed between the XOUT and CLKIN pins.
1 = device is configured to accept a CMOS level clock on the
CLKIN pin. The internal XOUT driver is disabled.
1 = enables the SYNCO output pad driver.
1 = inverts the SYNCO signal.
These bits select one of 16 different edge locations for the SYNCO
pulse relative to the output sample window. See Figure 24 for details.
1 = delays the phase between the RCLK output and the strobe
controlling the mixing signal. See Figure 23 for details.
1 = the last sample that is taken while RCLK is active remains held
while RCLK is inactive.
0 = sends the SDO signal to the output driver of Pin 13.
1 = sends the RCLK signal to the output driver of Pin 13.
000 = set the VOCM pin to VDD/2. Low power mode.
001 = use the external reference to drive VOCM.
010 = set the VOCM pin to VDD/2. Fast settling mode.
101 = set the VOCM pin to 1.2 V.
0
Rev. 0 | Page 22 of 24
0xC022
0x0F2
0x1D2
0xD72
0xC02
0x0F2
0xC02
0x0F2
0x1D2
0x972
0x7E2
0x882
0xC02
0x0F2
0xC02
0x0F2
0xC02
0x0F2
0x002
0xE02
0x232
0x022
0x242
0
1
0
1101
0
1
1
000
Data Sheet
Name
Clock
Configuration
Address
(Hex)
0x002B
ADA2200
Bits
[4:2]
Bit Name
CLKIN DIV[2:0]
[1:0]
RCLK DIV[1:0]
Description
The division factor between fCLKIN and fSI.
000 = divide by 1.
001 = divide by 16.
010 = divide by 64.
100 = divide by 256.
These bits set the division factor between fSO and fM.
00 = reserved.
01 = the frequency of RCLK is fSO/4.
10 = the frequency of RCLK is fSO/8.
11 = reserved.
1 = RCLK/SDO output pad driver is enabled.
Digital Pin
Configuration
Core Reset
0x002C
0
0x002D
0
RCLK/SDO output
enable
Core reset
Checksum
0x002E
[7:0]
Checksum value[7:0]
EEPROM
Status
0x002F
2
Checksum failed
1
Checksum passed
0
Boot from EEPROM
complete
2
NA/ means not applicable.
The filter coefficients listed are the default values programmed into the filter on reset. The value read back from the registers is 0x00.
VDD
ADA2200
BPF
INP
OUTP
8
0x0028[1]
INN
S/H
fNYQ/4
LPF
0x0024
TO
0x0027
OUTN
VOCM
0x002A[4]
0
VOCM
GEN
1
0x002A[6]
0x002B[4:2]
CLKIN
fCLKIN
{000,001,010,100}
fSI
÷ {1,16,64,256}
TRI
÷8
SYNC
GEN
fSO
{1,0}
÷ {4,8}
0x002A[2:0]
0
0x002B[0]
1
90°
fM
1
EN
RCLK/SDO
0
RCLK
0x002C[0]
0x002A[3]
0x0029[3:0]
0x0029[4]
0x0028[0]
CLKIN
1
XOUT
÷32
SDO
EN
0
EN
SPI/I2C
MASTER
CONTROL
REGISTERS
SCLK/SCL
SDIO/SDA
CS/A0
0x0029[5]
SYNCO
RST
Figure 33. Detailed Block Diagram
Rev. 0 | Page 23 of 24
BOOT
12295-037
1
1 = puts the device core into reset. The values of the SPI registers
are preserved. This does not initiate a boot from the EEPROM.
0 = core reset is deasserted.
This is the 8-bit checksum calculated by the ADA2200, performed
on the data it reads from the EEPROM.
1 = calculated checksum does not match the checksum byte read
from the EEPROM.
1 = calculated checksum matches the checksum byte read from
the EEPROM.
1 = boot from the EEPROM has completed.
0 = boot from the EEPROM has timed out. Wait 10,000 clock
cycles after the boot is initiated to check for boot completion.
Default1
000
10
1
0
N/A
N/A
N/A
N/A
ADA2200
Data Sheet
OUTLINE DIMENSIONS
5.10
5.00
4.90
16
9
4.50
4.40
4.30
6.40
BSC
1
8
PIN 1
1.20
MAX
0.15
0.05
0.20
0.09
0.30
0.19
0.65
BSC
COPLANARITY
0.10
SEATING
PLANE
8°
0°
0.75
0.60
0.45
COMPLIANT TO JEDEC STANDARDS MO-153-AB
Figure 34. 16-Lead Thin Shrink Small Outline Package [TSSOP]
(RU-16)
Dimensions shown in millimeters
ORDERING GUIDE
Model1
ADA2200ARUZ
ADA2200ARUZ-REEL7
ADA2200-EVALZ
ADA2200SDP-EVALZ
1
Temperature Range
−40°C to +85°C
−40°C to +85°C
Package Description
16-Lead Thin Shrink Small Outline Package [TSSOP]
16-Lead Thin Shrink Small Outline Package [TSSOP]
Evaluation board with EEPROM boot
Evaluation board with SDP-B interface option
Z = RoHS-Compliant Part.
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).
©2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D12295-0-8/14(0)
Rev. 0 | Page 24 of 24
Package Option
RU-16
RU-16