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AD1555BPZ

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
a
AD1555/AD1556
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2002
FUNCTIONAL BLOCK DIAGRAM
MUX
PGA
REF DIVIDER
DAC
MODE CONTROL
LOGIC
OVERVOLTAGE
DETECTION
CLOCK
GENERATION
LOOP
FILTER
REFIN REFCAP2 REFCAP1 AGND3
DGNDV
L
–V
A
+V
A
AGND2MODINPGAOUTAGND1 CLKIN SYNC BW0...BW2 RESET PWRDN GND V
L
AIN (+)
AIN (–)
TIN (+)
TIN (–)
AD1555
CB0...CB4
PGA
CONTROL
CONFIGURATION
REGISTER
STATUS
REGISTER
INPUT
MUX
MFLG
MDATA
TDATA
CSEL
MCLK
INPUT SHIFT
REGISTER
DIN
SCLK
CS
R/W
DOUT
DRDY
RSEL
CLOCK DIVIDER
DATA
OUTPUT
MUX
DATA
REGISTER
AD1556
H/S ERRORPGA0...PGA4
DIGITAL
FILTER
24-Bit - ADC
with Low Noise PGA
FEATURES
AD1555
Fourth Order - Modulator
Large Dynamic Range
116 dB Min, 120 dB Typical @ 1 ms
117 dB Typical @ 0.5 ms
Low Input Noise: 80 nV rms @ 4 ms with
Gain of 34,128
Low Distortion: –111 dB Max, –120 dB Typical
Low Intermodulation: 122 dB
Sampling Rate at 256 kSPS
Very High Jitter Tolerance
No External Antialias Filter Required
Programmable Gain Front End
Input Range: 2.25 V
Robust Inputs
Gain Settings: 1, 2.5, 8.5, 34, 128
Common-Mode Rejection (DC to 1 kHz)
93 dB Min, 101 dB Typical @ Gain of 1
77 mW Typical Low Power Dissipation
Standby Modes
AD1556
FIR Digital Filter/Decimator
Serial or Parallel Selection of Configuration
Output Word Rates: 250 SPS to 16 kSPS
6.2 mW Typ Low Power Dissipation
70 W in Standby Mode
Reference Design and Evaluation Board with
Software Available
APPLICATIONS
Seismic Data Acquisition Systems
Chromatography
Automatic Test Equipment
GENERAL DESCRIPTION
The AD1555 is a complete sigma-delta modulator, combined
with a programmable gain amplifier intended for low frequency,
high dynamic range measurement applications. The AD1555
outputs a ones-density bitstream proportional to the analog
input. When used in conjunction with the AD1556 digital filter/
decimator, a high performance ADC is realized.
The continuous-time analog modulator input architecture avoids
the need for an external antialias filter. The programmable gain
front end simplifies system design, extends the dynamic range,
and reduces the system board area. Low operating power and
standby modes makes the AD1555 ideal for remote battery-pow-
ered data acquisition systems.
The AD1555 is fabricated on Analog Devices’ BiCMOS process
that has high performance bipolar devices along with CMOS
transistors. The AD1555 and AD1556 are packaged, respectively,
in 28-lead PLCC and 44-lead MQFP packages and are specified
from –55°C to +85°C (AD1556 and AD1555 B Grade) and from
0°C to 85°C (AD1555 A Grade).
0
FREQUENCY – Hz
–120
–200
0
50
AMPLITUDE – dBr
100 150 200 250 300
–20
–100
–140
–180
–60
–80
–160
–40
350 400 450 500
f
IN
= 24.4Hz
SNR = 116.7dB
THD = –120.6dB
Figure 1. FFT Plot, Full-Scale AIN Input, Gain of 1
REV. B
AD1555/AD1556
–2–
AD1555BP AD1555AP
Parameter Notes Min Typ Max Min Typ Max Unit
PGA Gain Settings 1, 2.5, 8.5, 34, 128
AC ACCURACY
Dynamic Range
1
PGA Gain of 1 116.5 120 116 120 dB
PGA Gain of 2.5 116 119.5 115.5 119.5 dB
PGA Gain of 8.5 114 117.5 114 117.5 dB
PGA Gain of 34 104.5 109.5 104.5 109.5 dB
PGA Gain of 128 98 98 dB
Total Harmonic Distortion
2
PGA Gain of 1 –120 –111 –120 –107 dB
PGA Gain of 2.5 –116 –108 –116 –107 dB
PGA Gain of 8.5 –116 –106 –116 –105 dB
PGA Gain of 34 –115 –101 –115 –101 dB
PGA Gain of 128 –108 –108 dB
Jitter Tolerance
3
300 300 ps
Intermodulation Distortion
4
PGA Gain of 1 122 122 dB
DC ACCURACY
Absolute Gain Error
5
PGA Gain of 1, 2.5 –3.5 +3.5 –3.5 +3.5 %
PGA Gain of 8.5 –4.5 +4.5 –4.5 +4.5 %
PGA Gain of 34 –10 +10 –10 +10 %
Gain Stability Over Temperature
5
±15 ±15 ppm/°C
Offset
5, 6
All PGA Gain –60 –60 mV
Offset Drift
5, 6
66µV/°C
ANALOG INPUT
Full-Scale Nondifferential Input MODIN ±2.25 ±2.25 V
Input Impedance MODIN 20 20 k⍀
Full-Scale Differential Input PGA Gain of 1 ±2.25 ±2.25 V
Other PGA Gain Settings
See Table I
See Table I
Differential Input Impedance AIN, TIN Inputs 140 140 MΩ
Common-Mode Range ±2.25 ±2.25 V
Common-Mode Rejection Ratio V
CM
= ±2.25 V, f
IN
= 200 Hz
PGA Gain of 1 93 101 91 101 dB
PGA Gain of 2.5 95 102 91.5 102 dB
PGA Gain of 8.5, 34 95.5 108 94.5 108 dB
PGA Gain of 128 108 108 dB
Power Supply Rejection Ratio
7
50 50 dB
AIN to TIN Crosstalk Isolation f
IN
= 200 Hz 130 130 dB
Differential Input Current 130 130 nA
TEMPERATURE RANGE
8
Specified Performance T
MIN
to T
MAX
–55 +85 0 85 °C
REFERENCE INPUT
9
Input Voltage Range 2.990 3.0 3.010 2.990 3.0 3.010 V
Input Current 130 130 µA
DIGITAL INPUTS OUTPUTS
V
IL
–0.3 +0.8 –0.3 +0.8 V
V
IH
2.0 V
L
+ 0.3 2.0 V
L
+ 0.3 V
I
IL
–10 +10 –10 +10 µA
I
IH
–10 +10 –10 +10 µA
V
OL
I
SINK
= +2 mA 0.4 0.4 V
V
OH
I
SOURCE
= –2 mA 2.4 2.4 V
AD1555–SPECIFICATIONS
(+V
A
= +5 V; –V
A
= –5 V; V
L
= 5 V; AGND = DGND = 0 V; MCLK = 256 kHz; T
A
= T
MIN
to
T
MAX
, unless otherwise noted.)
REV. B
–3–
AD1555/AD1556
AD1556–SPECIFICATIONS
AD1556AS
Parameter Notes Min Typ Max Unit
FILTER PERFORMANCES
Pass-Band Ripple –0.05 +0.05 dB
Stop-Band Attenuation All Filters Except F
O
=16 kHz –135 dB
F
O
=16 kHz –86 dB
Filters Characteristics See Table II
DIGITAL INPUTS OUTPUTS
V
IL
–0.3 +0.8 V
V
IH
+2.0 V
L
+ 0.3 V
I
IL
–10 +10 µA
I
IH
–10 +10 µA
V
OL
I
SINK
= +2 mA +0.5 V
V
OH
I
SOURCE
= –2 mA V
L
– 0.6 V
POWER SUPPLIES
Specified Performance
V
L
2.85 5.25 V
Quiescent Currents
I(V
L
) 45mA
Power Dissipation V
L
= 3.3 V, F
O
= 1 kHz 6.2 8.5 mW
In Power-Down Mode 70 µW
TEMPERATURE RANGE
*
Specified Performance, T
MIN
to T
MAX
–55 +85 °C
*
Contact factory for extended temperature range.
Specifications subject to change without notice.
AD1555BP AD1555AP
Parameter Notes Min Typ Max Min Typ Max Unit
POWER SUPPLIES
Recommended Operating Conditions
+V
A
4.75 5 5.25 4.75 5 5.25 V
–V
A
–5.25 –5 –4.75 –5.25 –5 –4.75 V
V
L
4.75 5 5.25 4.75 5 5.25 V
Quiescent Currents
I(+V
A
)
10
810 810 mA
I(–V
A
)
10
8 9.5 8 9.5 mA
I(V
L
) 30 42 30 42 µA
Power Dissipation
10
77 96 77 96 mW
PGA in Standby Mode
11
56 70 56 70 mW
In Power-Down Mode
11, 12
Reference Input = 3 V 650 650 µW
Reference Input = 0 V 250 250 µW
NOTES
1
Tested at the output word rate F
O
= 1 kHz. F
O
is the AD1556 output word rate, the inverse of the sampling rate. See Tables I, Ia, Ib for other output
word rates.
2
Tested with a full-scale input signal at approximately 24 Hz.
3
This parameter is guaranteed by design.
4
Tested at the output word rate F
O
= 1 kHz with input signals of 30 Hz and 50 Hz, each 6 dB down full scale.
5
This specification is for the AD1555 only and does not include the errors from external components as, for instance, the external reference.
6
This offset specification is referred to the modulator output.
7
Characterized with a 100 mV p-p sine wave applied separately to each supply.
8
Contact factory for extended temperature range.
9
Recommended Reference: AD780BR.
10
Specified with analog inputs grounded.
11
See Table III for configuration conditions.
12
Specified with MCLK input grounded.
Specifications subject to change without notice.
(V
L
= 2.85 V to 5.25 V; CLKIN = 1.024 MHz; T
A
= T
MIN
to T
MAX
unless otherwise noted.)
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24

AD1555BPZ

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Analog to Digital Converters - ADC IC 256 ksps w/PGA
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