Analog Devices AD7400 1 prj Datasheet
Isolated Sigma-Delta Modulator
J
Preliminary Technical Data
FEATURES
Up to 20 MHz Data Rate (AD7401)
10 MHz Data Rate (AD7400)
nd
2
Order Modulator
±4 LSB INL @16 Bits
Onboard Digital Isolator
Onboard Reference
Low Power Operation:
15 mA @ 5 V
-40⬚C to +105⬚C Operating Range
16-ld SOIC Package
Safety and Regulatory Approvals
UL Recognition
3750 V
CSA Component Acceptance Notice ~5A
VDE Certificate of Conformity
DIN EN 60747-5-2 (VDE 0884 Part 2):2003-01
DIN EN 60950 (VDE 0805): 2001-12; EN 60950:2000
V
IORM
for 1 minute per UL 1577
RMS
= 840V
PEAK
V
FUNCTIONAL BLOCK DIAGRAM
DD1
AD7400/AD7401
APPLICATIONS
AC Motor Control
Data Acquisition Systems
A/D + Opto-Isolator Replacement
GENERAL DESCRIPTION
The AD7400/AD7401 are 2nd order sigma-delta modulators
that convert an analog input signal into a high speed 1-bit data
stream with onboard digital isolation based on Analog Devices’
iCoupler® technology. The AD7400/AD7401 operate from a 5 V
power supply and accept a differential input signal of ±200 mV.
The analog input is continuously sampled by the analog
modulator, eliminating the need for external sample and hold
circuitry. The input information is contained in the output
stream as a density of ones with data rates up to 20MHz. The
original information can be reconstructed with an appropriate
digital filter. The serial I/O may use a 5V or 3V supply (V
The serial interface is digitally isolated. High-speed CMOS,
V
DD2
DD2
).
VIN+
VIN-
T/H
BUF
REF
*MCLKIN pin on AD7401
Σ-∆ ADC
CONTROL LOGIC
UPDATE
ENCODE DECODE
UPDATE
ENCODE DECODE
GND1
Rev. Pr
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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.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
WATCHDOG
MDAT
WATCHDOG
MCLKOUT*
GND2
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
AD7400/AD7401 Preliminary Technical Data
combined with monolithic air core transformer technology, means the onboard isolation provides outstanding performance
characteristics superior to alternatives such as optocoupler devices. The parts provide an on-chip 2.5V reference. The AD7400/AD7401
are offered in a 16-lead SOIC package and have an operating temperature range of -40°C to +105°C.
TABLE OF CONTENTS
AD7400—Specifications.................................................................. 3
Pin Functional Descriptions........................................................8
AD7401—Specifications.................................................................. 4
TIMING SPECIFICATIONS1..................................................... 5
Absolute Maximum Ratings
1,3
......................................................... 6
REVISION HISTORY
Revision PrJ: Preliminary Version
Theory of Operation.....................................................................9
Outline Dimensions....................................................................... 10
Rev. PrJ | Page 2 of 10
Preliminary Technical Data AD7400/AD7401
AD7400—SPECIFICATIONS
Table 1. (V
otherwise noted.)
Parameter B Version
STATIC PERFORMANCE When Tested with Sinc3 Filter
Resolution
Integral Nonlinearity
Differential Nonlinearity
Offset Error
Offset Drift vs. Temperature
Offset Drift vs. V
Absolute Reference Voltage Tolerance ±1 %min/max
V
Drift vs. Temperature2 60
REF
V
Drift vs. V
REF
ANALOG INPUT
Input Voltage Range
DC Leakage Current ±1 µA max
DYNAMIC SPECIFICATIONS When Tested with Sinc3 Filter
Signal to Noise + Distortion Ratio (SINAD) 2 70
Total Harmonic Distortion (THD)
Peak Harmonic or Spurious Noise (SFDR)
Effective number of bits 12 Bits
Isolation Transient Immunity
Signal Delay 20
LOGIC OUTPUTS
Output High Voltage, VOH V
Output Low Voltage, VOL 0.4 V max IO = 20 µA
POWER REQUIREMENTS
V
+4.5/+5.5 Vmin/Vmax
DD1
V
+4.5/+5.5 Vmin/Vmax
DD2
+2.7/+3.3 Vmin/Vmax
7
I
18 mA max V
DD1
7
I
DD2
NOTES
1
Temperature ranges as follows: -40⬚C to +105⬚C
2
See Terminology section.
3
Sample tested @ 25⬚C to ensure compliance.
4
Filter as defined by Verilog Code.
5
All voltages are relative to their respective ground.
Specifications subject to change without notice.
= V
DD1
2
= 4.5V to 5.5V, , VIN+ = -200mV to +200mV and VIN- = 0V; TA = T
DD2
2
2
2
2
DD1
2
0.2 % typ
DD1
2
1
to T
MIN
1,5
Units Test Conditions/Comments
16 Bits min Filter output truncated to 16 Bits
±4 LSB max
±0.9 LSB max Guaranteed No Missed Codes to 15 bits
±0.5 mV max Bipolar Input Range
5
2
µV/⬚C max
µV/⬚C typ
0.05 mV/V typ
ppm/⬚C typ
±200 mV min/max For specified performance. Full range ±320mV.
VIN+ = 21Hz, 400mV
76
dBmin
dB typ
-80 dB typ
2
-80 dB typ
15
20
24
– 0.1 V min IO = -20 µA
DD2
5 mA max V
kV/µs min
kV/µs typ
µs typ
µs max
Delay through filter varies with actual value of onboard clock. Decimation by 256.
= 5.5V
DD1
= 5.5V
DD2
, f
MAX
sine wave
pk-pk
= 10MHz unless
MCLK
4
4
Rev. PrJ | Page 3 of 10
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