AD8401 Analog Devices, AD8401 Datasheet

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AD8401

Manufacturer Part Number
AD8401
Description
8-Bit I/o Port
Manufacturer
Analog Devices
Datasheet
a
GENERAL DESCRIPTION
The AD8401 is a complete data acquisition and control system
containing ADC, DAC, 4-channel MUX, and internal voltage
reference. Built using CBCMOS, this monolithic circuit offers
the user a complete system with very high package density and
reliability.
The converter is a successive approximation ADC with T/H,
and is capable of operating with conversion times as short as
2 s. Analog input bandwidth is 200 kHz, and DAC output volt-
age settling time is less than 4 s, making the AD8401 capable
of controlling servo loops with speed and precision.
The 8-bit data interface provides both read and write operation
for parallel bus interfaces to microcontrollers and DSP proces-
sors. An external 5 MHz clock sets the 2 s conversion rate.
Slower clocks reduce the conversion time and the internal power
dissipation. The standard control lines: Reset, Busy, Interrupt,
Read and Write complete the handshaking signals for micro-
processor communication. A start trigger ST input allows pre-
cise sampling intervals in synchronous sampling applications.
REV. 0
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
FEATURES
2 s ADC with T/H
4-Channel MUX
AD899 Compatible
+5 Volt Operation
On-Chip Reference
4 s Voltage Output DAC
Fast Bus Access Time—75 ns
APPLICATIONS
Servo Controls
Digitally Controlled Calibration
Process Control Equipment
The input multiplexer addressing is designed for direct interface
to the AD899 hard-disk drive, read-channel device with no extra
hardware or special software. Analog input range levels are like-
wise compatible with the AD899.
The AD8401 is designed to operate from a single +5 volt sup-
ply, which will give an ADC input range of 0 V to 3.0 V, and
DAC output range of 0 V to 2.5 V.
The AD8401 is offered in the SOIC-28 surface mount package,
and is guaranteed to operate over the extended industrial tem-
perature range of –40 C to +85 C.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
BUSY
V A
V B
V C
V D
I N
I N
I N
INT
IN
RS
ST
DGND
A0 A1
M
U
X
FUNCTIONAL BLOCK DIAGRAM
RD
T/H
CONTROL LOGIC
V
DD
8-Bit, 4-Channel Data
CLK CS
(+5.0V)
8-BIT ADC
Acquisition System
WR
1.25 REF
DATA I/O
DAC REG
ADC REG
(8 BITS)
8-BIT
DAC
AD8401
AG
AD8401
DAC
Fax: 617/326-8703
AG
ADC
V
OUT

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AD8401 Summary of contents

Page 1

... Analog input bandwidth is 200 kHz, and DAC output volt- age settling time is less than 4 s, making the AD8401 capable of controlling servo loops with speed and precision. The 8-bit data interface provides both read and write operation for parallel bus interfaces to microcontrollers and DSP proces- sors ...

Page 2

... AD8401–SPECIFICATIONS ADC ELECTRICAL CHARACTERISTICS Parameter Symbol STATIC PERFORMANCE Resolution N Total Unadjusted Error TUE Relative Accuracy INL Differential Nonlinearity DNL Offset Error V OSE Full-Scale Error A E Full-Scale DYNAMIC PERFORMANCE Signal-to-Noise Ratio SNR Total Harmonic Distortion THD Intermodulation Distortion IMD ...

Page 3

... L L Min Typ Max 8 2 –1 +1 –1 +1 –2 +2 –2.5 +2.5 –3 +3 –4 +4 –0.5 +0.5 –0.2 +0 +2.5 0.8 2.4 – AD8401 Units Bits LSB LSB LSB LSB LSB LSB LSB LSB LSB ...

Page 4

... ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD8401 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality ...

Page 5

... INT goes high on the rising edge RD. It will also be forced high when RESET is asserted. External Clock Input Pin. Accepts a TTL CMOS input logic levels. Analog ADC Ground Four Analog Inputs Address input that controls multiplexer. See Table I for address decode. –5– AD8401 DICE CHARACTERISTICS ...

Page 6

... An on-chip bandgap is provided as a voltage reference to both the DAC and the ADC. This reference is internal to the AD8401 and is not accessible to the user laser trimmed for both absolute accuracy and temperature coefficients. The refer- ence is internally buffered by a separate control amplifier for both the DAC and ADC to improve isolation between the converters ...

Page 7

... CLOCK The AD8401 uses an external clock that is TTL CMOS compatible. The external clock speed is 5 MHz and the duty cycle may vary from 30% to 70%. The external clock can be continuously operated between conversions. DIGITAL INTERFACE: ADC TIMING AND CONTROL Two basic ADC operating modes are available with the AD8401 ...

Page 8

... AD8401 An active low pulse, at any time, on the RESET pin asynchro- nously forces all DAC register bits to zero. The DAC output voltage becomes zero volts and stays at that value until a new data word is loaded into the DAC register with a new WR com- mand. The equivalent input logic for the DAC register loading is shown in Figure 9 ...

Page 9

... Figure 17. DAC Output Swing vs. Load Resistance 100 Figure 18. DAC Output Slew Rate Positive Transition 135 UNITS Figure 19. DAC Output Slew Rate Negative Transition 400 500 –9– AD8401 GND 100 1k 10k LOAD RESISTANCE – ...

Page 10

... AD8401 500mV 100 + + 1000pF TIME – /DIV Figure 20. DAC Output Swing with Capacitive Load Figure 22. Power Supply Rejection Ratio vs. Frequency 10.0 9.5 9.0 8.5 8.0 7 7.0 6.5 6.0 –50 Figure 21. Supply Current vs. Temperature OUTPUT = FULL SCALE 200mV ...

Page 11

... ADC. Therefore, to ensure correct operation of the ADC, the DAC register should not be updated while the ADC is converting. The AD8401 is configured for an input range of +3.0 volts Full Scale. The nominal transfer characteristic for this range is plot- ted in Figure 23. The output coding is natural binary with one LSB equal to 11 ...

Page 12

... AD8401 ADDRESS BUS AD899 Figure 24. AD8401 Interface to the AD899 Read-Channel Hard Disk Drive Circuit 0.0118 (0.30) 0.0040 (0.10) V (+5.0V AD8401 T/H IN 8-BIT ADC RESET CONTROL LOGIC INT BUSY DGND OUTLINE DIMENSIONS Dimensions shown in inches and (mm). ...

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