7/5/01 5 PM
PRELIMINARY TECHNICAL DATA
12-Bit SAR ADC
Preliminary Technical Data
Fast Throughput Rate: 3MSPS
Wide Input Bandwidth: 50MHz
No Pipeline Delays with SAR ADC
Excellent DC Accuracy Performance
Two Parallel Interface Modes
90mW (Full-Power) and 5mW (NAP Mode)
Standby Mode: 1µA max
Single +5V Supply Operation
Internal +2.5V Reference
Full-Scale Overrange Mode (using 13th bit)
System Offset Removal via User Access Offset Register
Nominal 0 to +2.5V Input with Shifted Range Capability
14-Bit Pin Compatible Upgrade (AD7484)
The AD7482 is a 12-bit, high speed, low power, succes-
sive-approximation ADC. The part features a parallel
interface with throughput rates of up to 3MSPS. The part
contains a low-noise, wide bandwidth track/hold amplifier
which can handle input frequencies in excess of 50MHz.
The conversion process is a proprietary algorithmic suc-
cessive-approximation technique which results in no
pipeline delays. The input signal is sampled and a conver-
sion is initiated on the falling edge of a CONVST signal.
The conversion process is controlled via an internally
trimmed oscillator. Interfacing is via standard parallel
signal lines making the part directly compatible with
microcontrollers and DSPs.
The AD7482 provides excellent ac and dc performance
specifications. Factory trimming ensures high dc accuracy
resulting in very low INL, offset and gain errors.
The part uses advanced design techniques to achieve very
low power dissipation at high throughput rates. Power
consumption in normal mode of operation is 90mW.
There are two power-saving modes: a NAP mode, which
keeps the reference circuitry alive for a quick power up
while consuming 5mW and a STANDBY mode which
reduces power consumption to a mere 5µW.
FUNCTIONAL BLOCK DIAGRAM
AVDD AGND CBIAS DVDD DGND
LOGIC AND I/O
The AD7482 features an on-board +2.5V reference but
the part can also accomodate an externally provided
+2.5V reference source. The nominal analog input range
is 0 to +2.5V but an offset shift capability allows this
nominal range to be offset by +/-200mV. This allows the
user considerable flexibility in setting the bottom end
reference point of the signal range, a useful feature when
using single-supply op-amps.
The AD7482 also provides the user with an 8% overrange
capability via a 13th bit. Thus, if the analog input range
strays outside the nominal by up to 8%, the user can still
accurately resolve the signal by using the 13th bit.
The AD7482 is powered from a +4.75V to +5.25V sup-
ply. The part also provides a VDRIVE pin which allows the
user to set the voltage levels for the digital interface lines.
The range for this VDRIVE pin is from +2.7V to +5.25V.
The part is housed in a 48-pin LQFP package and is
specified over a -40°C to +85°C temperature range.
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.
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World Wide Web Site: http://www.analog.com
© Analog Devices, Inc., 2001