REV. PrC 7/13/01
Preliminary Technical Data
PRELIMINARY TECHNICAL DATA
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.
G61
AD7484
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2001
3MSPS,
14-Bit SAR ADC
FUNCTIONAL BLOCK DIAGRAMFEATURES
Fast Throughput Rate: 3Msps
Wide Input Bandwidth: 50MHz
No Pipeline Delays with SAR ADC
Excellent DC Accuracy Performance
Two Parallel Interface Modes
Low Power:
90mW (Full-Power) and 5mW (NAP Mode)
Standby Mode: 1µA max
Single +5V Supply Operation
Internal +2.5V Reference
Full-Scale Overrange Mode (using 15th bit)
System Offset Removal via User Access Offset Register
Nominal 0 to +2.5V Input with Shifted Range Capability
Pin Compatible Upgrade of 12-Bit AD7482
GENERAL DESCRIPTION
The AD7484 is a 14-bit, high speed, low power, succes-
sive-approximation ADC. The part features a parallel
interface with throughput rates 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 the G43G4FG4EG56G53G54
signal. The conversion process is controlled via an inter-
nally trimmed oscillator. Interfacing is via standard
parallel signal lines making the part directly compatible
with microcontrollers and DSPs.
The AD7484 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.
The AD7484 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 AD7484 also provides the user with an 8% overrange
capability via a 15th 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 15th bit.
The AD7484 is powered from a +4.75V to +5.25V sup-
ply. The part also provides a V
DRIVE
pin which allows the
user to set the voltage levels for the digital interface lines.
The range for this V
DRIVE
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.
2.5 V
REFERENCE
NAP
MODE2
BUF
T/H
AV
DD
AGND C
BIAS
DV
DD
DGND
VREF3
VREF1
VREF2
VIN
14-Bit Error
Correcting SAR
X43X53 X52X44
WRITE
MODE1
X42X55X53
X59
CLIP
D0
STBY
D1
X52X45X53X45X54
D2
VDRIVE
D3
X43X4FX4EX56X53X54
D4
D14
D5
D13
D6
D12
D11
D10
D9
D8
CONTROL
LOGIC AND I/O
REGISTERS
D7
AD7484