AV
V
3 MSPS, 14-Bit SAR ADC
FEATURES
Fast throughput rate: 3 MSPS
Wide input bandwidth: 40 MHz
No pipeline delays with SAR ADC
Excellent dc accuracy performance
2 parallel interface modes
Low power: 90 mW (full power) and 2.5 mW (nap mode)
Standby mode: 2 μA maximum
Single 5 V supply operation
Internal 2.5 V reference
Full-scale overrange mode (using 15th bit)
System offset removal via user access offset register
Nominal 0 V to 2.5 V input with shifted range capability
Pin compatible upgrade of 12-bit AD7482
GENERAL DESCRIPTION
The AD7484 is a 14-bit, high speed, low power, successive
approximation ADC. The part features a parallel interface with
throughput rates up to 3 MSPS. The part contains a low noise,
wide bandwidth track-and-hold that can handle input frequencies
in excess of 40 MHz.
The conversion process is a proprietary algorithmic successive
approximation technique that results in no pipeline delays. The
input signal is sampled, and a conversion is initiated on the falling
edge of the
by an internally 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 the normal mode of operation is 90 mW. There are two power
saving modes: a nap mode, which keeps the reference circuitry
CONVST
signal. The conversion process is controlled
AD7484
FUNCTIONAL BLOCK DIAGRAM
DD
REFERENCE
REFSEL
VIN
AD7484
MODE1
MODE2
CLIP
NAP
STBY
RESET
CONVST
alive for a quick power-up while consuming 2.5 mW, and a
standby mode that reduces power consumption to a mere 10 μW.
The AD7484 features an on-board 2.5 V reference but can also
accommodate an externally provided 2.5 V reference source.
The nominal analog input range is 0 V to 2.5 V, but an offset
shift capability allows this nominal range to be offset by ±200 mV.
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 an 8% overrange capability via a
15th bit. Therefore, if the analog input range strays outside the
nominal range by up to 8%, the user can still accurately resolve
the signal by using the 15th bit.
The AD7484 is powered by a 4.75 V to 5.25 V supply. The part
also provides a V
DRIVE
levels for the digital interface lines. The range for this V
is 2.7 V to 5.25 V. The part is housed in a 48-lead LQFP package
and is specified over a −40°C to +85°C temperature range.
C
AGND
2.5V
T/H
CONTROL
LOGIC AND I/O
REGISTERS
CS
RD
WRITE
BIASDVDD
BUF
14-BIT
ALGORITHMIC
SAR
D0
D1
D2
BUSY
Figure 1.
D3
DGND
DRIVE
REFOUT
REFIN
D14
D13
D12
D11
D10
D9
D8
D7
D4
D5
D6
pin that allows the user to set the voltage
DRIVE
02642-001
pin
Rev. C
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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
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