PRELIMINARY TECHNICAL DATA
14-BIT,500kSPSDifferentialADCinSO/CSP
a
PreliminaryTechnicalData
AD7947*
GENERAL DESCRIPTION
FEATURES
The AD7947 is a 14-bit, 500kSPS, charge redistribution
successive-approximation, fully differential Analog-to-
Digital Converter which operates from a single power
supply, VDD, between 2V to 5.5V. It contains a very low
power high-speed 14-bit sampling ADC with no missing
codes, an internal conversion clock and a versatile serial
interface port. The part also contains a differential low
noise, wide bandwidth, very short aperture delay track/
hold circuit. On the CNV rising edge, it samples the
؎VREF difference between the two analog input IN+ and
IN-. The reference voltage REF is applied externally, can
be set up to the supply voltage.
14-bit Resolution with No Missing Codes
Throughput: 500kSPS (Warp mode)
450kSPS (Normal mode)
380kSPS (Impulse mode)
INL: ؎0.25LSB Typ, ؎0.7LSB Max (؎0.0043 % of
FSR)
DNL: ؎0.2LSB Typ, ؎0.5LSB Max
S/(N+D): 85dB Typ @ 20kHz
THD: –100dB Typ @ 20kHz
True Differential Analog input range: ؎VREF
0V to VREF with VREF up to VDD on Both Inputs
No Pipeline Delay
Single Supply Operation 2V to 5.5V with
1.8V/2.5V/3V/5V logic interface
Daisy Chain Multiple ADCs and Busy Indicator
Programmable Input Bandwidth
Serial Interface SPI/QSPI/Wire/DSP compatible
Typical Power Dissipation:
2mW @ 3V/100kSPS, 20mW @ 5V/380ksps,
1.6W @ 2.5V/100SPS
Stand-by current: 1 nA Typ
It features a very high sampling rate mode (Warp) for
synchronous applications, a fast mode (Normal) for asyn-
chronous applications and a reduced power mode
(Impulse) where the power scales linearly with through-
put.
The SPI compatible serial interface also features the abil-
ity, using the SDI input, to “Daisy chain” several ADCs
on a single 3 wire bus and provides an optional Busy indi-
cator. It is compatible with 1.8V, 2.5V, 3V or 5V logic
using the separate supply OVDD.
10-pin Package: -SOIC ( -SO8 size ) and
CSP ( 3mm x 3mm same space as SOT-23 )
Pin-for-Pin Compatible with the 16-bit AD7688
The AD7947 is housed in a 10-lead SOIC or 10-lead
CSP (Chip Scale package) with operation specified from
–40°C to +85°C.
APPLICATIONS
Battery Powered Equipment
Data Acquisition
Instrumentation
Medical Instruments
Process Control
FUNCTIONAL BLOCK DIAGRAM
SO, CSP/SOT23 16 and 14 Bit ADC
VDD REF
Type
100 kSPS
250 kSPS
AD7687
500 kSPS
AD7688
OVDD
AD7647
16 Bit True AD7684
Differential
16 Bit Pseudo AD7683
Differential
16 Bit Unipolar AD7680
14 Bit True
IN+
SWITCHED
CAP DAC
SDI
IN-
AD7685
AD7686
SCK
CONTROL
LOGIC
SDO
CNV
CLOCK
GND
AD7944
AD7942
AD7947
AD7946
Differential
14 Bit Pseudo
Differential
14 Bit Unipolar AD7940
*Patent pending.
REV. Pr A
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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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© Analog Devices, Inc., 2004