
14-Bit, 500 kSPS
PulSAR ADC in MSOP
AD7946
Rev. A
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FEATURES
14-bit resolution with no missing codes
Throughput: 500 kSPS
INL: ±0.4 LSB typical, ±1 LSB maximum (±0.0061% of FSR)
SINAD: 85 dB @ 20 kHz
THD: 100 dB @ 20 kHz
Pseudo differential analog input range
0 V to REF with REF up to VDD
No pipeline delay
Single-supply 5 V operation with
1.8 V/2.5 V/3 V/5 V logic interface
Serial interface, SPI/QSPI/MICROWIRE/DSP compatible
Daisy-chain multiple ADCs and BUSY indicator
Power dissipation
3.3 mW @ 5 V/100 kSPS
3.3 μW @ 5 V/100 SPS
Standby current: 1 nA
10-lead MSOP (MSOP-8 size) and
3 mm × 3 mm QFN (LFCSP) (SOT-23 size)
Pin-for-pin compatible with the 16-bit AD7686 APPLICATIONS
Battery-powered equipment
Data acquisition
Instrumentation
Medical instruments
Process control
APPLICATION DIAGRAM
AD7946
REF
GND
VDD
IN+
IN–
VIO
SDI
SCK
SDO
CNV
1.8V TO VDD
3- OR 4-WIRE INTERFACE
(SPI, DAISY CHAIN, CS)
0.5V TO 5V
5V
0V TO REF
04
65
6-
00
1
Figure 1.
GENERAL DESCRIPTION
The AD7946 is a 14-bit, charge redistribution, successive
approximation, analog-to-digital converter (ADC) that operates
from a single 5 V power supply, VDD. It contains a 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 low noise, wide bandwidth, short
aperture delay track-and-hold circuit. On the CNV rising edge,
it samples an analog input IN+ between 0 V to REF with respect
to a ground sense IN. The reference voltage, REF, is applied
externally and can be set up to the supply voltage.
Its power scales linearly with throughput.
The SPI-compatible serial interface also features the ability,
using the SDI input, to daisy-chain several ADCs on a single,
3-wire bus, or it provides an optional BUSY indicator. It is
compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate
supply VIO.
The AD7946 is housed in a 10-lead MSOP or a 10-lead QFN
(LFCSP) with operation specified from 40°C to +85°C.
Table 1. MSOP, QFN (LFCSP) 14-/16-/18-Bit PulSAR ADC
Type
100 kSPS
250 kSPS
400 kSPS to 500 kSPS
≥1000 kSPS
ADC Driver
14-Bit
16-Bit
18-Bit
1 Pin-for-pin compatible.