14-Bit, 250 kSPS PulSAR,
Pseudo Differential ADC in MSOP/LFCSP
Data Sheet
AD7942
Rev. C Document Feedback
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FEATURES
14-bit resolution with no missing codes
Throughput: 250 kSPS
INL: ±0.4 LSB typical, ±1 LSB maximum (±0.0061% of FSR)
SINAD: 85 dB at 20 kHz
THD: −100 dB at 20 kHz
Pseudo differential analog input range
0 V to V
REF
with V
REF
up to VDD
No pipeline delay
Single-supply 2.3 V to 5.5 V operation with
1.8 V/2.5 V/3 V/5 V logic interface
Proprietary serial interface
SPI-/QSPI-/MICROWIRE-/DSP-compatible
1
Daisy-chaining for multiple ADCs and busy indicator
Power dissipation
1.25 mW at 2.5 V/100 kSPS, 3.6 mW at 5 V/100 kSPS
1.25 μW at 2.5 V/100 SPS
Standby current: 1 nA
10-lead package: MSOP and 3 mm × 3 mm LFCSP
Pin-for-pin compatible with the 16-bit AD7685
APPLICATIONS
Battery-powered equipment
Data acquisition
Instrumentation
Medical instruments
Process controls
APPLICATION DIAGRAM
AD7942
REF
GND
VDD
IN+
IN–
VIO
SDI
SCK
SDO
CNV
1.8V TO VDD
3- OR 4-WIRE INTERFACE
(SPI, DAISY CHAIN, CS)
0.5
TO 5V 2.5
TO 5V
0
TO V
REF
04657-001
Figure 1.
GENERAL DESCRIPTION
The AD7942 is a 14-bit, charge redistribution, successive approxi-
mation PulSAR
® ADC that operates from a single power supply,
VDD, between 2.3 V to 5.5 V. 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 V
REF
with respect to a ground
sense, IN−. e reference voltage, V
REF
, is applied externally and
is set up to be the supply voltage. Its power scales linearly with
the 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 and provides an optional busy indicator. It is com-
patible with 1.8 V, 2.5 V, 3 V, or 5 V logic using a separate
supply (VIO).
The AD7942 is housed in a 10-lead MSOP or a 10-lead LFCSP
package yet fits in the same size footprint as the 8-lead MSOP
or SOT-23. Operation for the AD7942 is specified from −40°C
to +85°C.
1
Protected by U.S. Patent 6,703,961.
Table 1. MSOP, LFCSP/SOT-23, 14-/16-/18-Bit ADCs
Type 100 kSPS 250 kSPS 400 kSPS to 500 kSPS ≥1000 kSPS ADC Driver
14-Bit AD7940 AD7942
1
AD7946
1
16-Bit AD7680 AD7685
1
AD7686
1
AD7980
1
ADA4941-x
AD7683 AD7687
1
AD7688
1
AD7983
1
ADA4841-x
AD7684 AD7694 AD7693
1
18-Bit AD7691
1
AD7690
1
AD7982
1
ADA4941-x
AD7984
1
ADA4841-x
1
Pin-for-pin compatible to the AD7942.
