Datasheet

Single-Supply, Differential
18-Bit ADC Driver
ADA4941-1
Rev. C
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FEATURES
Single-ended-to-differential converter
Excellent linearity
Distortion −110 dBc @100 KHz for V
O
, dm = 2 V p-p
Low noise: 10.2 nV/√Hz, output-referred, G = 2
Extremely low power: 2.2 mA (3 V supply)
High input impedance: 24 MΩ
User-adjustable gain
High speed: 31 MHz, −3 dB bandwidth (G = +2)
Fast settling time: 300 ns to 0.005% for a 2 V step
Low offset: 0.8 mV max, output-referred, G = 2
Rail-to-rail output
Disable feature
Wide supply voltage range: 2.7 V to 12 V
Available in space-saving, 3 mm × 3 mm LFCSP
APPLICATIONS
Single-supply data acquisition systems
Instrumentation
Process control
Battery-power systems
Medical instrumentation
FUNCTIONAL BLOCK DIAGRAM
DIS
4
3
2
1
IN
OUT–OUT+
V+
REF
FB
V–
7
8
5
6
05704-001
Figure 1.SOIC/LSCSP Pinout
–60
–140
0.1 101 1000
FREQUENCY (kHz)
DISTORTION (dBc)
100
V
O
= 2V p-p
V
O
= 6V p-p
05704-045
–65
–70
–75
–80
–85
–90
–95
–100
–105
–110
–
115
–120
–125
–130
–135
HD3
HD2
HD3
HD2
Figure 2. Distortion vs. Frequency at Various Output Amplitudes
GENERAL DESCRIPTION
The ADA4941-1 is a low power, low noise differential driver for
ADCs up to 18 bits in systems that are sensitive to power. The
ADA4941-1 is configured in an easy-to-use, single-ended-to-
differential configuration and requires no external components
for a gain of 2 configuration. A resistive feedback network can
be added to achieve gains greater than 2. The ADA4941-1
provides essential benefits, such as low distortion and high
SNR, that are required for driving high resolution ADCs.
With a wide input voltage range (0 V to 3.9 V on a single 5 V
supply), rail-to-rail output, high input impedance, and a user-
adjustable gain, the ADA4941-1 is designed to drive single-
supply ADCs with differential inputs found in a variety of low
power applications, including battery-operated devices and
single-supply data acquisition systems.
The ADA4941-1 is ideal for driving the 16-bit and 18-bit
PulSAR® ADCs such as the AD7687, AD7690, and AD7691.
The ADA4941-1 is manufactured on ADI’s proprietary second-
generation XFCB process, which enables the amplifier to
achieve 18-bit performance on low supply currents.
The ADA4941-1 is available in a small 8-lead LFCSP as well as a
standard 8-lead SOIC and is rated to work over the extended
industrial temperature range, −40°C to +125°C.