LTC2383CMS-16#PBF Linear Technology, LTC2383CMS-16#PBF Datasheet - Page 10

• Manufacturer Part Number: LTC2383CMS-16#PBF
• Description: IC, ADC, 16BIT, 1MSPS, Serial-SPI, MSOP16
• Manufacturer: Linear Technology

Specifications of LTC2383CMS-16#PBF

• Resolution (bits): 16bit
• Sampling Rate: 1MSPS
• Input Channel Type: Differential
• Data Interface: Serial, SPI
• Supply Voltage Range - Analog: 2.375V To 2.625V
• Supply Current: 5.2mA
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
LTC2383-16
OVERVIEW
The LTC2383-16 is a low noise, low power, high speed 16-bit
successive approximation register (SAR) ADC. Operating
from a single 2.5V supply, the LTC2383-16 supports a
large ±2.5V fully differential input range, making it ideal
for high performance applications which require a wide
dynamic range. The LTC2383-16 achieves ±2LSB INL max,
no missing codes at 16-bits and 92dB SNR.
Fast 1Msps throughput with no cycle latency makes the
LTC2383-16 ideally suited for a wide variety of high speed
applications. An internal oscillator sets the conversion time,
easing external timing considerations. The LTC2383-16
dissipates only 13mW at 1Msps, while an auto power-down
feature is provided to further reduce power dissipation
during inactive periods.
CONVERTER OPERATION
The LTC2383-16 operates in two phases. During the
acquisition phase, the charge redistribution capacitor D/A
converter (CDAC) is connected to the IN
to sample the differential analog input voltage. A rising
edge on the CNV pin initiates a conversion. During the
conversion phase, the 16-bit CDAC is sequenced through a
successive approximation algorithm, effectively comparing
the sampled input with binary-weighted fractions of the
reference voltage (e.g. V
the differential comparator. At the end of conversion, the
CDAC output approximates the sampled analog input. The
ADC control logic then prepares the 16-bit digital output
code for serial transfer.
TRANSFER FUNCTION
The LTC2383-16 digitizes the full-scale voltage of 2 × REF
into 2
REF = 2.5V. The ideal transfer function is shown in Figure 2.
The output data is in 2’s complement format.
ANALOG INPUT
The analog inputs of the LTC2383-16 are fully differential
in order to maximize the signal swing that can be digitized.
The analog inputs can be modeled by the equivalent
10
16
levels, resulting in an LSB size of 76μV with
REF
/2, V
REF
/4 … V
REF
+
/65536) using
and IN
–
pins
circuit shown in Figure 3. The diodes at the input provide
ESD protection. In the acquisition phase, each input sees
approximately 45pF (C
with 40Ω (R
switch. Any unwanted signal that is common to both
inputs will be reduced by the common mode rejection of
the ADC. The inputs draw a current spike while charging
the C
the analog inputs draw only a small leakage current.
INPUT DRIVE CIRCUITS
A low impedance source can directly drive the high
impedance inputs of the LTC2383-16 without gain error.
A high impedance source should be buffered to minimize
settling time during acquisition and to optimize the
distortion performance of the ADC. Minimizing settling
IN
capacitors during acquisition. During conversion,
Figure 3. The Equivalent Circuit for the
Differential Analog Input of the LTC2383-16
IN
IN
011...111
011...110
000...001
000...000
111...111
111...110
100...001
100...000
+
–
Figure 2. LTC2383-16 Transfer Function
ON
REF
REF
) from the on-resistance of the sampling
–FSR/2
IN
) from the sampling CDAC in series
R
R
INPUT VOLTAGE (V)
ON
ON
BIPOLAR
–1
LSB
ZERO
C
C
IN
IN
0V
FSR = +FS – –FS
1LSB = FSR/65536
LSB
1
FSR/2 – 1LSB
BIAS
VOLTAGE
238316 F03
238316 F02
238316f