20-bit

20-Bit 1Msps SAR ADC
0.5ppm INL
Up to 5V
2.5V to 5V
2.5V
REF
VDD
Integral Nonlinearity vs Output Code
2.0
1.5
IN+
LTC2378-20
Up to 5V
IN–
OVDD = 1.8V to 5V
SPI
I/O
1.0
INL ERROR (ppm)
0V
0.5
0
–0.5
–1.0
GND
–1.5
–2.0
0V
0
262144
524288
786432
OUTPUT CODE
1048576
No Latency SAR ADC Achieves 104dB SNR
The LTC®2378-20 SAR ADC achieves 20 bits of resolution with outstanding 0.5ppm INL and 104dB SNR performance with no
cycle latency and sample rates up to 1Msps. The LTC2378-20 offers uncompromised performance, low power dissipation and
excellent temperature stability for high precision signal chains. The unique digital gain compression feature eliminates the need for
a negative ADC driver supply while preserving the full resolution of the ADC, dramatically lowering the total power consumption of
the signal chain. The LTC2378-20 family includes pin-compatible 20-/18-/16-bit SAR ADCs from 250ksps to 2Msps with serial SPI
interface and explicit Busy and Chain pins that simplify digital timing.
Features
1Msps Throughput Rate
±0.5ppm INL (Typ), ±2ppm INL (Max)
104dB SNR (Typ) at fIN = 2kHz
–125dB THD (Typ) at fIN = 2kHz
Low Power: 21mW at 1Msps, 21μW
at 1ksps
Fully Differential Input Range ±VREF
VREF Input Range from 2.5V to 5.1V
Digital Gain Compression
–40°C to 85°C Guaranteed
Temperature Range
16-Pin MSOP and 4mm × 3mm DFN
Packages
n
Complete 20-Bit/18-Bit/16-Bit Pin-Compatible SAR ADC Family
n
250ksps
500ksps
1Msps
20-Bit
104dB SNR
2376-20
2377-20
2378-20
18-Bit
101dB SNR
2376-18
2377-18
2378-18
16-Bit
96dB SNR
2376-16
2377-16
2378-16
n
n
n
n
n
n
n
n
L, LT, LTC, LTM, Linear Technology and the Linear logo are
registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
1.6Msps
2Msps
2379-18
2380-16
Digital Gain Compression
ANALOG INPUT
DIGITAL OUTPUT
5V
4.5V
+FS = 011…111
ALL 1,048,576 CODES!
–FS = 100…000
0.5V
0V
REFERENCE = 5V
The LTC2378-20 family offers the digital gain compression (DGC) feature, which eliminates the driver amplifier’s negative supply
while preserving the full resolution of the ADC. When enabled, the ADC performs a digital scaling function that maps zero‑scale
code from 0V to 0.1 • VREF and full-scale code from VREF to 0.9 • VREF allowing the amplifier to operate from a single positive
supply. The elimination of the negative supply dramatically reduces the total power consumption of the signal chain and reduces
component count while simplifying the design.
LTC6362 Precision, Low Power SAR ADC Driver
5V
VIN
LTC6655-4.096
VOUT_F
4.096V
VOUT_S
1k
10µF
1k
V+
1k
3.28V
0V
–3.28V
8
+
1
–
3
5
LTC6362
1k
VCM
47µF
1k
VCM
2.5V
6800pF
0.41V
IN+
35.7Ω
V–
1k
6
6800pF
n
n
n
n
n
n
n
n
n
n
1mA Supply Current
Single 2.8V to 5.25V Supply
Single-Ended or Fully Differential Input
Fully Differential Output
200µV Max Offset Voltage
260nA Max Input Bias Current
Fast Settling: 550ns to 18-Bit, 8VP-P Output
Low Distortion: –116dBc at 1kHz, 8VP-P
Rail-to-Rail Inputs and Outputs
Low Power Shutdown: 70µA
8-Lead MSOP and 3mm × 3mm 8-Lead DFN Packages
128k Point FFT Plot with
fIN = 2kHz for Circuit Shown Above
0
SNR = 100dB
THD = –110dB
SINAD = 99.7dB
SFDR = 113dB
–20
–40
AMPLITUDE (dBFS)
REF/DGC
0.41V
Features
n
VDD
IN–
35.7Ω
3.69V
REF
LTC2378-20
3300pF
4
2
3.69V
–60
–80
–100
–120
–140
–160
–180
0
100
200
300
FREQUENCY (kHz)
400
500
The LTC®6362 fully differential amplifier achieves high precision on a tight power budget. The LTC6362 can drive 16-, 18- and
20-bit SAR ADCs on a single 5V, 1mA supply. The LTC6362 easily scales and shifts AC- or DC-coupled signals to the input range
of the ADC. It is ideal for driving the 20-bit 1Msps LTC2378-20 SAR ADC with the digital gain compression feature. When paired
with the LTC6655-4.096 for the reference, the entire signal chain solution can be powered from a single 5V supply, minimizing
power consumption, reducing complexity and achieving up to 100dB of SNR.
www.linear.com/2378-20 n 1-800-4-LINEAR
0115B
Similar pages