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