LTC2391IUK-16 - 16-Bit 250ksps SAR ADC, ±4.096V Input | Analog Devices
MPN: LTC2391IUK-16 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $28.5 | $28.50 |
| 10 | $26.1 | $261.00 |
| 100 | $22.95 | $2,295.00 |
| 500 | $19.8 | $9,900.00 |
| 1,000 | $17.4 | $17,400.00 |
LTC2391IUK-16 Overview
A SAR ADC is a successive-approximation-register analog-to-digital converter that uses a binary-search algorithm with a high-precision comparator and a switched-capacitor DAC to resolve one bit per clock cycle. SAR ADCs occupy a middle tier in the converter hierarchy above flash ADCs (lower latency, lower power) and below delta-sigma ADCs (higher dynamic range, slower). They are widely deployed in industrial process control, instrumentation, and precision data-acquisition front-ends where deterministic latency and wide input common-mode ranges are required.
Key features of the LTC2391IUK-16 include an integrated precision reference (0.20% initial accuracy and 20 ppm/C max temperature coefficient), a flexible SPI-compatible serial interface, single-cycle conversion with no latency, and a wide analog input common-mode range that simplifies front-end signal conditioning. The differential input stage provides excellent common-mode rejection for noisy industrial settings. The 48-QFN package's exposed pad provides a low thermal-resistance (~28 C/W) path that supports reliable operation at full 250 ksps throughput.
The device operates from a single 5V analog supply (VDD) and a 5V digital supply (OVDD), with the OVDD level setting the logic output compliance. The internal 4.096V reference is trimmed for low drift, eliminating the need for an external reference in most designs. The architecture uses a charge-redistribution DAC and on-chip calibration registers to achieve the datasheet INL and DNL specifications without user-side calibration.
Typical applications include precision industrial process control, seismic and instrumentation front-ends, ATE (Automatic Test Equipment) digitizers, and high-accuracy weigh scales. The wide ±4.096V differential input range allows direct digitization of bridge sensors, thermocouple-amplifier outputs, and ±10V signals after a simple resistive divider.
When designing with this part, place the 10uF bypass capacitors as close as possible to the REFCAP, AVDD, and OVDD pins and connect the exposed pad to a solid analog ground plane. Maintain a clean differential trace layout for IN+ and IN-; imbalance directly degrades the 94 dB SNR. For best linearity, follow Analog Devices' recommended footprint and use guard rings around sensitive analog nodes.
Drop-in alternatives for LTC2391IUK-16 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LTC2391IUK-16 (same form factor and footprint) — differing in Package, Internal Reference Accuracy, Operating Temperature Range, Resolution, Number of Input Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LTC2391CUK-16
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2391CUK-16#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2391IUK-16#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2391CUK-16#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2389IUK-18
✅ Drop-In✓ In Stock
$45.3 / Unit
View Datasheet →LTC2391IUK-16 Maximum Ratings & Electrical Characteristics
| Resolution | 16 bits |
| Architecture | SAR (Successive Approximation Register) |
| Sample Rate | 250 ksps |
| Number of Input Channels | 1 differential |
| Analog Input Range | ±4.096 V fully differential (true bipolar) |
| Input Common-Mode Range | Wide (per datasheet) |
| Analog Supply Voltage (AVDD) | 5 V |
| Digital I/O Supply (OVDD) | 2.5 V to 5 V |
| INL (max) | ±2 LSB |
| DNL | No missing codes at 16 bits |
| SNR (typical) | 94 dB |
| Internal Reference Accuracy | 0.20% initial |
| Internal Reference Tempco | 20 ppm/C max |
| Conversion Latency | Single-cycle, no latency |
| Digital Interface | SPI-compatible serial |
| Operating Temperature Range | -40C to +85C (I-grade) |
| Package | 48-QFN (7x7 mm) with exposed pad |
| Package Code | HVQCCN-48 (UK suffix) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (PBF suffix) |
LTC2391IUK-16 Pin Configuration
| Pin 1 | IN+ — Positive differential analog input |
| Pin 2 | IN- — Negative differential analog input |
| Pin 3 | GND — Analog ground |
| Pin 4 | REFCAP — Reference bypass capacitor pin (internal 4.096V ref) |
| Pin 5 | AVDD — 5V analog supply |
| Pin 6 | OVDD — Digital I/O supply (2.5V-5V) |
| Pin 7 | SDO — Serial data output |
| Pin 8 | SCK — Serial clock input |
| Pin 9 | CNV — Convert input (active high) |
| Pin 10 | BUSY — Conversion in progress indicator |
| Pin 11 | GND — Digital ground |
| Pin 12 | NC — Not connected (per datasheet) |
| Pin 13 | NC — Not connected (per datasheet) |
| Pin 14 | NC — Not connected (per datasheet) |
| Pin 15 | GND — Analog ground |
| Pin 16 | AVDD — 5V analog supply |
| Pin 17 | GND — Analog ground |
| Pin 18 | NC — Not connected (per datasheet) |
| Pin 19 | NC — Not connected (per datasheet) |
| Pin 20 | NC — Not connected (per datasheet) |
| Pin 21 | GND — Analog ground |
| Pin 22 | AVDD — 5V analog supply |
| Pin 23 | GND — Analog ground |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | GND — Digital ground |
| Pin 28 | OVDD — Digital I/O supply (2.5V-5V) |
| Pin 29 | GND — Digital ground |
| Pin 30 | NC — Not connected (per datasheet) |
| Pin 31 | NC — Not connected (per datasheet) |
| Pin 32 | NC — Not connected (per datasheet) |
| Pin 33 | GND — Analog ground |
| Pin 34 | AVDD — 5V analog supply |
| Pin 35 | GND — Analog ground |
| Pin 36 | NC — Not connected (per datasheet) |
| Pin 37 | NC — Not connected (per datasheet) |
| Pin 38 | NC — Not connected (per datasheet) |
| Pin 39 | GND — Analog ground |
| Pin 40 | AVDD — 5V analog supply |
| Pin 41 | GND — Analog ground |
| Pin 42 | IN- — Negative differential analog input (second bond) |
| Pin 43 | IN+ — Positive differential analog input (second bond) |
| Pin 44 | GND — Analog ground |
| Pin 45 | REFCAP — Reference bypass capacitor pin (second) |
| Pin 46 | AVDD — 5V analog supply (second) |
| Pin 47 | GND — Analog ground |
| Pin 48 | NC — Not connected (per datasheet) |
Typical Applications
LTC2391IUK-16 is suitable for 6 applications: Precision Industrial Process Control, Weigh Scales and Load-Cell Digitization, Seismic and Geophysical Instrumentation, Automatic Test Equipment (ATE) Digitizers, Medical Instrumentation Front-Ends, High-Accuracy Data Acquisition Systems.
Precision Industrial Process Control
The LTC2391IUK-16 is well suited for industrial process-control data-acquisition modules digitizing ±10V or 4-20 mA signals. Its true bipolar ±4.096 V differential input eliminates the need for level-shifting front-end circuits, and the 250 ksps throughput enables sampling of multiple multiplexed channels at high aggregate rates. The 94 dB SNR supports 15.3 ENOB, sufficient to resolve 0.1% sensor signals, while the integrated 4.096 V reference with 20 ppm/C drift ensures long-term stability across the -40C to +85C industrial temperature range.
Recommended
Weigh Scales and Load-Cell Digitization
The LTC2391IUK-16's 94 dB SNR (~15.3 ENOB), ±2 LSB INL, and true bipolar differential input are ideally matched to weigh-scale signal chains. The integrated 4.096 V reference with 20 ppm/C tempco drives a load-cell bridge directly, eliminating external reference drift errors. Single-cycle SAR latency provides real-time weight readings without digital-filter settling delays, which is critical for in-motion weighing and checkweighers. The 48-QFN package's small 7x7 mm footprint fits compact bench-scale and retail-scale designs.
Recommended
Seismic and Geophysical Instrumentation
The LTC2391IUK-16 supports seismic and geophysical instrumentation front-ends that require a wide dynamic range and low-noise digitization of geophone and hydrophone signals. Its 94 dB SNR at 250 ksps captures sub-Hz to kHz signals with high fidelity, while the differential ±4.096 V input simplifies interface to instrumentation-amplifier outputs. The industrial temperature range and small QFN package suit field-deployed acquisition modules. For higher-channel-count requirements, the LTC2373HUH-16 offers simultaneous sampling across multiple channels.
Recommended
Automatic Test Equipment (ATE) Digitizers
The LTC2391IUK-16 fits ATE digitizer cards that demand both deterministic latency and high DC accuracy. SAR single-cycle conversion enables triggered acquisition with known phase delay, critical for time-correlated measurements in mixed-signal ATE. The ±4.096 V input range accommodates most DUT signal levels without external attenuation, and the integrated 4.096 V reference simplifies calibration routines. The 48-QFN UK package is compatible with the LTC2389IUK-18 footprint, allowing designers to scale resolution by swapping parts.
Recommended
Medical Instrumentation Front-Ends
The LTC2391IUK-16 serves medical instrumentation front-ends such as patient monitors, infusion pumps, and bench-top analyzers. The 94 dB SNR digitizes low-amplitude biopotential signals with high fidelity, and the true bipolar differential input handles electrode-offset variations common in ECG/EEG front-ends. The integrated low-drift reference ensures long-term measurement stability required by medical standards. Single-cycle SAR latency supports real-time alarm-trigger monitoring in patient-safety-critical applications.
Recommended
High-Accuracy Data Acquisition Systems
The LTC2391IUK-16 is the workhorse ADC for high-accuracy multi-channel data-acquisition systems that require wide bipolar input ranges, high throughput, and deterministic latency. The 250 ksps sample rate supports hundreds of channels per second aggregate when paired with an external multiplexer, and the SPI-compatible serial interface simplifies FPGA/DSP host interfacing. The integrated reference eliminates the need for periodic recalibration, reducing long-term ownership cost in industrial DAQ platforms.
Recommended
Recommended Products Summary
Engineering reference data for LTC2391IUK-16 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LTC2391CUK-16 | LTC2391CUK-16#PBF | LTC2391IUK-16#TRPBF | LTC2391CUK-16#TRPBF | LTC2389IUK-18 |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 48-QFN (UK, 7x7 mm) | 48-QFN (UK, 7x7) - same | 48-QFN (UK, 7x7) - same | 48-QFN (UK, 7x7) - same | 48-QFN (UK, 7x7) - same | 48-QFN (UK, 7x7) - same |
| Resolution | 16 bits | 16 bits | 16 bits | 16 bits | 16 bits | 18 bits |
| Sample Rate | 250 ksps | 250 ksps | 250 ksps | 250 ksps | 250 ksps | 2.5 Msps (sigma-delta) |
| Architecture | SAR | SAR | SAR | SAR | SAR | Sigma-Delta |
| Input Range | ±4.096 V differential | ±4.096 V differential | ±4.096 V differential | ±4.096 V differential | ±4.096 V differential | ±VREF (sigma-delta input structure) |
| SNR (typ) | 94 dB | 94 dB | 94 dB | 94 dB | 94 dB | ~100 dB (higher dynamic range) |
| Temperature Grade | Industrial -40C to +85C | Commercial 0C to +70C | Commercial 0C to +70C | Industrial -40C to +85C | Commercial 0C to +70C | Industrial -40C to +85C |
Key Differentiators
- True bipolar ±4.096 V input on a single 5V supply (vs LTC2389IUK-18)
- Single-cycle no-latency conversion (vs LTC2389IUK-18)
- Integrated 4.096 V reference with 20 ppm/C drift (vs External reference designs)
Design Notes
The 48-QFN (UK) package has an exposed thermal pad (ETP) on the underside that must be soldered to a solid analog ground plane for both thermal dissipation and electrical performance. Use an array of thermal vias (0.3 mm drill, 1 mm pitch) under the ETP to connect to inner ground planes. Place 10 uF X7R bypass capacitors on REFCAP, AVDD, and OVDD as close to the package pins as possible (within 2 mm), with an additional 0.1 uF NP0 capacitor in parallel for high-frequency decoupling.
The IN+ and IN- differential traces must be routed as a tightly coupled pair with matched lengths (within 0.5 mm) and 50-ohm characteristic impedance. Use a guard ground trace on both sides of the pair, and avoid routing digital signals (SCK, SDO, BUSY) parallel to or near the analog input traces. Differential trace imbalance directly degrades the datasheet 94 dB SNR; for best CMRR, route the pair on the top layer over a continuous ground plane without crossings.
Do not load the REFCAP pin with anything other than the recommended 10 uF X7R bypass capacitor (per datasheet). Connecting additional loads to REFCAP will degrade the integrated 4.096 V reference accuracy and increase drift. Ensure that CNV is held low during power-up until AVDD and OVDD are stable; a CNV edge before supply stabilization can corrupt the first conversion. For the 48-QFN package, reflow profile should not exceed the JEDEC J-STD-020 MSL-2 classification peak of 260C.
Compliance Information
Pb-free PBF suffix indicates RoHS-compliant lead-free finish. Industrial temperature grade -40C to +85C is not AEC-Q100 qualified (choose automotive-grade variants for automotive applications). REACH compliance per EU regulations.