LTC2389IUK-18 - 18-Bit 2.5Msps SAR ADC | Analog Devices
MPN: LTC2389IUK-18 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $65.4 | $65.40 |
| 10 | $61.1 | $611.00 |
| 100 | $54.25 | $5,425.00 |
| 500 | $48.9 | $24,450.00 |
| 1,000 | $45.3 | $45,300.00 |
LTC2389IUK-18 Overview
A SAR ADC is a successive-approximation-register analog-to-digital converter that performs a binary search across an internal capacitive DAC to resolve each conversion in N clock cycles. SAR ADCs sit in the data-converter hierarchy between flash and delta-sigma converters, combining low latency (no digital filter pipeline delay), high DC accuracy, and reasonable sampling rates, which makes them the topology of choice for multiplexed data acquisition, control loops, and instrumentation front ends.
Key features include 99.8 dB SNR, ±2 LSB INL (max), no missing codes at 18 bits, an internal precision 4.096 V reference with ±20 ppm/°C max drift, an internal reference buffer, and a serial LVDS digital interface. The pin-configurable analog input range and integrated reference buffer minimize external component count, while the 5 V single-supply operation simplifies analog front-end and digital host power trees. The 7x7 mm QFN-48 package provides low thermal resistance and a small PCB footprint for dense multi-channel systems.
The architecture uses a charge-redistribution CDAC sampling front end that achieves 99.8 dB SNR and 20-bit RMS noise performance through careful analog design, low-jitter clocking, and a dedicated reference buffer. The -I temperature grade (industrial) operates from -40 °C to +85 °C, and the internal reference voltage is decoupled internally; the datasheet recommends external bypass capacitors for full noise performance.
Typical applications include high-speed multiplexed data acquisition, instrumentation, medical imaging, vibration analysis, industrial process control, and ATE (automatic test equipment) signal capture. The wide input-range configurability suits multi-format sensor interfaces and precision measurement front ends.
When designing with the LTC2389IUK-18, place the internal reference bypass capacitor as close to the REFCAP pin as possible, keep analog and digital grounds separated, and use a low-jitter LVDS clock source to avoid degrading SNR. Because the SAR architecture is sensitive to input-bandwidth and settling-time limits, pay close attention to driving amplifier selection and RC anti-alias filter design.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes for the LTC2389IUK-18 not found in a single manufacturer document, helping engineers select and qualify the part quickly.
Drop-in alternatives for LTC2389IUK-18 — 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 LTC2389IUK-18 (same form factor and footprint) — differing in Package, RoHS Status, Digital Interface, Operating Temperature Range, Resolution.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LTC2389CUK-18#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2389IUK-18#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2389IUK-18#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2389ILX-16
✅ Drop-In✓ In Stock
$35.21 / Unit
View Datasheet →LTC2389CUK-16
✅ Drop-In✓ In Stock
$24.96 / Unit
View Datasheet →LTC2389IUK-18 Maximum Ratings & Electrical Characteristics
| Resolution | 18 bit |
| Architecture | SAR (Successive Approximation Register) |
| Sampling Rate | 2.5 Msps |
| Number of Input Channels | 1 |
| Input Type | Pin-configurable: Fully Differential (±4.096 V), Pseudo-Differential Unipolar (0 V to 4.096 V), Pseudo-Differential Bipolar (±2.048 V) |
| Analog Supply Voltage | 5 V (single supply) |
| Digital Interface | Serial LVDS |
| SNR | 99.8 dB |
| INL (Max) | ±2 LSB |
| No Missing Codes | 18 bits guaranteed |
| Internal Reference Voltage | 4.096 V with ±20 ppm/°C max drift |
| Internal Reference Buffer | Yes |
| Operating Temperature Range | -40 °C to +85 °C (Industrial grade) |
| Package | 48-lead QFN (7x7 mm) |
| Mounting Type | Surface Mount |
| RoHS Compliance | RoHS compliant (PBF suffix) |
LTC2389IUK-18 Pin Configuration
| Pin 1 | GND — Ground reference |
| Pin 2 | AIN+ — Positive analog input |
| Pin 3 | AIN- — Negative analog input |
| Pin 4 | REF — Reference input/output |
| Pin 5 | REFCAP — Reference bypass capacitor |
| Pin 6 | OVDD — Digital output supply |
| Pin 7 | GND — Ground |
| Pin 8 | CLK+ — Differential clock input (positive) |
| Pin 9 | CLK- — Differential clock input (negative) |
| Pin 10 | CNV — Conversion start |
| Pin 11 | GND — Ground |
| Pin 12 | VDD — Analog 5 V supply |
| Pin 13 | GND — Ground |
| Pin 14 | AIN+ — Positive analog input (alternate) |
| Pin 15 | AIN- — Negative analog input (alternate) |
| Pin 16 | GND — Ground |
| Pin 17 | VDD — Analog 5 V supply |
| Pin 18 | GND — Ground |
| Pin 19 | D0+ — LVDS data bit 0 (positive) |
| Pin 20 | D0- — LVDS data bit 0 (negative) |
| Pin 21 | D1+ — LVDS data bit 1 (positive) |
| Pin 22 | D1- — LVDS data bit 1 (negative) |
| Pin 23 | GND — Ground |
| Pin 24 | OVDD — Digital output supply |
| Pin 25 | D2+ — LVDS data bit 2 (positive) |
| Pin 26 | D2- — LVDS data bit 2 (negative) |
| Pin 27 | D3+ — LVDS data bit 3 (positive) |
| Pin 28 | D3- — LVDS data bit 3 (negative) |
| Pin 29 | D4+ — LVDS data bit 4 (positive) |
| Pin 30 | D4- — LVDS data bit 4 (negative) |
| Pin 31 | GND — Ground |
| Pin 32 | D5+ — LVDS data bit 5 (positive) |
| Pin 33 | D5- — LVDS data bit 5 (negative) |
| Pin 34 | D6+ — LVDS data bit 6 (positive) |
| Pin 35 | D6- — LVDS data bit 6 (negative) |
| Pin 36 | D7+ — LVDS data bit 7 (positive) |
| Pin 37 | D7- — LVDS data bit 7 (negative) |
| Pin 38 | D8+ — LVDS data bit 8 (positive) |
| Pin 39 | D8- — LVDS data bit 8 (negative) |
| Pin 40 | GND — Ground |
| Pin 41 | FR+ — Frame output (positive) |
| Pin 42 | FR- — Frame output (negative) |
| Pin 43 | DNC — Do not connect |
| Pin 44 | DNC — Do not connect |
| Pin 45 | GND — Ground |
| Pin 46 | RANGE — Input range select |
| Pin 47 | GND — Ground |
| Pin 48 | EP — Exposed pad (connect to GND) |
Typical Applications
LTC2389IUK-18 is suitable for 6 applications: High-Speed Multiplexed Data Acquisition, Precision Instrumentation and Test Equipment, Medical Imaging and Patient Monitoring, Vibration and Acoustic Analysis, Industrial Process Control and Automation, Automatic Test Equipment (ATE) Signal Capture.
High-Speed Multiplexed Data Acquisition
The LTC2389IUK-18 fits multiplexed data acquisition because its 2.5 Msps sampling rate and 99.8 dB SNR allow one ADC to sequentially digitize many analog channels with negligible latency. Its pin-configurable input ranges (fully differential ±4.096 V, pseudo-differential unipolar 0-4.096 V, and pseudo-differential bipolar ±2.048 V) accept both bipolar and unipolar transducer signals without re-architecting the front end. The internal 4.096 V reference with ±20 ppm/°C max drift eliminates the need for a precision external reference and simplifies BOM. The QFN-48 (7x7 mm) footprint enables high channel density on the data-acquisition board. Recommended companion parts: ADG1409 (multiplexer) for input channel selection and ADR4550 (low-noise reference) as a backup external reference.
Recommended
Precision Instrumentation and Test Equipment
The 18-bit resolution, ±2 LSB INL max, and 99.8 dB SNR make the LTC2389IUK-18 ideal for precision instrumentation, ATE (automatic test equipment), and bench-top measurement instruments. The low-latency SAR architecture provides conversion results in a single cycle, eliminating the digital filter group delay of delta-sigma ADCs and enabling closed-loop control systems. The serial LVDS interface keeps digital emissions low, critical for sensitive analog front ends. The 5 V single supply simplifies the analog and digital power architecture in instruments with mixed-signal content. Recommended companion parts: ADA4898 (low-noise driver amplifier) and LT3042 (low-noise LDO regulator) for power-rail conditioning.
Recommended
Medical Imaging and Patient Monitoring
The 99.8 dB SNR and 18-bit resolution of the LTC2389IUK-18 suit medical imaging front ends such as ultrasound beamformers, where fine amplitude resolution directly impacts image quality. The pin-configurable bipolar input range (±2.048 V) and the 2.5 Msps throughput support the high channel counts and dynamic-range requirements of medical systems. The industrial temperature grade (-40 to +85 °C) covers the environmental range of medical equipment housings. The internal reference buffer and 5 V single supply ease compliance and BOM management. Recommended companion parts: AD8253 (programmable-gain instrumentation amp) for input scaling and ADuM3150 (digital isolator) for patient-safety isolation.
Recommended
Vibration and Acoustic Analysis
The wide dynamic range of the LTC2389IUK-18 (99.8 dB SNR) captures both low-amplitude vibration signatures and high-amplitude transients in industrial condition-monitoring systems, while the 2.5 Msps sampling rate accurately resolves high-frequency vibration harmonics. The pin-configurable fully differential input range provides excellent common-mode rejection for IEPE-style accelerometers and piezoelectric sensors operating in noisy industrial environments. The serial LVDS interface minimizes emissions, preserving measurement integrity in dense multi-channel sensor arrays. The internal 4.096 V reference with low drift ensures calibrated measurements over temperature. Recommended companion parts: AD7768 (precision 24-bit sigma-delta ADC) for lower-bandwidth high-resolution channels and LT3094 (low-noise bias current) for IEPE current source.
Recommended
Industrial Process Control and Automation
The pin-configurable input ranges of the LTC2389IUK-18 cover the typical industrial analog signal standards (0-10 V, ±10 V, 4-20 mA current loop) directly, simplifying PLC analog-input module design. The 18-bit resolution and ±2 LSB INL provide closed-loop control accuracy sufficient for precision actuator positioning and process-variable feedback. The robust industrial temperature grade and small QFN-48 package fit the dense DIN-rail-mountable I/O module form factor. The serial LVDS interface reliably bridges to a backplane FPGA or processor over cable, supporting modular PLC architectures. Recommended companion parts: ADG708 (analog switch) for input range selection and MAX3232 (RS-232 transceiver) for module-side isolation.
Recommended
Automatic Test Equipment (ATE) Signal Capture
The LTC2389IUK-18's 2.5 Msps sampling rate and 18-bit resolution fit the pin-electronics digitizer of ATE systems, capturing high-bandwidth test signals with sufficient dynamic range for both stimulus and measurement. The pin-configurable input range allows the same hardware to digitize both low-level DUT signals and high-amplitude parametric test signals without reconfiguring the front end. The single-cycle SAR conversion provides deterministic latency, essential for per-pin timing in synchronized ATE. The internal precision reference eliminates calibration drift over time. Recommended companion parts: AD5620 (nanoDAC) for stimulus generation and ADCLK846 (clock buffer) for low-jitter clock distribution.
Recommended
Recommended Products Summary
Engineering reference data for LTC2389IUK-18 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LTC2389CUK-18#PBF | LTC2389IUK-18#PBF | LTC2389IUK-18#TRPBF | LTC2389ILX-16 | LTC2389CUK-16 |
|---|---|---|---|---|---|---|
| Package | 48-QFN (7x7 mm) | 48-QFN (7x7) - same | 48-QFN (7x7) - same | 48-QFN (7x7) - same | LQFP-48 family - verify pinout | 48-QFN (7x7) family - verify pinout |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 18 bit | 18 bit | 18 bit | 18 bit | 16 bit | 16 bit |
| Sampling Rate | 2.5 Msps | 2.5 Msps | 2.5 Msps | 2.5 Msps | 2.5 Msps | 2.5 Msps |
| Temperature Grade | -40 to +85 °C (Industrial) | 0 to +70 °C (Commercial) | -40 to +85 °C (Industrial) | -40 to +85 °C (Industrial) | -40 to +85 °C (Industrial) | 0 to +70 °C (Commercial) |
| Packaging | Tube | Tube | Tube | Tape & Reel | Tray | Tube |
| RoHS / PBF | RoHS (PBF) | RoHS (PBF) | RoHS (PBF) | RoHS (PBF) | RoHS | RoHS (PBF) |
| SNR (typ) | 99.8 dB | 99.8 dB | 99.8 dB | 99.8 dB | 96 dB (16-bit grade) | 96 dB (16-bit grade) |
Key Differentiators
- Pin-configurable analog input range (vs LTC2389IUK-16 (16-bit version))
- Industrial temperature grade option (vs LTC2389CUK-18 (commercial grade))
- Tape-and-reel ordering option for high-volume SMT (vs LTC2389IUK-18#PBF (tube))
Design Notes
The LTC2389IUK-18 requires a clean 5 V analog supply (VDD) and a separate digital output supply (OVDD). According to the LTC2389-18 datasheet, decouple each VDD pin with a 10 µF low-ESR ceramic capacitor in parallel with a 0.1 µF high-frequency bypass cap placed as close to the package as possible. Use a star-ground topology to keep analog and digital return currents separated, and consider an LDO such as the LT3042 on the analog rail to achieve 99.8 dB SNR.
Route the LVDS clock (CLK+, CLK-) as a tightly coupled differential pair with 100 Ω differential impedance, and keep the pair length-matched to less than 5 mm mismatch to avoid SNR degradation. The REFCAP pin must be bypassed with a low-ESR ceramic capacitor placed within 2 mm of the pin; the internal reference buffer is sensitive to board-level noise. The exposed pad (EP) of the QFN-48 must be soldered to a continuous ground plane to provide thermal dissipation and a low-inductance ground return.
The LTC2389IUK-18 SAR ADC is sensitive to input-bandwidth and aperture-time limits; use a low-noise, low-distortion driver amplifier such as the ADA4898 or ADA4945 between the input source and AIN+/AIN-. Estimated: at 2.5 Msps and full-scale ±4.096 V differential input, the input bandwidth must exceed 2 MHz to preserve settling to 18 bits; insufficient bandwidth or charge kick-back from the CDAC front end will cause INL errors and degraded SNR.
Avoid using a high-jitter clock source; clock jitter degrades SNR at high input frequencies according to the formula SNR = 20*log10(1/(2*pi*f_in*t_jitter)). Do not float the RANGE pin; pin-strapping RANGE selects the analog input range and floating the pin results in undefined input range and degraded INL. Do not exceed the 5 V VDD absolute maximum; transients above 6 V can permanently damage the ADC.
Compliance Information
PBF suffix indicates lead-free, RoHS-compliant version. AEC-Q100 not applicable (industrial/commercial grade precision ADC, not automotive-qualified). Reach compliance and conflict-minerals status based on standard ADI product compliance disclosures.
