LTC2321IUFD-12 - Dual 12-Bit+Sign 2Msps SAR ADC | Analog Devices
MPN: LTC2321IUFD-12 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $16.1 | $16.10 |
| 10 | $14.49 | $144.90 |
| 100 | $12.88 | $1,288.00 |
| 500 | $11.27 | $5,635.00 |
| 1,000 | $9.66 | $9,660.00 |
LTC2321IUFD-12 Overview
An SAR ADC is a successive approximation register analog-to-digital converter that performs a binary search through an internal DAC to digitize an analog input in N conversion cycles. SAR converters occupy the middle ground between slow but precise delta-sigma ADCs and very fast but pipeline-limited flash ADCs, combining low latency, deterministic throughput, and excellent DC accuracy. Within the broader signal-chain taxonomy, the LTC2321IUFD-12 sits under: ADC -> data converter -> mixed-signal IC -> semiconductor. It is part of Analog Devices' LTC2321 family, which shares a common 28-QFN (4x5) footprint across 12-bit, 14-bit, and 16-bit resolutions.
Key specifications include an 8V peak-to-peak differential input range, 73 dB SNR, ±0.5 LSB INL (typical), no missing codes at 12 bits, and an onboard 20 ppm/°C max low-drift 2.048V or 4.096V temperature-compensated reference. The high-speed SPI-compatible serial interface supports both single-ended CMOS and LVDS modes, giving the part flexible data-link options for FPGA, DSP, and MCU hosts. The wide common-mode range simplifies front-end signal conditioning and supports high-CMRR designs.
Typical applications include motor control and phase-current sensing, multi-axis position encoders, simultaneous-sampling data-acquisition front-ends, and high-speed instrumentation. Its dual-channel architecture with matched sampling eliminates inter-channel skew for control loops that require phase-accurate measurements.
When designing with the LTC2321IUFD-12, choose the 3.3V or 5V supply carefully to match the LVDS or CMOS I/O domain of the host. Decouple the AVDD and REFCAP pins locally with low-ESR ceramic capacitors, and route the analog and digital grounds using a star-ground or split-plane technique to minimize coupling of digital switching noise into the analog front end.
This page synthesizes distributor pricing, drop-in alternatives drawn from the same 28-QFN family, and practical design notes not found in the manufacturer datasheet, giving engineers a one-stop engineering reference for the LTC2321IUFD-12.
Drop-in alternatives for LTC2321IUFD-12 — 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 LTC2321IUFD-12 (same form factor and footprint) — differing in Resolution, Differential Input Range, Number of Channels, Package, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LTC2321CUFD-12
✅ Drop-In✓ In Stock
$6.1 / Unit
View Datasheet →LTC2321HUFD-12
✅ Drop-In✓ In Stock
$5.62 / Unit
View Datasheet →LTC2321IUFD-12#TRPBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2321CUFD-12#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LTC2321IUFD-14
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$10.4 / Unit
View Datasheet →LTC2321IUFD-12 Maximum Ratings & Electrical Characteristics
| Resolution | 12-bit + sign |
| Number of Channels | 2 |
| Sampling Rate | 2 Msps per channel |
| Architecture | SAR (Successive Approximation Register) |
| Input Type | Differential |
| Differential Input Range | 8 V peak-to-peak |
| SNR | 73 dB |
| INL (typical) | ±0.5 LSB |
| No Missing Codes | 12 bits guaranteed |
| Internal Reference | 2.048V or 4.096V, 20 ppm/°C max TC |
| Supply Voltage | 3.3 V or 5 V single supply |
| Digital Interface | SPI-compatible, CMOS or LVDS |
| Conversion Latency | Zero cycle latency |
| Operating Temperature Range | -40 C to +85 C (I grade suffix) |
| Package | 28-pin QFN (4x5 mm) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (PBF suffix indicates lead-free) |
LTC2321IUFD-12 Pin Configuration
| Pin 1 | GND — Ground (analog and digital star-ground connection) |
| Pin 2 | AVDD — Analog supply voltage (3.3V or 5V) |
| Pin 3 | REF — Reference voltage output (2.048V or 4.096V) |
| Pin 4 | REFCAP — Reference bypass capacitor |
| Pin 5 | IN1+ — Channel 1 positive differential input |
| Pin 6 | IN1- — Channel 1 negative differential input |
| Pin 7 | IN2+ — Channel 2 positive differential input |
| Pin 8 | IN2- — Channel 2 negative differential input |
| Pin 9 | GND — Ground |
| Pin 10 | OVDD — Digital I/O supply |
| Pin 11 | GND — Ground |
| Pin 12 | SCK — Serial clock input |
| Pin 13 | SDI — Serial data input (configuration) |
| Pin 14 | SDO — Serial data output |
| Pin 15 | SDO- — LVDS negative serial data output |
| Pin 16 | GND — Ground |
| Pin 17 | CNV — Convert / start-of-conversion input |
| Pin 18 | BUSY — Conversion-in-progress output |
| Pin 19 | LVDS_MODE — LVDS / CMOS mode select |
| Pin 20 | GND — Ground |
| Pin 21 | GND — Ground (exposed pad / thermal pad) |
| Pin 22 | NC — Not connected (per datasheet) |
| Pin 23 | NC — Not connected (per datasheet) |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | NC — Not connected (per datasheet) |
| Pin 28 | GND — Ground |
Typical Applications
LTC2321IUFD-12 is suitable for 6 applications: Motor Control Phase-Current Sensing, Multi-Axis Position Encoders and Resolver Front-Ends, Simultaneous-Sampling Data Acquisition Front-Ends, High-Speed Instrumentation and Test Equipment, Power-Quality and Energy-Monitoring Systems, Medical Imaging and Diagnostic Equipment Front-End.
Motor Control Phase-Current Sensing
The LTC2321IUFD-12's dual differential inputs with 8V peak-to-peak range and 2 Msps per channel simultaneously sample two motor phase currents with zero latency, eliminating inter-channel skew in field-oriented control loops. The 73 dB SNR provides sufficient dynamic range to resolve low-side shunt currents down to tens of milliamps while the wide common-mode range tolerates high switching transients from the inverter. Placed between the current-sense amplifiers and the DSP/FPGA control loop, it provides the timing jitter budget typical of deterministic motor-control firmware.
Recommended
Multi-Axis Position Encoders and Resolver Front-Ends
The LTC2321IUFD-12 digitizes resolver-to-digital converter analog outputs or quadrature encoder signals at 2 Msps per channel with deterministic latency. Its zero-cycle-latency architecture eliminates phase ambiguity between the two axes, which is critical for resolver-derived angle measurement. The internal 2.048V or 4.096V reference simplifies excitation-rail sharing with the resolver carrier. Compared to discrete ADC + op-amp front-ends, this part saves PCB area and reduces BOM count in encoder channels.
Recommended
Simultaneous-Sampling Data Acquisition Front-Ends
The LTC2321IUFD-12's two matched SAR ADCs sample two channels concurrently at 2 Msps each, making it well suited to multi-channel data acquisition systems where phase alignment between channels matters. The SPI-compatible LVDS interface allows long-distance isolation between the analog front end and a remote FPGA-based acquisition engine. Compared to time-interleaved architectures, no inter-channel sample-skew calibration is needed.
Recommended
High-Speed Instrumentation and Test Equipment
The LTC2321IUFD-12 provides 2 Msps per channel with 73 dB SNR and ±0.5 LSB INL typical for automated test equipment and bench-instrument input stages. The differential architecture supports high-CMRR measurement of bridge sensors and thermocouple references. Compared to general-purpose 12-bit ADCs, the differential input and integrated reference reduce external component count in production tester designs.
Recommended
Power-Quality and Energy-Monitoring Systems
The LTC2321IUFD-12 samples voltage and current waveforms simultaneously at 2 Msps per channel, capturing harmonic content up to the Nyquist limit for FFT-based power-quality analysis. The wide common-mode range handles high-side shunt-resistor measurements in three-phase power meters. Compared to dedicated energy-metering ICs, the dual SAR architecture provides more flexible sample-rate control for IEC 61000-4-7-compliant harmonic analysis.
Recommended
Medical Imaging and Diagnostic Equipment Front-End
The LTC2321IUFD-12's low-noise SAR architecture suits ultrasound, patient-monitoring, and diagnostic-imaging front-ends where deterministic latency and dual-channel sampling matter. The 73 dB SNR provides sufficient dynamic range for ultrasound beamformer inputs, while the differential 8V peak-to-peak range supports direct connection to piezoelectric transducer preamplifier outputs. Compared to discrete multi-IC solutions, the integrated reference and dual SAR architecture reduce channel-to-channel mismatch in array applications.
Recommended
Recommended Products Summary
Engineering reference data for LTC2321IUFD-12 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LTC2321CUFD-12 | LTC2321HUFD-12 | LTC2321IUFD-12#TRPBF | LTC2321CUFD-12#PBF | LTC2321IUFD-14 |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | QFN-28 (4x5) | QFN-28 (4x5) - same | QFN-28 (4x5) - same | QFN-28 (4x5) - same | QFN-28 (4x5) - same | QFN-28 (4x5) - same |
| Resolution | 12-bit + sign | 12-bit + sign | 12-bit + sign | 12-bit + sign | 12-bit + sign | 14-bit + sign |
| Sampling Rate | 2 Msps / channel | 2 Msps / channel | 2 Msps / channel | 2 Msps / channel | 2 Msps / channel | 2 Msps / channel |
| Number of Channels | 2 differential | 2 differential | 2 differential | 2 differential | 2 differential | 2 differential |
| Differential Input Range | 8 V peak-to-peak | 8 V peak-to-peak | 8 V peak-to-peak | 8 V peak-to-peak | 8 V peak-to-peak | 8 V peak-to-peak |
| Internal Reference | 2.048V or 4.096V, 20 ppm/C | 2.048V or 4.096V, 20 ppm/C | 2.048V or 4.096V, 20 ppm/C | 2.048V or 4.096V, 20 ppm/C | 2.048V or 4.096V, 20 ppm/C | 2.048V or 4.096V, 20 ppm/C |
| Operating Temperature Range | -40 C to +85 C | 0 C to +70 C | -40 C to +125 C | -40 C to +85 C | 0 C to +70 C | -40 C to +85 C |
Key Differentiators
- Dual matched SAR channels with zero latency (vs LTC2314HTS8-14 (single-channel))
- Wide 8V peak-to-peak differential input range (vs LTC2241IUP-12 (single-ended, lower input range))
- Integrated 20 ppm/C low-drift reference (vs AD7768 (requires external reference))
Design Notes
Place the AVDD decoupling capacitor as close as possible to the AVDD pin using a low-ESR 10 uF ceramic in parallel with a 0.1 uF X7R ceramic for high-frequency noise. Connect the exposed thermal pad on the bottom of the QFN package to a solid ground plane using a via array (typically 4-9 vias) to minimize thermal resistance and provide a low-impedance ground return for the analog front end. Route the differential input traces as a matched-length, ground-referenced pair to preserve common-mode rejection.
The LTC2321IUFD-12 requires both AVDD (analog 3.3V or 5V) and OVDD (digital I/O) rails; these may be tied together if the host uses the same supply, or separated to allow level shifting to a different host logic domain. Use a ferrite bead or pi-filter between AVDD and OVDD when they share a rail to prevent digital switching noise from coupling into the analog section. Estimated: a 10 uH ferrite in series with 10 uF + 0.1 uF caps on each side typically provides >40 dB attenuation above 10 MHz.
When using the LVDS interface option, route the SDO+/SDO- pair as a 100 ohm differential microstrip with matched length (±1 mm) and continuous ground reference. Avoid splitting the ground plane beneath the LVDS traces. The CMOS SDO output is more susceptible to noise coupling at high SCK frequencies above 50 MHz; in that regime prefer LVDS for robust data integrity over cable or backplane.
Compliance Information
Lead-free finish indicated by #PBF suffix per Analog Devices nomenclature. RoHS and REACH compliance per manufacturer product page.
