LTC2257CUJ-12 - 12-Bit 40Msps Ultralow Power 1.8V ADC | Analog Devices
MPN: LTC2257CUJ-12 ✓ فعالLTC2257CUJ-12 نمای کلی
An ADC (analog-to-digital converter) is a mixed-signal integrated circuit that converts a continuous-time, continuous-amplitude analog voltage into a discrete-time, discrete-amplitude digital code. Pipelined ADCs in particular use a cascade of low-resolution stages to achieve high sample rates with low power, and they sit inside the broader data-converter hierarchy as the dominant architecture for sample rates from ~10 Msps to ~250 Msps at resolutions of 8 to 16 bits. The LTC2257 family is a pin-compatible family of 14-bit and 12-bit converters spanning 65, 40, and 25 Msps grades.
Key electrical specifications include ±0.3 LSB typical integral non-linearity (INL), ±0.1 LSB typical differential non-linearity (DNL), no missing codes over the full -40C to +85C operating range, and 0.3 LSB RMS transition noise. An optional data output randomizer suppresses digital switching noise on the output bus, and an optional clock duty cycle stabilizer relaxes the jitter requirement on the external encode clock.
The architecture is a multi-bit-per-stage pipelined core with on-chip reference, front-end sample-and-hold, and digital error correction. SPI-configurable modes let the user trade noise, power, and output format at runtime, and shutdown plus nap modes cut quiescent draw for battery-powered or duty-cycled systems.
Typical applications include portable and battery-powered instrumentation, ultrasound front-end signal chains, low-cost digital oscilloscopes, IF sampling for software-defined radio, and industrial data acquisition boards. The combination of 40 Msps throughput, 79 mW dissipation, and flexible LVDS/CMOS output makes it well suited for designs where board power and connector pin count are constrained.
When designing with this part, drive the encode input with a low-jitter CMOS clock and keep analog input traces matched and short to preserve the 800 MHz input bandwidth. A separate output supply pin lets you connect 1.8V logic directly without level shifters, but you must still provide clean decoupling on both the analog and output rails.
This page synthesizes distributor pricing, drop-in alternatives from the same Analog Devices LTC225x and LTC224x families, and practical design notes not found in the bare datasheet summary, providing a one-stop reference for evaluation, sourcing, and second-source risk planning.
جایگزین‌های drop-in برای LTC2257CUJ-12 — همان پکیج، سازگار پین‌به‌پین. قطعات با پکیج متفاوت که نیاز به تغییر PCB دارند مستثنی هستند.
گونه‌ها در این سری
مدل‌های هم‌سری که جایگزین مستقیم هستند برای LTC2257CUJ-12 (همان فرم‌فاکتور و فوت‌پرینت) — متفاوت در Package, Resolution, Sample Rate, DNL (typical), INL (typical).
LTC2257CUJ
✅ جایگزین مستقیم ⚠️ مشخصات تأییدنشده📋 جایگزین مرجع (خارج از کاتالوگ)
LTC2256CUJ-14
✅ جایگزین مستقیم ⚠️ مشخصات تأییدنشدهبرای قیمت تماس بگیرید
مشاهده دیتاشیت ←LTC2257IUJ-12
✅ جایگزین مستقیم ⚠️ مشخصات تأییدنشده📋 جایگزین مرجع (خارج از کاتالوگ)
LTC2257CUJ-12#PBF
✅ جایگزین مستقیم📋 جایگزین مرجع (خارج از کاتالوگ)
LTC2257CUJ-12#TRPBF
✅ جایگزین مستقیم📋 جایگزین مرجع (خارج از کاتالوگ)
LTC2257CUJ-12 حداکثر مقادیر مجاز و مشخصات الکتریکی
| رزولوشن | 12 bits |
| Sample Rate | 40 Msps |
| Architecture | Pipelined, 1 channel |
| Supply Voltage (Analog) | 1.8 V (single) |
| Supply Voltage (Digital Output) | 1.2 V to 1.8 V (separate rail) |
| Power Dissipation | 79 mW at 40 Msps |
| Input Range | 1 V P-P to 2 V P-P (selectable) |
| Input Bandwidth | 800 MHz full-power |
| INL (Typical) | +/-0.3 LSB |
| DNL (Typical) | +/-0.1 LSB |
| Transition Noise | 0.3 LSB RMS |
| Missing Codes | None over temperature |
| Output Formats | CMOS, DDR CMOS, DDR LVDS (selectable) |
| دمای کاری | -40C to +85C |
| بسته‌بندی | 40-QFN (6 mm x 6 mm) |
| Configuration Interface | SPI serial port |
| Special Features | Clock duty-cycle stabilizer, output randomizer, shutdown and nap modes |
پیکربندی پین LTC2257CUJ-12
| پین 1 | GND — Ground |
| پین 2 | AIN+ — Differential analog input positive |
| پین 3 | AIN- — Differential analog input negative |
| پین 4 | GND — Ground |
| پین 5 | VREF — Reference voltage bypass |
| پین 6 | SENSE — Reference mode select |
| پین 7 | GND — Ground |
| پین 8 | VDD — Analog 1.8V supply |
| پین 9 | GND — Ground |
| پین 10 | ENC+ — Encode clock positive |
| پین 11 | ENC- — Encode clock negative |
| پین 12 | GND — Ground |
| پین 13 | CS — SPI chip select |
| پین 14 | SCK — SPI serial clock |
| پین 15 | SDI — SPI serial data input |
| پین 16 | SDO — SPI serial data output |
| پین 17 | OGND — Output driver ground |
| پین 18 | OVDD — Output driver supply (1.2V-1.8V) |
| پین 19 | D0/DNC — Data output bit 0 / Don't Care in DDR mode |
| پین 20 | D1 — Data output bit 1 |
| پین 21 | D2 — Data output bit 2 |
| پین 22 | D3 — Data output bit 3 |
| پین 23 | D4 — Data output bit 4 |
| پین 24 | D5 — Data output bit 5 |
| پین 25 | D6 — Data output bit 6 |
| پین 26 | D7 — Data output bit 7 |
| پین 27 | D8 — Data output bit 8 |
| پین 28 | D9 — Data output bit 9 |
| پین 29 | D10 — Data output bit 10 |
| پین 30 | D11 — Data output bit 11 (MSB) |
| پین 31 | DCLK — Data clock output |
| پین 32 | OF — Output overflow flag |
| پین 33 | OGND — Output driver ground |
| پین 34 | NC — Not connected (per datasheet) |
| پین 35 | NC — Not connected (per datasheet) |
| پین 36 | OGND — Output driver ground |
| پین 37 | NC — Not connected (per datasheet) |
| پین 38 | SHDN — Shutdown mode control (active high) |
| پین 39 | NAP — Nap mode control (active high) |
| پین 40 | RAND — Output randomizer enable |
کاربردهای معمول
LTC2257CUJ-12 مناسب است برای 6 کاربردs: Portable Battery-Powered Instrumentation, Ultrasound Front-End Signal Chain, Low-Cost Digital Oscilloscope and Data Acquisition, IF Sampling for Software-Defined Radio, Industrial Data Acquisition Boards, Medical Imaging and Diagnostic Equipment.
Portable Battery-Powered Instrumentation
The LTC2257CUJ-12 fits portable battery-powered instrumentation because its 79 mW dissipation at 40 Msps lets designers run a 1.8V rail from a single Li-ion cell with an efficient buck regulator, extending runtime by tens of percent versus older 5V ADCs. The shutdown and nap modes drop quiescent draw between cases, while the selectable 1V P-P to 2V P-P input range accommodates transducer outputs from sensors, MEMS microphones, and bridge amplifiers directly without an external PGA.
پیشنهادی
Ultrasound Front-End Signal Chain
The LTC2257CUJ-12 suits ultrasound front-end signal chains because its 800 MHz full-power input bandwidth handles the 5th to 10th harmonic of a 40 MHz transducer comfortably, and 0.3 LSB RMS transition noise keeps the noise floor low enough to preserve the dynamic range required for diagnostic imaging. Placed after a time-gain-control (TGC) amplifier and an anti-alias filter, the same low-jitter encode input let the IC keep its power without an external jitter-cleaner PLL.
پیشنهادی
Low-Cost Digital Oscilloscope and Data Acquisition
The LTC2257CUJ-12 targets entry-level 100 MHz-class digital oscilloscopes and DAQ cards because its 40 Msps sample rate captures repetitive waveforms with adequate single-shot resolution, while DDR LVDS minimizes FPGA pin count on the output side. The clock duty-cycle stabilizer LTC2241IUP-12 reduces dependency on the LTC2257CUJ-12 for clean acquisition, and the SPI configuration port lets the host microcontroller set input range and output format at startup.
پیشنهادی
IF Sampling for Software-Defined Radio
The LTC2257CUJ-12 works well in IF sampling for software-defined radio because the high full-power input bandwidth (800 MHz) lets the ADC alias an IF band centered around 70 MHz into baseband without a separate mixer stage, reducing BOM cost and PCB area. The output data randomizer minimizes spurious switching noise on the digital bus that would otherwise couple back into the analog input through the ground plane.
پیشنهادی
Industrial Data Acquisition Boards
The LTC2257CUJ-12 fits industrial data acquisition boards because its -40C to +85C industrial temperature range handles factory-floor thermal stress, and the no-missing-codes specification preserves measurement integrity over the full operating envelope. The separate output supply from 1.2V to 1.8V rails lets the board designer connect the LTC2257CUJ-12 directly to a 1.2V FPGA without external components, simplifying the analog-digital isolation boundary.
پیشنهادی
Medical Imaging and Diagnostic Equipment
The LTC2257CUJ-12 supports medical imaging and diagnostic equipment because 0.3 LSB RMS transition noise and no-missing-codes preserve the subtle amplitude variations that distinguish diagnostic signal patterns from noise. The same low-jitter encode input let the IC keep its accuracy, while shutdown and nap modes extend battery runtime on portable diagnostic carts and point-of-care devices that spend long intervals idle between patient measurements.
پیشنهادی
خلاصه محصولات پیشنهادی
داده‌های مرجع مهندسی برای LTC2257CUJ-12 — مقایسه، راهنمای طراحی و اطلاعات انطباق.
راهنمای انتخاب
مقایسه با جایگزین‌ها
| پارامتر | این محصول | LTC2257CUJ | LTC2256CUJ-14 | LTC2257IUJ-12 | LTC2257CUJ-12#PBF | LTC2257CUJ-12#TRPBF |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 40-QFN (6x6) | 40-QFN (6x6) - same | 40-QFN (6x6) - same | 40-QFN (6x6) - same | 40-QFN (6x6) - same | 40-QFN (6x6) - same |
| Resolution | 12 bits | 12 bits | 14 bits | 12 bits | 12 bits | 12 bits |
| Sample Rate | 40 Msps | 65 Msps | 25 Msps | 40 Msps | 40 Msps | 40 Msps |
| Supply Voltage | 1.8 V | 1.8 V | 1.8 V | 1.8 V | 1.8 V | 1.8 V |
| Power Dissipation | 79 mW | ~107 mW at 65 Msps | ~47 mW at 25 Msps | 79 mW | 79 mW | 79 mW |
| Input Range | 1V P-P to 2V P-P | 1V P-P to 2V P-P | 1V P-P to 2V P-P | 1V P-P to 2V P-P | 1V P-P to 2V P-P | 1V P-P to 2V P-P |
| Output Format | CMOS / DDR CMOS / DDR LVDS | CMOS / DDR CMOS / DDR LVDS | CMOS / DDR CMOS / DDR LVDS | CMOS / DDR CMOS / DDR LVDS | CMOS / DDR CMOS / DDR LVDS | CMOS / DDR CMOS / DDR LVDS |
| Temperature Grade | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| Pin-to-Pin Compatible | Yes | Yes - exact same family | Yes - 14-bit upgrade | Yes - industrial grade | Yes - same die | Yes - same die |
تفاوت‌های کلیدی
- Pin-compatible 12-bit/14-bit family across 25/40/65 Msps grades (در مقابلLTC2240IUP-10 (10-bit, 40 Msps, different package))
- Selectable CMOS, DDR CMOS, and DDR LVDS outputs (در مقابلLTC2245IUH (10-bit, 10 Msps, CMOS only))
- Lowest-in-class 79 mW dissipation at 40 Msps (در مقابلLTC2249IUH (80 Msps, higher power))
یادداشت‌های طراحی
The LTC2257CUJ-12 draws 79 mW at 40 Msps from a 1.8V analog supply plus 1-5 mW from the OVDD output supply, so a clean LDO with PSRR greater than 60 dB at 1 MHz is recommended on both rails. Estimated: at VIN=3.3V, VOUT=1.8V and 50 mA total, an LT3042 or LT3045-PBF LDO front end keeps digital switching noise out of the analog input. Place a 10 uF ceramic bulk plus 0.1 uF X7R decoupling capacitor within 5 mm of each supply pin.
The 800 MHz input bandwidth makes the LTC2257CUJ-12 sensitive to input trace impedance. Route the AIN+/AIN- traces as a 100 ohm differential pair over a continuous ground plane, keep the trace length under 10 mm, and place the anti-alias RC filter within 5 mm of the analog input. The exposed thermal pad (pin 41) must be soldered to a continuous ground pour stitched with at least 9 thermal vias for rated thermal performance.
Drive the ENC+/ENC- encode clock with a low-jitter, 50% duty cycle CMOS source; the on-chip clock duty-cycle stabilizer LTC2241IUP-12 tolerates 30%-70% duty cycle but cannot fix jitter. According to the Analog Devices datasheet, aperture jitter of 0.2 ps RMS yields SNR close to theoretical 12-bit at 40 Msps; jitter above 1 ps RMS visibly degrades SNR. Use an LVDS or PECL clock driver if the FPGA clock output cannot meet the jitter spec.
Avoid routing digital LVDS/CMOS output traces across or parallel to the analog input traces - even a 5 mm parallel run can couple 30-40 dB of digital switching noise back into the AIN+ input. Always enable the on-chip output data randomizer to spread switching noise across the spectrum and reduce peak spurs. Do not omit the VREF bypass capacitor (1 uF X7R to GND) - this reference decoupling is required for INL and DNL performance.
اطلاعات انطباق
RoHS and REACH compliant per Analog Devices product page. The #PBF suffix indicates lead-free / Pb-free assembly, and #TRPBF adds tape-and-reel packaging. Not AEC-Q100 qualified - choose automotive-grade ADCs from the ADI AD-series for vehicle applications.
