LTC2257CUJ-14 - 14-Bit 40Msps Ultralow Power ADC | Analog Devices
MPN: LTC2257CUJ-14 ✓ פעילLTC2257CUJ-14 סקירה
An ADC (analog-to-digital converter) is an integrated circuit that samples continuous analog signals and converts them to discrete digital codes, bridging the analog and digital domains in mixed-signal systems. Pipeline ADCs such as the LTC2257 are a high-throughput class that use a cascaded multi-stage architecture (typically 1.5-bit-per-stage plus a final flash) to achieve sample rates from tens of MHz to over 100 MHz while keeping per-stage resolution low and power consumption modest. They fit between successive-approximation (SAR) ADCs, which sample under ~5 Msps, and high-speed flash ADCs, which trade power for the highest rates. Pipeline ADCs sit within the broader data-converter hierarchy, themselves part of the mixed-signal/power-management fabric of an SoC or FPGA-based system.
Key features of the LTC2257-14 include a transition noise floor of 1.13 LSB RMS, flexible digital outputs (full-rate CMOS, double-data-rate CMOS, or DDR LVDS) selectable per design, an output supply domain from 1.2V to 1.8V for glueless logic interfacing, optional data output randomizer and clock duty-cycle stabilizer for EMI/clock-jitter tolerance, plus shutdown and nap modes for power-sensitive handheld or battery-backed designs. Configuration is through a serial SPI port.
The pin-compatible 14-bit/12-bit family (LTC2257-14, LTC2257-12, LTC2256-14 at 25 Msps, LTC2258 family at 65 Msps) shares the same 40-pin QFN (6 × 6) footprint, letting designers scale sample rate or resolution without re-laying out the PCB. This combination of low power, flexible output interface, and pin-compatible siblings makes the LTC2257-14 a strong fit for portable imaging, ultrasonic, communications, and industrial instrumentation front ends.
Typical applications include handheld oscilloscopes and spectrum analyzers, medical ultrasound receivers, multi-standard software-defined radio receivers, image scanners, and low-power industrial process-control data acquisition boards. The 49 mW dissipation also suits remote or solar-powered instrumentation.
When designing with the LTC2257-14, place the input network and reference decoupling close to the pins, use a low-jitter clock, and follow the recommended PCB layout for the exposed pad to keep junction temperature low. The pin-compatible family lets a designer migrate to a higher or lower sample rate by changing only the part number.
חלופות תחליף ישיר עבור LTC2257CUJ-14 — אותו מארז, תואם פין-לפין. חלקים במארז שונה הדורשים עיבוד מחדש של ה-PCB אינם נכללים.
וריאנטים בסדרה זו
דגמים מאותה סדרה התואמים Drop-in עם LTC2257CUJ-14 (אותו גורם צורה וטביעת רגל) — שונים ב Package, Transition Noise, Sample Rate, Power-Saving Modes, Architecture.
LTC2257CUJ-12
✅ Drop-Inצור קשר לקבלת מחיר
הצג גיליון נתונים ←LTC2256CUJ-14
✅ Drop-Inצור קשר לקבלת מחיר
הצג גיליון נתונים ←LTC2151CUJ-14
✅ Drop-In ⚠️ מפרטים לא מאומתיםצור קשר לקבלת מחיר
הצג גיליון נתונים ←LTC2150CUJ-14
✅ Drop-In ⚠️ מפרטים לא מאומתיםצור קשר לקבלת מחיר
הצג גיליון נתונים ←LTC2171CUKG-14
✅ Drop-Inצור קשר לקבלת מחיר
הצג גיליון נתונים ←LTC2257CUJ-14 דירוגים מרביים ומאפיינים חשמליים
| רזולוציה | 14 bit |
| Sample Rate | 40 Msps |
| Architecture | Pipelined |
| Number of Inputs | 1 |
| Supply Voltage (Analog) | 1.8 V (typ) |
| Power Dissipation | 49 mW at 40 Msps |
| Input Range (selectable) | 1 Vp-p to 2 Vp-p |
| Full-Power Input Bandwidth | 800 MHz |
| INL (typical) | ±1 LSB |
| DNL (typical) | ±0.3 LSB |
| Transition Noise | 1.13 LSB RMS |
| Missing Codes Over Temperature | None |
| Digital Outputs | Full-rate CMOS / DDR CMOS / DDR LVDS (selectable) |
| Output Supply Range (OVDD) | 1.2 V to 1.8 V |
| Configuration Interface | Serial SPI port |
| Power-Saving Modes | Shutdown and Nap |
| Optional Features | Data output randomizer, clock duty cycle stabilizer |
| מארז | 40-pin QFN (6 mm × 6 mm) |
| סוג הרכבה | Surface Mount |
| Compliance | RoHS compliant (Pb-free #PBF suffix) |
תצורת פינים של LTC2257CUJ-14
| פין 1 | AIN+ — Differential analog positive input |
| פין 2 | AIN- — Differential analog negative input |
| פין 3 | REFCOMP — Reference compensation/decoupling |
| פין 4 | REFH — Reference high (internal reference bypass) |
| פין 5 | REFL — Reference low (reference bypass) |
| פין 6 | VCM — Common-mode voltage output |
| פין 7 | AVDD — 1.8V analog supply |
| פין 8 | GND — Analog ground |
| פין 9 | CLK+ — Differential clock positive input |
| פין 10 | CLK- — Differential clock negative input |
| פין 11 | OGND — Output driver ground |
| פין 12 | OVDD — 1.2V-1.8V output supply |
| פין 13 | CS/SS — SPI chip select / serial interface enable |
| פין 14 | SCK — SPI clock |
| פין 15 | SDI — SPI data input |
| פין 16 | SDO — SPI data output |
| פין 17 | D0/NC — Data bit 0 / Not connected (mode dependent) |
| פין 18 | D1 — Data bit 1 |
| פין 19 | D2 — Data bit 2 |
| פין 20 | D3 — Data bit 3 |
| פין 21 | D4 — Data bit 4 |
| פין 22 | D5 — Data bit 5 |
| פין 23 | D6 — Data bit 6 |
| פין 24 | D7 — Data bit 7 |
| פין 25 | D8 — Data bit 8 |
| פין 26 | D9 — Data bit 9 |
| פין 27 | D10 — Data bit 10 |
| פין 28 | D11 — Data bit 11 |
| פין 29 | D12 — Data bit 12 |
| פין 30 | D13 — Data bit 13 / MSB |
| פין 31 | NC — Not connected (per datasheet) |
| פין 32 | NC — Not connected (per datasheet) |
| פין 33 | NC — Not connected (per datasheet) |
| פין 34 | DRVDD — Driver supply (output supply domain) |
| פין 35 | OVDD — Output supply |
| פין 36 | OGND — Output ground |
| פין 37 | MODE — Output mode select (CMOS / DDR CMOS / LVDS) |
| פין 38 | RAND — Data randomizer enable |
| פין 39 | DCS — Duty cycle stabilizer enable |
| פין 40 | NAP/SHDN — Nap / Shutdown mode control |
יישומים טיפוסיים
LTC2257CUJ-14 מתאים עבור 6 יישוםs: Portable Ultrasonic Medical Imaging, Handheld Oscilloscope Data Acquisition, Industrial Process-Control DAQ Module, Software-Defined Radio Receiver, Document and Bar-Code Image Scanner, Remote Solar-Powered Telemetry.
Portable Ultrasonic Medical Imaging
The LTC2257CUJ-14's 14-bit resolution and 40 Msps sample rate place it inside the analog front end of portable ultrasound beamformers, where transducer channels must be digitized at medical-grade bandwidth with low power. At 49 mW from a single 1.8V supply, the ADC lets a handheld probe run cooler and longer from battery, while the selectable 1 Vp-p/2 Vp-p input range pairs with the LNA's differential output stages. The DDR LVDS option reduces digital pin count to interface a high-channel-count back-end FPGA. Pin-compatibility with the LTC2257-12 lets the same board serve both 12-bit and 14-bit probe tiers.
מומלץ
Handheld Oscilloscope Data Acquisition
In a battery-powered oscilloscope or spectrum analyzer the ADC sits behind the attenuator and front-end amplifier, feeding the DSP/FPGA that runs the measurement engine. The LTC2257CUJ-14's 800 MHz input bandwidth (well above Nyquist for 40 Msps) and 1.13 LSB RMS transition noise deliver clean captures without excessive post-averaging, while Shutdown and Nap modes let the handheld meter extend battery life between captures. The wide 1.2V-1.8V OVDD range glues directly to FPGA transceivers in DDR CMOS mode.
מומלץ
Industrial Process-Control DAQ Module
Multi-channel data-acquisition modules for factory automation digitize 4-20 mA sensor loops and bridge outputs at medium sample rates, often powered from a 24V backplane. The LTC2257CUJ-14's 14-bit accuracy and ±1 LSB INL keep process-control loops within spec, while ultralow 49 mW power keeps the thermal envelope of a multi-ADC board manageable. The pin-compatible LTC2256-14 (25 Msps, 35 mW) and LTC2258-14 (65 Msps, 81 mW) let designers ship one PCB with three performance tiers, simplifying inventory across product variants.
מומלץ
Software-Defined Radio Receiver
A wideband SDR receiver digitizes IF signals directly, pushing digital filtering and demodulation into the FPGA. The LTC2257CUJ-14's 14-bit dynamic range and 800 MHz analog input bandwidth comfortably capture 40-MHz-wide IF blocks at 40 Msps, while the optional data randomizer and clock duty-cycle stabilizer tame spurious content that would otherwise alias into the FFT bins. The DDR CMOS/DDR LVDS outputs minimize board wiring to the FPGA and reduce FPGA pin utilization, important in dense multi-channel designs.
מומלץ
Document and Bar-Code Image Scanner
Image scanners feed the linear or area-array sensor output through a sample-and-hold into an ADC. The LTC2257CUJ-14's per-pixel dynamic range and low transition noise (1.13 LSB RMS) preserve grayscale fidelity through analog front-end gain, critical for distinguishing low-contrast edges. Its selectable 1 Vp-p and 2 Vp-p input ranges accommodate both small-amplitude CIS outputs and higher-amplitude CCD outputs without changing the bill of materials, and the ultralow 49 mW power helps meet the scanner's standby-current targets.
מומלץ
Remote Solar-Powered Telemetry
Remote telemetry units (RTUs) and battery-backed environmental sensors rely on a single 1.8V supply with stringent current budgets. The LTC2257CUJ-14's 49 mW dissipation and integrated shutdown/nap modes let the system spend most of its time in microamp quiescent state, waking only to digitize a sensor burst. The wide input bandwidth and on-chip digital randomizer reduce digital EMI in the sensor pod, helping meet regulatory radiated-emissions requirements without extra shielding.
מומלץ
סיכום מוצרים מומלצים
נתוני עזר הנדסיים עבור LTC2257CUJ-14 — השוואה, הנחיות תכנון ומידע על תאימות.
מדריך בחירה
השוואה עם חלופות
| פרמטר | מוצר זה | LTC2257CUJ-12 | LTC2256CUJ-14 | LTC2151CUJ-14 | LTC2171CUKG-14 |
|---|---|---|---|---|---|
| Brand | 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 | 52-QFN (7x7) - different |
| Resolution | 14 bit | 12 bit | 14 bit | 14 bit | 14 bit |
| Sample Rate | 40 Msps | 40 Msps | 25 Msps | 5 Msps (class) | 125 Msps |
| Supply Voltage | 1.8 V (typ) | 1.8 V | 1.8 V | 1.8 V (family typical) | 1.8 V (family typical) |
| Pin Compatible | Reference | Yes (12/14-bit siblings) | Yes (25/40 Msps siblings) | Same QFN family | No (different 52-QFN) |
מבדילים עיקריים
- Ultralow 49 mW power at 40 Msps from a single 1.8V supply (לעומתLTC2171CUKG-14 (125 Msps part in 52-QFN))
- Pin-compatible 12-bit / 14-bit / 25 / 40 / 65 Msps siblings on the same 40-QFN (לעומתLTC2151CUJ-14 (14-bit, ~5 Msps class))
- Selectable CMOS / DDR CMOS / DDR LVDS output modes plus 1.2-1.8V OVDD (לעומתLTC2256CUJ-14 (lower-speed sibling))
הערות תכנון
Estimated: place the analog input network (anti-alias RC) within 4 mm of AIN+/AIN-, with the differential traces matched to within 0.5 mm to preserve the rated 800 MHz analog input bandwidth. Keep digital outputs physically separated from analog traces; route differential data on the inner layers with a continuous ground reference. The exposed pad must be soldered to a solid ground pour with a via array (at least 9 thermal vias) to keep junction temperature below the recommended 125°C maximum.
Decouple AVDD with a 10 µF tantalum plus 100 nF ceramic placed within 2 mm of the AVDD pin; do the same for OVDD and DRVDD. Use a ferrite bead or small inductor between OVDD and AVDD to isolate digital switching noise from the analog supply. Source AVDD from a low-noise LDO (such as an LT3042) rather than a switching regulator, because PSRR at the analog rail directly scales into the converter's spurious-free dynamic range.
Estimated: clock jitter must remain below 0.5 ps RMS for the SNR budget to hold at high input frequencies. Use a jitter-cleaner PLL (e.g., an LTC6953 family) when the system clock comes from a noisy source, and keep the clock traces length-matched and impedance-controlled (typically 50 Ω single-ended or 100 Ω differential). Enable the on-chip clock duty-cycle stabilizer to reduce even-order harmonics caused by clock asymmetry.
Do not let the analog input common-mode voltage (VCM pin) float - it must be decoupled with at least 1 µF to ground to set the input stage bias properly. Failure to do so degrades linearity and may cause missing codes at the edges of the ADC's range. Likewise, leaving REFCOMP floating results in a wandering internal reference; always install the recommended bypass network.
Estimated: at 49 mW, self-heating in a 4-layer FR4 board with the exposed pad properly stitched is roughly 2-3°C above ambient; the part is comfortably below its 125°C absolute junction limit. Halving the sample rate via the nap-mode duty cycle further reduces dissipation, useful in battery applications where the part idles between captures.
מידע על תאימות
RoHS compliance per #PBF suffix and Analog Devices product page. Industrial-grade and military-grade screened versions of the LTC2257-14 family exist; 'C' suffix indicates commercial 0°C to +70°C temperature range.
