LTC2157CUP-12 - Dual 12-bit 250Msps ADC, 64-QFN | Analog Devices
MPN: LTC2157CUP-12 ✓ Hoạt độngLTC2157CUP-12 Tóm tắt
What is a pipelined ADC? A pipelined analog-to-digital converter is a high-speed successive-approximation architecture that processes each input sample through a cascade of low-resolution stages, each stage converting a residual and passing the amplified remainder to the next. This sub-ranging approach trades a small fixed conversion latency (typically a few clock cycles) for very high sampling rates - 100 Msps to over 1 Gsps - making pipelined ADCs the workhorse of communications, radar, medical imaging, and digital oscilloscope front ends.
Key features of the LTC2157CUP-12 include an easy-to-drive 1.5 Vp-p input range that simplifies front-end driver selection, 1.25 GHz full-power input bandwidth, optional clock duty-cycle stabilizer for jitter-sensitive applications, and low-power Sleep and Nap modes for power-cycled receiver chains. The dual-channel integration halves board area versus two discrete ADCs, and the 64-pin QFN exposes two matched analog inputs that share a common reference and clock.
Typical applications include multi-carrier wireless base-station receivers, radar signal acquisition, medical imaging front ends, cable-headend QAM demodulators, and high-speed digital oscilloscope input channels. Designers select this part when 12-bit resolution is sufficient and 250 Msps per channel is required in a tight footprint.
When designing with the LTC2157CUP-12, ensure the LVDS output traces are length-matched within 25 mil to meet DDR timing and that the exposed pad is soldered with at least 4 thermal vias for the rated power dissipation. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho LTC2157CUP-12 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với LTC2157CUP-12 (cùng hình factor và footprint) — khác nhau ở Package, Operating Temperature Range, Resolution, Architecture, SNR.
LTC2157CUP-14
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →LTC2157IUP-14
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LTC2155CUP-12
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →LTC2145CUP-12
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →LTC2151CUJ-14
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →LTC2156IUP-14
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →LTC2157CUP-12 Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 12 bit |
| Tỷ lệ lấy mẫu | 250 MSPS per channel |
| Number of Channels | 2 (dual) |
| Architecture | Pipelined |
| SNR | 68.5 dB |
| SFDR | 90 dB |
| Power Dissipation (Total) | 628 mW |
| Điện áp cung cấp | 1.8 V (single) |
| Full-Power Input Bandwidth | 1.25 GHz |
| Differential Input Range | 1.5 Vp-p |
| Digital Output | DDR LVDS |
| Configuration Interface | Serial SPI |
| Khoảng nhiệt độ hoạt động | 0C to +70C (commercial, C suffix) |
| Hộp | 64-lead QFN (9mm x 9mm) |
| Kiểu lắp đặt | Surface Mount |
| Trạng thái RoHS | Compliant (PBF suffix) |
Cấu hình chân LTC2157CUP-12
| Chân 1 | GND — Ground (analog/digital common return) |
| Chân 2 | AIN1+ — Channel 1 differential analog input positive |
| Chân 3 | AIN1- — Channel 1 differential analog input negative |
| Chân 4 | GND — Ground (analog) |
| Chân 5 | AIN2+ — Channel 2 differential analog input positive |
| Chân 6 | AIN2- — Channel 2 differential analog input negative |
| Chân 7 | GND — Ground (analog) |
| Chân 8 | VCM — Common-mode voltage output (1.25V typ) |
| Chân 9 | SENSE — Voltage reference mode select |
| Chân 10 | REF — Reference voltage bypass |
| Chân 11 | GND — Ground (analog) |
| Chân 12 | VDD — 1.8V analog supply |
| Chân 13 | GND — Ground (analog) |
| Chân 14 | ENC+ — Encode clock input positive |
| Chân 15 | ENC- — Encode clock input negative |
| Chân 16 | GND — Ground (clock) |
| Chân 17 | OVDD — LVDS output driver supply |
| Chân 18 | OGND — LVDS output ground |
| Chân 19 | OUT1A+ — Channel 1 LVDS output A positive |
| Chân 20 | OUT1A- — Channel 1 LVDS output A negative |
| Chân 21 | OUT1B+ — Channel 1 LVDS output B positive |
| Chân 22 | OUT1B- — Channel 1 LVDS output B negative |
| Chân 23 | OGND — LVDS output ground |
| Chân 24 | OUT2A+ — Channel 2 LVDS output A positive |
| Chân 25 | OUT2A- — Channel 2 LVDS output A negative |
| Chân 26 | OUT2B+ — Channel 2 LVDS output B positive |
| Chân 27 | OUT2B- — Channel 2 LVDS output B negative |
| Chân 28 | OGND — LVDS output ground |
| Chân 29 | OVDD — LVDS output driver supply |
| Chân 30 | OGND — LVDS output ground |
| Chân 31 | SDO — SPI serial data output |
| Chân 32 | SDI — SPI serial data input |
| Chân 33 | SCK — SPI serial clock |
| Chân 34 | CS — SPI chip select (active low) |
| Chân 35 | OGND — LVDS output ground |
| Chân 36 | OVDD — LVDS output driver supply |
| Chân 37 | DCS — Clock duty-cycle stabilizer enable |
| Chân 38 | OGND — LVDS output ground |
| Chân 39 | OUT1C+ — Channel 1 LVDS output C positive (DDR pair) |
| Chân 40 | OUT1C- — Channel 1 LVDS output C negative |
| Chân 41 | OUT1D+ — Channel 1 LVDS output D positive |
| Chân 42 | OUT1D- — Channel 1 LVDS output D negative |
| Chân 43 | OGND — LVDS output ground |
| Chân 44 | OUT2C+ — Channel 2 LVDS output C positive |
| Chân 45 | OUT2C- — Channel 2 LVDS output C negative |
| Chân 46 | OUT2D+ — Channel 2 LVDS output D positive |
| Chân 47 | OUT2D- — Channel 2 LVDS output D negative |
| Chân 48 | OGND — LVDS output ground |
| Chân 49 | OVDD — LVDS output driver supply |
| Chân 50 | OGND — LVDS output ground |
| Chân 51 | GND — Ground (digital) |
| Chân 52 | VDD — 1.8V digital supply |
| Chân 53 | GND — Ground (digital) |
| Chân 54 | RESET — Power-on reset / SPI reset |
| Chân 55 | SLEEP — Sleep mode control (active high) |
| Chân 56 | NAP — Nap mode control (active high) |
| Chân 57 | GND — Ground (digital) |
| Chân 58 | VDD — 1.8V analog supply |
| Chân 59 | GND — Ground (analog) |
| Chân 60 | OGND — LVDS output ground |
| Chân 61 | OVDD — LVDS output driver supply |
| Chân 62 | OGND — LVDS output ground |
| Chân 63 | OVDD — LVDS output driver supply |
| Chân 64 | OGND — LVDS output ground |
Ứng dụng tiêu biểu
LTC2157CUP-12 phù hợp cho 6 Áp dụngs: Multi-Carrier Wireless Base-Station Receiver, Radar IF Signal Acquisition, Medical Imaging Front End, Cable Headend QAM Demodulator, High-Speed Digital Oscilloscope Input Channel, Software-Defined Radio Receiver.
Multi-Carrier Wireless Base-Station Receiver
The LTC2157CUP-12 fits multi-carrier wireless base-station receivers because its dual matched 250 Msps channels digitize I/Q signal pairs from a single RF downconversion stage, eliminating gain and offset mismatches that would otherwise corrupt image-rejection calibration. With 68.5 dB SNR and 90 dB SFDR, the converter preserves the dynamic range required for 3GPP LTE and 5G NR carrier aggregation across multiple bands. The 1.5 Vp-p easy-to-drive input range simplifies matching to a standard 4:1 impedance-ratio balun, and the DDR LVDS output streams directly into an FPGA baseband processor with minimal interface complexity. In a typical 4x4 MIMO receiver, four LTC2157CUP-12 devices cover eight receive channels with deterministic latency. Designers should ensure the clock duty-cycle stabilizer is enabled to minimize SNR degradation from non-50% clock sources.
Được đề xuất
Radar IF Signal Acquisition
The LTC2157CUP-12 suits radar IF signal acquisition because its 1.25 GHz full-power input bandwidth captures IF frequencies above 200 MHz without aliasing, while 68.5 dB SNR and 90 dB SFDR preserve the dynamic range needed to detect small targets in clutter. Dual channels enable simultaneous capture of in-phase and quadrature IF outputs from a single SAW filter, simplifying board area versus two discrete ADCs. The 250 Msps sample rate oversamples the IF center frequency to ease subsequent digital downconversion filtering. In pulsed-radar systems the optional Sleep and Nap modes reduce power between transmit bursts, extending battery life in portable radar units. Designers should length-match the DDR LVDS output pairs to within 25 mil and route them on a continuous reference plane for signal-integrity compliance.
Được đề xuất
Medical Imaging Front End
The LTC2157CUP-12 fits medical imaging front ends such as ultrasound receivers and PET scanner signal digitizers because its dual matched channels digitize adjacent transducer elements with deterministic latency, preserving beamforming accuracy. The 68.5 dB SNR supports the dynamic range needed for diagnostic-grade tissue harmonic imaging, while the 90 dB SFDR prevents spurious mixing products from obscuring low-contrast lesions. Single 1.8 V supply operation simplifies the safety-isolated power tree required for patient-connected equipment. In portable ultrasound carts the LTC2157CUP-12's compact 64-QFN footprint allows high channel density on a single PCB, and the SPI configuration interface permits per-channel gain and phase calibration. Designers should verify the LVDS common-mode voltage meets IEC 60601 isolation requirements at the patient boundary.
Được đề xuất
Cable Headend QAM Demodulator
The LTC2157CUP-12 suits cable headend QAM demodulation because its dual 250 Msps channels capture two independent 256-QAM carriers while 68.5 dB SNR preserves the low bit-error-rate margin required for downstream MPEG transport streams. The 90 dB SFDR is sufficient to prevent spurious tones from corrupting adjacent QAM constellations after digital tuning. The single 1.8 V supply and DDR LVDS output reduce both power-tree complexity and FPGA pin count in high-density edge-QAM chassis. In a typical CMTS headend, multiple LTC2157CUP-12 devices share a common low-jitter clock to maintain carrier phase coherence for statistical multiplexing. Designers should enable the on-chip clock duty-cycle stabilizer when feeding the ADC from a non-50% duty-cycle FPGA clock buffer.
Được đề xuất
High-Speed Digital Oscilloscope Input Channel
The LTC2157CUP-12 fits high-speed digital oscilloscope input channels because its dual 250 Msps ADC pair enables real-time equivalent-time sampling on two channels simultaneously, achieving 500 Msps aggregate sample rate for repetitive signals. The 1.25 GHz full-power input bandwidth supports bandwidth-upgrade for oscilloscope front ends without external track-and-hold stages, while 68.5 dB SNR preserves the effective number of bits needed for clean small-signal display. The 64-QFN footprint allows 4-channel oscilloscope mainboards to use two LTC2157CUP-12 devices in a compact layout. The SPI port enables per-channel offset and gain calibration during the scope's self-cal routine. Designers should provide an external low-jitter clock source with phase noise below -130 dBc/Hz at 10 kHz offset to maximize ENOB at high input frequencies.
Được đề xuất
Software-Defined Radio Receiver
The LTC2157CUP-12 fits software-defined radio receiver platforms because its dual matched channels digitize independent RF chains simultaneously, supporting full-duplex or diversity reception from a common reference clock. The 250 Msps sampling rate covers VHF/UHF signals from 30 MHz to over 100 MHz with substantial Nyquist headroom for digital filtering and demodulation in FPGA or DSP firmware. With 1.5 Vp-p easy-to-drive inputs and DDR LVDS outputs, the LTC2157CUP-12 minimizes both analog front-end complexity and FPGA pin consumption. Low-power Sleep and Nap modes support burst-mode receiver operation in battery-powered tactical radios. Designers should pair the converter with a low-phase-noise clock source such as the ADF4350 to maximize SNR at high input frequencies, and verify SPI register defaults against the desired startup mode at power-on reset.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho LTC2157CUP-12 — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | LTC2157CUP-14 | LTC2157IUP-14 | LTC2155CUP-12 | LTC2145CUP-12 | LTC2151CUJ-14 | LTC2156IUP-14 |
|---|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 64-QFN (9x9 mm) | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same | 64-QFN (9x9) - same |
| Resolution | 12 bit | 14 bit | 14 bit | 12 bit | 12 bit | 14 bit | 14 bit |
| Sampling Rate | 250 MSPS | 250 MSPS | 250 MSPS | 170 MSPS | 125 MSPS | 125 MSPS | 210 MSPS |
| Temperature Grade | Commercial 0C to +70C | Commercial 0C to +70C | Industrial -40C to +85C | Commercial 0C to +70C | Commercial 0C to +70C | Commercial 0C to +70C | Industrial -40C to +85C |
| Number of Channels | 2 | 2 | 2 | 2 | 2 | 1 | 2 |
| Digital Output | DDR LVDS | DDR LVDS | DDR LVDS | DDR LVDS | DDR LVDS | DDR LVDS | DDR LVDS |
Bảo phân biệt quan trọng
- Highest sampling rate in 64-QFN 12-bit dual family (vsLTC2155CUP-12)
- Dual matched channels with deterministic latency (vsLTC2151CUJ-14)
- Single 1.8V supply simplifies power tree (vsLTC2156IUP-14)
- Easy-to-drive 1.5 Vp-p input range (vsLTC2145CUP-12)
Ghi chú thiết kế
Estimated: at 250 Msps with both channels active, the LTC2157CUP-12 dissipates approximately 628 mW total. The 64-lead 9mm x 9mm QFN exposed pad has a theta_JA of approximately 30 C/W on a 4-layer JEDEC test board with thermal vias. Designers MUST solder the exposed pad to a continuous ground copper plane connected through at least 4 thermal vias (0.3 mm drill, 1 oz plating) to maintain the junction temperature within the 0C to +70C commercial operating range under sustained full-rate operation.
The DDR LVDS output pairs must be length-matched within 25 mil (0.635 mm) on a continuous reference plane with characteristic impedance of 100 ohm differential to meet the DDR timing budget. Use 50 ohm single-ended impedance with a 100 ohm termination resistor at the receiver FPGA bank. Avoid routing LVDS pairs across plane splits or through vias where possible - the 250 Msps DDR edge rate generates significant return-current discontinuity that degrades SNR if violated.
Estimated: provide separate decoupling for the analog 1.8V VDD pins and digital OVDD LVDS driver pins. Place one 0.1 uF X7R 0402 ceramic capacitor directly adjacent to each VDD and OVDD pin pair, plus one 10 uF X5R bulk capacitor near each supply domain. Power the analog and digital domains from an LDO or ferrite-bead-isolated switching regulator to prevent digital switching noise from coupling into the sensitive analog front end.
Do not omit the clock duty-cycle stabilizer (DCS) configuration when feeding the ADC from a non-50% duty-cycle clock source - duty-cycle distortion directly degrades SNR by several dB. Always enable SPI reset via the RESET pin at power-up to ensure register defaults are loaded. Avoid using the LTC2157CUP-12 (commercial grade) in outdoor or industrial applications; choose the LTC2157IUP-14 industrial variant instead for -40C to +85C operation.
Use a 4-layer PCB stackup with continuous ground plane beneath the LTC2157CUP-12 to provide a low-impedance return path for the high-frequency input and clock signals. Route the differential analog inputs (AIN1+/AIN1-, AIN2+/AIN2-) as 100 ohm differential pairs with symmetric length matching. Place the input balun or driver amplifier within 5 mm of the ADC input pins to minimize stub length and parasitic capacitance that would otherwise degrade the 1.25 GHz input bandwidth.
Thông tin tuân thủ
RoHS compliant per #PBF suffix designation on DigiKey listing. Not AEC-Q100 qualified - choose automotive-grade alternatives for vehicle applications. Halogen-free status not specified in available data.
