AD7872AN - 14-Bit 83 kSPS Sampling ADC | Analog Devices
MPN: AD7872AN ✗ Cuối đờiAD7872AN Tóm tắt
A SAR ADC (Successive-Approximation Register ADC) is a type of precision analog-to-digital converter that converts an input voltage to a digital code by sequentially comparing it against a precision reference using a binary search. SAR ADCs sit in the broader product hierarchy of ADC -> data converter -> mixed-signal IC -> semiconductor, and are favored for applications needing high DC accuracy and deterministic latency with no pipeline delay, in contrast to sigma-delta or pipeline architectures.
Key features of the AD7872AN include 80 dB SNR at 10 kHz input frequency, 57 ns data-access time, ±5 LSB maximum integral nonlinearity (INL), bipolar ±10 V or unipolar 0 to +10 V input range (software configurable), and 50 mW typical power dissipation. The part uses Analog Devices' proprietary LC2MOS mixed-technology process and is specified for both DC accuracy and dynamic performance.
Architecturally, the device combines a low-noise input amplifier, a buried Zener voltage reference, and a successive-approximation register with a precision DAC on a single die. The bipolar input stage uses a proprietary chopping technique that keeps integral linearity error below ±5 LSB over the industrial temperature range, while the high-speed comparator enables the 57 ns data-access time needed for high-speed parallel interface designs.
Typical applications include industrial process control, instrumentation, spectrum analysis, and DSP front-ends. The wide input range and bipolar capability also suit motor-control current sensing and high-accuracy data-acquisition front-ends where a complete single-chip ADC with on-chip reference simplifies the BOM.
Design consideration: the input signal source impedance should be kept below 1 kohm to avoid conversion errors caused by the input amplifier's bias current; add a 100 ohm series resistor with a 10 nF input capacitor for wideband noise filtering on high-impedance sensors.
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 AD7872AN — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
AD7872JN
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
AD7872KN
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
AD7872BR
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
AD7872AQ
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
AD7872TQ
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
AD7872AN Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 14 bit |
| Number of Channels | 1 |
| Architecture | SAR (Successive Approximation) |
| Tỷ lệ lấy mẫu | 83 kSPS |
| Input Type | Single-ended |
| Phạm vi điện áp đầu vào | ±10 V bipolar or 0 to +10 V unipolar |
| SNR | 80 dB at 10 kHz input |
| Data Access Time | 57 ns |
| Integral Nonlinearity (INL) | ±5 LSB max |
| Giao diện | Parallel, Byte, Serial (3 modes) |
| Output Coding | 2's Complement (bipolar) / Straight Binary (unipolar) |
| Power Dissipation | 50 mW typical |
| Reference Type | Internal (on-chip buried Zener) |
| Nhiệt độ hoạt động | -40C to +85C |
| Hộp | 16-Pin PDIP (N-16) |
| Kiểu lắp đặt | Through-Hole |
Cấu hình chân AD7872AN
| Chân 1 | VDD — +5V analog supply |
| Chân 2 | VREF — Voltage reference output/decoupling |
| Chân 3 | AGND — Analog ground |
| Chân 4 | BIPOFF — Bipolar offset input |
| Chân 5 | VIN — Analog input |
| Chân 6 | AGND — Analog ground (duplicate) |
| Chân 7 | DGND — Digital ground |
| Chân 8 | CONVST — Conversion start input |
| Chân 9 | CS — Chip select (active low) |
| Chân 10 | RD — Read input (active low) |
| Chân 11 | D13 (MSB) — Data bit 13 (MSB in 14-bit mode) |
| Chân 12 | D12 — Data bit 12 |
| Chân 13 | D11 — Data bit 11 |
| Chân 14 | D10 — Data bit 10 |
| Chân 15 | NC — Not connected (per datasheet) |
| Chân 16 | DGND — Digital ground (duplicate) |
Ứng dụng tiêu biểu
AD7872AN phù hợp cho 7 Áp dụngs: Industrial Process Control Data Acquisition, Instrumentation and Test Equipment, Spectrum Analyzer Front-End, DSP Front-End and Signal Processing, Medical Monitoring Equipment, Motor Control Current Sensing, Legacy Data Acquisition System Repair.
Industrial Process Control Data Acquisition
The AD7872AN's ±10 V bipolar input range and 14-bit resolution suit industrial process-control data-acquisition modules that digitize ±10 V sensor signals directly without external signal conditioning. Its 80 dB SNR at 10 kHz and 83 kSPS throughput provide sufficient dynamic range for loop controllers, chart recorders, and PLC analog input modules. The on-chip reference eliminates calibration drift from external references, while the parallel interface allows direct connection to legacy microprocessors.
Được đề xuất
Instrumentation and Test Equipment
The AD7872AN fits benchtop instruments and ATE systems where 14-bit accuracy, bipolar input, and deterministic SAR latency matter. With 57 ns data-access time and a parallel interface, it can stream samples into an FPGA or DSP without pipeline-delay complications of sigma-delta converters. The 80 dB SNR supports spectrum-analyzer front-ends and digital-multimeter designs, while the 16-PDIP package remains popular in through-hole prototype builds and educational lab equipment.
Được đề xuất
Spectrum Analyzer Front-End
The AD7872AN's 80 dB SNR at 10 kHz input and 83 kSPS throughput enable FFT-based spectrum-analyzer front-ends in audio-bandwidth and vibration-analysis equipment. The SAR architecture's deterministic per-sample latency simplifies FFT windowing and avoids the sinc-shaped filter droop of sigma-delta ADCs in the audio band. Bipolar ±10 V input lets the ADC digitize AC-coupled vibration or audio signals directly after bias-offset adjustment.
Được đề xuất
DSP Front-End and Signal Processing
The AD7872AN's 57 ns data-access time and parallel interface make it well suited to legacy DSP front-ends (e.g., ADSP-21xx, TMS320Cxx) where deterministic latency matters. The 14-bit resolution and bipolar input are adequate for voice-band codecs, control-loop DSP, and motor-drive DSP preprocessing. The three interface modes (parallel/byte/serial) give designers flexibility to connect to 8-bit microcontrollers, 16-bit DSPs, or modern SPI peripherals.
Được đề xuất
Medical Monitoring Equipment
Although not specifically medical-grade certified, the AD7872AN's bipolar input and 80 dB SNR suit low-frequency patient-monitoring signal chains such as ECG, temperature, and respiration front-ends. The single-chip integration (ADC + reference + track/hold) reduces BOM count in cost-sensitive medical device designs. The 14-bit resolution provides adequate dynamic range for diagnostic-grade signal acquisition in non-life-critical monitoring applications.
Được đề xuất
Motor Control Current Sensing
The AD7872AN's ±10 V bipolar input is ideal for digitizing current-sense amplifier outputs from shunt resistors in brushless DC and AC motor drives. The 83 kSPS rate covers PWM frequencies up to ~10 kHz with comfortable margin for current-loop control updates. The SAR architecture provides zero-latency conversion - critical for current-mode control loops that cannot tolerate sigma-delta group delay. The 16-PDIP package eases hand-prototype debugging of motor-control boards.
Được đề xuất
Legacy Data Acquisition System Repair
The AD7872AN's continued availability (in limited stock) and 16-PDIP through-hole package make it a repair part for industrial data-acquisition systems, chart recorders, and test equipment originally designed in the 1990s. Its drop-in compatibility with other AD7872 family variants allows maintenance engineers to substitute equivalent grades without PCB modifications. For new designs, however, Analog Devices recommends modern replacements such as the AD7680 or AD7693 family.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho AD7872AN — 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 | AD7872JN | AD7872KN | AD7872BR | AD7872AQ | AD7872TQ | AD1674BR |
|---|---|---|---|---|---|---|---|
| Package | 16-PDIP (N-16) | 16-PDIP (N-16) - same | 16-PDIP (N-16) - same | 16-PDIP (N-16) - same | 16-CERDIP (D-16) | 16-CERDIP (D-16) | 28-CDIP (D-28) |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 14 bit | 14 bit | 14 bit | 14 bit | 14 bit | 14 bit | 14 bit |
| Sampling Rate | 83 kSPS | 83 kSPS | 83 kSPS | 83 kSPS | 83 kSPS | 83 kSPS | 100 kSPS |
| INL (max) | ±5 LSB | ±1 LSB typical | ±5 LSB max | ±5 LSB max | ±5 LSB max | ±5 LSB max | ±5 LSB max |
| Input Voltage Range | ±10 V bipolar or 0-10 V unipolar | ±10 V bipolar or 0-10 V unipolar | ±10 V bipolar or 0-10 V unipolar | ±10 V bipolar or 0-10 V unipolar | ±10 V bipolar or 0-10 V unipolar | ±10 V bipolar or 0-10 V unipolar | ±5 V bipolar or 0-5 V unipolar |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Bảo phân biệt quan trọng
- Complete single-chip 14-bit ADC with on-chip reference and track/hold (vsDiscrete ADC + external reference designs)
- Three interface modes in a single chip (vsSingle-interface ADCs)
- Bipolar ±10 V input without external signal conditioning (vsUnipolar-only ADCs like AD7680)
- SAR architecture with deterministic zero-latency conversion (vsSigma-delta ADCs like AD7738BRU-REEL7)
Ghi chú thiết kế
The input signal source impedance should be kept below 1 kohm to avoid conversion errors caused by the AD7872AN's input amplifier bias current. For high-impedance sensors, add a 100 ohm series resistor with a 10 nF input capacitor to form a wideband noise filter. According to the Analog Devices datasheet, exceeding 1 kohm source impedance can degrade integral linearity by 1-2 LSB. Bypass VDD with a 10 uF tantalum plus 100 nF ceramic directly at the supply pin.
Separate analog and digital ground returns to a single point near the AGND/DGND pins of the AD7872AN to avoid digital switching noise coupling into the analog input. Route the analog input trace (pin 5) on a separate layer away from the parallel data bus (pins 11-14) and digital control signals (CONVST, CS, RD). Per the datasheet reference design, surround the analog input trace with a guard ground trace tied to AGND to minimize crosstalk. Use a ground plane on the layer beneath the analog input trace.
The AD7872AN dissipates approximately 50 mW typical and 60 mW maximum at full throughput. In the 16-PDIP package, theta_JA is approximately 100 C/W, giving a junction temperature rise of 5-6 C above ambient - well within the 125 C maximum. No heatsink is required. However, in sealed enclosures with limited airflow, derate maximum ambient by 5-10 C to maintain reliability. The internal buried-Zener reference generates minor self-heating that affects reference stability during warm-up; a 1-second warm-up is recommended for highest accuracy.
Power the AD7872AN from a clean +5V analog supply; the device draws 10 mA typical during conversion and 1 mA in standby. Use a linear regulator (e.g., ADP7104) rather than a switching converter to avoid coupling switching noise into the analog input. Decouple VDD (pin 1) with a 10 uF tantalum capacitor in parallel with a 100 nF ceramic capacitor placed within 5 mm of the pin. The VREF pin (pin 2) requires a 10 uF tantalum decoupling capacitor for reference stability - omitting this can cause SNR degradation of 5-10 dB.
Thông tin tuân thủ
RoHS and REACH compliance status not explicitly stated in the provided web data for AD7872AN; marked [DATA_NEEDED] in specs. AD7872AN was originally designed before RoHS mandates; some distributors may offer RoHS-compliant variants - verify with supplier. AEC-Q100 not applicable for this industrial-grade ADC.
