ADS8887 - 18-Bit 100kSPS True-Differential SAR ADC | TI
MPN: ADS8887 ✓ Hoạt độngADS8887 Tóm tắt
A SAR ADC is a type of analog-to-digital converter that uses a binary search algorithm to convert an analog input into a digital output, consisting of a comparator, a capacitive DAC, and successive approximation logic. SAR ADCs, a subset of data converters in mixed-signal electronics, are known for high speed, low power, and excellent accuracy in data acquisition, industrial process control, and medical instrumentation.
Key features include 18-bit resolution, a 100 kSPS maximum sampling rate, and a true-differential input that rejects common-mode noise. The device runs from a single 2.7-V to 3.6-V analog supply with a separate digital supply for the serial interface. An external reference between 2.5 V and 5 V lets designers optimize the input range per application. A power-down mode reduces current to microamperes, suiting battery-powered systems.
Technically, the ADS8887 uses a charge-redistribution SAR architecture with a capacitive DAC, achieving INL of ±1 LSB and SNR of 100 dB. An internal oscillator and track-and-hold circuit reduce external component count. The SPI-compatible serial interface supports 3-wire and 4-wire modes and daisy-chaining for multi-channel systems; the 10 MHz input bandwidth accurately samples high-frequency signals.
Typical applications include precision data acquisition, industrial automation, medical imaging, and portable instrumentation. The true-differential input makes it ideal for bridge sensors, thermocouples, and other differential signal sources, plus battery-powered data loggers and IoT devices.
Design tip: provide a low-impedance reference source, bypass the reference with a 10-uF capacitor, and drive the analog input from a low-impedance source such as an op amp to achieve full datasheet performance.
Bộ thay thế dễ dàng lắp đặt cho ADS8887 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
ADS8866IDGSR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
ADS8885IDGSR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
ADS8881IDGSR
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
ADS8860IDGSR
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
AD7920
⚡ Đồng gói ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
ADS8887 Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 18 bit |
| Tỷ lệ lấy mẫu | 100 kSPS |
| Input Type | True-differential, 1 channel |
| Reference Voltage Range | 2.5 V to 5 V (external) |
| Analog Supply (AVDD) | 2.7 V to 3.6 V |
| Giao diện | SPI-compatible serial (3-wire/4-wire, daisy-chain) |
| SNR | 100 dB |
| INL | ±1 LSB |
| Input Bandwidth | 10 MHz |
| Architecture | SAR, charge redistribution with capacitive DAC |
| Nhiệt độ hoạt động | -40C to +85C (I grade) |
| Hộp | 10-VSSOP (DGS) |
| Kiểu lắp đặt | Surface Mount |
| Trạng thái RoHS | Compliant |
Cấu hình chân ADS8887
| Chân 1 | IN+ — Non-inverting differential analog input |
| Chân 2 | IN- — Inverting differential analog input |
| Chân 3 | GND — Ground reference |
| Chân 4 | REF — External reference input, 2.5 V to 5 V |
| Chân 5 | CONVST — Conversion start control |
| Chân 6 | DVDD — Digital interface supply |
| Chân 7 | SCLK — Serial clock input |
| Chân 8 | DIN — Serial data input (command register) |
| Chân 9 | DOUT/RDY — Serial data output / ready indicator |
| Chân 10 | AVDD — Analog supply, 2.7 V to 3.6 V |
Ứng dụng tiêu biểu
ADS8887 phù hợp cho 6 Áp dụngs: Precision Data Acquisition, Industrial Process Control, Medical Instrumentation, Portable and Battery-Powered Instruments, IoT Sensor Nodes, Automated Test and Measurement.
Precision Data Acquisition
The ADS8887 fits precision DAQ front ends where its 18-bit resolution, 100 dB SNR, and ±1 LSB INL resolve microvolt-level signals. The true-differential input rejects common-mode noise from industrial environments, and the 100-kSPS rate captures fast transients. Placed after an op-amp driver with 10-uF reference bypass, it digitizes multi-channel sensor arrays via SPI daisy-chaining without adding switching noise.
Được đề xuất
Industrial Process Control
In factory automation and process control, the ADS8887 digitizes 4-20 mA loops, bridge transducers, and pressure sensors with 18-bit accuracy. Its 2.5-V to 5-V external reference allows signal-range optimization without scaling circuitry, while the differential input suppresses motor and relay common-mode noise. Power-down mode between conversions lowers system power in always-on monitoring nodes.
Được đề xuất
Medical Instrumentation
Medical diagnostic equipment benefits from the ADS8887's 100 dB SNR and low-noise differential input, which preserve small biosignals such as ECG and impedance-measurement channels. The miniature 10-VSSOP package conserves board space in portable and handheld devices, and the internal oscillator removes an external clock source, reducing component count in size-constrained medical designs.
Được đề xuất
Portable and Battery-Powered Instruments
For handheld meters and field instruments, the ADS8887's microampere power-down current extends battery life dramatically: the ADC wakes on CONVST, converts at 100 kSPS, and returns to shutdown. Its 2.7-V to 3.6-V single analog supply runs directly from Li-ion or two-cell stacks, and the tiny 10-VSSOP footprint fits compact enclosures typical of portable test gear.
Được đề xuất
IoT Sensor Nodes
IoT edge nodes use the ADS8887 to digitize thermocouples, RTDs, and bridge sensors with 18-bit resolution while minimizing energy per sample. SPI-compatible 3-wire and daisy-chain modes let one MCU bus serve multiple converters, and the internal oscillator saves board area. Combined with a low-power MCU and buck regulator, duty-cycled sampling keeps average current in the microamp range.
Được đề xuất
Automated Test and Measurement
Bench instruments and automated test equipment exploit the ADS8887's 10 MHz input bandwidth and 100-kSPS throughput to sample wideband signals accurately. The true-differential input maintains dynamic range when measuring grounded or floating sources, and ±1 LSB INL guarantees monotonic, repeatable readings. Daisy-chain SPI simplifies scaling from one channel to multi-channel arrays in modular ATE.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho ADS8887 — 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 | ADS8866IDGSR | ADS8885IDGSR | ADS8881IDGSR | ADS8860IDGSR |
|---|---|---|---|---|---|
| Package | 10-VSSOP (DGS) | 10-VSSOP (DGS) - same | 10-VSSOP (DGS) - same | 10-VSSOP (DGS) - same | 10-VSSOP (DGS) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Resolution | 18 bit | 16 bit | 16 bit | 18 bit | 16 bit |
| Input Type | True-differential | Pseudo-differential | True-differential | True-differential | Pseudo-differential |
| Reference Range | 2.5 V to 5 V | 2.5 V to 5 V | 2.5 V to 5 V | 2.5 V to 5 V | 2.5 V to 5 V |
| Interface | SPI (3/4-wire, daisy-chain) | SPI (3/4-wire, daisy-chain) | SPI (3/4-wire, daisy-chain) | SPI (3/4-wire, daisy-chain) | SPI (3/4-wire, daisy-chain) |
Bảo phân biệt quan trọng
- 18-bit resolution at 100 kSPS (vsADS8866IDGSR)
- True-differential input (vsADS8866IDGSR)
- Family software compatibility (vsADS8885IDGSR)
Ghi chú thiết kế
Provide a low-impedance reference source and bypass the REF pin with a 10-uF capacitor close to the pin, per the ADS8887 datasheet typical application circuit. Separate analog ground and digital return paths, joining them at a single star point under the converter. Keep the SPI clock lines away from IN+/IN- traces to avoid digital coupling into the analog front end during acquisition.
The SAR capacitive DAC injects charge kickback onto IN+ and IN- at the start of each acquisition. Drive both differential inputs from a low-impedance source such as an op amp (for example OPA2375 or OPA2192) with an RC filter sized so the inputs settle within the acquisition window; otherwise SNR degrades below the specified 100 dB and INL errors appear near code transitions.
Decouple AVDD (2.7 V to 3.6 V) and DVDD each with 0.1-uF ceramics placed within 2 mm of the pins. Remember the REF voltage may exceed AVDD - reference integrity, not AVDD, sets the full-scale range. Use the CONVST-controlled power-down mode between conversions in battery designs to keep average current in the microampere range.
Thông tin tuân thủ
RoHS compliant per TI product page and distributor listings.
