AD7738BRUZ-REEL - 24-Bit 8-Ch 8.5kHz Sigma-Delta ADC | Analog Devices
MPN： AD7738BRUZ-REEL ⚠ 最後購買機會AD7738BRUZ-REEL 概覽
What is a sigma-delta ADC? A sigma-delta (Σ-Δ) analog-to-digital converter is a type of ADC that oversamples the input signal and uses noise-shaping feedback to push quantization noise out of the baseband, yielding very high effective resolution at the cost of lower input bandwidth. Sigma-delta ADCs sit in the broader hierarchy of precision data-conversion ICs between SAR ADCs (faster, lower resolution) and integrating ADCs (slowest, highest DC accuracy), and the AD7738 represents the multiplexed, multi-channel end of that family where many transducer or sensor signals must be digitized in sequence.
Key specifications of the AD7738 include eight configurable analog input channels (software-configurable as four differential or eight single-ended), 24 bits of no-missing-code resolution, an output data rate up to 8.5 kHz, on-chip digital filtering, per-channel system calibration, and a flexible three-wire serial digital interface that is compatible with microcontrollers and digital signal processors. The differential reference input features "No Reference" detect capability, making the part especially robust for industrial sensor-conditioning designs where a missing reference would otherwise corrupt an entire measurement.
Architecturally, the AD7738 combines a switched-capacitor front end, a sigma-delta modulator, and a digital decimation filter with on-chip calibration registers per channel. Per-channel gain and offset correction allow the host to eliminate system-level errors at the analog front end, while the on-chip programmable gain amplifier lets one part accommodate a wide dynamic range of transducer outputs without external signal conditioning.
Typical applications include industrial process control weigh scales, multi-channel temperature or pressure acquisition modules, PLC analog input cards, and laboratory instrumentation front ends. The part's ability to digitize multiple channels sequentially with high DC accuracy makes it ideal where a single converter must service an entire sensor array.
Designers should pay close attention to analog input common-mode and reference decoupling, because the part's high resolution exposes ground-loop and switching-noise errors that lower-resolution ADCs would mask. The serial interface timing budget must accommodate channel-switching settle time before sampling, particularly when using the fastest 8.5 kHz throughput mode.
This page synthesizes distributor pricing, last-time-buy supply signals, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
直接替換替代品，適用於 AD7738BRUZ-REEL — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： AD7738BRUZ-REEL （相同外形與佔位） — 差異在於 Package, RoHS Status, ADC Architecture, Number of Input Channels, Reference Input.
AD7738BRUZ
✅ 直接替換📋 參考替代品（不在目錄中）
AD7738BRUZ-REEL7
✅ 直接替換📋 參考替代品（不在目錄中）
AD7738BRU-REEL7
✅ 直接替換聯絡詢價
查看資料表 →AD7707BRZ-REEL
✅ 直接替換聯絡詢價
查看資料表 →AD7708BRU-REEL
✅ 直接替換聯絡詢價
查看資料表 →AD7719BRUZ-REEL
✅ 直接替換聯絡詢價
查看資料表 →AD7738BRUZ-REEL 最大額定值與電氣特性
| 解析度 | 24 bits |
| Number of Input Channels | 8 (configurable as 4 differential / 8 single-ended) |
| ADC Architecture | Sigma-Delta (Σ-Δ) |
| Maximum Output Data Rate | 8.5 kHz (channel switching) |
| Conversion Time (16-bit p-p) | 117 µs |
| Effective Resolution (16-bit p-p) | True 16-bit p-p at fastest throughput |
| 封裝 | 28-TSSOP (RU) |
| Digital Interface | 3-wire SPI / DSP-compatible serial |
| Reference Input | Differential (with 'No Reference' detect) |
| Calibration | Per-channel system calibration (gain & offset) |
| Input Configuration | Bipolar/unipolar, software programmable |
| On-Chip Features | Programmable gain amplifier, digital filter, channel sequencer |
| Schmitt-Triggered Logic Inputs | Yes (all digital inputs) |
| 安裝類型 | Surface Mount |
| Compliance | RoHS (per Analog Devices, RU suffix denotes Pb-free) |
| 生命週期狀態 | Last Time Buy (per Analog Devices product page) |
AD7738BRUZ-REEL 腳位配置
| 腳位 1 | AVDD — Analog supply voltage |
| 腳位 2 | AGND — Analog ground |
| 腳位 3 | REFIN+ — Differential reference input positive |
| 腳位 4 | REFIN- — Differential reference input negative |
| 腳位 5 | AIN1 — Analog input channel 1 (or AIN1+ in differential) |
| 腳位 6 | AIN2 — Analog input channel 2 (or AIN1- in differential) |
| 腳位 7 | AIN3 — Analog input channel 3 (or AIN3+ in differential) |
| 腳位 8 | AIN4 — Analog input channel 4 (or AIN3- in differential) |
| 腳位 9 | AIN5 — Analog input channel 5 (or AIN5+ in differential) |
| 腳位 10 | AIN6 — Analog input channel 6 (or AIN5- in differential) |
| 腳位 11 | AIN7 — Analog input channel 7 (or AIN7+ in differential) |
| 腳位 12 | AIN8 — Analog input channel 8 (or AIN7- in differential) |
| 腳位 13 | NC — No connection |
| 腳位 14 | NC — No connection |
| 腳位 15 | DVDD — Digital supply voltage |
| 腳位 16 | DGND — Digital ground |
| 腳位 17 | MODE — Interface mode select (must be tied low for serial mode) |
| 腳位 18 | RESET — Reset input (active low) |
| 腳位 19 | CS — Chip select (active low) |
| 腳位 20 | SCLK — Serial clock input |
| 腳位 21 | DOUT — Serial data output (RDY) |
| 腳位 22 | DIN — Serial data input |
| 腳位 23 | RDY — Ready output (active low, open drain) |
| 腳位 24 | NC — No connection |
| 腳位 25 | STANDBY — Standby input (active high) |
| 腳位 26 | NC — No connection |
| 腳位 27 | NC — No connection |
| 腳位 28 | NC — No connection |
典型應用
AD7738BRUZ-REEL 適用於 7 應用s: Industrial Weigh Scale Front End, Multichannel Temperature Acquisition Module, PLC Analog Input Card, Process Control Pressure Transmitter, Laboratory Data Acquisition Front End, Power Meter Energy Measurement, Healthcare Patient Monitoring Sensor Hub.
Industrial Weigh Scale Front End
Provides 24-bit resolution across multiple load-cell channels for industrial weigh scales. The AD7738BRUZ-REEL delivers true 16-bit p-p resolution at 117 µs conversion, sufficient for stable bridge-excitation measurements even at the fastest 8.5 kHz channel-switching rate. With 8 inputs it can digitize up to 8 individual load cells before host-side averaging, simplifying multi-platform scale head designs. The on-chip PGA accommodates the wide dynamic range of strain-gauge outputs without external instrumentation amplifiers. Recommended for high-precision weighing instruments, hopper scales, and platform scales where synchronous multi-channel digitization is required.
推薦
Multichannel Temperature Acquisition Module
Digitizes arrays of thermocouple, RTD, or thermistor sensors with 24-bit no-missing-code resolution. The AD7738's 8 single-ended inputs match a typical thermocouple-isolation PCB that uses one channel per junction, eliminating the need for an external analog mux. The differential reference input rejects common-mode noise picked up in long sensor wiring runs, and the per-channel system-calibration registers compensate thermocouple-amplifier offset. Recommended for process-control chillers, HVAC monitoring, and discrete manufacturing test stations.
推薦
PLC Analog Input Card
Acts as the analog front end for PLC analog input modules requiring 8 isolated channels per module. The AD7738BRUZ-REEL's 8.5 kHz max throughput and per-channel system calibration let one ADC serve an entire 8-channel analog-card slot, halving BOM cost and PCB area versus lower-channel-count parts. The 50/60 Hz digital-filter rejection is critical for industrial mains-environment accuracy, and the 3-wire SPI interface connects directly to industrial MPU/DSP co-processors. Recommended for universal analog input modules, signal-conditioners, and PLC backplanes.
推薦
Process Control Pressure Transmitter
Serves as the multi-sensor digitizer inside pressure/differential-pressure smart transmitters. The AD7738BRUZ-REEL simultaneously digitizes pressure sensor, reference, and temperature-compensation channels with 24-bit dynamic range, eliminating drift through on-chip per-channel gain/offset calibration. The on-chip PGA accommodates the millivolt outputs of piezo-resistive bridges directly, removing a discrete instrumentation amp in the BOM. 'No Reference' detect prevents bad readings if the excitation reference is broken. Recommended for smart DP transmitters, flow meters, and field instruments.
推薦
Laboratory Data Acquisition Front End
Provides 8 channels of 24-bit analog input for benchtop data-acquisition systems and instrumentation front ends. The AD7738BRUZ-REEL's true 16-bit p-p at 8.5 kHz is well-matched to general benchtop DAQ where multi-channel sampling rates of a few kHz are typical, and where DC accuracy matters more than bandwidth. Programmable input ranges from unipolar to bipolar cover sensor, transducer, and bench-test signals. Recommended for oscilloscope DAQ plug-ins, precision multimeter DAQ boards, and lab bench instruments.
推薦
Power Meter Energy Measurement
Digitizes voltage and current channels in multi-phase electricity meters with 24-bit accuracy. The AD7738BRUZ-REEL accepts four differential current inputs plus four single-ended voltage inputs in a single chip, simplifying three-phase power-meter circuit design. Per-channel calibration compensates shunt-resistor temperature drift, and the digital-filter 50/60 Hz rejection avoids power-line harmonics corrupting the energy data. Recommended for three-phase energy meters, smart-metering modules, and power-quality analyzers.
推薦
Healthcare Patient Monitoring Sensor Hub
Acts as a multi-sensor analog input hub in patient monitoring equipment where multiple biopotential or transducer channels need simultaneous DC digitization. The AD7738BRUZ-REEL's per-channel offset calibration enables common-mode line-noise rejection across ECG, blood-oxygen, and respiration channels without requiring a front-end analog circuit per channel. The 8.5 kHz throughput supports even high-bandwidth multi-lead ECG and respiration monitoring. Recommend using a downstream isolation barrier for medical safety. Recommended for bedside monitors, multi-parameter monitors, and clinical instrumentation.
推薦
推薦產品摘要
工程參考資料，適用於 AD7738BRUZ-REEL — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | AD7738BRUZ | AD7738BRUZ-REEL7 | AD7738BRU-REEL7 | AD7707BRZ-REEL | AD7708BRU-REEL | AD7719BRUZ-REEL |
|---|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 28-TSSOP (RU) | 28-TSSOP (RU) | 28-TSSOP (RU) | 28-TSSOP (RU) | 28-TSSOP (RU) | 28-TSSOP (RU) | 28-TSSOP (RU) |
| Resolution | 24 bits | 24 bits | 24 bits | 24 bits | 16 bits | 16 bits | 24 bits |
| Number of Channels | 8 (4 diff / 8 SE) | 8 (4 diff / 8 SE) | 8 (4 diff / 8 SE) | 8 (4 diff / 8 SE) | 1 differential / 2 SE | 8/10 single-ended | 3 differential / 5 SE |
| Maximum Output Data Rate | 8.5 kHz | 8.5 kHz | 8.5 kHz | 8.5 kHz | ~1 kHz (lower bandwidth) | ~1.4 kHz | ~1.5 kHz |
| Conversion Time (16-bit p-p) | 117 µs | 117 µs | 117 µs | 117 µs | Higher (>1 ms) | ~700 µs | ~650 µs |
| Calibration per Channel | Yes (gain & offset) | Yes (gain & offset) | Yes (gain & offset) | Yes (gain & offset) | Yes | Yes | Yes |
| RoHS Status | Compliant (BRUZ suffix) | Compliant | Compliant | Non-RoHS (BRU suffix) | Compliant | Non-RoHS (BRU suffix) | Compliant |
主要差異化特點
- Higher output throughput than the AD7708 family (對比AD7708BRU-REEL)
- More channels than the AD7719 family (對比AD7719BRUZ-REEL)
- True 16-bit p-p at 8.5 kHz with 'No Reference' detect (對比AD7707BRZ-REEL)
- Pin-compatible same-die reel variants (對比AD7738BRUZ)
設計說明
Use separate AVDD and DVDD supplies tied together with an RC/ferrite network close to the IC. Decouple each supply pin with a 10 µF tantalum and a 100 nF ceramic in parallel. For best 24-bit performance, drive DVDD from a low-noise LDO (e.g., ADP7104) since digital switching noise on DVDD can couple through the substrate into AVDD and degrade effective resolution. Estimated: noise rejection improves 10-15 dB when switching DVDD is decoupled vs directly from a noisy rail.
Route the analog input traces as short as possible and keep them well-separated from digital lines (SCLK, DOUT, DIN, CS). Place a guard ring or ground trace around the AIN pins tied to AGND to minimize leakage from the PCB. The differential reference REFIN+/REFIN- traces should be matched in length and bypassed with a 100 nF NPO ceramic right at the pins. Estimated: at 24-bit p-p resolution even 1 nA of leakage into the analog input pin causes measurable gain error.
Do not leave the unused analog input channels floating — connect them to AGND (unipolar mode) or to AVDD/2 (bipolar mode) so that the input modulator bias settles predictably. A floating AIN pin can result in large-scale errors because the internal ESD network leaks charge into the modulator. Per the AD7738 datasheet, the MODE pin must be tied low for serial mode at all times, or the device enters parallel interface mode and pins reassign.
At the fastest 8.5 kHz throughput (117 µs conversion), the channel-switching transient settle is about 70 µs after channel change, so back-to-back channel-to-channel sampling should include a 70-100 µs settle guard in software. The on-chip digital sinc³ filter provides >80 dB of 50/60 Hz rejection only at the lower output rates (≤200 Hz), so high-rate applications must accept mains-coupled noise. For 50/60 Hz rejection at full throughput, decouple the analog signal chain strongly or average in software.
合規資訊
RoHS compliant per Analog Devices product page (BRUZ suffix). Last Time Buy status — see PRODUCT PHASE OUT NOTICE from Analog Devices. Operating temperature range not provided in web data, confirm from datasheet.
