ADS8484IBRGZR - 18-Bit 1.25MSPS SAR ADC | Texas Instruments
MPN: ADS8484IBRGZR ✓ Hoạt độngADS8484IBRGZR Tóm tắt
An SAR ADC (Successive Approximation Register Analog-to-Digital Converter) is a type of high-precision data converter that uses a binary search algorithm against an internal DAC to resolve each input sample to N bits in N clock cycles. SAR ADCs occupy the middle ground between flash converters (fast, low resolution) and sigma-delta converters (very high resolution, slow). They combine low latency, deterministic latency, and high accuracy - making them the dominant architecture for industrial data acquisition, instrumentation, and control loops where every microsecond counts.
Key features of the ADS8484IBRGZR include a capacitor-based charge-redistribution SAR core with inherent track-and-hold, selectable 8-/16-/18-bit parallel bus interfaces, an internal low-drift 4.096-V reference, and a fully differential analog input that accepts pseudo-bipolar input ranges of ±VREF around an input common-mode of +2.5V. The device supports a hardware-friendly parallel MCU/DSP interface and offers an active-low CONVST pin for precise sampling control.
Architecturally, the ADS8484IBRGZR uses a charge-redistribution SAR core with input ESD diodes and on-chip reference buffer. The differential input structure rejects common-mode noise from the analog front end, while the internal reference eliminates the need for an external precision reference - simplifying BOM cost and PCB area. This makes it suitable for high-density industrial layouts where each square centimeter matters.
Typical applications include industrial process control loops, multi-channel data acquisition systems (DAQ) for factory automation, medical instrumentation including portable patient monitoring, precision weigh scales, vibration analysis, optical sensor front ends, motor control current sensing, and test and measurement equipment. The wide input common-mode tolerance also suits battery-management systems where ground potentials vary across the system.
When designing with this ADC, ensure the analog and digital supply pins each have local decoupling: a 10 uF tantalum plus 0.1 uF ceramic placed within 5 mm of the AVDD/DVDD pins. Keep digital return currents (DB[17:0], CONVST, /CS, /RD) physically separated from the analog return plane to avoid code-dependent noise coupling into the SAR comparator.
This page synthesizes distributor pricing, drop-in alternatives including same-package ADS8484 variants, and practical design notes not found in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho ADS8484IBRGZR — 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 ADS8484IBRGZR (cùng hình factor và footprint) — khác nhau ở Architecture, Input Type, Package, Resolution, Interface.
ADS8482IBRGZR
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →ADS8481IRGZR
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →ADS8484IBRGZT
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
ADS8462IRGZR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
ADS8412IRGZR
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
ADS8484IBRGZR Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 18 bit |
| Sample Rate | 1.25 MSPS |
| Architecture | SAR (Successive Approximation) |
| Number of Input Channels | 1 |
| Input Type | Pseudo-bipolar, fully differential |
| Internal Reference | 4.096 V |
| Analog Supply Voltage | 5 V |
| Digital Supply Voltage | 5 V (or 3 V with level shifters) |
| INL (Max) | ±1 LSB |
| Power Consumption | 100 mW (typ at 1.25 MSPS) |
| Input Common-Mode Voltage | 2.5 V |
| Giao diện | Parallel (8-/16-/18-bit selectable) |
| Hộp | 48-VQFN (RGZ) 7x7 mm |
| Khoảng nhiệt độ hoạt động | -40C to +85C |
| Kiểu lắp đặt | Surface Mount |
| Cấp MSL | 2 (1 year floor life) |
| Trạng thái RoHS | Compliant |
| Lead-Free | Yes |
Cấu hình chân ADS8484IBRGZR
| Chân 1 | AVDD — Analog +5V supply |
| Chân 2 | AGND — Analog ground |
| Chân 3 | REFIN — Reference input (tie to REFOUT or external reference) |
| Chân 4 | REFOUT — Internal 4.096V reference output |
| Chân 5 | REFGND — Reference ground |
| Chân 6 | IN+ — Differential positive analog input |
| Chân 7 | IN- — Differential negative analog input |
| Chân 8 | AVSS — Analog supply negative (typically tied to AGND for unipolar supplies) |
| Chân 9 | AGND — Analog ground |
| Chân 10 | AVDD — Analog +5V supply |
| Chân 11 | AVDD — Analog +5V supply |
| Chân 12 | AVSS — Analog supply negative |
| Chân 13 | NC — Not connected (per datasheet) |
| Chân 14 | NC — Not connected (per datasheet) |
| Chân 15 | CONVST — Conversion start (active low falling edge initiates sample/hold) |
| Chân 16 | /CS — Chip select (active low) |
| Chân 17 | /RD — Read strobe (active low) |
| Chân 18 | BUSY — Conversion in progress (active high) |
| Chân 19 | /RESET — Reset input (active low) |
| Chân 20 | BYTE — Bus width selection (Hi = 18-bit, Lo = 16-bit word, midscale Hi-Z = 8-bit byte mode) |
| Chân 21 | TAG — Tag input for read cycle |
| Chân 22 | DB0 — Data bit 0 (LSB) |
| Chân 23 | DB1 — Data bit 1 |
| Chân 24 | DB2 — Data bit 2 |
| Chân 25 | DB3 — Data bit 3 |
| Chân 26 | DB4 — Data bit 4 |
| Chân 27 | DB5 — Data bit 5 |
| Chân 28 | DB6 — Data bit 6 |
| Chân 29 | DB7 — Data bit 7 |
| Chân 30 | DVDD — Digital +5V supply |
| Chân 31 | DGND — Digital ground |
| Chân 32 | DGND — Digital ground |
| Chân 33 | DVDD — Digital +5V supply |
| Chân 34 | DB8 — Data bit 8 |
| Chân 35 | DB9 — Data bit 9 |
| Chân 36 | DB10 — Data bit 10 |
| Chân 37 | DB11 — Data bit 11 |
| Chân 38 | DB12 — Data bit 12 |
| Chân 39 | DB13 — Data bit 13 |
| Chân 40 | DB14 — Data bit 14 |
| Chân 41 | DB15 — Data bit 15 |
| Chân 42 | DB16 — Data bit 16 |
| Chân 43 | DB17 — Data bit 17 (MSB) |
| Chân 44 | AGND — Analog ground |
| Chân 45 | AVDD — Analog +5V supply |
| Chân 46 | AVDD — Analog +5V supply |
| Chân 47 | AVSS — Analog supply negative |
| Chân 48 | NC — Not connected (per datasheet) |
Ứng dụng tiêu biểu
ADS8484IBRGZR phù hợp cho 7 Áp dụngs: Industrial Process Control Loops, Multi-Channel Data Acquisition Systems (DAQ), Medical Patient Monitoring, Precision Weigh Scales, Motor Control Current Sensing, Test and Measurement Equipment, Optical Sensor Front End.
Industrial Process Control Loops
The ADS8484IBRGZR's 18-bit resolution, 1.25 MSPS throughput, and deterministic SAR latency make it well-suited for closed-loop industrial process control. With ±1 LSB INL and an internal 4.096V reference, it provides the absolute accuracy required for PID feedback from thermocouples, RTDs, pressure transducers, and load cells. The differential input rejects common-mode noise from 4-20 mA loops, while the parallel bus interfaces directly to DSP controllers without requiring a serialization stage, keeping the control loop sample-to-output delay predictable.
Được đề xuất
Multi-Channel Data Acquisition Systems (DAQ)
In a multi-channel DAQ card, the ADS8484IBRGZR paired with an analog multiplexer front end delivers 18-bit precision at high sample rates for vibration analysis, acoustic measurement, and structural health monitoring. The internal 4.096V reference eliminates one external component per channel, simplifying the BOM. Its micropower 100 mW dissipation at 1.25 MSPS allows dense channel counts on a single PCB without thermal issues, while the deterministic SAR latency simplifies channel-to-channel synchronization without inter-channel skew.
Được đề xuất
Medical Patient Monitoring
The ADS8484IBRGZR's 18-bit resolution captures the small dynamic range of biomedical signals such as ECG, SpO2 photoplethysmography, and respiration waveforms. Its 1.25 MSPS throughput comfortably oversamples these signals, allowing digital filtering to improve SNR beyond the 18-bit native resolution. The differential input structure suppresses 50/60 Hz mains-coupled common-mode interference common in clinical environments, while the internal reference simplifies the isolated power domains required for patient-connected IEC 60601-1 designs.
Được đề xuất
Precision Weigh Scales
Load-cell-based weigh scales need high-resolution sigma-accuracy ADCs to resolve microgram-level changes. The ADS8484IBRGZR with its 18-bit resolution, low INL, and internal reference enables direct connection to bridge-type load cells without external instrumentation amplifiers in many designs. The differential input accepts the millivolt-level signals from a 4-wire load cell bridge, and the 1.25 MSPS throughput supports multi-axis simultaneous sampling when multiple ADCs are synchronized via their CONVST pins.
Được đề xuất
Motor Control Current Sensing
Field-oriented control (FOC) of three-phase motors requires precise, low-latency current sensing in each phase. The ADS8484IBRGZR's deterministic SAR latency - effectively one conversion clock from sample to output - makes it well-suited for the inner current loop of FOC drives, where lag from a sigma-delta modulator would compromise dynamic response. The internal 4.096V reference and ±4.096V differential input range align naturally with shunt-resistor current sensors biased at 2.5V, allowing direct PCB connection without signal conditioning.
Được đề xuất
Test and Measurement Equipment
Bench-top and modular instruments such as digital multimeters, oscilloscopes, and spectrum analyzers require high-accuracy data conversion. The ADS8484IBRGZR's 18 bits at 1.25 MSPS supports wide-bandwidth digitizer front ends, while the parallel data bus simplifies interfacing with FPGAs implementing custom DSP. The internal reference simplifies calibration routines - designers only need to perform a single-point gain trim, since the reference is already factory-trimmed and temperature-compensated per the TI datasheet.
Được đề xuất
Optical Sensor Front End
Photodiode and photomultiplier front ends for spectroscopy, LIDAR, and CT scanners benefit from the ADS8484IBRGZR's combination of high resolution and fast sampling. A transimpedance amplifier feeding the differential inputs captures the small photocurrents with the 18-bit dynamic range needed to resolve low-light signals. The 1.25 MSPS speed accommodates pulsed-light time-of-flight measurements, and the internal 4.096V reference stabilizes the input common-mode bias for repeatable photon-counting statistics across operating conditions.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho ADS8484IBRGZR — 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 | ADS8482IBRGZR | ADS8481IRGZR | ADS8484IBRGZT | ADS8462IRGZR | ADS8412IRGZR |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 48-VQFN (RGZ) 7x7 mm | 48-VQFN (RGZ) 7x7 mm - same | 48-VQFN (RGZ) 7x7 mm - same | 48-VQFN (RGZ) 7x7 mm - same | 48-VQFN (RGZ) 7x7 mm - same | 48-VQFN (RGZ) 7x7 mm - same |
| Resolution | 18 bit | 16 bit | 18 bit | 18 bit | 16 bit | 16 bit |
| Architecture | SAR | SAR | SAR | SAR | SAR | SAR |
| Input Channels | 1 | 1 | 1 | 1 | 1 | 1 |
Bảo phân biệt quan trọng
- Higher resolution (18-bit) at full sample rate (vsADS8482IBRGZR)
- Faster sample rate at full 18-bit resolution (vsADS8481IRGZR)
- Higher-resolution drop-in for speed-focused designs (vsADS8412IRGZR)
- Internal 4.096V reference simplifies BOM (vsADS8481IRGZR)
Ghi chú thiết kế
Place a 10 uF tantalum and a 0.1 uF ceramic decoupling capacitor within 5 mm of each AVDD pin and each DVDD pin. Route the analog ground plane under the analog pins (AVDD, AGND, REFIN, REFOUT, IN+, IN-) and the digital ground plane under the digital bus (DB[17:0], /CS, /RD, CONVST). Use a single-point ground tie between AGND and DGND directly under the exposed thermal pad to prevent ground-loop currents through the IC substrate, per the TI ADS8484 datasheet layout recommendation. Keep switching power supply returns away from the analog input traces to avoid code-dependent noise injection into the SAR comparator.
The 18-bit parallel bus DB[17:0] should be routed as impedance-controlled matched-length traces (target 50 ohm to ground) to a single DSP or FPGA. According to the TI ADS8484 datasheet timing diagram, /RD and /CS should be tied to logic ground during bursts, and CONVST must be glitch-free - any noise on CONVST during conversion directly adds to the SAR comparator's decision threshold, increasing aperture jitter and degrading SNR. Use a dedicated DSP GPIO with Schmitt-trigger input for CONVST, and reserve one DSP GPIO for the BUSY signal to avoid polling timing errors.
Do not leave the BYTE pin floating when using 18-bit bus mode - it must be tied to logic high; floating mid-scale voltage places the part into 8-bit byte mode and only the lower 8 bits of the conversion appear on the bus. According to the TI ADS8484 datasheet pin description table, BYTE state must be set before the first conversion. Also, do not exceed the absolute maximum analog input of AVDD + 0.3 V on IN+ or IN-; the input ESD diodes will forward-conduct and damage the part. For over-voltage protection, add external clamping diodes or a TVS to the analog input traces.
Estimated: At +5V analog supply and 1.25 MSPS continuous sampling, the ADS8484IBRGZR dissipates approximately 100 mW (per TI datasheet). With the 48-VQFN package and a typical 4-layer PCB with thermal vias under the exposed pad, the theta_JA is approximately 30 C/W, giving a self-heating rise of only 3 C above ambient. No external heatsink is needed. However, when stacking multiple ADCs on a single board for multi-channel DAQ, leave at least 10 mm of copper-pour spacing between ICs to allow thermal relief; the cumulative 500 mW-1 W dissipation of a 5-10 ADC array can create a hot spot if placed in a tightly packed arrangement without airflow.
Thông tin tuân thủ
RoHS compliant per TI product page. Industrial -40C to +85C temperature range, not AEC-Q100 qualified - automotive applications require a Q100-qualified ADC. Halogen-free and lead-free per TI MSL-2 packaging specification.
