ADS8484IBRGZR - 18-Bit 1.25MSPS SAR ADC | Texas Instruments
MPN: ADS8484IBRGZR ✓ نشطADS8484IBRGZR نظرة عامة
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.
بدائل مباشرة لـ ADS8484IBRGZR — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع ADS8484IBRGZR (نفس عامل الشكل والبصمة) — يختلف في Architecture, Input Type, Package, Resolution, Interface.
ADS8482IBRGZR
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←ADS8481IRGZR
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←ADS8484IBRGZT
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
ADS8462IRGZR
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
ADS8412IRGZR
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
ADS8484IBRGZR الحدود القصوى والخصائص الكهربائية
| الدقة | 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 |
| الواجهة | Parallel (8-/16-/18-bit selectable) |
| العلبة | 48-VQFN (RGZ) 7x7 mm |
| نطاق درجة حرارة التشغيل | -40C to +85C |
| نوع التركيب | Surface Mount |
| مستوى MSL | 2 (1 year floor life) |
| حالة RoHS | Compliant |
| Lead-Free | Yes |
تكوين أطراف ADS8484IBRGZR
| دبوس 1 | AVDD — Analog +5V supply |
| دبوس 2 | AGND — Analog ground |
| دبوس 3 | REFIN — Reference input (tie to REFOUT or external reference) |
| دبوس 4 | REFOUT — Internal 4.096V reference output |
| دبوس 5 | REFGND — Reference ground |
| دبوس 6 | IN+ — Differential positive analog input |
| دبوس 7 | IN- — Differential negative analog input |
| دبوس 8 | AVSS — Analog supply negative (typically tied to AGND for unipolar supplies) |
| دبوس 9 | AGND — Analog ground |
| دبوس 10 | AVDD — Analog +5V supply |
| دبوس 11 | AVDD — Analog +5V supply |
| دبوس 12 | AVSS — Analog supply negative |
| دبوس 13 | NC — Not connected (per datasheet) |
| دبوس 14 | NC — Not connected (per datasheet) |
| دبوس 15 | CONVST — Conversion start (active low falling edge initiates sample/hold) |
| دبوس 16 | /CS — Chip select (active low) |
| دبوس 17 | /RD — Read strobe (active low) |
| دبوس 18 | BUSY — Conversion in progress (active high) |
| دبوس 19 | /RESET — Reset input (active low) |
| دبوس 20 | BYTE — Bus width selection (Hi = 18-bit, Lo = 16-bit word, midscale Hi-Z = 8-bit byte mode) |
| دبوس 21 | TAG — Tag input for read cycle |
| دبوس 22 | DB0 — Data bit 0 (LSB) |
| دبوس 23 | DB1 — Data bit 1 |
| دبوس 24 | DB2 — Data bit 2 |
| دبوس 25 | DB3 — Data bit 3 |
| دبوس 26 | DB4 — Data bit 4 |
| دبوس 27 | DB5 — Data bit 5 |
| دبوس 28 | DB6 — Data bit 6 |
| دبوس 29 | DB7 — Data bit 7 |
| دبوس 30 | DVDD — Digital +5V supply |
| دبوس 31 | DGND — Digital ground |
| دبوس 32 | DGND — Digital ground |
| دبوس 33 | DVDD — Digital +5V supply |
| دبوس 34 | DB8 — Data bit 8 |
| دبوس 35 | DB9 — Data bit 9 |
| دبوس 36 | DB10 — Data bit 10 |
| دبوس 37 | DB11 — Data bit 11 |
| دبوس 38 | DB12 — Data bit 12 |
| دبوس 39 | DB13 — Data bit 13 |
| دبوس 40 | DB14 — Data bit 14 |
| دبوس 41 | DB15 — Data bit 15 |
| دبوس 42 | DB16 — Data bit 16 |
| دبوس 43 | DB17 — Data bit 17 (MSB) |
| دبوس 44 | AGND — Analog ground |
| دبوس 45 | AVDD — Analog +5V supply |
| دبوس 46 | AVDD — Analog +5V supply |
| دبوس 47 | AVSS — Analog supply negative |
| دبوس 48 | NC — Not connected (per datasheet) |
التطبيقات النموذجية
ADS8484IBRGZR مناسب لـ 7 التطبيقs: 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.
موصى به
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.
موصى به
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.
موصى به
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.
موصى به
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.
موصى به
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.
موصى به
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.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ ADS8484IBRGZR — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | 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 |
أبرز الفروقات
- Higher resolution (18-bit) at full sample rate (مقابلADS8482IBRGZR)
- Faster sample rate at full 18-bit resolution (مقابلADS8481IRGZR)
- Higher-resolution drop-in for speed-focused designs (مقابلADS8412IRGZR)
- Internal 4.096V reference simplifies BOM (مقابلADS8481IRGZR)
ملاحظات التصميم
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.
معلومات الامتثال
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.
