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Texas Instruments ADS1235IRHBT
- Part No.:
- ADS1235IRHBT
- Manufacturer:
- Texas Instruments
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
ADS1235IRHBT.pdf
- Description:
- IC ADC 24BIT SIGMA-DELTA 32VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:227
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Product details
Overview
ADS1235IRHBT from Texas Instruments is a precision 24-bit delta-sigma ADC with integrated PGA, designed for bridge sensor signal conditioning in high-accuracy weigh scale and pressure measurement systems. It delivers 120,000 noise-free counts at 10 SPS with ±7 mV to ±5 V input range, gain options of 1/64/128, and simultaneous 50/60 Hz line rejection.
For engineers reviewing the ADS1235IRHBT datasheet, ADS1235IRHBT pinout, ADS1235IRHBT application, or ADS1235IRHBT equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative parts, and supply-chain support for industrial sensor interface designs.
Technical Context
The ADS1235IRHBT integrates a low-noise PGA (1 GΩ input impedance), dual-reference multiplexer, AC/DC bridge excitation control, and a programmable Sinc4 digital filter. Its chop mode enables zero-drift operation with 1 nV/°C offset drift and 0.5 ppm/°C gain drift - critical for long-term stability in strain-gauge applications.
It supports three differential or five single-ended inputs, includes built-in diagnostics (reference monitor, overrange detection, CRC), and features an internal 7.3728 MHz oscillator. The device operates across –40°C to +125°C and accepts 5-V analog (±2.5 V) and 2.7–5.25 V digital supplies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 24-bit no-missing-codes output - ensures full dynamic range utilization without code gaps in precision weighing. |
| Data Rate | 2.5 to 7200 SPS - selectable for trade-off between noise (e.g., 120,000 noise-free counts at 10 SPS) and throughput. |
| PGA Gain | 1, 64, or 128 - enables direct interface to low-output bridge sensors (e.g., ±10 mV full-scale) without external amplification. |
| Input Range | ±7 mV to ±5 V differential - accommodates both microvolt-level strain gauges and higher-level industrial sensors. |
| Line Rejection | Simultaneous 50 Hz and 60 Hz - eliminates mains interference without external notch filters or software post-processing. |
| Offset Drift | 1 nV/°C (chop mode) - reduces calibration frequency in temperature-varying environments like factory-floor scales. |
| Supply Range | Analog: 4.75–5.25 V (AVDD–AVSS); Digital: 2.7–5.25 V (DVDD) - supports mixed-supply systems and simplifies power architecture. |
Pinout & Package
The ADS1235IRHBT is housed in a 5-mm × 5-mm VQFN-32 (RHB) package with exposed thermal pad soldered to AVSS. Pin count and layout match TI's standard RHB footprint for mechanical and thermal compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AIN0–AIN5 | Analog input/output | Supports three differential (AIN0/AIN1, AIN2/AIN3, AIN4/AIN5) or five single-ended channels; also serve as GPIOs or AC-excitation outputs. |
| REFP0 / REFN0 | Reference input | Differential reference pair (0.9 V to AVDD–AVSS) - enables ratiometric measurements and eliminates reference drift impact. |
| CAPP / CAPN | PGA output | Connect 4.7-nF C0G capacitor across these pins to stabilize PGA feedback loop and suppress high-frequency noise. |
| SCLK / DIN / DOUT/DRDY / CS | Serial interface | 4-wire SPI-compatible interface with dual-function DOUT/DRDY pin - reduces PCB routing complexity and supports daisy-chaining. |
| START / PWDN / RESET | Control input | Hardware-triggered conversion start, ultra-low-power shutdown (2–8 µA), and synchronous reset - essential for battery-powered or event-driven systems. |
| BYPASS | Analog output | Internal subregulator bypass node - requires 1-µF capacitor to DGND to ensure stable internal voltage reference and low-noise operation. |
Key Features
| Feature | Design Value |
|---|---|
| Chop-mode zero-drift operation | Reduces offset drift to 1 nV/°C - maintains accuracy over wide temperature ranges without periodic recalibration. |
| AC-bridge excitation control | Generates synchronized AC drive signals (ACX1/ACX2) and blanking timing - eliminates thermoelectric drift in long sensor cables. |
| Single-cycle settling mode | Enables fast response to step inputs (e.g., load impact on scale) without waiting for filter settling - improves system responsiveness. |
| Integrated temperature sensor | On-die sensor with 420 µV/°C coefficient - allows real-time thermal compensation of sensor and ADC errors in closed-loop systems. |
| Missing reference monitor | Detects open-circuit or shorted reference inputs and asserts fault flag - prevents silent erroneous conversions in safety-critical measurement paths. |
Applications
| Weigh Scales | Pressure Transducers |
|---|---|
|
Use Scenario: High-precision platform scales used in pharmaceutical dispensing where ±0.001% full-scale accuracy is required. IC Role / Device Role / Timing Role: Primary ADC digitizing millivolt-level Wheatstone bridge output from load cells; performs ratiometric conversion using internal reference. Use Value: 120,000 noise-free counts at 10 SPS and 1 nV/°C offset drift enable Class III legal-for-trade certification without external calibration hardware. |
Use Scenario: Industrial pressure transmitters monitoring hydraulic systems in oil & gas pipelines with ambient temperature swings from –40°C to +85°C. IC Role / Device Role / Timing Role: Signal conditioner converting bridge output from piezoresistive pressure sensor; uses AC excitation to cancel cable-induced thermal EMFs. Use Value: Simultaneous 50/60 Hz rejection and internal temperature sensor allow real-time thermal compensation - reducing total error to <0.05% FS over temperature. |
| Dynamic Weighing Systems | Process Analytics Sensors |
|
Use Scenario: Conveyor-based checkweighers operating at 200 units/minute requiring stable readings despite vibration and EMI. IC Role / Device Role / Timing Role: High-speed ADC running at 7200 SPS in single-cycle settling mode; interfaces directly to strain-gauge array via AIN0–AIN5 multiplexer. Use Value: 7200 SPS throughput with Sinc1 filter and 24-bit resolution enables accurate weight capture per item even during motion - eliminating need for mechanical dampening. |
Use Scenario: In-line liquid density analyzers in chemical processing plants measuring small capacitance or resistance changes in process fluids. IC Role / Device Role / Timing Role: Precision front-end ADC for resistive or capacitive bridge sensors; uses CRC and signal overrange monitoring for functional safety compliance (IEC 61508). Use Value: Built-in diagnostics (CRC, reference monitor, overrange flag) provide SIL-2 capable fault detection - reducing external BMS complexity and validation effort. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar precision delta-sigma ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS1232IRHBT | 2-channel input, no AC-excitation capability, identical PGA and noise performance. | Lacks ACX1/ACX2 outputs and associated timing control - unsuitable for thermally unstable bridge installations. | Select when only two differential inputs are needed and cable-induced drift is negligible. |
| AD7793BRUZ | 3-channel, 24-bit ΣΔ ADC with 4.17–480 SPS range; no integrated AC excitation or chop mode. | Higher offset drift (15 nV/°C) and no simultaneous 50/60 Hz rejection - requires external filtering or software correction. | Choose for lower-cost, lower-speed (<500 SPS) industrial RTD or thermocouple applications where AC excitation is unnecessary. |
Compared with ADS1232IRHBT and AD7793BRUZ, the ADS1235IRHBT uniquely combines AC-bridge excitation, chop-mode zero-drift, and simultaneous line-frequency rejection - making it the only option among the three qualified for high-stability, high-speed bridge sensor systems operating across extended temperature ranges.
Availability
ADS1235IRHBT is available at Aetrix Electronics and suitable for weigh scales, pressure transducers, and dynamic weighing systems requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.
Supply support for ADS1235IRHBT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision data acquisition and sensor interface ICs.
The ADS1235IRHBT belongs to TI's high-precision delta-sigma ADC product line, engineered specifically for bridge-based sensing in industrial weighing, force, and pressure measurement - emphasizing zero-drift stability, diagnostic integrity, and system-level noise immunity.
FAQ
What is the maximum usable data rate of the ADS1235IRHBT while maintaining 24-bit effective resolution?
The ADS1235IRHBT achieves true 24-bit effective resolution up to 400 SPS in Sinc4 filter mode with gain = 128 and chop enabled. At 7200 SPS (Sinc1 mode), effective resolution drops to ~18.5 bits due to increased noise bandwidth - verified in Figure 19 of the SBAS824 datasheet. For full 24-bit performance, use ≤400 SPS with appropriate digital filter configuration. The ADS1235IRHBT's data rate flexibility allows matching resolution to application speed requirements without changing hardware.
Does the ADS1235IRHBT require an external crystal or can it operate with its internal oscillator?
Yes, the ADS1235IRHBT can operate fully autonomously using its internal 7.3728 MHz oscillator - CLKIN is tied to DGND in this configuration. The oscillator is specified at ±0.5% accuracy over temperature and does not require external components. External clock input (1–8 MHz) is optional for systems needing tighter timing synchronization or reduced jitter; however, the internal oscillator is sufficient for all standard bridge sensor applications. This capability simplifies BOM and layout for the ADS1235IRHBT.
How does the AC-excitation feature of the ADS1235IRHBT eliminate thermal EMF errors in bridge sensor wiring?
The ADS1235IRHBT generates complementary AC drive signals (ACX1/ACX2) that reverse polarity at precise intervals, causing thermoelectric voltages induced in sensor leads to alternate polarity and cancel out over successive conversions. Combined with internal blanking timing (td(ACX)), the ADS1235IRHBT ensures measurement occurs only during stable AC periods. This eliminates DC drift from copper-iron junctions in long cables - a common source of error in weigh scales. The ADS1235IRHBT implements this entirely in hardware, requiring no external circuitry or firmware intervention.
Can the ADS1235IRHBT's GPIO pins be used simultaneously with analog input functions?
No - pins AIN0–AIN3 are multifunctional but not time-multiplexed in concurrent operation. When configured as GPIOs (via register control), their analog input functionality is disabled. Conversely, when used as analog inputs (e.g., AIN0/AIN1 for differential channel 0), GPIO output capability on those pins is inactive. The ADS1235IRHBT's GPIO mode is intended for auxiliary control (e.g., relay drivers, LED indicators) in systems where fewer than five analog channels are needed - not for mixed-signal concurrent use. This behavior is defined in the "Pin Functions" table of the ADS1235IRHBT datasheet.
What is the purpose of the CAPP and CAPN pins on the ADS1235IRHBT, and what capacitor value is required?
CAPP and CAPN are dedicated PGA output terminals requiring a 4.7-nF C0G (NP0) ceramic capacitor connected differentially between them. This capacitor stabilizes the PGA's internal feedback network, suppresses high-frequency oscillation, and defines the antialias filter cutoff (~60 kHz). Using non-C0G dielectrics or incorrect values degrades noise performance and may cause instability. The ADS1235IRHBT's PGA architecture mandates this external capacitor - it is not optional. Layout must minimize trace length and avoid vias near CAPP/CAPN to preserve signal integrity.
ADS1235IRHBT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 32-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Number of Bits:
- 24
- Sampling Rate (Per Second):
- 7.2k
- Number of Inputs:
- 6
- Input Type:
- Differential, Single Ended
- Data Interface:
- SPI
- Configuration:
- MUX-PGA-ADC
- Ratio - S/H:ADC:
- 0:1
- Number of A/D Converters:
- 1
- Architecture:
- Sigma-Delta
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- 4.75V ~ 5.25V
- Voltage - Supply, Digital:
- 2.7V ~ 5.25V
- Features:
- Internal Oscillator, PGA, Temperature Sensor
- Operating Temperature:
- -40°C ~ 125°C
- Supplier Device Package:
- 32-VQFN (5x5)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
ADS1235IRHBT FAQ
1.How can I place an order for ADS1235IRHBT through Aetrix?
Please submit a Request for Quotation (RFQ) for ADS1235IRHBT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ADS1235IRHBT reliable?
The price and inventory of ADS1235IRHBT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADS1235IRHBT is usually 5 days.
3.What payment methods are accepted for ADS1235IRHBT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADS1235IRHBT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADS1235IRHBT?
ADS1235IRHBT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADS1235IRHBT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ADS1235IRHBT?
For technical support, including ADS1235IRHBT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADS1235IRHBT requirements.
6.How does Aetrix verify that ADS1235IRHBT is sourced from the original manufacturer or authorized distributors?
All ADS1235IRHBT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ADS1235IRHBT meets industry standards.
7.What is the process for return or replacement of ADS1235IRHBT?
All ADS1235IRHBT units undergo pre-shipment inspection (PSI). If there is an issue with ADS1235IRHBT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ADS1235IRHBT part is unused and in its original packaging.
Return procedure for ADS1235IRHBT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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