HI7191IBZ - 24-Bit Sigma-Delta ADC | ±5V 20-SOIC | Renesas
MPN: HI7191IBZ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $35.02 | $35.02 |
| 10 | $31.45 | $314.50 |
| 100 | $27.8 | $2,780.00 |
| 500 | $24.3 | $12,150.00 |
| 1,000 | $21.1 | $21,100.00 |
HI7191IBZ Overview
A sigma-delta (Σ-Δ) analog-to-digital converter is a precision converter architecture that oversamples the input signal at a much higher frequency than the target output rate and uses noise shaping to push quantization noise out of the baseband. The Σ-Δ family sits within the broader hierarchy of analog-to-digital converters -> data converters -> signal chain ICs -> mixed-signal semiconductors, and is the dominant topology for high-resolution (>20-bit), low-bandwidth precision measurement applications such as weigh scales, strain gauges, thermocouples, and industrial instrumentation front-ends.
Key features include an internal programmable-gain instrumentation amplifier (PGIA) providing gains from 1 to 128 to eliminate external pre-amplifiers, on-demand auto-calibration of the line-to-ground and reference paths, and 24-bit noise-free resolution. Both the analog signal inputs and the reference input are fully differential, maximizing common-mode rejection for sensor-bridge and ratiometric measurement topologies.
Architecturally, the device combines a chopper-stabilized instrumentation amplifier, a second-order sigma-delta modulator, and a digital decimation filter. Calibration registers compensate for offset and gain errors, allowing system designers to achieve better than 20-bit effective resolution in real measurement channels. The ±5V supply requirement supports high common-mode input ranges, which is essential when interfacing directly to bridge-type sensors in industrial environments.
Typical applications include precision weigh scales, industrial process-control analog front-ends, strain-gauge and load-cell signal chains, and laboratory instrumentation. The on-demand calibration feature is particularly valuable for systems that must retain accuracy across long unattended operation.
When designing with this part, allocate adequate decoupling at each V+ and V- pin (typically 10 µF tantalum in parallel with 0.1 µF ceramic) and follow a star-ground layout for the analog ground return, because residual common-mode disturbance on the reference directly translates into gain error.
This page synthesizes distributor pricing, pin-compatible drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for HI7191IBZ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with HI7191IBZ (same form factor and footprint) — differing in Supply Voltage, Resolution, Operating Temperature Range, Package, Reference Input Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
HI7191IBZ-T
✅ Drop-In✓ In Stock
$17.4 / Unit
View Datasheet →HI7191IB
✅ Drop-In✓ In Stock
$7.9 / Unit
View Datasheet →HI7190IBZ
✅ Drop-In📋 Reference alternative (not in catalog)
HI7190IB
✅ Drop-In📋 Reference alternative (not in catalog)
HI7191IBZ Maximum Ratings & Electrical Characteristics
| Part Number | HI7191IBZ |
| Manufacturer | Renesas Electronics (formerly Intersil) |
| Converter Type | Sigma-Delta (Σ-Δ) |
| Resolution | 24 bit |
| Number of Input Channels | 1 differential |
| Conversion Rate | up to 2 kSPS |
| Supply Voltage | ±5 V (dual supply) |
| Analog Input Type | Fully differential |
| Reference Input Type | Fully differential |
| Internal PGA Gain Range | 1 to 128 |
| On-Demand Calibration | Yes (offset + gain) |
| Package | 20-SOIC (7.50 mm wide body) |
| Mounting Type | Surface Mount |
| Operating Temperature Range | Industrial grade (see datasheet) |
| Lifecycle Status | Obsolete (per Renesas product page) |
| RoHS Status | Compliant (lead-free IBZ suffix) |
HI7191IBZ Pin Configuration
| Pin 1 | V+ — Positive analog supply (+5V) |
| Pin 2 | IN+ — Positive differential analog input |
| Pin 3 | IN- — Negative differential analog input |
| Pin 4 | AGND — Analog ground reference |
| Pin 5 | REF+ — Positive differential reference input |
| Pin 6 | REF- — Negative differential reference input |
| Pin 7 | BUFFER — Reference buffer output |
| Pin 8 | CAL — On-demand calibration control |
| Pin 9 | MODE — Mode selection pin |
| Pin 10 | DGND — Digital ground |
| Pin 11 | DVDD — Digital supply (+5V) |
| Pin 12 | CLK — External clock input |
| Pin 13 | XIN — Crystal input / system clock |
| Pin 14 | XOUT — Crystal output |
| Pin 15 | DOUT — Serial data output |
| Pin 16 | DRDY — Data ready output flag |
| Pin 17 | SCLK — Serial interface clock |
| Pin 18 | CS — Chip select (active low) |
| Pin 19 | RESET — Reset input |
| Pin 20 | V- — Negative analog supply (-5V) |
Typical Applications
HI7191IBZ is suitable for 7 applications: Precision Weigh Scales, Industrial Process-Control Analog Front-End, Strain-Gauge / Load-Cell Signal Chain, Laboratory and Benchtop Instrumentation, Thermocouple and Temperature Measurement Front-End, Medical and Diagnostic Equipment Front-End, Data Acquisition Systems (DAQ) - Low-Frequency Channels.
Precision Weigh Scales
The HI7191IBZ is a strong fit for precision weigh-scale front-ends where the load-cell bridge output (typically 1-3 mV/V at 2.5V excitation) must be resolved to six-digit accuracy. Its 24-bit sigma-delta architecture delivers >20 noise-free bits at low output data rates, and the integrated programmable-gain instrumentation amplifier (gains 1-128) amplifies the low-level bridge signal without an external pre-amp. The fully differential inputs reject common-mode noise from motor and relay wiring, while the differential reference input enables ratiometric measurement that cancels excitation-supply drift. On-demand auto-calibration compensates offset and gain drift over time, critical for commercial scales requiring annual re-calibration intervals.
Recommended
Industrial Process-Control Analog Front-End
The HI7191IBZ suits industrial process-control analog front-ends reading 4-20 mA loop signals, RTD outputs, or low-level transducer voltages with high common-mode voltages. Its ±5V dual supply tolerates common-mode swings well beyond 5V when the signal source sits at a different ground potential, and the 24-bit resolution resolves sub-µV signal changes for closed-loop control stability. The integrated PGA with gains up to 128 eliminates external instrumentation amplifiers, and the sigma-delta architecture provides strong 50/60 Hz power-line rejection that is essential in factory environments. Combined with on-demand calibration, the part supports 24/7 unattended operation with minimal recalibration overhead.
Recommended
Strain-Gauge / Load-Cell Signal Chain
The HI7191IBZ excels in strain-gauge and load-cell signal chains where the Wheatstone bridge output must be amplified and digitized with minimum added noise. Its integrated PGIA with programmable gains of 1-128 directly accommodates full-scale bridge outputs from 1 mV to 1 V, removing the need for external low-noise instrumentation amplifiers. The fully differential signal inputs and differential reference input support true ratiometric measurement, eliminating drift due to excitation supply variation. The 24-bit sigma-delta architecture delivers noise-free resolution suitable for stress-monitoring, structural-health, and force-feedback applications in industrial machinery and aerospace test stands.
Recommended
Laboratory and Benchtop Instrumentation
The HI7191IBZ fits high-precision benchtop instruments - multimeters, picoammeters, micro-ohmmeters, and laboratory data loggers - where 24-bit resolution and low noise are mandatory. Its differential inputs and reference support direct connection to high-impedance sensors and ratiometric measurement topologies, while the on-chip PGIA eliminates the noise and cost penalty of external amplifiers. The sigma-delta architecture inherently provides digital averaging for repeatable readings, and the part's 2 kSPS maximum output data rate is more than sufficient for slowly-varying DC measurements. Wide industrial temperature range and dual ±5V supply make the part compatible with traditional analog instrumentation power architectures.
Recommended
Thermocouple and Temperature Measurement Front-End
The HI7191IBZ serves thermocouple and precision temperature-measurement front-ends where millivolt-level thermoelectric voltages must be digitized with sub-µV noise floor. Its integrated programmable-gain amplifier brings low-level thermocouple outputs (typically 10-50 µV/°C) up to the ADC's full-scale range, while the 24-bit resolution delivers 0.001°C-class effective resolution after cold-junction compensation. The differential inputs reject common-mode thermocouple-bench noise, and the on-demand calibration ensures stable measurements across the industrial temperature range. Combined with an external precision RTD for cold-junction compensation, the part provides a complete thermocouple digitizer in a single IC footprint.
Recommended
Medical and Diagnostic Equipment Front-End
The HI7191IBZ is suitable for medical and analytical equipment front-ends where high-resolution analog measurement is required - blood analyzers, infusion pump flow meters, and laboratory diagnostic instruments. Its 24-bit resolution and low noise floor support direct digitization of low-level sensor outputs from photodiodes, conductivity probes, and pressure transducers without external pre-amplification. The integrated PGA provides signal conditioning in a single chip, reducing BOM cost and improving reliability in mission-critical medical applications. Sigma-delta architecture inherently rejects line-frequency interference (50/60 Hz) common in clinical environments, and the differential reference input supports ratiometric measurement where sensor excitation is the ADC's reference.
Recommended
Data Acquisition Systems (DAQ) - Low-Frequency Channels
The HI7191IBZ serves as the precision low-frequency channel in multi-channel data-acquisition systems where one or two channels require 24-bit resolution while other channels use faster SAR ADCs. Its sigma-delta architecture provides excellent common-mode rejection at 50/60 Hz line frequency, essential for industrial DAQ modules installed near power wiring. The integrated PGA removes external conditioning stages, reducing PCB area and BOM cost, while the fully differential inputs accept both single-ended and differential sensor outputs with minimal external circuitry. On-demand calibration maintains accuracy over long unattended acquisition campaigns, and the part's small 20-SOIC footprint fits compact DAQ module form factors.
Recommended
Recommended Products Summary
Engineering reference data for HI7191IBZ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | HI7191IBZ-T | HI7191IB | HI7190IBZ | HI7190IB |
|---|---|---|---|---|---|
| Package | 20-SOIC (7.50 mm wide) | 20-SOIC (7.50 mm wide) | 20-SOIC (7.50 mm wide) | 20-SOIC (7.50 mm wide) | 20-SOIC (7.50 mm wide) |
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
| Resolution | 24 bit | 24 bit | 24 bit | 24 bit | 24 bit |
| Supply Voltage | ±5 V | ±5 V | ±5 V | ±5 V | ±5 V |
| Internal PGA | Yes (1 to 128) | Yes (1 to 128) | Yes (1 to 128) | Yes | Yes |
| Differential Inputs | Yes (signal + reference) | Yes (signal + reference) | Yes (signal + reference) | Yes | Yes |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Integrated PGIA eliminates external instrumentation amplifiers (vs TI ADS1252 (24-bit sigma-delta, no integrated PGA))
- Fully differential signal AND reference inputs (vs Typical 24-bit ADCs with single-ended reference only)
- On-demand auto-calibration (vs Older sigma-delta ADCs requiring manual calibration)
Design Notes
Use a low-noise, low-dropout linear regulator (e.g. LT3042 or ADP7104) to derive the analog ±5V supplies from a system 12V rail; switch-mode supplies inject noise that the sigma-delta modulator will see as increased noise floor. Place a 10 µF tantalum (or low-ESR ceramic) in parallel with a 0.1 µF ceramic at each supply pin (V+, V-, DVDD), located within 5 mm of the IC. Estimated: at 5 mA analog current, an LT3042 with 0.8 µVrms noise adds less than 0.5 LSB at 24-bit full scale.
Implement a star-ground topology where AGND and DGND connect only at the IC's AGND pin (pin 4). Route analog and digital grounds on separate inner planes and join them at a single point. Keep digital signals (CLK, DOUT, DRDY, SCLK, CS) routed away from the analog inputs (IN+, IN-, REF+, REF-) to avoid digital-noise coupling into the modulator.
Do not exceed the absolute maximum differential input voltage on IN+/IN- or REF+/REF- (typically ±V+); over-voltage can permanently damage the input ESD cells. Issue CAL after every power-up and after any input-mode change to cancel offset and gain drift. Estimated: without calibration, the typical offset drift of 10 nV/°C can produce a 100 µV error across the industrial temperature range, which is significant at 24-bit resolution.
Place the external reference decoupling capacitor (typically 10 µF ceramic or tantalum) directly across REF+ and REF- pins, with traces kept short and symmetrical. If using an external clock, route the CLK trace on a separate inner layer or guarded on both sides with AGND. For optimal common-mode rejection, ensure the input traces to IN+ and IN- are length-matched and routed as a differential pair with constant 50 Ω or 100 Ω impedance.
Compliance Information
IBZ suffix indicates lead-free / RoHS-compliant packaging per industry convention. Reach, halogen-free, and conflict-mineral status not explicitly stated in the verified web data; not automotive-qualified (AEC-Q100 not applicable for industrial instrumentation ADC).
