AD7794BRUZ - 24-Bit Sigma-Delta ADC, 6-Channel | Analog Devices
MPN: AD7794BRUZ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.29 | $7.29 |
| 10 | $6.94 | $69.40 |
| 100 | $6.2 | $620.00 |
| 500 | $5.85 | $2,925.00 |
| 1,000 | $5.46 | $5,460.00 |
AD7794BRUZ Overview
A sigma-delta ADC is an oversampling converter that uses a modulator and digital filter to achieve very high resolution and excellent noise performance. The AD7794BRUZ sits directly between a sensor or transducer and the host processor, eliminating the need for an external gain stage in many precision measurement chains. It belongs to the precision ADC family within data acquisition ICs and is optimized for small-amplitude sensor signals, especially bridge, RTD, thermocouple, and load-cell outputs.
Key features include 24-bit resolution, six differential analog inputs, a programmable gain amplifier with gains of 1, 2, 4, 8, 16, 32, 64, and 128, and low input noise of 40 nV/√Hz. The ADC also includes an internal low drift band gap reference, accepts up to two external differential references, and contains a temperature sensor for cold-junction compensation. Its digital filter provides 50 Hz/60 Hz rejection, which improves accuracy in noisy industrial environments while simplifying anti-alias filtering.
The AD7794BRUZ is architected as a complete analog front end for high precision measurement applications. The on-chip in-amp allows low-level signals from bridge sensors to be connected directly to the ADC, while programmable excitation current sources simplify RTD excitation. The bias voltage generator sets the common-mode level of each channel to AVDD/2, allowing the ADC interface to bipolar sensors and improving dynamic range. Its low 500 µA current consumption makes it well suited for portable and battery-operated systems.
Typical applications include process control, temperature measurement, pressure sensing, weigh scales, portable instrumentation, and multi-channel data acquisition. The combination of high resolution, low noise, and low power makes the AD7794BRUZ suitable for precision industrial and medical sensor interfaces. When designing with this ADC, use clean analog and digital supply decoupling, place a solid analog ground plane, bypass both reference input pairs with 0.1 µF capacitors, and consider SPI isolation when the converter is used in electrically noisy environments.
Drop-in alternatives for AD7794BRUZ — 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 AD7794BRUZ (same form factor and footprint) — differing in Package, Resolution, Data Interface, Internal Reference, Number of Input Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD7794CRUZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD7794BRU
✅ Drop-In📋 Reference alternative (not in catalog)
AD7795BRUZ
✅ Drop-In✓ In Stock
$5.6 / Unit
View Datasheet →AD7731BRUZ
⚡ Same Package📋 Reference alternative (not in catalog)
AD7794BRUZ Maximum Ratings & Electrical Characteristics
| Resolution | 24-bit |
| Number of Channels | 6 differential inputs |
| Converter Type | Sigma-Delta ADC |
| Interface | SPI |
| Input Type | Differential |
| Supply Voltage | 2.7 V to 5.25 V |
| Supply Current | 500 µA typical |
| Input Noise | 40 nV/√Hz |
| Programmable Gain | 1, 2, 4, 8, 16, 32, 64, 128 |
| Internal Reference | Yes, low drift band gap |
| External Reference | Up to 2 differential references |
| On-Chip In-Amp | Yes |
| Temperature Sensor | Yes |
| Filter Rejection | 50 Hz / 60 Hz |
| Operating Temperature | -40°C to +105°C |
| Package | 24-Lead TSSOP |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
AD7794BRUZ 24-lead tssop Pin Configuration Guide
Pin configuration for AD7794BRUZ (24-lead tssop package). This analog component features input, output, and power supply pins. Refer to the manufacturer datasheet for offset null, compensation, and enable pin configurations. Ideal for signal conditioning and amplifier circuits.
No detailed pinout data available for AD7794BRUZ.
Refer to the datasheet for full pin configuration.
Typical Applications
AD7794BRUZ is suitable for 6 applications: Process Control and Industrial Transmitters, Temperature Measurement with RTD and Thermocouple, Pressure Sensing and Bridge Transducers, Weigh Scales and Load Cell Front Ends, Portable and Battery-Powered Instrumentation, Multi-Channel Data Acquisition Systems.
Process Control and Industrial Transmitters
AD7794BRUZ is ideal for process control transmitters that measure temperature, pressure, or flow and send a 4-20 mA output to a PLC. The 24-bit resolution and 6 differential inputs allow the ADC to read multiple sensor channels, while the on-chip in-amp and programmable gain up to 128 directly interface to low-level bridge signals. The internal 50 Hz/60 Hz rejection reduces line-frequency interference in factory environments. Using an isolated SPI interface such as the ADuM1201ARZ protects the host controller from industrial noise. The low 500 µA supply current is also compatible with loop-powered transmitter power budgets. This ADC simplifies the analog front end, reducing external component count and improving measurement accuracy.
Recommended
Temperature Measurement with RTD and Thermocouple
The AD7794BRUZ supports RTD and thermocouple temperature sensing with its programmable excitation current sources, internal reference, and on-chip temperature sensor. For a 3-wire RTD, the excitation current sources can drive the RTD while the ADC measures the voltage ratio, and the internal band gap reference provides ratiometric accuracy. The 24-bit resolution and 40 nV/√Hz noise allow stable temperature readings with high precision. The built-in temperature sensor helps with cold-junction compensation for thermocouple probes. This implementation minimizes external analog circuitry, which is important in multi-channel temperature data loggers and industrial temperature transmitters that operate over the -40°C to +105°C range.
Recommended
Pressure Sensing and Bridge Transducers
Pressure sensors frequently use strain-gauge or piezo-resistive bridge outputs with small full-scale signals. The AD7794BRUZ's on-chip instrumentation amplifier and programmable gain of 128 allow direct connection to such bridges without an external PGIA. The bias voltage generator sets the common-mode voltage to AVDD/2, simplifying bipolar bridge excitation. The 24-bit resolution supports high accuracy over a wide pressure range, and the internal reference helps maintain ratiometric performance. Its low power consumption is important when the pressure sensor is battery-powered or powered over a long cable. Multiple bridge channels can be handled by the six differential inputs, enabling multi-sensor pressure acquisition in one ADC.
Recommended
Weigh Scales and Load Cell Front Ends
Load cell output signals are low-level, bridge-type voltages that require high resolution and low noise for accurate weight measurement. The AD7794BRUZ is a strong fit because its 24-bit sigma-delta architecture, on-chip PGA, and excitation current sources create a complete load-cell analog front end. The low input noise of 40 nV/√Hz directly affects the minimum detectable weight change, and the 50 Hz/60 Hz rejection suppresses power-line pickup in industrial scales. The SPI interface connects directly to a microcontroller or digital indicator. Using an external low-drift reference like AD780ARZ can further improve gain accuracy over temperature, while zero-drift amplifiers can be used for additional filtering.
Recommended
Portable and Battery-Powered Instrumentation
With a 2.7 V to 5.25 V supply range and only 500 µA typical current consumption, the AD7794BRUZ is ideal for handheld multimeters, battery-powered data loggers, and field instruments. The six differential input channels allow several sensor types to share one ADC, reducing component count. The internal reference and in-amp further cut external parts, saving board space and extending battery life. The SPI interface runs at low clock speeds to minimize digital switching current. In portable designs, careful power sequencing and decoupling of AVDD and DVDD are important, and a power-management IC such as ADP1031ACPZ-2 can provide isolated, low-noise power rails when needed.
Recommended
Multi-Channel Data Acquisition Systems
The AD7794BRUZ provides six differential inputs that can be used as a compact multi-channel data acquisition front end, which is critical for vibration monitoring, industrial DAQ, and test and measurement equipment. Its 24-bit resolution and programmable gain reduce the need for external mux amplifiers. The on-chip temperature sensor and internal reference allow self-calibration and cold-junction compensation. The 50 Hz/60 Hz rejection is beneficial when the DAQ operates near AC sources. For systems requiring more analog inputs, an external analog multiplexer such as the ADG709BRUZ-REEL7 can expand channel count, and digital isolators keep the SPI bus isolated from noisy field wiring. This configuration reduces system cost and PCB area while maintaining excellent performance.
Recommended
Recommended Products Summary
Engineering reference data for AD7794BRUZ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD7794CRUZ | AD7794BRU | AD7795BRUZ | AD7731BRUZ |
|---|---|---|---|---|---|
| Package | 24-Lead TSSOP | 24-Lead TSSOP | 24-Lead TSSOP | 24-Lead TSSOP | 24-Lead TSSOP |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 24-bit | 24-bit | 24-bit | 16-bit | 24-bit |
| Interface | SPI | SPI | SPI | SPI | SPI |
| RoHS / Lead-Free Finish | Yes / Yes | Yes / Yes | No / No (tin/lead) | Yes / Yes | RoHS yes / Lead-free no |
Key Differentiators
- Standard industrial temperature grade with lower power consumption (vs AD7794CRUZ)
- RoHS compliant and lead-free finish (vs AD7794BRU)
- True 24-bit resolution in a pin-compatible footprint (vs AD7795BRUZ)
Design Notes
Decouple AVDD and DVDD with 10 µF and 0.1 µF ceramic capacitors placed close to the supply pins. The AD7794BRUZ operates from 2.7 V to 5.25 V, and a clean, low-noise supply is necessary to preserve the 24-bit performance. If the ADC shares a supply with digital circuitry, use a ferrite bead or small inductor to isolate the analog rail. For noise-sensitive reference inputs, bypass REFIN1+/REFIN1- and REFIN2+/REFIN2- with 0.1 µF capacitors.
Use a solid analog ground plane under the AD7794BRUZ and keep digital ground currents separate from analog ground. Place the ADC close to the sensor or signal source to minimize trace length and noise pickup. Avoid routing SPI clock and data lines directly under analog inputs. A star-ground or split-ground arrangement is often used in industrial designs where the ADC connects to both a low-level bridge and a noisy digital bus. Follow the layout recommendations in the AD7794/AD7795 datasheet for best performance.
In industrial and noisy environments, isolate the SPI interface with a digital isolator such as the ADuM1201ARZ and keep the serial clock lines short. The 50 Hz/60 Hz rejection built into the digital filter helps reject line-frequency interference, but high-frequency noise can still couple through long cables. Add series resistors (typically 10-50 Ω) on SCLK, DIN, and DOUT/RDY traces to reduce ringing. If the sensor is remote, use shielded twisted-pair wiring and reference the analog ground at a single point.
Compliance Information
AD7794BRUZ has Z suffix indicating lead-free and RoHS-compliant finish per distributor and ADI product data. REACH, halogen-free, and conflict-minerals declarations are not explicitly provided in the verified web data.
