Part A
AD7709ARUZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1974 PCS
- Package
- TSSOP-24
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7709ARUZ and AD7705BRU-REEL7 are both 16-bit sigma-delta ADCs from Analog Devices in a TSSOP-16 package, sharing a compatible serial interface and core conversion architecture, so the AD7705BRU-REEL7 can serve as a functional replacement candidate for the AD7709ARUZ. However, the AD7709ARUZ integrates additional on-chip features such as a programmable current source and expanded input multiplexing, and the two devices differ in supply voltage range and resolution at the highest output update rates. Designers should validate channel configuration, excitation/sensor-bias requirements, and supply rail compatibility against the target application before committing to the substitution.
Resolution and ADC Architecture
High match
Package Type
High match
Supply Voltage Range
Validation required
On-Chip Current Source and Input Multiplexing
Not compatible
Parts at a glance
Part B
AD7705BRU-REEL7
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 9291 PCS
- Package
- TSSOP-16
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7709ARUZ | AD7705BRU-REEL7 | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 16 | Both are 16-bit sigma-delta ADCs, so resolution is equivalent for substitutability. |
| Number of ADC Input Channels | 4 (differential) / 8 (single-ended) | 2 (differential) / 4 (single-ended) | The AD7709 offers more input channels, which affects how many signals can be measured without external multiplexing. |
| On-chip PGA Gain Range | 1 to 128 | 1 to 128 | Programmable gain allows direct interfacing with low-level sensors; both provide the same gain range. |
| On-chip Excitation / Current Sources | Yes (dual current sources for RTD/sensor excitation) | No | The AD7709 includes excitation current sources useful for resistive sensor applications, which the AD7705 lacks. |
| On-chip Temperature Sensor | Yes | No | An internal temperature sensor enables ambient compensation; its absence in the AD7705 requires external sensing. |
| Output Data Rate (max) | Up to 105 Hz (typical) | Up to 500 Hz | Higher output data rate supports faster measurement updates; the AD7705 can sample faster than the AD7709. |
| Supply Voltage Range | 2.7 V to 5.25 V | 2.7 V to 5.25 V | Both operate over the same supply range, allowing use in similar low-voltage systems. |
| Package | 24-lead TSSOP | 16-lead TSSOP | Different package pin counts and footprints affect PCB layout and are not drop-in compatible. |
| Serial Interface | SPI-compatible (3-wire) | SPI-compatible (3-wire) | Both use a similar serial interface, simplifying firmware reuse across designs. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7709ARUZ | AD7705BRU-REEL7 |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 105 | 500 |
| Number of Inputs | 2, 4 | 2 |
| Input Type | Differential, Pseudo-Differential | Differential |
| Data Interface | SPI, DSP | SPI, DSP |
| Configuration | MUX-PGA-ADC | MUX-PGA-ADC |
| Number of A/D Converters | 1 | 1 |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External |
| Voltage - Supply, Analog | 2.7V ~ 3.3V, 5V | 2.7V ~ 3.3V, 5V |
| Voltage - Supply, Digital | 2.7V ~ 3.3V, 5V | 2.7V ~ 3.3V, 5V |
| Features | PGA | PGA |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
Frequently asked questions
What are the key architectural differences between the AD7709ARUZ and the AD7705BRU-REEL7?
The AD7709ARUZ is a 16-bit sigma-delta ADC with an on-chip programmable gain amplifier (PGA) and a 4-channel input multiplexer, housed in a 24-lead TSSOP. The AD7705BRU-REEL7 is a 16-bit sigma-delta ADC with a 2-channel differential input multiplexer and PGA, supplied in a 16-lead TSSOP and delivered on a 7-inch reel. The AD7709 integrates more input channels and additional on-chip features, while the AD7705 offers a smaller package and fewer channels.
Are the AD7709ARUZ and AD7705BRU-REEL7 pin-compatible?
No. The AD7709ARUZ uses a 24-lead TSSOP package, while the AD7705BRU-REEL7 uses a 16-lead TSSOP package. The different pin counts and pin assignments mean they are not drop-in replacements and require different PCB footprints.
Do both devices support the same supply voltage range?
Both parts operate from a single 2.7 V to 5.25 V supply, per their respective manufacturer datasheets. This overlapping supply range allows both to be used in 3 V and 5 V systems, but the surrounding circuit and reference configuration must be validated for each part.
How do the input channel configurations compare?
The AD7709ARUZ provides a 4-channel input multiplexer that can be configured for differential or single-ended inputs. The AD7705BRU-REEL7 provides a 2-channel differential input multiplexer. Designs requiring more input channels should account for the AD7709's additional multiplexer channels, while the AD7705 is suited to two differential input signals.
What is the difference in resolution and output data rate between these two ADCs?
Both are 16-bit sigma-delta ADCs. The AD7705BRU-REEL7 offers programmable output update rates from 20 Hz to 500 Hz. The AD7709ARUZ also provides 16-bit resolution with a programmable output update rate; designers should consult the respective datasheets for the exact update-rate ranges and filter settings, as these differ between the two parts.
Can the AD7705BRU-REEL7 be used as a substitute for the AD7709ARUZ in an existing design?
Not directly. The AD7705BRU-REEL7 has fewer input channels and a different package and pinout than the AD7709ARUZ. A substitution would require redesigning the PCB footprint, revalidating the input multiplexer configuration, and confirming that the reduced channel count meets the application requirements against the manufacturer datasheets.
What does the "REEL7" suffix indicate on the AD7705BRU-REEL7?
The "REEL7" suffix indicates that the AD7705BRU devices are supplied on a 7-inch tape-and-reel packaging format, which is intended for automated surface-mount assembly. The AD7709ARUZ is supplied in tube or tray packaging depending on the ordering option; the reel suffix is specific to the AD7705BRU-REEL7 ordering code.