Part A
AD7709ARU
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1879 Stückzahl
- Package
- TSSOP-24
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Replacement verdict
Not a drop-in replacement
The AD7705BRUZ and AD7709ARU are not drop-in replacements for one another. Although both are 16-bit sigma-delta ADCs from Analog Devices, they differ in channel count, package footprint, and integrated feature set, so a direct board-level substitution is not possible without design changes.
Different channel count
Different package footprint
Different integrated features
Different supply configuration
Parts at a glance
Part B
AD7705BRUZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 3428 Stückzahl
- Package
- TSSOP-16
- Series
- Datenerfassung mit Analog to Digital Converters (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 | AD7705BRUZ | AD7709ARU | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 16 | Both are 16-bit sigma-delta ADCs, so resolution is equivalent for precision measurement applications. |
| Number of input channels | 2 differential | 2 differential (plus 2 pseudo-differential) | Channel count determines how many sensor signals can be measured without external multiplexing. |
| Interface type | SPI (3-wire serial) | SPI (3-wire serial) | Both use a serial SPI-compatible interface, allowing similar microcontroller connectivity. |
| Supply voltage (VDD) | 2.7 V to 3.3 V (or 5 V) | 2.7 V to 3.3 V (or 5 V) | Supply range affects compatibility with the system power rail and logic levels. |
| On-chip PGA | Yes (gain 1 to 128) | Yes (gain 1 to 128) | A programmable gain amplifier allows direct connection of low-level sensors without external amplification. |
| On-chip current sources | No | Yes (two matched excitation current sources) | Integrated current sources simplify RTD and resistive sensor excitation, reducing external components. |
| Package | 16-lead TSSOP | 16-lead TSSOP | Identical package footprint enables drop-in board replacement without layout changes. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Matching temperature ratings ensure equivalent environmental robustness for industrial use. |
| Output data rate | Up to 500 Hz | Up to 105 Hz | Maximum update rate affects how fast the system can sample changing signals. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7709ARU | AD7705BRUZ |
|---|---|---|
| Part Status | Obsolete | Active |
| 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 primary functional differences between the AD7705BRUZ and the AD7709ARU?
The AD7705BRUZ is a 2-channel, 16-bit sigma-delta ADC with a programmable gain amplifier (PGA) and an SPI-compatible serial interface, housed in a 16-lead TSSOP. The AD7709ARU is a 4-channel, 16-bit sigma-delta ADC that integrates a PGA, an on-chip temperature sensor, and additional system features, housed in a 24-lead TSSOP. The AD7709ARU provides more input channels and integrated functions, while the AD7705BRUZ is a simpler 2-channel converter.
Are the AD7705BRUZ and AD7709ARU pin-compatible?
No. The AD7705BRUZ is supplied in a 16-lead TSSOP (RU-16 package), while the AD7709ARU is supplied in a 24-lead TSSOP (RU-24 package). The different package sizes and pin counts mean the two devices are not pin-compatible and cannot be interchanged on the same PCB footprint without redesign.
Do both devices support the same serial interface?
Both devices use an SPI-compatible serial interface for communication with a host microcontroller. However, the register maps and command structures differ between the AD7705BRUZ and AD7709ARU, so firmware written for one device cannot be used unchanged with the other without adapting the register access and configuration sequences.
How do the input channel counts compare between the AD7705BRUZ and AD7709ARU?
The AD7705BRUZ provides two differential input channels (or four pseudo-differential input configurations) with a programmable gain amplifier. The AD7709ARU provides four differential input channels with a PGA. Designs requiring more analog input channels should consider the AD7709ARU, while the AD7705BRUZ suits two-channel measurement applications.
Does the AD7709ARU include features not present in the AD7705BRUZ?
Yes. The AD7709ARU integrates additional on-chip system features, including a temperature sensor and general-purpose output/current-source functions, which are not available on the AD7705BRUZ. These integrated features can reduce external component count in system designs, whereas the AD7705BRUZ is a more basic 2-channel sigma-delta ADC.
Can the AD7705BRUZ be used as a drop-in replacement for the AD7709ARU?
No. Because the two devices differ in package size (16-lead vs 24-lead TSSOP), channel count, register map, and integrated features, the AD7705BRUZ is not a drop-in replacement for the AD7709ARU. Any substitution requires a PCB redesign and firmware changes validated against the respective manufacturer datasheets.
Which device is better suited for multi-channel sensor measurement systems?
The AD7709ARU is generally better suited for multi-channel sensor measurement systems because it offers four differential input channels plus an integrated temperature sensor and additional system functions. The AD7705BRUZ, with only two input channels, is more appropriate for simpler two-channel measurement designs where the additional features of the AD7709ARU are not required.