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
Not a drop-in replacement
The AD7709ARUZ and AD7707BRU are both 16-bit sigma-delta ADCs from Analog Devices, but they differ fundamentally in input channel configuration, package footprint, and supply voltage range, so neither part can directly substitute for the other without a full schematic and layout redesign.
Different input channel configuration
Different package footprint
Different supply voltage range
Different interface and feature set
Parts at a glance
Part B
AD7707BRU
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 8840 PCS
- Package
- TSSOP-20
- 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 | AD7707BRU | 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 | 4 differential / 8 single-ended (with PGA) | 3 differential / 5 single-ended | Channel count determines how many sensor signals can be multiplexed into one converter; the AD7709 offers more inputs. |
| Programmable gain amplifier (PGA) range | 1 to 128 | 1 to 128 | PGA gain range affects the ability to interface small-amplitude signals directly without external amplification. |
| Output data rate | Up to 105 Hz (19.79 Hz to 105 Hz) | Up to 500 Hz (programmable) | Higher output data rates support faster measurement loops; the AD7707 can update faster than the AD7709. |
| Supply voltage | 2.7 V to 5.25 V | 2.7 V to 3.3 V (DVDD), 4.75 V to 5.25 V (AVDD) | Supply requirements affect compatibility with the system power rail; the AD7707 needs a separate 5 V analog supply. |
| Interface type | SPI / 3-wire serial | SPI / 3-wire serial | Both use a compatible serial interface, simplifying drop-in replacement at the digital interface level. |
| Package | 24-lead TSSOP | 20-lead TSSOP | Different package pin counts and footprints mean the parts are not physically drop-in compatible on the same PCB. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings mean both suit the same industrial environmental conditions. |
| On-chip features | PGA, current sources, reference detect, burnout current | PGA, reference detect, burnout current | Integrated current sources in the AD7709 simplify RTD/sensor excitation, which the AD7707 lacks. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7709ARUZ | AD7707BRU |
|---|---|---|
| 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 | 1, 2 |
| Input Type | Differential, Pseudo-Differential | Pseudo-Differential, Single Ended |
| 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 differences between the AD7709ARUZ and the AD7707BRU?
The AD7709ARUZ is a 16-bit sigma-delta ADC with a 4-channel input multiplexer, on-chip programmable gain amplifier, and current sources, housed in a 24-lead TSSOP. The AD7707BRU is a 16-bit sigma-delta ADC with a 3-channel input multiplexer (one high-level and two low-level inputs) and is specified for higher performance grades, also in a 24-lead TSSOP. The AD7709 is optimized for low-level signal conditioning with integrated excitation current sources, while the AD7707 is designed for mixed high-level and low-level input applications.
Are the AD7709ARUZ and AD7707BRU pin-compatible?
No. Although both devices are offered in a 24-lead TSSOP package, their pin functions differ. The AD7709ARUZ includes dedicated pins for its current sources and 4-channel multiplexer, while the AD7707BRU has a different multiplexer configuration with one high-level input channel. A direct drop-in replacement is not possible without verifying pin assignments against the respective datasheets.
What is the resolution and architecture of both ADCs?
Both the AD7709ARUZ and AD7707BRU are 16-bit sigma-delta analog-to-digital converters. They use a sigma-delta modulation architecture with on-chip digital filtering, providing high resolution for low-frequency signal measurement applications.
How do the input channel configurations differ between the two parts?
The AD7709ARUZ provides a 4-channel input multiplexer with fully differential or single-ended input options and an on-chip programmable gain amplifier. The AD7707BRU provides a 3-channel input multiplexer consisting of one high-level input channel and two low-level input channels, allowing direct connection of higher-voltage signals without external attenuation.
Do both devices include on-chip current sources for sensor excitation?
The AD7709ARUZ includes on-chip programmable current sources intended for direct excitation of resistive sensors such as RTDs and thermistors. The AD7707BRU does not include these integrated excitation current sources; external excitation circuitry would be required for sensor applications.
What are the supply voltage and interface characteristics of these ADCs?
Both devices operate from a single supply and include a serial interface for communication with a microcontroller or DSP. The AD7709ARUZ and AD7707BRU are specified for operation over the industrial temperature range. Detailed supply voltage ranges, reference requirements, and interface timing should be confirmed in the respective manufacturer datasheets before design implementation.
Which device is better suited for RTD or thermistor measurement?
The AD7709ARUZ is generally better suited for RTD and thermistor measurement because it integrates programmable excitation current sources and a 4-channel multiplexer, reducing external component count. The AD7707BRU lacks integrated current sources, so external excitation circuitry would be needed for such sensor applications.
Can the AD7707BRU replace the AD7709ARUZ in an existing design?
Not directly. The two devices differ in multiplexer channel configuration, integrated current sources, and pin functions. A replacement would require schematic and layout changes, and the system performance must be revalidated against the target specifications using the AD7707BRU datasheet.