Part A
AD7709ARU
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1879 PCS
- Package
- TSSOP-24
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7709ARU and AD7707BRU are both 16-bit sigma-delta ADCs from Analog Devices in a TSSOP-24 package, sharing a comparable signal-chain architecture and supply framework. However, they differ in input channel configuration, on-chip PGA gain range, and specified performance grades, so the AD7707BRU can serve as a functional candidate only after the channel count, gain requirements, and accuracy budget are validated against the target application.
Input Channel Configuration
Validation required
PGA Gain Range
Validation required
Package Type
High match
Resolution and Accuracy Grade
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7709ARU | AD7707BRU | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 16 | Both are 16-bit sigma-delta ADCs, so resolution is equivalent and not a differentiator for substitutability. |
| Number of input channels | 4 (2 differential / 4 single-ended) | 3 (2 differential / 3 single-ended) | Channel count affects how many signals can be measured; the AD7709 offers one additional input channel. |
| Input type / PGA | PGA with gain 1 to 128 | PGA with gain 1 to 128 | Programmable gain allows small signals to be amplified; both provide similar gain ranges. |
| Supply voltage | 2.7 V to 3.6 V (single supply) | 2.7 V to 3.6 V (single supply) | Supply range determines compatibility with the system power rail; both operate over the same low-voltage range. |
| Interface | SPI / 3-wire serial | SPI / 3-wire serial | Serial interface compatibility is essential for direct drop-in replacement in existing digital designs. |
| Package | 20-lead TSSOP | 20-lead TSSOP | Identical package and pin count simplify PCB layout substitution. |
| On-chip reference | No (external reference required) | No (external reference required) | Both require an external reference, so reference circuitry must be provided in either case. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Industrial temperature range suitability is the same for both parts. |
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 | AD7709ARU | AD7707BRU |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Obsolete | 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 primary functional differences between the AD7709ARU and AD7707BRU?
The AD7709ARU is a 16-bit sigma-delta ADC with a 4-channel input multiplexer, 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, PGA, and a high-voltage input capability (up to ±10 V) on one channel, also in a 24-lead TSSOP. The AD7707BRU is specified for higher voltage input ranges and includes a low-level input channel, while the AD7709ARU integrates excitation current sources for RTD/sensor applications.
Are the AD7709ARU and AD7707BRU pin-compatible?
No. Although both are 24-lead TSSOP devices, their pin functions differ. The AD7709ARU includes current source pins and a different multiplexer configuration, while the AD7707BRU provides high-voltage input pins and a different reference arrangement. Pin-to-pin replacement is not possible without PCB redesign.
Can the AD7709ARU be used as a direct substitute for the AD7707BRU in an existing design?
No. The two devices differ in input voltage range, multiplexer channel count, integrated current sources, and pinout. The AD7707BRU supports high-voltage inputs up to ±10 V on one channel, which the AD7709ARU does not. A direct substitution would require verification of input range, reference configuration, and PCB layout against the respective datasheets.
What are the resolution and data rate specifications for these ADCs?
Both the AD7709ARU and AD7707BRU are 16-bit sigma-delta ADCs. The AD7709ARU offers programmable output update rates typically from 4.17 Hz to 105 Hz. The AD7707BRU provides programmable output update rates typically from 4.17 Hz to 105 Hz as well. Both achieve 16-bit no-missing-codes resolution at specified update rates per their datasheets.
Which device is better suited for RTD or thermocouple sensor applications?
The AD7709ARU is better suited for RTD applications because it integrates matched excitation current sources for ratiometric measurement. The AD7707BRU is better suited for thermocouple or high-level signal applications because it includes a high-voltage input channel capable of accepting signals up to ±10 V, along with a low-level input channel for small signals.
Do both devices support the same supply voltage range?
No. The AD7709ARU operates from a single 2.7 V to 5.25 V supply. The AD7707BRU operates from a single 2.7 V to 5.25 V supply for the digital and low-voltage analog sections, but its high-voltage input channel requires an additional higher voltage supply (typically ±5 V or up to ±10 V) to accommodate the extended input range. Designers must account for the additional supply rail when using the AD7707BRU.
What interface do these ADCs use for communication with a microcontroller?
Both the AD7709ARU and AD7707BRU use a 3-wire serial interface compatible with SPI, QSPI, MICROWIRE, and DSP standards. They support read and write operations for configuration, calibration, and data retrieval. The interface timing and register maps differ between the two devices, so firmware must be adapted accordingly.