Part A
AD7739BRUZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1798 PCS
- Package
- TSSOP-24
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7739BRUZ and AD7731BRU are both high-resolution sigma-delta ADCs from Analog Devices in the same TSSOP-24 package, but they differ in resolution, channel count, and interface architecture. The AD7739BRUZ offers higher resolution and a faster programmable output data rate, while the AD7731BRU provides a lower-noise PGA front end with a different digital interface. Designers should validate channel configuration, timing, and firmware compatibility before substituting one for the other in an existing design.
Resolution
Validation required
Channel Count
Validation required
Digital Interface
Validation required
Package Type
High match
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7739BRUZ | AD7731BRU | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit sigma-delta ADCs, so nominal resolution is equivalent for high-precision measurement applications. |
| Number of input channels | 8 (differential) | 3 (differential) | Channel count determines how many sensor inputs can be multiplexed without external switching; the AD7739 supports more channels. |
| Maximum output data rate | 15.1 kSPS | 6.4 kSPS | Higher output data rate enables faster sampling of dynamic signals and shorter system settling times. |
| Programmable gain amplifier (PGA) range | 1 to 128 | 1 to 128 | PGA gain range affects the ability to directly interface small-amplitude sensors; both offer the same gain span. |
| Supply voltage (analog) | 5 V | 5 V | Analog supply compatibility ensures the parts can be used in the same signal-chain power architecture. |
| Digital interface | SPI-compatible serial | SPI-compatible serial | A matching serial interface allows drop-in communication with the same host microcontroller or DSP. |
| Package | 24-lead TSSOP | 24-lead TSSOP | Identical package and pin count simplify PCB layout reuse and assembly compatibility. |
| Operating temperature range | -40 to +105 °C | -40 to +85 °C | A wider temperature range supports use in harsher industrial environments; the AD7739 offers extended upper range. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7739BRUZ | AD7731BRU |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Number of Bits | 24 | 24 |
| Sampling Rate(Per Second) | 15.1k | 6.4k |
| Number of Inputs | 4, 8 | 3, 5 |
| Input Type | Differential, Single Ended | Differential |
| Data Interface | SPI, DSP | SPI, DSP |
| Configuration | MUX-ADC | MUX-PGA-ADC |
| Number of A/D Converters | 1 | 1 |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External |
| Voltage - Supply, Analog | 5V | 5V |
| Voltage - Supply, Digital | 2.7V ~ 3.6V, 5V | 5V |
| Features | True Bipolar | PGA |
| Operating Temperature | -40°C ~ 105°C | -40°C ~ 85°C |
Frequently asked questions
What are the primary differences between the AD7739BRUZ and the AD7731BRU?
The AD7739BRUZ is a 24-bit, 8-channel sigma-delta ADC with a maximum output rate of 15.1 kSPS, housed in a 24-lead TSSOP. The AD7731BRU is a 24-bit, 3-channel sigma-delta ADC with a maximum output rate of 6.4 kSPS, housed in a 24-lead TSSOP. The AD7739 offers more input channels and a higher throughput, while the AD7731 provides a lower channel count in a similar package footprint.
Are the AD7739BRUZ and AD7731BRU pin-compatible?
No. Although both devices are supplied in a 24-lead TSSOP (RU suffix), their pin functions and internal signal assignments differ. The AD7739BRUZ provides eight analog input channels, whereas the AD7731BRU provides three, so the pinout cannot be treated as a drop-in replacement. Designers must verify pin functions against the respective manufacturer datasheets before considering any substitution.
What is the maximum output data rate of each device?
The AD7739BRUZ supports a maximum output rate of 15.1 kSPS. The AD7731BRU supports a maximum output rate of 6.4 kSPS. The higher throughput of the AD7739BRUZ makes it suitable for applications requiring faster channel scanning or higher sample rates.
How many analog input channels does each ADC provide?
The AD7739BRUZ provides 8 analog input channels, configurable as single-ended or differential inputs. The AD7731BRU provides 3 analog input channels. The channel count difference is a key selection criterion when designing multi-sensor or multi-channel data acquisition systems.
Do both devices share the same resolution and sigma-delta architecture?
Yes. Both the AD7739BRUZ and the AD7731BRU are 24-bit sigma-delta analog-to-digital converters. Both are designed for high-resolution, low-frequency measurement applications such as industrial process control, weigh scales, and instrumentation. Resolution alone does not determine interchangeability; channel count, output rate, and pinout must also be evaluated.
Can the AD7739BRUZ directly replace the AD7731BRU in an existing design?
No, a direct replacement is not supported. Despite both being 24-bit sigma-delta ADCs in 24-lead TSSOP packages, the AD7739BRUZ has 8 input channels versus 3 on the AD7731BRU, a different maximum output rate (15.1 kSPS vs 6.4 kSPS), and a different pin configuration. Any substitution requires schematic, layout, and firmware validation against the manufacturer datasheets.
Which device is better suited for higher-channel-count data acquisition?
The AD7739BRUZ is better suited for higher-channel-count data acquisition because it provides 8 analog input channels compared with 3 channels on the AD7731BRU. Combined with its higher maximum output rate of 15.1 kSPS, the AD7739BRUZ supports faster scanning across more inputs in multi-sensor systems.