Part A
AD7705BRZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5488 Stückzahl
- Package
- SOIC-16
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Replacement verdict
Not a drop-in replacement
The AD7705BRZ and AD7703BR-REEL are not drop-in replacements for one another. Although both are Analog Devices sigma-delta ADCs, they differ in resolution, input channel architecture, output interface, and package footprint, so a direct board-level substitution is not possible without redesign.
Different resolution
Different input channel architecture
Different output interface
Different package footprint
Parts at a glance
Part B
AD7703BR-REEL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 444 Stückzahl
- Package
- SOIC-20
- 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 | AD7705BRZ | AD7705BRZ | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 16 | Both are 16-bit sigma-delta ADCs, so resolution is identical and not a differentiator. |
| Number of input channels | 2 differential | 2 differential | Channel count determines how many signals can be measured without external multiplexing. |
| Interface | SPI-compatible serial | SPI-compatible serial | The digital interface must match the host microcontroller to allow direct connection. |
| Supply voltage | 2.7 V to 3.3 V (DVDD), 2.7 V to 5.25 V (AVDD) | 2.7 V to 3.3 V (DVDD), 2.7 V to 5.25 V (AVDD) | Supply range must be compatible with the system power rails for proper operation. |
| Package | 16-lead SOIC | 16-lead SOIC | Package footprint affects PCB layout and whether a part is a drop-in replacement. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range must cover the application environment for reliable operation. |
| PGA gain range | 1 to 128 | 1 to 128 | Programmable gain allows small signals to be amplified for better effective resolution. |
| Data output rate | Up to 500 Hz | Up to 500 Hz | Output rate determines the maximum sampling speed for the measurement application. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7705BRZ | AD7703BR-REEL |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 20 |
| Sampling Rate(Per Second) | 500 | 4k |
| Number of Inputs | 2 | 1 |
| Input Type | Differential | Single Ended |
| Data Interface | SPI, DSP | SPI |
| Configuration | MUX-PGA-ADC | S/H-ADC |
| Ratio - S / H: ADC | - | 1:1 |
| Number of A/D Converters | 1 | 1 |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External |
| Voltage - Supply, Analog | 2.7V ~ 3.3V, 5V | 5V |
| Voltage - Supply, Digital | 2.7V ~ 3.3V, 5V | 5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Features | PGA | - |
Frequently asked questions
What are the primary functional differences between the AD7705BRZ and the AD7703BR-REEL?
The AD7705BRZ is a 2-channel, 16-bit sigma-delta ADC with an on-chip programmable gain amplifier (PGA) and a serial interface, housed in a 16-lead SOIC package. The AD7703BR-REEL is a single-channel, 20-bit sigma-delta ADC with a serial interface, supplied in a 20-lead SOIC package on tape and reel. The AD7705BRZ offers two differential input channels and selectable gain, while the AD7703BR-REEL provides higher resolution (20 bits) on a single channel.
Are the AD7705BRZ and AD7703BR-REEL pin-compatible or package-compatible?
No. The AD7705BRZ uses a 16-lead SOIC package, while the AD7703BR-REEL uses a 20-lead SOIC package. The pin counts and pin functions differ, so they are not drop-in replacements and require different PCB land patterns.
What is the resolution and channel count of each device?
The AD7705BRZ provides 16-bit resolution with two differential input channels. The AD7703BR-REEL provides 20-bit resolution with a single channel. The higher bit count of the AD7703BR-REEL suits applications requiring finer resolution on one signal, while the AD7705BRZ suits multi-channel medium-resolution measurements.
Do both devices include a programmable gain amplifier (PGA)?
The AD7705BRZ includes an on-chip PGA with selectable gain settings, allowing direct connection of low-level signals. The AD7703BR-REEL does not include an on-chip PGA; its input range is fixed and external signal conditioning is required for low-level inputs.
What digital interface do these ADCs use?
Both devices use a serial digital interface for communication with a host controller. The AD7705BRZ provides a serial interface compatible with SPI/QSPI/MICROWIRE-style connections, and the AD7703BR-REEL also uses a serial output interface. Exact timing and register maps differ and must be checked against each datasheet.
What are the supply voltage requirements for each part?
The AD7705BRZ operates from a single 2.7 V to 3.3 V or 5 V supply (per its datasheet), while the AD7703BR-REEL operates from a 5 V supply. Designers should confirm the exact supply range and analog/digital supply configuration in the respective manufacturer datasheets before substitution.
Can the AD7705BRZ directly replace the AD7703BR-REEL in an existing design?
No. Differences in resolution (16-bit vs 20-bit), channel count (2 vs 1), PGA availability, package size (16-lead vs 20-lead SOIC), and supply requirements prevent a direct replacement. Any substitution requires schematic, layout, and firmware changes validated against both datasheets.
Which device is better suited for multi-channel low-level signal acquisition?
The AD7705BRZ is better suited for multi-channel low-level signal acquisition because it integrates a PGA and provides two differential input channels, reducing external component count. The AD7703BR-REEL is intended for single-channel high-resolution measurements where 20-bit resolution is required.