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 AD7703AR-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 count
Different output interface
Different package footprint
Parts at a glance
Part B
AD7703AR-REEL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 71 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 | AD7703AR-REEL | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 20 | Higher resolution allows detection of smaller signal changes, which directly affects measurement precision and dynamic range. |
| Number of ADC channels | 2 (differential) | 1 (differential) | Channel count determines how many independent analog inputs can be measured without external multiplexing. |
| Interface type | SPI / 3-wire serial | Serial (SPI-compatible) | Interface compatibility affects whether the part can drop into an existing digital bus and firmware design. |
| Maximum output data rate | 500 SPS | 4 kSPS | Data rate limits how fast the system can sample signals; higher rates suit faster-changing inputs. |
| Supply voltage (analog) | 2.7 V to 3.3 V (or 5 V) | 5 V | Supply voltage compatibility determines whether the part works in low-voltage or 5 V systems without level shifting. |
| Package type | 16-lead SOIC | 20-lead SOIC | Package footprint and pin count affect PCB layout and whether a direct board replacement is possible. |
| Input gain / PGA | Programmable gain (1 to 128) | Fixed gain (calibrated) | Programmable gain allows adaptation to different sensor signal amplitudes; fixed gain limits input range flexibility. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range confirms suitability for industrial and extended-environment applications. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7705BRZ | AD7703AR-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 key architectural differences between the AD7705BRZ and the AD7703AR-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 AD7703AR-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 AD7703AR-REEL provides higher resolution on a single channel.
Do the AD7705BRZ and AD7703AR-REEL have the same resolution and accuracy?
No. The AD7705BRZ provides 16-bit resolution, whereas the AD7703AR-REEL provides 20-bit resolution. The AD7703AR-REEL therefore offers finer quantization for low-level signals, while the AD7705BRZ targets applications requiring two input channels with programmable gain at 16-bit resolution.
Can the AD7705BRZ and AD7703AR-REEL be used with the same supply voltage?
Both devices operate from a single 5 V supply (with the AD7705BRZ also supporting 3 V operation per its datasheet). The AD7703AR-REEL is specified for 5 V operation. Designers should confirm the exact supply range and reference configuration against the respective manufacturer datasheets before interchange.
Are the AD7705BRZ and AD7703AR-REEL pin-compatible?
No. The AD7705BRZ is a 16-lead SOIC device, while the AD7703AR-REEL is a 20-lead SOIC device. Different package sizes and pin counts mean the two are not pin-compatible and cannot be dropped into the same PCB land pattern without redesign.
What input channel configuration does each device support?
The AD7705BRZ provides two differential input channels (AIN1 and AIN2) with a programmable gain amplifier, allowing direct connection of low-level sensors. The AD7703AR-REEL provides a single differential input channel without an integrated PGA, so external signal conditioning may be required for low-level inputs.
What interface do the AD7705BRZ and AD7703AR-REEL use for communication?
Both devices use a serial interface for communication with a host microcontroller or DSP. The AD7705BRZ uses a SPI-compatible serial interface, while the AD7703AR-REEL uses a serial interface with separate data and clock lines. Designers should verify the exact timing and protocol requirements in each datasheet.
Which device is better suited for multi-channel sensor applications?
The AD7705BRZ is better suited for multi-channel applications because it integrates two differential input channels with a programmable gain amplifier in a single 16-lead package. The AD7703AR-REEL, being single-channel, would require external multiplexing to handle multiple sensors.
What package and ordering format differences should be considered?
The AD7705BRZ is supplied in a 16-lead SOIC package in tube or standard reel quantities depending on the ordering code. The AD7703AR-REEL is supplied in a 20-lead SOIC package on tape and reel, as indicated by the "-REEL" suffix. PCB footprint, assembly handling, and reflow profiles must be validated for each package separately.