Part A
AD7705BRZ-REEL
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 7181 PCS
- Package
- SOIC-16
- Series
- Acquisition de données - Convertisseur analogique - numérique (ADC)
Replacement verdict
Not a drop-in replacement
The AD7705BRZ-REEL and AD7701AR are not drop-in replacements for one another. They differ in resolution, input channel architecture, digital interface, and package footprint, so substituting one for the other requires a full board and firmware redesign rather than a direct swap.
Different resolution
Different input architecture
Different digital interface
Different package footprint
Parts at a glance
Part B
AD7701AR
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 8718 PCS
- Package
- SOIC-20
- Series
- Acquisition de données - Convertisseur analogique - numérique (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-REEL | AD7701AR | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 16 | Both are 16-bit ADCs, so resolution is equivalent for precision measurement applications. |
| Number of input channels | 2 (differential) | 1 (single-ended) | The AD7705 offers two differential inputs, enabling multi-channel or differential sensing, while the AD7701 provides only a single-ended input. |
| Input type | Differential | Single-ended | Differential inputs reject common-mode noise and are preferred for low-level sensor signals; single-ended is simpler but less noise-immune. |
| Architecture | Sigma-delta (charge-balancing) | Sigma-delta (charge-balancing) | Both use sigma-delta conversion, providing high resolution and good noise performance for low-frequency signals. |
| Output interface | SPI / 3-wire serial | Serial (SPI-compatible) | Both provide serial output, but the exact protocol and timing differ, affecting microcontroller compatibility and firmware design. |
| Supply voltage (V) | 2.7 to 3.3 (DVDD), 2.7 to 5.25 (AVDD) | 5 (single supply) | The AD7705 supports lower and split supply voltages, while the AD7701 requires a 5 V supply, affecting system power design. |
| Package | 16-lead SOIC | 20-lead SOIC | Different package sizes and pin counts affect PCB layout and are not drop-in footprint compatible. |
| Operating temperature range (°C) | -40 to +85 | -40 to +85 | Both cover the industrial temperature range, so environmental suitability is equivalent. |
| On-chip PGA / gain | Yes (gain 1 to 128) | No (external gain required) | The AD7705 integrates a programmable gain amplifier for direct low-level signal conditioning, while the AD7701 needs external amplification. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7705BRZ-REEL | AD7701AR |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| 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-REEL and the AD7701AR?
The AD7705BRZ-REEL is a 2-channel, 16-bit sigma-delta ADC with an on-chip programmable gain amplifier (PGA) and a serial SPI-compatible interface, housed in a 16-lead SOIC. The AD7701AR is a single-channel, 16-bit sigma-delta ADC with a serial interface and a 20-lead SOIC package. The AD7705 integrates a PGA and two differential input channels, while the AD7701 provides a single channel without an integrated PGA.
Do the AD7705BRZ-REEL and AD7701AR have the same resolution and output rate?
Both devices provide 16-bit resolution. The AD7705BRZ-REEL offers programmable output update rates from 20 Hz to 500 Hz, while the AD7701AR provides a fixed 4 kHz output update rate. The output rate configurations are therefore not equivalent between the two parts.
Can the AD7705BRZ-REEL and AD7701AR be used with the same supply voltage?
The AD7705BRZ-REEL operates from a 2.7 V to 3.3 V or 4.75 V to 5.25 V supply, depending on the specified grade. The AD7701AR operates from a 5 V supply. Designs must verify the exact grade and supply range against the respective manufacturer datasheets before sharing a common rail.
Are the AD7705BRZ-REEL and AD7701AR pin-compatible?
No. The AD7705BRZ-REEL is supplied in a 16-lead SOIC package, while the AD7701AR is supplied in a 20-lead SOIC package. The differing package sizes and pin counts mean the two devices are not pin-compatible and require different PCB land patterns.
What input channel configuration does each device support?
The AD7705BRZ-REEL provides two differential input channels with an on-chip PGA, allowing direct connection of low-level signals. The AD7701AR provides a single input channel and does not include an integrated PGA, so external signal conditioning may be required for low-level inputs.
Do both devices use a serial interface for communication?
Yes. Both the AD7705BRZ-REEL and the AD7701AR use a serial interface for communication with a host controller. The AD7705BRZ-REEL uses an SPI-compatible serial interface, while the AD7701AR uses a serial interface as specified in its datasheet. Engineers should confirm the exact interface timing and protocol from the respective manufacturer documentation.
Which device is better suited for multi-channel low-level signal acquisition?
The AD7705BRZ-REEL is better suited for multi-channel low-level signal acquisition because it integrates a PGA and provides two differential input channels. The AD7701AR, with a single channel and no integrated PGA, is more appropriate for single-channel applications where external gain stages are acceptable.