Part A
AD7705BRZ
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 5488 PCS
- Package
- SOIC-16
- Series
- Acquisition de données - Convertisseur analogique - numérique (ADC)
Replacement verdict
Not a drop-in replacement
The AD7705BRZ and AD7703CR are both 16-bit sigma-delta ADCs from Analog Devices, but they differ fundamentally in resolution architecture, interface, channel count, and package, so the AD7705BRZ cannot serve as a direct drop-in substitute for the AD7703CR without redesign of the digital interface, signal chain, and board layout.
Different interface type
Different channel count
Different package footprint
Different input configuration
Parts at a glance
Part B
AD7703CR
Analog Equipment GmbH.
- Lifecycle
- Active
- Stock
- 5914 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 | AD7703CR | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 20 | Higher resolution allows detection of smaller signal changes, which is critical for precision measurement applications. |
| Number of ADC Input Channels | 2 (differential) | 1 (differential) | More input channels enable multiplexed measurement of multiple signals without external switching hardware. |
| Maximum Sampling Rate (sps) | 500 | 4k | A higher sampling rate supports faster-changing signals and higher-throughput data acquisition systems. |
| Interface Type | SPI / QSPI / MICROWIRE / DSP-compatible serial | Serial (SPI-compatible) | Interface compatibility determines whether the part can drop into an existing digital bus architecture without redesign. |
| Supply Voltage (V) | 2.7 to 3.3 (or 5) | 5 | Supply voltage compatibility is essential for direct substitution in a given power rail design. |
| Package Type | 16-lead SOIC | 20-lead SOIC | Different package footprints require PCB layout changes, affecting direct board-level substitutability. |
| On-Chip PGA | Yes (gain 1 to 128) | No | An integrated PGA allows direct connection of low-level sensors without external amplification, simplifying the signal chain. |
| Operating Temperature Range (°C) | -40 to +85 | -40 to +85 | Matching temperature ranges ensure both parts suit the same environmental conditions for the target application. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7705BRZ | AD7703CR |
|---|---|---|
| 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 differences between the AD7705BRZ and the AD7703CR?
The AD7705BRZ is a 16-bit, 2-channel sigma-delta ADC with an SPI-compatible serial interface, housed in a 16-lead SOIC package. The AD7703CR is a 20-bit, single-channel sigma-delta ADC with a serial interface, housed in a 20-lead SOIC package. Key differences include resolution (16-bit vs 20-bit), channel count (2 vs 1), and package pin count (16 vs 20).
Are the AD7705BRZ and AD7703CR pin-compatible?
No. The AD7705BRZ uses a 16-lead SOIC package, while the AD7703CR uses a 20-lead SOIC package. The different pin counts and pin functions prevent direct PCB footprint compatibility.
Can the AD7705BRZ and AD7703CR be used interchangeably in an existing design?
No. Beyond package differences, the devices differ in resolution (16-bit vs 20-bit), number of input channels (2 vs 1), and register/interface architecture. A direct substitution is not possible without redesign and validation against the respective datasheets.
What are the supply voltage requirements for the AD7705BRZ and AD7703CR?
The AD7705BRZ operates from a 2.7 V to 3.3 V or 4.75 V to 5.25 V supply (VDD), with a separate VDD for the digital interface. The AD7703CR operates from a 5 V ±5% supply. Designers should verify exact supply ranges in the respective manufacturer datasheets.
How do the serial interfaces of the AD7705BRZ and AD7703CR differ?
The AD7705BRZ provides an SPI-compatible 3-wire serial interface. The AD7703CR provides a serial interface with a different frame format and control register structure. The interface protocols are not directly interchangeable, and firmware must be adapted accordingly.
Which device offers higher resolution, the AD7705BRZ or the AD7703CR?
The AD7703CR offers higher resolution at 20 bits, compared to 16 bits for the AD7705BRZ. The AD7703CR is therefore better suited to applications requiring finer resolution on a single channel.
How many input channels does each device support?
The AD7705BRZ supports two differential input channels (or four pseudo-differential inputs depending on configuration). The AD7703CR supports a single differential input channel. Channel count is a primary selection criterion between the two parts.
What are the operating temperature ranges for the AD7705BRZ and AD7703CR?
Both the AD7705BRZ and AD7703CR are specified for the industrial temperature range of −40°C to +85°C. Designers should confirm the exact grade and temperature specification in the manufacturer datasheet for the specific orderable part number.