Part A
AD7705BRZ-REEL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 7181 PCS
- Package
- SOIC-16
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Replacement verdict
Not a drop-in replacement
The AD7705BRZ-REEL and AD7703CR are both 16-bit sigma-delta ADCs, but they differ fundamentally in resolution architecture, interface type, channel configuration, and package footprint. The AD7705BRZ-REEL offers two differential input channels with an SPI-compatible serial interface in a 16-lead SOIC package, while the AD7703CR provides a single-channel 20-bit-capable sigma-delta converter with a serial interface in a 20-lead SOIC package. These differences in channel count, digital interface protocol, and physical footprint prevent direct board-level substitution without redesign.
Different channel count
Different interface type
Different package footprint
Different resolution architecture
Parts at a glance
Part B
AD7703CR
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5914 PCS
- Package
- SOIC-20
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (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 | AD7703CR | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 20 | Higher resolution allows detection of smaller signal changes; the AD7703 offers 4 extra bits, improving precision for low-level measurements. |
| Number of input channels | 2 (differential) | 1 (differential) | Channel count determines how many signal sources can be measured; the AD7705 supports two differential inputs while the AD7703 supports only one. |
| Interface type | SPI / 3-wire serial | Serial (SPI-compatible) | Interface compatibility affects how easily the ADC connects to a host microcontroller; both are serial but differ in protocol details. |
| Maximum output data rate | 500 SPS | 4 kSPS | Data rate limits how fast signals can be sampled; the AD7703 supports much higher throughput for faster-changing inputs. |
| Supply voltage (analog) | 2.7 V to 3.3 V (or 5 V) | 5 V | Supply requirements affect system power design; the AD7705 supports lower-voltage operation while the AD7703 requires a 5 V supply. |
| Package | 16-lead SOIC | 20-lead SOIC | Package footprint and pin count affect PCB layout and drop-in substitutability; the two parts are not footprint-compatible. |
| Input type | Differential | Differential | Both accept differential inputs, which reject common-mode noise; this is a shared characteristic relevant to signal integrity. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range determines suitability for industrial environments; both cover the standard industrial range. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7705BRZ-REEL | 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 key architectural differences between the AD7705BRZ-REEL and the AD7703CR?
The AD7705BRZ-REEL 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 AD7703CR is a single-channel, 20-bit sigma-delta ADC with a serial interface, housed in a 20-lead SOIC package. The AD7705 offers two differential input channels and selectable gain, while the AD7703 provides higher resolution on a single channel.
What is the resolution and channel count of each device?
The AD7705BRZ-REEL provides 16-bit resolution with two fully differential input channels. The AD7703CR provides 20-bit resolution with one differential input channel. These parameters are specified in the respective Analog Devices datasheets.
Do the AD7705BRZ-REEL and AD7703CR have the same package and pinout?
No. The AD7705BRZ-REEL is supplied in a 16-lead SOIC package, while the AD7703CR is supplied in a 20-lead SOIC package. The pin counts and pin functions differ, so the two devices are not pin-compatible and cannot be interchanged on the same PCB land pattern without redesign.
What are the supply voltage requirements for each part?
The AD7705BRZ-REEL operates from a single 2.7 V to 3.3 V or 4.75 V to 5.25 V supply (with separate AVDD and DVDD pins). The AD7703CR operates from a single 5 V supply. Designers should confirm exact supply ranges and decoupling requirements in the respective datasheets before substitution.
Can the AD7705BRZ-REEL and AD7703CR be used interchangeably in an existing design?
No. The devices differ in resolution (16-bit vs 20-bit), channel count (2 vs 1), package size (16-lead vs 20-lead SOIC), and supply configuration. A direct drop-in replacement is not possible; any substitution requires schematic, layout, and firmware changes validated against the manufacturer datasheets.
What interface do these ADCs use for communication with a microcontroller?
Both the AD7705BRZ-REEL and the AD7703CR use a serial interface for communication. The AD7705 provides a SPI-compatible serial interface, while the AD7703 uses a serial interface with separate data and clock lines. Exact timing and protocol details are specified in the Analog Devices datasheets for each part.
Which device is better suited for multi-channel low-frequency measurement applications?
The AD7705BRZ-REEL is better suited for multi-channel low-frequency measurement because it provides two differential input channels with an on-chip PGA, allowing direct connection of low-level sensors. The AD7703CR, with a single channel and 20-bit resolution, is better suited to applications requiring higher resolution on one signal path.