Part A
AD7891ASZ-1
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5058 PCS
- Package
- SOIC-8
- Series
- Acquisição de dados - ADCs-DACs - Objetivo Especial
Replacement verdict
Not a drop-in replacement
The AD7891ASZ-1 and AD7890AR-2 are not drop-in replacements for one another. Although both are 12-bit successive-approximation ADCs from Analog Devices, they differ in input channel architecture, package footprint, and interface configuration, so a direct board-level substitution is not possible without redesign.
Different input architecture
Different package footprint
Different channel count
Different interface configuration
Parts at a glance
Part B
AD7890AR-2
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 7872 PCS
- Package
- SOIC-24
- Series
- Acquisição de dados - ADCs-DACs - Objetivo Especial
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7891ASZ-1 | AD7890AR-2 | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 8 | 8 | Channel count determines how many analog signals can be multiplexed into a single converter; both provide 8 single-ended inputs. |
| Resolution | 12 bit | 12 bit | Resolution sets the smallest detectable signal change; both are 12-bit converters, so quantization granularity is equivalent. |
| Sampling Rate | 500 kSPS | 117 kSPS | Maximum throughput limits the highest frequency signal that can be captured; the AD7891ASZ-1 samples significantly faster than the AD7890AR-2. |
| Input Type | Single-ended | Single-ended | Input configuration affects signal conditioning and grounding requirements; both accept single-ended analog inputs. |
| Supply Voltage | 5 V | 5 V | Supply voltage must match the system rail; both operate from a single 5 V supply. |
| Interface | Parallel | Serial (SPI/QSPI) | The digital interface determines how the converter connects to the host processor; the AD7891ASZ-1 uses a parallel bus while the AD7890AR-2 uses a serial interface. |
| Package | 44-Lead MQFP | 24-Lead SOIC | Package footprint and pin count affect PCB layout and board space; the two parts are not drop-in compatible. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range defines the environments in which the part is guaranteed to meet specifications; both cover the industrial range. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7891ASZ-1 | AD7890AR-2 |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Type | Data Acquisition System (DAS) | Data Acquisition System (DAS) |
| Number of Channels | 8 | 8 |
| Resolution(Bits) | 12 b | 12 b |
| Sampling Rate(Per Second) | 500k | 117k |
| Data Interface | Serial, Parallel | SPI |
| Voltage Supply Source | Single Supply | Single Supply |
| Voltage - Supply | 5V | 5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the key architectural differences between the AD7891ASZ-1 and AD7890AR-2?
The AD7891ASZ-1 is an 8-channel, 12-bit data acquisition system with a parallel interface and a 1.6 µs conversion time, housed in a 44-lead MQFP package. The AD7890AR-2 is an 8-channel, 12-bit data acquisition system with a serial interface and a 5 µs conversion time, housed in a 24-lead SOIC package. The primary differences are the interface type (parallel vs. serial), conversion speed, and package footprint.
Are the AD7891ASZ-1 and AD7890AR-2 pin-compatible or package-compatible?
No. The AD7891ASZ-1 uses a 44-lead MQFP package, while the AD7890AR-2 uses a 24-lead SOIC package. The pin counts, pin functions, and PCB land patterns differ, so they are not drop-in replacements for each other.
Can the AD7891ASZ-1 and AD7890AR-2 be used interchangeably in an existing design?
No, not without redesign. The AD7891ASZ-1 requires a parallel microprocessor interface, whereas the AD7890AR-2 uses a serial interface. The host controller, PCB layout, and firmware must be adapted to the respective interface and package. Direct substitution is not possible.
How do the conversion times of the AD7891ASZ-1 and AD7890AR-2 compare?
The AD7891ASZ-1 has a specified conversion time of 1.6 µs, while the AD7890AR-2 has a conversion time of 5 µs. The AD7891ASZ-1 therefore offers faster throughput for applications requiring higher sampling rates.
What are the analog input voltage ranges for the AD7891ASZ-1 and AD7890AR-2?
Both devices are 12-bit, 8-channel data acquisition systems. The AD7891ASZ-1 is specified for a ±10 V input range (with a ±5 V option depending on the model suffix), and the AD7890AR-2 is specified for a ±10 V input range. Designers should confirm the exact input range from the respective manufacturer datasheet for the specific grade ordered.
Do the AD7891ASZ-1 and AD7890AR-2 support the same power supply configuration?
Both devices operate from a single +5 V supply for the analog and digital sections, with the AD7891ASZ-1 also requiring a ±5 V or ±10 V analog input range configuration. The AD7890AR-2 operates from a +5 V supply. Exact supply tolerances and current consumption should be verified against the manufacturer datasheets for each part.
Which part is better suited for space-constrained designs?
The AD7890AR-2 is better suited for space-constrained designs because it is housed in a 24-lead SOIC package, whereas the AD7891ASZ-1 uses a larger 44-lead MQFP package. The serial interface of the AD7890AR-2 also reduces the number of required PCB traces.
Which part is preferable when high-speed parallel data transfer is required?
The AD7891ASZ-1 is preferable when high-speed parallel data transfer is required, as it provides a parallel microprocessor interface and a faster 1.6 µs conversion time. The AD7890AR-2 uses a serial interface and has a 5 µs conversion time, making it more suitable for systems where serial communication and reduced pin count are priorities.