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-4 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-4
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 6793 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-4 | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 8 | 8 | Channel count determines how many analog signals can be sampled; both are 8-channel devices, so channel capacity is equivalent. |
| Resolution | 12 bit | 12 bit | Resolution sets the smallest detectable analog step; both are 12-bit, so measurement precision is comparable. |
| Sampling Rate | 500 kSPS | 117 kSPS | Maximum throughput affects how fast signals can be captured; the AD7891 supports significantly higher sampling rates than the AD7890. |
| Input Type | Single-ended | Single-ended | Input configuration determines signal wiring and common-mode handling; both use single-ended inputs, so front-end design is similar. |
| Supply Voltage | 5 V | 5 V | Supply voltage must match the system rail; both operate from a 5 V supply, simplifying power design substitution. |
| Interface Type | Parallel | Serial (SPI/QSPI/MICROWIRE) | The digital interface dictates how the ADC connects to the host processor; parallel vs serial interfaces are not directly interchangeable without redesign. |
| Package / Mounting | 44-Lead MQFP (Surface Mount) | 24-Lead SOIC (Surface Mount) | Package footprint and pin count affect PCB layout; different packages require different board layouts and cannot be drop-in replaced. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C | Temperature range defines environmental limits; both cover the industrial range, so thermal suitability is equivalent. |
| Reference Type | External | External | Reference configuration affects accuracy and external component count; both require an external reference, so supporting circuitry is similar. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7891ASZ-1 | AD7890AR-4 |
|---|---|---|
| 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 primary functional differences between the AD7891ASZ-1 and the AD7890AR-4?
The AD7891ASZ-1 is an 8-channel, 12-bit data acquisition system (DAS) with a parallel interface, while the AD7890AR-4 is an 8-channel, 12-bit DAS with a serial interface. Both integrate a track-and-hold amplifier, a successive approximation ADC, and a multiplexer, but they differ in their digital output interface and package options.
Are the AD7891ASZ-1 and AD7890AR-4 pin-compatible or package-compatible?
No. The AD7891ASZ-1 is supplied in a 44-lead MQFP package, whereas the AD7890AR-4 is supplied in a 24-lead SOIC package. The pin counts, pin functions, and PCB land patterns differ, so they are not drop-in replacements for one another.
What are the specified analog input voltage ranges for each device?
The AD7891ASZ-1 offers selectable input ranges of ±10 V, ±5 V, and 0 V to +5 V (with a 0 V to +10 V option depending on the model suffix). The AD7890AR-4 provides a fixed input range of ±10 V. Designers must confirm the exact range configuration against the respective datasheet for their specific grade.
How do the throughput rates of the AD7891ASZ-1 and AD7890AR-4 compare?
Both devices are 12-bit successive approximation ADCs. The AD7891ASZ-1 is specified for a throughput rate of 500 kSPS, while the AD7890AR-4 is specified for 117 kSPS. The higher throughput of the AD7891ASZ-1 makes it better suited to faster multiplexed acquisition applications.
What digital interface does each part use, and how does that affect system design?
The AD7891ASZ-1 uses a parallel microprocessor interface, which requires a parallel data bus and address lines. The AD7890AR-4 uses a serial interface compatible with SPI/QSPI/MICROWIRE, requiring fewer I/O pins. The choice affects board routing, microcontroller pin count, and firmware complexity.
Do both parts operate from the same supply voltages?
Both devices require a +5 V analog supply and a +5 V digital supply for their standard operating modes. The AD7891ASZ-1 additionally requires a ±5 V or ±10 V analog input range configuration depending on the selected model. Always verify the exact supply and reference requirements in the manufacturer datasheet for the specific grade.
Can the AD7890AR-4 be used as a direct substitute for the AD7891ASZ-1 in an existing design?
No. Because the two parts differ in package, pinout, digital interface (serial vs. parallel), throughput rate, and input range options, a direct substitution is not possible. Any replacement requires PCB redesign, firmware changes, and validation against the target system requirements.