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 AD7890BR-2 are not drop-in replacements for one another. Although both are Analog Devices 12-bit successive-approximation ADCs, they differ in channel architecture, package footprint, and interface configuration, so substituting one for the other requires board-level redesign and validation rather than direct replacement.
Different channel architecture
Different package footprint
Different interface configuration
Different input signal range
Parts at a glance
Part B
AD7890BR-2
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 167 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 | AD7890BR-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 offer 8 channels, so system-level channel capacity is equivalent. |
| Resolution | 12 bit | 12 bit | Resolution sets the smallest detectable analog step; identical 12-bit resolution means comparable measurement granularity. |
| Sampling Rate | 500 kSPS | 117 kSPS | Maximum throughput affects how fast signals can be digitized; the AD7891ASZ-1 supports significantly higher sampling rates than the AD7890BR-2. |
| Input Type | Single-ended | Single-ended | Input configuration determines signal conditioning requirements; both accept single-ended inputs, simplifying interchangeability. |
| Supply Voltage | 5 V | 5 V | Supply voltage must match the host system rails; both operate from a single 5 V supply, easing board-level substitution. |
| Interface Type | Parallel | Serial | The digital interface dictates how the converter connects to the host processor; parallel vs. serial output requires different pin routing and firmware. |
| Package / Mounting | 28-Lead SOIC (Surface Mount) | 24-Lead SOIC (Surface Mount) | Package footprint and pin count affect PCB layout compatibility; differing lead counts mean the parts are not drop-in replacements. |
| 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; identical industrial ranges support similar applications. |
| Reference Type | Internal | Internal | An internal reference reduces external component count and board space; both integrating references simplifies system design equivalently. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7891ASZ-1 | AD7890BR-2 |
|---|---|---|
| Supplier | - | 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 | Serial |
| Voltage Supply Source | Single Supply | Single Supply |
| Voltage - Supply | 5V | 0V ~ 2.5V |
| 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 AD7890BR-2?
The AD7891ASZ-1 is an 8-channel, 12-bit data acquisition system with a 1.6 µs successive approximation ADC and an on-chip track-and-hold amplifier, offering a throughput rate of 500 kSPS. The AD7890BR-2 is an 8-channel, 12-bit data acquisition system with a 5 µs successive approximation ADC, also featuring an on-chip track-and-hold, with a maximum throughput rate of 200 kSPS. Both integrate an 8-channel multiplexer, but the AD7891ASZ-1 provides faster conversion and higher throughput, while the AD7890BR-2 offers a slower, lower-power alternative.
Are the AD7891ASZ-1 and AD7890BR-2 pin-compatible?
No. The AD7891ASZ-1 is supplied in a 44-lead MQFP package, while the AD7890BR-2 is supplied in a 24-lead SOIC package. The pin counts, pin functions, and package footprints differ, so they are not drop-in replacements for each other.
What are the analog input voltage ranges for each device?
The AD7891ASZ-1 offers selectable input ranges of ±10 V, ±5 V, and 0 V to +2.5 V (with a 2.5 V reference) via configuration pins. The AD7890BR-2 provides a fixed input range of ±10 V. Designs requiring flexible input scaling should account for this difference.
How do the throughput rates and conversion times compare?
The AD7891ASZ-1 has a conversion time of 1.6 µs and a maximum throughput rate of 500 kSPS. The AD7890BR-2 has a conversion time of 5 µs and a maximum throughput rate of 200 kSPS. For high-speed multiplexed acquisition, the AD7891ASZ-1 is the faster option.
What are the supply voltage and power consumption specifications?
The AD7891ASZ-1 operates from a single +5 V supply for the digital and analog sections, with power consumption typically around 60 mW. The AD7890BR-2 operates from a +5 V supply and typically consumes about 30 mW. The AD7890BR-2 is the lower-power choice, while the AD7891ASZ-1 trades higher power for faster throughput.
What digital interface does each device provide?
Both devices provide a parallel digital interface for connection to microprocessors and DSPs. The AD7891ASZ-1 offers a 12-bit parallel output with a standard microprocessor interface, while the AD7890BR-2 also provides a 12-bit parallel output. The interface timing and control signals differ, so firmware and glue logic must be adapted accordingly.
Can the AD7890BR-2 be used as a direct replacement for the AD7891ASZ-1 in an existing design?
No. The two devices differ in package (24-lead SOIC vs 44-lead MQFP), input range options, throughput rate, and power consumption. A direct substitution is not possible without redesigning the PCB footprint, revalidating the analog front end, and updating the digital interface timing.