Part A
AD7891ASZ-2
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1328 PCS
- Package
- QFP-44
- Series
- Acquisição de dados - ADCs-DACs - Objetivo Especial
Replacement verdict
Compatible functional replacement candidate
The AD7891ASZ-2 and AD7891AS-1 are functionally compatible 8-channel 12-bit data acquisition systems sharing the same package, pinout, and core architecture, making them viable replacement candidates. The primary distinction lies in their specified analog input ranges and corresponding performance grades, so the replacement is valid provided the target application's input signal span and accuracy requirements are validated against the ASZ-2's configuration.
Package Type
High match
Channel Count
High match
Analog Input Range
Validation required
Accuracy Grade
Validation required
Parts at a glance
Part B
AD7891AS-1
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 3359 PCS
- Package
- QFP-44
- 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-2 | AD7891AS-1 | Why it matters |
|---|---|---|---|
| Number of Input Channels | 8 | 8 | Channel count determines how many analog signals the ADC can multiplex and digitize, directly affecting system architecture. |
| Resolution | 12 bit | 12 bit | Resolution sets the smallest detectable analog change and thus measurement precision. |
| Sampling Rate | 500 kSPS | 500 kSPS | Maximum sampling rate limits the bandwidth of signals that can be accurately captured. |
| Input Type | Single-ended | Single-ended | Input configuration determines whether the ADC measures signals referenced to ground or differentially. |
| Supply Voltage | 5 V | 5 V | Supply voltage must match the system power rail for direct compatibility. |
| Interface Type | Parallel | Parallel | Interface type determines how the ADC connects to the host processor or FPGA. |
| Package / Case | 44-Lead MQFP | 44-Lead MQFP | Package footprint affects PCB layout and mechanical compatibility for drop-in replacement. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range determines suitability for industrial versus commercial environments. |
| Reference Type | External | External | Reference configuration affects accuracy stability and whether an external reference must be supplied. |
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-2 | AD7891AS-1 |
|---|---|---|
| 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 | 500k |
| Data Interface | Serial, Parallel | Serial, Parallel |
| 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 differences between the AD7891ASZ-2 and AD7891AS-1?
Both are 8-channel, 12-bit successive-approximation ADCs from Analog Devices in a 44-lead MQFP package. The primary difference is the input voltage range and corresponding speed grade: the AD7891AS-1 offers a ±10 V input range with a 1.6 µs conversion time (500 kSPS), while the AD7891ASZ-2 offers a ±5 V input range with a 1.6 µs conversion time (500 kSPS). The "Z" suffix in AD7891ASZ-2 denotes RoHS-compliant lead-free packaging, whereas AD7891AS-1 is the non-RoHS version.
Are the AD7891ASZ-2 and AD7891AS-1 pin-compatible?
Yes. Both devices are offered in the same 44-lead MQFP (MQFP-44) package with identical pin assignments, so they are pin-compatible. However, because the analog input ranges differ (±5 V vs ±10 V), the surrounding signal-conditioning circuitry must be reviewed before substitution.
What is the resolution and architecture of these AD7891 devices?
Both the AD7891ASZ-2 and AD7891AS-1 are 12-bit successive-approximation register (SAR) ADCs with 8 single-ended input channels (or 4 differential channels via configuration), an on-chip track-and-hold amplifier, and a parallel interface. They provide 12-bit resolution with no missing codes.
What are the analog input voltage ranges for each part?
The AD7891AS-1 provides a bipolar ±10 V input range, while the AD7891ASZ-2 provides a bipolar ±5 V input range. The input range is a factory-set characteristic of each grade and cannot be changed by the user.
Do the AD7891ASZ-2 and AD7891AS-1 differ in conversion speed or throughput?
No. Both grades share the same 1.6 µs conversion time and 500 kSPS throughput rate. The speed grade is common across the AD7891 family; the suffix distinguishes input range and package compliance rather than conversion performance.
What supply voltages do the AD7891ASZ-2 and AD7891AS-1 require?
Both devices operate from a single +5 V analog supply (VDD) and a separate +5 V digital supply (VDRIVE), with the VDRIVE pin allowing interfacing to 3 V or 5 V logic systems. An on-chip reference is included, and an external reference may also be used.
Is the AD7891ASZ-2 a drop-in RoHS replacement for the AD7891AS-1?
Electrically and mechanically it is pin-compatible, and the "Z" suffix indicates RoHS-compliant lead-free construction. However, because the AD7891ASZ-2 has a ±5 V input range versus the ±10 V range of the AD7891AS-1, it is not a functional drop-in replacement unless the system's analog input scaling is adjusted accordingly.
What interface and operating temperature range do these ADCs support?
Both parts provide a parallel microprocessor interface with a fast data access time suitable for direct connection to DSPs and microcontrollers. They are specified for the industrial temperature range of −40 °C to +85 °C.