Part A
AD7654ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 2675 Stückzahl
- Package
- LQFP-48
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7654ASTZ is a functionally compatible replacement candidate for the AD7654AST, sharing the same converter architecture, resolution, channel configuration, and package footprint. The primary distinction is the RoHS-compliant lead finish of the ASTZ variant, which requires validation against the original design's soldering process and compliance requirements before substitution.
Resolution and Architecture
High match
Channel Count and Input Configuration
High match
Package Type and Pinout
High match
Lead Finish and RoHS Compliance
Validation required
Parts at a glance
Part B
AD7654AST
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 7850 Stückzahl
- Package
- LQFP-48
- Series
- Datenerfassung mit Analog to Digital Converters (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 | AD7654ASTZ | AD7654AST | Why it matters |
|---|---|---|---|
| Resolution | 16 bit | 16 bit | Both parts provide the same conversion resolution, so measurement precision is unchanged. |
| Number of ADC Inputs / Channels | 4 (2 pseudo-differential pairs) | 4 (2 pseudo-differential pairs) | Channel count and configuration determine how many signals can be digitized without external multiplexing. |
| Sampling Rate | 500 kSPS | 500 kSPS | Identical throughput means the same signal bandwidth and system timing can be supported. |
| Supply Voltage | 5 V analog and digital | 5 V analog and digital | Matching supply requirements allow the same power rails and decoupling to be reused. |
| Interface Type | SPI / Serial (SPI-compatible) | SPI / Serial (SPI-compatible) | The same digital interface ensures firmware and host connections remain compatible. |
| Package / Case | 48-LQFP | 48-LQFP | Identical package and footprint allow drop-in board replacement without layout changes. |
| RoHS / Lead-Free Status | RoHS compliant, lead-free | Non-RoHS, contains lead | The Z suffix denotes lead-free/RoHS compliance, which affects regulatory compliance and solder process compatibility. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Same temperature range means equivalent environmental robustness for the application. |
| Input Type | Pseudo-differential, unipolar/bipolar | Pseudo-differential, unipolar/bipolar | Matching input configuration supports the same sensor and signal conditioning front end. |
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 | AD7654ASTZ | AD7654AST |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 500k | 500k |
| Number of A/D Converters | 1 | 1 |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Number of Inputs | 2, 4 | - |
| Input Type | Pseudo-Differential, Single Ended | - |
| Data Interface | SPI, Parallel, DSP | - |
| Configuration | MUX-S/H-MUX-ADC | - |
| Ratio - S / H: ADC | 2:1 | - |
| Architecture | SAR | - |
| Reference Type | External | - |
| Voltage - Supply, Analog | 5V | - |
| Voltage - Supply, Digital | 5V | - |
| Features | Simultaneous Sampling | - |
Frequently asked questions
What is the difference between the AD7654ASTZ and the AD7654AST?
The AD7654ASTZ and AD7654AST are functionally identical 16-bit, 500 kSPS, dual simultaneous-sampling successive-approximation ADCs from Analog Devices. The suffix difference is packaging/ordering-related: the "Z" designation denotes RoHS-compliant lead-free construction, while the non-Z version reflects the earlier lead-containing (non-RoHS) package variant. Both are specified in the same 48-lead LQFP package and share the same electrical datasheet parameters.
Are the AD7654ASTZ and AD7654AST pin-compatible?
Yes. Both devices are offered in the same 48-lead LQFP (ST-48) package with identical pin assignments as defined in the Analog Devices AD7654 datasheet. The only distinction is the RoHS/lead-free construction of the package finish, so the PCB land pattern and pin functions are the same.
Can the AD7654ASTZ be used as a drop-in replacement for the AD7654AST?
In most designs, yes, because the two share the same package, pinout, and specified electrical performance. The AD7654ASTZ is the RoHS-compliant version, so it is the appropriate choice for lead-free assembly processes. Designers should confirm that their board assembly and soldering profile are compatible with the lead-free finish and verify against the current Analog Devices datasheet before substituting.
What are the key performance specifications shared by the AD7654ASTZ and AD7654AST?
Both are 16-bit, 500 kSPS, dual simultaneous-sampling SAR ADCs with a 5 V analog supply and a separate 2.7 V to 5.25 V digital supply. They feature a parallel and serial interface, an on-chip 2.5 V reference, and are specified for operation over the industrial temperature range. These parameters are common to both orderable variants per the Analog Devices AD7654 datasheet.
Does the "Z" suffix affect the electrical performance of the AD7654?
No. The "Z" suffix in Analog Devices part numbering denotes RoHS compliance (lead-free package finish) and does not change the specified electrical performance. The AD7654ASTZ and AD7654AST share the same datasheet specifications for resolution, throughput, linearity, and power consumption.
Which variant should be selected for a new lead-free PCB assembly?
The AD7654ASTZ should be selected for new designs requiring RoHS-compliant, lead-free assembly, since it carries the lead-free package finish. The AD7654AST is the legacy non-RoHS variant and is generally not preferred for new lead-free production. Final selection should be confirmed against current Analog Devices product status and availability.
Are the AD7654ASTZ and AD7654AST available in the same package type?
Yes. Both are supplied in the 48-lead LQFP package as documented in the Analog Devices AD7654 datasheet. The package outline and pin count are identical; the difference is limited to the RoHS/lead-free construction of the package finish.