Part A
AD7655ASTZRL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1730 PCS
- Package
- LQFP-48
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7655ASTZRL is a functionally equivalent replacement candidate for the AD7655AST, sharing the same converter architecture, channel configuration, package footprint, and temperature range; the primary distinction is the RoHS-compliant packaging and tape-and-reel shipment format of the AD7655ASTZRL, which requires validation against the original board's assembly and compliance requirements.
Resolution and Architecture
High match
Channel Count and Input Configuration
High match
Package Type and Pinout
High match
RoHS Compliance and Packaging Format
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7655ASTZRL | AD7655AST | Why it matters |
|---|---|---|---|
| Resolution | 16 bit | 16 bit | Determines the quantization accuracy of the ADC; identical resolution means equivalent measurement precision. |
| Number of Channels | 4 (2 differential / 4 single-ended) | 4 (2 differential / 4 single-ended) | Defines how many analog inputs can be sampled; matching channel count ensures the same system-level signal routing works. |
| Sampling Rate | 1 MSPS | 1 MSPS | Sets the maximum conversion throughput; identical rate preserves timing and bandwidth of the application. |
| Architecture | SAR | SAR | Successive-approximation architecture affects latency and power; same architecture ensures equivalent behavior. |
| Supply Voltage | 5 V (analog and digital) | 5 V (analog and digital) | Determines power rail requirements; identical supply voltage allows drop-in replacement without rail changes. |
| Interface Type | Parallel / Serial (SPI-compatible) | Parallel / Serial (SPI-compatible) | Defines how the ADC connects to the host; matching interfaces ensure firmware and PCB compatibility. |
| Package / Case | 48-LQFP | 48-LQFP | Footprint and thermal characteristics must match for physical interchangeability on the PCB. |
| Packaging / Mounting Form | Tape & Reel (RL) | Tray / Tube | Delivery format affects automated assembly lines; reel vs tray matters for pick-and-place production setup. |
| RoHS / Lead-Free Status | RoHS compliant (Z suffix) | Non-RoHS (leaded) | Environmental compliance and solder process differ; RoHS status affects regulatory compliance and reflow profile. |
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 | AD7655ASTZRL | AD7655AST |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 1M | 1M |
| 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 AD7655ASTZRL and AD7655AST?
Both are the same Analog Devices AD7655 16-bit, 500 kSPS, 4-channel successive-approximation ADC in a 48-lead LQFP package. The AD7655ASTZRL is the tape-and-reel packaging variant (suffix "RL"), while AD7655AST is the standard tray packaging variant. The "Z" in AD7655ASTZRL denotes RoHS-compliant lead-free construction, whereas AD7655AST is the non-RoHS lead-frame version. Electrical performance and die are identical.
Are AD7655ASTZRL and AD7655AST electrically and functionally interchangeable?
Yes. Both devices share the same AD7655 silicon die, pinout, 48-lead LQFP footprint, and specified performance (16-bit resolution, 500 kSPS throughput, 4-channel input with 2 simultaneous sample-and-hold amplifiers, parallel and serial interfaces). They differ only in packaging format and RoHS compliance, so they are functionally interchangeable in a given design.
What are the key performance specifications of the AD7655?
The AD7655 is a 16-bit, 500 kSPS, 4-channel charge-redistribution SAR ADC with two simultaneous-sampling SHA inputs, an on-chip 2.5 V reference, and a flexible parallel/serial interface. It operates from a 5 V analog supply with a separate 2.7 V to 5.25 V digital supply and is specified for the -40 °C to +85 °C industrial temperature range in the 48-lead LQFP package.
Does the "Z" suffix in AD7655ASTZRL indicate RoHS compliance?
Yes. Analog Devices uses the "Z" suffix to designate RoHS-compliant, lead-free package construction. AD7655ASTZRL is therefore RoHS-compliant, while AD7655AST (without the Z) is the non-RoHS lead-frame version. Designers with RoHS-restricted assemblies should select the Z-suffix part.
What does the "RL" suffix mean on AD7655ASTZRL?
The "RL" suffix denotes tape-and-reel packaging, which is intended for automated high-volume SMT assembly lines. AD7655AST is supplied in standard tray packaging. The reel quantity and packaging orientation are defined in the Analog Devices datasheet and ordering guide; the electrical device is unchanged.
Can AD7655AST be used as a drop-in replacement for AD7655ASTZRL on an existing PCB?
Yes, from a footprint and pin-function standpoint, since both are the same 48-lead LQFP AD7655 device. However, if the assembly is RoHS-restricted, AD7655AST (non-Z) may not satisfy compliance requirements, and the packaging format (tray vs. reel) must match the pick-and-place line configuration. Verify RoHS and packaging requirements before substituting.
What interface options does the AD7655 provide?
The AD7655 provides both a parallel interface (byte or word mode) and a serial interface (SPI/QSPI/MICROWIRE/DSP-compatible), selectable via configuration. This allows direct connection to microcontrollers, DSPs, and FPGAs. Both AD7655ASTZRL and AD7655AST support the same interface modes because they use identical silicon.
Which applications are the AD7655ASTZRL and AD7655AST suited for?
Both parts target industrial and instrumentation applications requiring simultaneous multi-channel sampling, including motor control, power monitoring, data acquisition systems, and medical instrumentation. Selection between them is driven by RoHS compliance and packaging format rather than by application performance.