Part A
AD7655ASTZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5580 PCS
- Package
- LQFP-48
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7655ASTZ and AD7654AST are both 16-bit successive-approximation ADCs from Analog Devices in the same 48-lead LQFP package, sharing identical resolution, supply architecture, and serial interface, making them strong functional replacement candidates. However, the AD7655ASTZ provides four independent simultaneous-sampling channels while the AD7654AST offers two differential channel pairs, so the replacement is only valid where the reduced channel count and different input configuration are acceptable. Designers must validate the input topology and channel requirements before substituting.
Resolution
High match
Package Type
High match
Channel Count
Validation required
Input Configuration
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 | AD7655ASTZ | AD7654AST | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 4 (2 simultaneous pairs, pseudo-differential) | 4 (2 simultaneous pairs, pseudo-differential) | Channel count and simultaneity determine how many signals can be sampled at once; both offer 4 channels in 2 simultaneous pairs, so channel architecture is functionally equivalent. |
| Resolution | 16 bits | 16 bits | Resolution sets the smallest detectable signal change; both are 16-bit, so precision is equivalent for substitutability. |
| Sampling Rate (max) | 1 MSPS | 500 kSPS | Maximum throughput limits how fast signals can be digitized; the AD7655ASTZ runs at twice the rate, which matters for higher-bandwidth or faster-scanning applications. |
| Input Type | Pseudo-differential (unipolar/bipolar) | Pseudo-differential (unipolar/bipolar) | Input configuration determines signal compatibility; both support pseudo-differential unipolar and bipolar inputs, so they interface similarly to sensors and front-ends. |
| Supply Voltage (analog) | 5 V | 5 V | Analog supply voltage must match the system rail; both operate from a 5 V analog supply, simplifying drop-in replacement. |
| Interface | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Digital interface compatibility determines whether the part can connect to the host processor without redesign; both offer parallel and serial options. |
| Package | 48-Lead LQFP | 48-Lead LQFP | Package and pinout affect PCB footprint and layout; identical LQFP-48 packages allow the same board layout to be reused. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range defines the environments where the part is guaranteed to meet specs; both cover the industrial range, so environmental suitability is equivalent. |
| Power Consumption (typical) | ~120 mW at 1 MSPS | ~90 mW at 500 kSPS | Power draw affects thermal budget and supply sizing; the higher-throughput AD7655ASTZ consumes more power, which matters in power-sensitive designs. |
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 | AD7655ASTZ | AD7654AST |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 1M | 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 are the key differences between the AD7655ASTZ and the AD7654AST?
The AD7655ASTZ is a 16-bit, 1 MSPS, dual-channel simultaneous-sampling successive-approximation ADC with two on-chip track-and-hold amplifiers and a flexible parallel/serial interface, housed in a 48-lead LQFP. The AD7654AST is a 16-bit, 500 kSPS, dual-channel simultaneous-sampling SAR ADC in a 48-lead LQFP with a similar pinout family but lower throughput. The primary differences are sampling rate (1 MSPS vs 500 kSPS) and the associated timing and power specifications.
Can the AD7655ASTZ and AD7654AST be used interchangeably in an existing design?
No, they are not drop-in interchangeable without validation. Although both are 16-bit dual simultaneous-sampling SAR ADCs in 48-lead LQFP packages, the AD7655ASTZ supports 1 MSPS while the AD7654AST supports 500 kSPS, and their timing, power, and interface timing parameters differ. The design must be re-verified against the respective datasheets before substitution.
Do the AD7655ASTZ and AD7654AST have the same package and pinout?
Both devices are offered in a 48-lead LQFP package. However, pin functions and interface configuration should be confirmed against each device's official datasheet, as the two parts belong to different speed grades and their pin assignments and control-signal behavior must be verified individually before layout reuse.
What is the maximum sampling rate of each device?
The AD7655ASTZ provides a maximum throughput of 1 MSPS. The AD7654AST provides a maximum throughput of 500 kSPS. Both are 16-bit successive-approximation ADCs with dual simultaneous-sampling capability.
What interface options do these ADCs support?
Both the AD7655ASTZ and AD7654AST provide a flexible parallel interface and a serial interface for connection to DSPs and microcontrollers. The exact interface modes, word lengths, and timing must be confirmed from the respective manufacturer datasheets.
Are the AD7655ASTZ and AD7654AST suitable for simultaneous sampling of two channels?
Yes. Both devices are dual-channel ADCs with simultaneous-sampling capability, making them suitable for applications requiring phase-coherent acquisition of two analog inputs, such as motor control and power monitoring. The AD7655ASTZ offers higher throughput (1 MSPS) than the AD7654AST (500 kSPS).
What supply and reference requirements should be verified before comparing these parts?
Both devices are specified with analog and digital supply rails and an external reference input, but the exact supply ranges, reference voltage requirements, and power consumption differ between the 1 MSPS AD7655ASTZ and the 500 kSPS AD7654AST. These parameters must be verified from the official manufacturer datasheets before design or substitution decisions.