Part A
AD7654ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 2675 PCS
- Package
- LQFP-48
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7651AST and AD7654ASTZ share the same 16-bit SAR architecture, 48-lead LQFP package, and identical pinout, making the AD7651AST a viable functional substitute for the AD7654ASTZ in many designs. However, the AD7654ASTZ provides two simultaneous-sampling channels versus the single channel of the AD7651AST, and the two devices differ in throughput rate and serial interface configuration. Engineers should validate timing, channel-count requirements, and digital interface compatibility before committing to this substitution.
Package Type
High match
Resolution
High match
Channel Count
Validation required
Throughput Rate
Not compatible
Parts at a glance
Part B
AD7651AST
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 965 PCS
- Package
- LQFP-48
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (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 | AD7651AST | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 2 (simultaneous sampling) | 1 | Determines how many analog signals can be digitized; the AD7654 supports two simultaneous channels while the AD7651 supports only one, affecting multi-signal acquisition designs. |
| Resolution | 16 bits | 16 bits | Both provide 16-bit resolution, so precision and dynamic range are equivalent for substitutability in terms of quantization. |
| Sampling Rate | 500 kSPS | 100 kSPS | The maximum throughput differs significantly; the AD7654 can sample five times faster, which matters for higher-bandwidth signal acquisition. |
| Input Configuration | Pseudo-differential (2 channels) | Single-ended | Input topology affects how signals connect and common-mode rejection; pseudo-differential inputs offer better noise immunity than single-ended. |
| Interface Type | SPI / Parallel (selectable) | SPI / Parallel (selectable) | Both support serial and parallel interfaces, so host connectivity options are equivalent. |
| Supply Voltage | 5 V analog (AVDD), 5 V digital (DVDD) | 5 V analog (AVDD), 5 V digital (DVDD) | Matching supply requirements simplifies power-rail design and allows drop-in compatibility in the same system. |
| Package | 48-lead LQFP | 48-lead LQFP | Identical package and pin count support PCB footprint compatibility, though pinout must still be verified. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Equivalent industrial temperature ranges mean both suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7654ASTZ | AD7651AST |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 500k | 100k |
| 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 primary differences between the AD7654ASTZ and the AD7651AST?
The AD7654ASTZ is a dual, simultaneous-sampling 16-bit SAR ADC with two channels, while the AD7651AST is a single-channel 16-bit SAR ADC. The AD7654ASTZ offers 500 kSPS per channel with two ADCs sampling concurrently, whereas the AD7651AST provides 100 kSPS on a single channel. Both are 16-bit successive-approximation ADCs from Analog Devices in 48-lead LQFP packages, but they differ in channel count, throughput, and internal architecture.
Are the AD7654ASTZ and AD7651AST pin-compatible or footprint-compatible?
No. Although both devices are housed in 48-lead LQFP packages, they are not pin-compatible. The AD7654ASTZ uses a dual-ADC architecture with separate analog input pins for two channels and simultaneous-sampling control, while the AD7651AST is a single-channel device with a different pin function assignment. A direct drop-in replacement is not possible without PCB redesign and validation against the respective datasheets.
What are the resolution and throughput specifications of each device?
Both the AD7654ASTZ and AD7651AST provide 16-bit resolution. The AD7654ASTZ delivers 500 kSPS per channel across two simultaneously sampled channels, giving an aggregate throughput of 1 MSPS. The AD7651AST delivers 100 kSPS on a single channel. These throughput figures are specified in the respective Analog Devices datasheets.
Do both parts support the same analog input voltage range?
Both devices support a bipolar analog input range of ±10 V (with a 5 V reference) and are designed for industrial signal acquisition. The AD7654ASTZ provides two such input channels with simultaneous sampling, while the AD7651AST provides one channel. Designers should confirm the exact input configuration and reference requirements in each datasheet before substitution.
What digital interface do the AD7654ASTZ and AD7651AST use?
Both devices provide a parallel digital interface for connection to microprocessors and DSPs, with a serial interface option available on the AD7654ASTZ. The AD7651AST offers a parallel interface. The exact interface modes, timing, and pin assignments differ between the two parts and must be verified against the respective datasheets.
Can the AD7651AST be used as a replacement for the AD7654ASTZ in an existing design?
No, not as a direct replacement. The AD7651AST is a single-channel 100 kSPS device, whereas the AD7654ASTZ is a dual-channel 500 kSPS-per-channel simultaneous-sampling device. Replacing one with the other would reduce channel count and throughput and would require PCB and firmware changes. Any substitution must be validated against the target design requirements and the manufacturer datasheets.
What are the typical applications for each device?
The AD7654ASTZ is suited to applications requiring simultaneous sampling of two channels at high throughput, such as motor control, power monitoring, and multi-axis data acquisition. The AD7651AST is suited to single-channel, lower-throughput precision measurement applications. Both are 16-bit SAR ADCs intended for industrial and instrumentation use, as described in the Analog Devices product documentation.