Part A
AD7655ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5580 PCS
- Package
- LQFP-48
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7651ASTZRL is a functionally compatible replacement candidate for the AD7655ASTZ in many designs, sharing the same 16-bit SAR architecture, 48-lead LQFP package, and parallel interface family. However, the AD7655ASTZ provides four simultaneous-sampling channels versus a single channel on the AD7651ASTZRL, so the substitution is only valid where single-channel acquisition is acceptable and the throughput and reference configuration are revalidated against the target application.
Resolution and Architecture
High match
Channel Count
Not compatible
Package Type
High match
Throughput Rate
Validation required
Parts at a glance
Part B
AD7651ASTZRL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 3821 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 | AD7655ASTZ | AD7651ASTZRL | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 2 (simultaneous sampling) | 1 | Determines how many analog signals can be digitized; the AD7655 supports two simultaneous channels while the AD7651 supports only one, affecting multi-channel system architecture. |
| Resolution | 16 bits | 16 bits | Both provide 16-bit resolution, so precision and dynamic range are equivalent for substitutability in terms of accuracy. |
| Sampling Rate | 1 MSPS | 100 kSPS | The AD7655 samples ten times faster, which is critical for high-speed or multiplexed applications; the AD7651 is limited to lower-bandwidth signals. |
| Input Configuration | 4-channel, single-ended/pseudo-differential (2 simultaneous) | Single-ended/pseudo-differential, 1 channel | Input topology dictates how many and what type of sensors can be connected; the AD7655 offers more flexible multi-channel input routing. |
| Interface Type | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Both support the same digital interfaces, so host-side connectivity is compatible between the two parts. |
| Supply Voltage (Analog) | 5 V | 5 V | Identical analog supply requirements mean the same power rail can be reused without redesign. |
| Package / Mounting | 48-LQFP, surface mount | 48-LQFP, surface mount | Same package and footprint allow drop-in board compatibility without layout changes. |
| Power Consumption | ~120 mW typical | ~25 mW typical | The AD7651 consumes significantly less power, which matters for portable or thermally constrained designs. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings ensure equivalent environmental robustness for industrial applications. |
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 | AD7651ASTZRL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 1M | 100k |
| Number of Inputs | 2, 4 | 1 |
| Input Type | Pseudo-Differential, Single Ended | Pseudo-Differential |
| Data Interface | SPI, Parallel, DSP | SPI, Parallel, DSP |
| Configuration | MUX-S/H-MUX-ADC | S/H-ADC |
| Ratio - S / H: ADC | 2:1 | 1:1 |
| Number of A/D Converters | 1 | 1 |
| Architecture | SAR | SAR |
| Reference Type | External | External, Internal |
| Voltage - Supply, Analog | 5V | 5V |
| Voltage - Supply, Digital | 5V | 5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Features | Simultaneous Sampling | - |
Frequently asked questions
What are the key differences between the AD7655ASTZ and the AD7651ASTZRL?
The AD7655ASTZ is a dual-channel, 16-bit, 1 MSPS successive-approximation ADC with two simultaneous-sampling SAR cores, while the AD7651ASTZRL is a single-channel, 16-bit, 100 kSPS PulSAR ADC. The AD7655 offers two simultaneous input channels at higher throughput, whereas the AD7651 provides one channel at lower speed with lower power consumption.
Are the AD7655ASTZ and AD7651ASTZRL pin-compatible?
No. The AD7655ASTZ is supplied in a 48-lead LQFP package, and the AD7651ASTZRL is supplied in a 48-lead LQFP package as well, but the two devices have different pin functions and internal architectures (dual simultaneous-sampling SAR versus single-channel PulSAR). They are not direct drop-in replacements and require separate PCB layouts.
What are the resolution and throughput specifications of each device?
Both devices provide 16-bit resolution. The AD7655ASTZ offers a maximum throughput of 1 MSPS per channel with two simultaneous-sampling channels, while the AD7651ASTZRL offers a maximum throughput of 100 kSPS on a single channel.
How do the input configurations differ between the AD7655ASTZ and AD7651ASTZRL?
The AD7655ASTZ provides two independent, simultaneously sampled analog input channels, each configurable for unipolar or bipolar input ranges. The AD7651ASTZRL provides a single analog input channel with a selectable input range. Designs requiring simultaneous multi-channel sampling should use the AD7655ASTZ.
Which device is better suited for low-power portable applications?
The AD7651ASTZRL is generally better suited for low-power, lower-speed applications because its single-channel PulSAR architecture operates at 100 kSPS with correspondingly lower power consumption. The AD7655ASTZ, with dual 1 MSPS simultaneous-sampling cores, is intended for higher-throughput multi-channel systems where power is less constrained.
Do both parts support the same digital interface?
Both devices provide a parallel digital interface for connection to a host processor or DSP, but the interface timing, conversion control, and data output formats differ because of their different architectures. Designers must consult the respective datasheets for exact interface timing and configuration.
Can the AD7651ASTZRL be used as a substitute for the AD7655ASTZ in an existing design?
No, not as a direct substitute. The AD7651ASTZRL is single-channel and limited to 100 kSPS, whereas the AD7655ASTZ provides two simultaneous 1 MSPS channels. Substitution would require redesign of the analog front end, timing, and PCB layout, and would not preserve the dual simultaneous-sampling capability.