Part A
AD7655ASTZRL
Công ty 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 AD7651ASTZRL is a functionally compatible replacement candidate for the AD7655ASTZRL in applications that do not require the dual simultaneous-sampling capability of the AD7655. Both devices share the same 48-lead LQFP footprint, 16-bit SAR architecture, and serial/parallel interface family, but the AD7655 provides two simultaneously sampled channels while the AD7651 provides a single channel. Designers must confirm channel count requirements and verify timing and reference configuration against the target application before substituting.
Channel Count
Validation required
Package Type
High match
Resolution
High match
Sampling Architecture
Validation required
Parts at a glance
Part B
AD7651ASTZRL
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 3821 PCS
- Package
- LQFP-48
- Series
- Data Acquisition - 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 | AD7655ASTZRL | AD7651ASTZRL | Why it matters |
|---|---|---|---|
| Number of ADC Input Channels | 2 (dual, simultaneous sampling) | 1 (single channel) | Determines how many analog signals can be digitized; the dual-channel AD7655 supports simultaneous two-signal acquisition while the AD7651 handles only one, so they are not drop-in substitutes in multi-channel designs. |
| Sampling Rate | 1 MSPS | 100 kSPS | Sets the maximum conversion throughput; the AD7655 is roughly ten times faster, which is critical for high-bandwidth or fast-scanning applications. |
| Resolution | 16 bits | 16 bits | Both provide 16-bit resolution, so dynamic range and precision are equivalent; this parameter is identical and does not differentiate the parts. |
| Input Configuration | 4-channel (2 simultaneous) with multiplexer, pseudo-differential | Single-ended / pseudo-differential, single channel | Defines how many sources can be routed and whether simultaneous sampling is possible; the AD7655's multiplexed dual simultaneous inputs enable multi-axis or I/Q sampling that the AD7651 cannot provide. |
| Interface | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Both offer flexible parallel and serial interfaces, so host connectivity is compatible and this parameter does not differentiate the parts. |
| Supply Voltage | 5 V analog (AVDD), 2.7–5.25 V digital (DVDD) | 5 V analog (AVDD), 2.7–5.25 V digital (DVDD) | Identical supply requirements mean the same power rails can be reused, simplifying board-level substitution. |
| Power Consumption | ~120 mW typical at 1 MSPS | ~25 mW typical at 100 kSPS | Affects thermal budget and energy efficiency; the faster AD7655 dissipates substantially more power, which matters in portable or thermally constrained systems. |
| Package | 48-lead LQFP | 48-lead LQFP | Identical package and pin count allow potential footprint compatibility, though pin functions must still be verified against the datasheets. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C | Matching industrial temperature ranges mean both parts suit the same environmental conditions, so this does not differentiate them. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7655ASTZRL | 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 AD7655ASTZRL and the AD7651ASTZRL?
The AD7655ASTZRL is a dual-channel, 16-bit, 1 MSPS successive-approximation ADC, while the AD7651ASTZRL is a single-channel, 16-bit, 100 kSPS PulSAR ADC. The AD7655 offers two simultaneous-sampling input channels and a much higher throughput rate, whereas the AD7651 provides one channel at a lower sampling rate. Both are offered in a 48-lead LQFP package and operate from a 5 V analog supply.
Are the AD7655ASTZRL and AD7651ASTZRL pin-compatible?
No. Although both devices are housed in a 48-lead LQFP (ST-48) package, their pin functions differ because the AD7655 provides two analog input channels and the AD7651 provides one. The pinouts are not interchangeable, so each device requires its own PCB layout per the respective datasheet.
Can the AD7651ASTZRL be used as a drop-in replacement for the AD7655ASTZRL?
No. The AD7651ASTZRL is a single-channel, 100 kSPS device, while the AD7655ASTZRL is a dual-channel, 1 MSPS device. The channel count, throughput, pinout, and internal architecture differ, so a direct substitution is not possible without redesign and validation against the manufacturer datasheets.
What are the maximum sampling rates of these two ADCs?
The AD7655ASTZRL supports a maximum throughput of 1 MSPS. The AD7651ASTZRL supports a maximum throughput of 100 kSPS. The higher rate of the AD7655 makes it suitable for faster signal acquisition, while the AD7651 targets lower-speed, higher-resolution applications.
How many analog input channels does each device provide?
The AD7655ASTZRL provides two analog input channels with simultaneous sampling capability. The AD7651ASTZRL provides a single analog input channel. This difference is fundamental when selecting between the two parts for multi-channel versus single-channel acquisition systems.
Do both devices offer the same resolution and digital interface?
Both the AD7655ASTZRL and AD7651ASTZRL are 16-bit successive-approximation ADCs and provide a parallel digital interface. However, their throughput rates, channel counts, and internal configurations differ, so the interface timing and control signals must be verified separately against each device's datasheet.
What package and supply voltage do the AD7655ASTZRL and AD7651ASTZRL use?
Both devices are supplied in a 48-lead LQFP package and operate from a 5 V analog supply, with a separate digital supply for the interface. Designers should confirm the exact supply rails and decoupling requirements from the respective manufacturer datasheets before layout.