Part A
AD7654ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 2675 Stückzahl
- Package
- LQFP-48
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7655ASTZRL and AD7654ASTZ are both 16-bit successive-approximation ADCs from Analog Devices in compatible 48-lead LQFP packages with similar supply and interface characteristics, making the AD7654ASTZ a viable functional replacement candidate for the AD7655ASTZRL in many designs. However, the two devices differ in analog input architecture and channel configuration, so input topology, multiplexing behavior, and sampling timing must be validated against the target application before substitution.
Resolution and ADC Architecture
High match
Analog Input Configuration
Validation required
Package Type
High match
Channel Count and Multiplexing
Validation required
Parts at a glance
Part B
AD7655ASTZRL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1730 Stückzahl
- Package
- LQFP-48
- Series
- Datenerfassung mit 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 | AD7654ASTZ | Why it matters |
|---|---|---|---|
| Number of ADC Input Channels | 4 (2 simultaneous pairs, pseudo-differential) | 4 (2 simultaneous pairs, pseudo-differential) | Channel count and simultaneity determine whether the device can sample multiple signals at the same instant, which is critical for phase-sensitive or multi-axis measurements. |
| Resolution | 16 bits | 16 bits | Resolution sets the smallest detectable signal change and the achievable dynamic range of the conversion. |
| Maximum Throughput (Sample Rate) | 1 MSPS | 500 kSPS | The maximum sample rate bounds the bandwidth of signals that can be digitized and directly affects timing budget in the system. |
| Input Voltage Range | 0 V to 5 V (unipolar) or ±10 V (bipolar, software selectable) | 0 V to 5 V (unipolar) or ±10 V (bipolar, software selectable) | The selectable input range determines compatibility with the sensor or signal chain without external level shifting. |
| Supply Voltage | 5 V analog (AVDD), 2.7 V to 5.25 V digital (DVDD) | 5 V analog (AVDD), 2.7 V to 5.25 V digital (DVDD) | Supply requirements dictate power rail design and logic-level compatibility with the host processor. |
| Interface Type | Parallel (byte/word) and Serial (SPI/QSPI/MICROWIRE/DSP) | Parallel (byte/word) and Serial (SPI/QSPI/MICROWIRE/DSP) | The available digital interfaces determine how easily the ADC connects to the host controller and whether glue logic is needed. |
| Package / Pin Count | 48-lead LQFP | 48-lead LQFP | Package and pin count affect PCB footprint and whether a drop-in replacement is physically possible. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | The temperature range determines suitability for industrial versus commercial environments. |
| Power Consumption (Typical) | Approximately 120 mW at 1 MSPS | Approximately 90 mW at 500 kSPS | Power dissipation impacts thermal design and is a key constraint in portable or densely packed systems. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7654ASTZ | AD7655ASTZRL |
|---|---|---|
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Active |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 500k | 1M |
| Number of Inputs | 2, 4 | 2, 4 |
| Input Type | Pseudo-Differential, Single Ended | Pseudo-Differential, Single Ended |
| Data Interface | SPI, Parallel, DSP | SPI, Parallel, DSP |
| Configuration | MUX-S/H-MUX-ADC | MUX-S/H-MUX-ADC |
| Ratio - S / H: ADC | 2:1 | 2:1 |
| Number of A/D Converters | 1 | 1 |
| Architecture | SAR | SAR |
| Reference Type | External | External |
| Voltage - Supply, Analog | 5V | 5V |
| Voltage - Supply, Digital | 5V | 5V |
| Features | Simultaneous Sampling | Simultaneous Sampling |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
Frequently asked questions
What are the key architectural differences between the AD7655ASTZRL and the AD7654ASTZ?
The AD7655ASTZRL is a dual-channel, 16-bit, 1 MSPS successive-approximation (SAR) ADC with two independent simultaneous-sampling ADCs, each with its own track-and-hold and a multiplexer that allows four pseudo-differential input pairs. The AD7654ASTZ is a dual-channel, 16-bit, 500 kSPS SAR ADC featuring two simultaneous-sampling ADCs with a 4-channel input multiplexer configurable as two pseudo-differential pairs or four single-ended inputs. The primary differences are throughput (1 MSPS vs 500 kSPS) and input channel configuration.
Are the AD7655ASTZRL and AD7654ASTZ pin-compatible and package-compatible?
Both devices are offered in a 48-lead LQFP package, but they are not drop-in replacements. Pin functions and the input multiplexer configuration differ between the two parts, so the PCB layout and digital interface routing must be verified against each device's datasheet before substitution. Package compatibility alone does not guarantee functional interchangeability.
What are the sampling rate and resolution specifications for each device?
The AD7655ASTZRL provides 16-bit resolution at a maximum throughput of 1 MSPS per channel with simultaneous sampling on both channels. The AD7654ASTZ provides 16-bit resolution at a maximum throughput of 500 kSPS. Both use SAR conversion architecture with internal track-and-hold amplifiers.
How do the analog input configurations differ between the AD7655ASTZRL and AD7654ASTZ?
The AD7655ASTZRL offers four pseudo-differential input pairs (two per ADC) selectable through an on-chip multiplexer, supporting simultaneous sampling of two channels. The AD7654ASTZ provides a 4-channel multiplexer that can be configured as two pseudo-differential input pairs or four single-ended inputs, also with simultaneous sampling of two channels. The channel count and configuration flexibility differ, so system input topology must be matched to the selected part.
Do both devices support the same digital interface and reference options?
Both the AD7655ASTZRL and AD7654ASTZ provide a parallel digital interface and support internal or external reference operation, with an on-chip reference buffer. However, timing, control register behavior, and interface mode details differ between the two datasheets, so firmware and timing budgets must be validated separately for each device.
What are the typical power supply and power consumption characteristics of these ADCs?
Both devices operate from a 5 V analog supply with a separate digital supply (typically 2.7 V to 5.25 V) and include power-down modes. Because the AD7655ASTZRL runs at up to 1 MSPS and the AD7654ASTZ at up to 500 kSPS, power consumption scales with throughput; exact supply current and power figures should be taken from the respective manufacturer datasheets rather than assumed equal.
Can the AD7654ASTZ be used as a direct replacement for the AD7655ASTZRL in an existing design?
No direct replacement should be assumed. Although both are 16-bit dual simultaneous-sampling SAR ADCs in 48-lead LQFP packages, they differ in maximum throughput (1 MSPS vs 500 kSPS), input multiplexer configuration, and interface timing. A substitution requires review of the analog front end, digital timing, and firmware against the AD7654ASTZ datasheet.
Which device is better suited for higher-throughput simultaneous-sampling applications?
The AD7655ASTZRL is the higher-throughput option, specified at up to 1 MSPS per channel with simultaneous sampling, making it suitable for faster data-acquisition and control-loop applications. The AD7654ASTZ at 500 kSPS is appropriate where lower throughput is acceptable and its 4-channel multiplexer configuration better matches the system input requirements.