Part A
AD7654ASTZ
아날로그 디바이스(주)
- Lifecycle
- Active
- Stock
- 2675 PCS
- Package
- LQFP-48
- Series
- 데이터 수집 - 아날로그 변환기(ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7655ASTZ and AD7654ASTZ 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, so the AD7654ASTZ can serve as a functional replacement candidate for the AD7655ASTZ provided the reduced channel count and lower throughput are acceptable for the target design.
Resolution
High match
Package Type
High match
Channel Count
Validation required
Throughput Rate
Validation required
Parts at a glance
Part B
AD7655ASTZ
아날로그 디바이스(주)
- Lifecycle
- Active
- Stock
- 5580 PCS
- Package
- LQFP-48
- Series
- 데이터 수집 - 아날로그 변환기(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 | AD7654ASTZ | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 2 (simultaneous sampling) | 4 (2 simultaneous pairs) | Channel count determines how many analog signals can be digitized; the AD7654 offers twice the input channels, enabling more complex multi-signal acquisition. |
| Resolution | 16 bits | 16 bits | Both provide 16-bit resolution, so precision and dynamic range are equivalent for signal conversion. |
| Sampling Rate (max) | 1 MSPS | 500 kSPS | Maximum throughput affects the highest signal bandwidth that can be captured; the AD7655 supports twice the sampling rate of the AD7654. |
| Input Configuration | 2 single-ended / 2 pseudo-differential | 4 single-ended / 2 pseudo-differential | Input topology determines how many signals can be measured and whether differential or single-ended sources are supported. |
| Package / Pin Count | 48-lead LQFP | 48-lead LQFP | Package and pin count affect PCB footprint and layout compatibility; both share the same package, easing board-level substitution. |
| Supply Voltage (Analog) | 5 V | 5 V | Analog supply voltage must match the system rail; identical 5 V operation allows reuse of the same power design. |
| Interface Type | Parallel / Serial (SPI/QSPI/MICROWIRE/DSP) | Parallel / Serial (SPI/QSPI/MICROWIRE/DSP) | Interface compatibility determines whether the device can connect to the host processor without redesign; both support the same interface options. |
| Power Consumption (typ) | ~120 mW at 1 MSPS | ~90 mW at 500 kSPS | Power consumption impacts thermal budget and supply sizing; the AD7654 draws less power but at a lower throughput. |
| Internal Reference | Yes (2.5 V) | Yes (2.5 V) | An internal reference simplifies system design by eliminating an external reference; both include a 2.5 V reference. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7654ASTZ | AD7655ASTZ |
|---|---|---|
| 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 AD7655ASTZ and AD7654ASTZ?
The AD7655ASTZ is a 16-bit, 1 MSPS, dual-channel simultaneous-sampling successive-approximation (SAR) ADC with two on-chip track-and-hold amplifiers and a flexible parallel/serial interface. The AD7654ASTZ is a 16-bit, 500 kSPS, dual-channel SAR ADC that also supports simultaneous sampling of two inputs but operates at half the throughput rate of the AD7655. Both are pin-compatible members of Analog Devices' PulSAR family in 48-lead LQFP packages, but the AD7655 provides higher speed while the AD7654 targets lower-power, lower-rate applications.
Are the AD7655ASTZ and AD7654ASTZ pin-compatible and package-compatible?
Yes. Both devices are offered in the same 48-lead LQFP (STZ suffix) package with the same pinout, which allows a common PCB footprint. However, pin compatibility does not guarantee functional equivalence; the maximum sampling rate, power consumption, and some timing parameters differ, so firmware and clocking must be validated against the respective datasheets before substitution.
What are the maximum sampling rates of the AD7655ASTZ and AD7654ASTZ?
The AD7655ASTZ supports a maximum throughput of 1 MSPS per channel, while the AD7654ASTZ supports a maximum throughput of 500 kSPS per channel. Designs requiring the higher rate must use the AD7655ASTZ; the AD7654ASTZ is suitable only where 500 kSPS is sufficient.
Do both parts support simultaneous sampling of two channels?
Yes. Both the AD7655ASTZ and AD7654ASTZ are dual-channel SAR ADCs with two independent track-and-hold amplifiers that sample both inputs simultaneously, making them suitable for applications requiring phase-coherent acquisition such as motor control and power monitoring. The difference lies in throughput and power, not in the simultaneous-sampling architecture.
What supply voltages and reference options do the AD7655ASTZ and AD7654ASTZ require?
Both devices operate from a 5 V analog supply (AVDD) and a 2.7 V to 5.25 V digital supply (DVDD), and both support an external reference plus an internal reference option. The analog input range is configured via the reference and input span settings. Designers should confirm exact reference and supply limits in the respective Analog Devices datasheets, as the internal reference specifications and allowable input spans must be verified for each part.
How do power consumption figures compare between the AD7655ASTZ and AD7654ASTZ?
Because the AD7655ASTZ runs at up to 1 MSPS and the AD7654ASTZ at up to 500 kSPS, the AD7655ASTZ typically dissipates more power at full rate. Both parts offer power-down modes to reduce consumption between conversions. Exact typical and maximum power figures should be taken from the official Analog Devices datasheets for each device, as they depend on supply voltages and throughput.
Can the AD7654ASTZ be used as a drop-in replacement for the AD7655ASTZ in an existing design?
Not unconditionally. Although the package and pinout match, the AD7654ASTZ has a lower maximum throughput (500 kSPS versus 1 MSPS) and different timing and power characteristics. A drop-in replacement is only valid if the system's sampling rate, timing margins, and power budget are re-verified against the AD7654ASTZ datasheet. For new designs requiring 1 MSPS, the AD7655ASTZ should be specified.
What interface options do the AD7655ASTZ and AD7654ASTZ provide?
Both devices provide a parallel interface and a serial interface for host communication, along with conversion start and busy/status signals. The parallel interface supports word-width readout, and the serial interface supports daisy-chaining in multi-converter systems. Specific timing and mode configuration details differ slightly and must be confirmed in each device's datasheet.