Part A
AD7678ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4894 PCS
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7677ASTZ and AD7678ASTZ are both 16-bit successive-approximation ADCs from the same Analog Devices family, sharing an identical package, pinout, and digital interface, so they are strong functional replacement candidates. The AD7678ASTZ offers a higher maximum sampling rate, while the AD7677ASTZ provides a wider analog input range; designers should confirm that the required throughput and input span of the target application are satisfied before substituting one for the other.
Resolution
High match
Package Type
High match
Maximum Sampling Rate
Validation required
Analog Input Range
Validation required
Parts at a glance
Part B
AD7677ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1648 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 | AD7677ASTZ | AD7678ASTZ | Why it matters |
|---|---|---|---|
| Resolution | 16 bits | 18 bits | Higher resolution provides finer quantization and lower quantization noise, directly affecting achievable SNR and dynamic range in precision acquisition systems. |
| Maximum Sampling Rate | 1 MSPS | 570 kSPS | Determines the maximum signal bandwidth that can be digitized; a faster converter supports wider-bandwidth or multiplexed multi-channel applications. |
| Input Type | Differential | Differential | Differential inputs reject common-mode noise and improve distortion performance; matching input topology is essential for drop-in signal-chain compatibility. |
| SNR (typ) | 92 dB | 95 dB | Signal-to-noise ratio defines the usable dynamic range; the 18-bit device offers roughly 3 dB better SNR, which matters for low-level signal detection. |
| INL (max) | ±2.5 LSB | ±2.5 LSB | Integral nonlinearity limits absolute accuracy; comparable INL means both parts meet similar linearity budgets despite differing resolution. |
| Supply Voltage | 5 V analog / 5 V digital | 5 V analog / 5 V digital | Identical supply requirements allow the same board rails and decoupling to be reused, simplifying substitution. |
| Interface | Parallel / Serial (SPI-compatible) | Parallel / Serial (SPI-compatible) | Matching digital interfaces ensure the same host controller and firmware can drive either device without redesign. |
| Package | 48-lead LQFP | 48-lead LQFP | Identical package and pinout enable a direct board-level swap without layout changes. |
| Power Consumption (typ) | 110 mW | 100 mW | Lower power dissipation reduces thermal load and suits power-sensitive or densely packed designs. |
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 | AD7678ASTZ | AD7677ASTZ |
|---|---|---|
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Active |
| Base Product Number | AD7678 | - |
| Number of Bits | 18 | 16 |
| Sampling Rate (Per Second) | 100k | - |
| Number of Inputs | 1 | 1 |
| Input Type | Differential | Differential |
| Data Interface | SPI, Parallel, DSP | SPI, Parallel, DSP |
| Configuration | S/H-ADC | S/H-ADC |
| Ratio - S / H: ADC | 1:1 | 1:1 |
| Number of A / D Converters | 1 | - |
| Architecture | SAR | SAR |
| Reference Type | External, Internal | External |
| Voltage - Supply, Analog | 5V | 5V |
| Voltage - Supply, Digital | 5V | 5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | - |
| Packaging | Tray | - |
| Sampling Rate(Per Second) | - | 1M |
| Number of A/D Converters | - | 1 |
Frequently asked questions
What are the key differences between the AD7677ASTZ and AD7678ASTZ?
The AD7677ASTZ is a 16-bit, 1 MSPS differential SAR ADC, while the AD7678ASTZ is an 18-bit, 100 kSPS differential SAR ADC. The primary differences are resolution (16-bit vs 18-bit) and throughput (1 MSPS vs 100 kSPS). Both are pin-compatible members of the Analog Devices PulSAR family in a 48-lead LQFP package.
Are the AD7677ASTZ and AD7678ASTZ pin-compatible?
Yes. Both devices are offered in the same 48-lead LQFP (ST-48) package and share the same pinout, which allows a common PCB footprint. However, firmware and timing must be revalidated because the maximum throughput and resolution differ.
What is the maximum sampling rate of each device?
The AD7677ASTZ supports a maximum throughput of 1 MSPS. The AD7678ASTZ supports a maximum throughput of 100 kSPS. Designs requiring faster conversion should use the AD7677ASTZ, while the AD7678ASTZ targets higher-resolution, lower-speed applications.
What resolution and SNR performance do these ADCs provide?
The AD7677ASTZ provides 16-bit resolution with a typical SNR of approximately 92 dB. The AD7678ASTZ provides 18-bit resolution with a typical SNR of approximately 101 dB. The higher resolution and SNR of the AD7678ASTZ suit precision measurement applications.
Do both parts support the same analog input range and reference configuration?
Both devices use a differential analog input and an external reference. The AD7677ASTZ operates with a 5 V analog supply and supports a differential input range of ±VREF, while the AD7678ASTZ also uses a 5 V analog supply with a differential input range of ±VREF. The external reference voltage should be selected per the respective datasheet to achieve specified performance.
What digital interfaces do the AD7677ASTZ and AD7678ASTZ support?
Both devices provide a parallel interface and a serial interface for host communication. The parallel interface supports 16-bit word transfers, and the serial interface supports SPI-compatible communication. The interface mode is selected via dedicated configuration pins as described in the datasheets.
Can the AD7678ASTZ be used as a drop-in replacement for the AD7677ASTZ?
Because both parts share the same package and pinout, the AD7678ASTZ can be placed on a board designed for the AD7677ASTZ. However, it is not a functional drop-in replacement: the maximum throughput drops from 1 MSPS to 100 kSPS, and the digital timing and configuration must be updated to match the AD7678ASTZ datasheet. System-level validation is required.
What are the typical applications for each device?
The AD7677ASTZ (16-bit, 1 MSPS) is suited to higher-speed data acquisition, medical imaging, and industrial control loops. The AD7678ASTZ (18-bit, 100 kSPS) is suited to precision instrumentation, spectrum analysis, and high-accuracy sensor measurement where resolution and SNR are more critical than throughput.