Part A
AD7678ASTZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4894 PCS
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7678ASTZ is a viable functional replacement candidate for the AD7674ASTZ, sharing the same 18-bit SAR architecture, LQFP-48 package, and identical pinout, with the primary distinction being a lower maximum throughput rate of 100 kSPS versus 800 kSPS. Designers should validate timing margins and throughput requirements before substituting in high-speed acquisition paths.
Resolution
High match
Package Type
High match
Sampling Rate
Validation required
Interface Type
High match
Parts at a glance
Part B
AD7674ASTZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4562 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 | AD7674ASTZ | AD7678ASTZ | Why it matters |
|---|---|---|---|
| Resolution | 18 bits | 18 bits | Both are 18-bit SAR ADCs, so resolution is identical and not a differentiator for substitutability. |
| Maximum Sampling Rate | 800 kSPS | 100 kSPS | The AD7674 supports a much higher throughput, which is critical for high-speed acquisition; the AD7678 is limited to lower-speed applications. |
| Input Type | Differential | Pseudo-differential (single-ended) | Differential inputs offer better noise immunity and common-mode rejection; pseudo-differential inputs simplify single-ended signal interfacing. |
| INL (Integral Nonlinearity) | ±2.5 LSB max | ±2.5 LSB max | Identical linearity specifications mean both meet the same accuracy class for precision measurement. |
| SNR (Signal-to-Noise Ratio) | 101 dB typ | 101 dB typ | Equivalent noise performance indicates comparable dynamic range for both converters. |
| Supply Voltage (Analog) | 5 V | 5 V | Same analog supply simplifies power design and allows drop-in replacement in the analog domain. |
| Power Consumption | ~110 mW typ | ~55 mW typ | Lower power in the AD7678 benefits portable or thermally constrained designs, while the AD7674 trades power for speed. |
| Package | 48-lead LQFP | 48-lead LQFP | Identical package and pinout enable direct PCB footprint compatibility between the two parts. |
| Interface | SPI / Parallel | SPI / Parallel | Same digital interface options allow reuse of existing microcontroller or FPGA glue logic. |
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 | AD7674ASTZ |
|---|---|---|
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Active |
| Base Product Number | AD7678 | - |
| Number of Bits | 18 | 18 |
| 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, Internal |
| 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) | - | 800k |
| Number of A/D Converters | - | 1 |
Frequently asked questions
What are the key differences between the AD7674ASTZ and AD7678ASTZ?
Both are 18-bit, 800 kSPS successive-approximation ADCs from Analog Devices in a 48-lead LQFP package, but they differ in resolution and accuracy. The AD7674ASTZ is an 18-bit part with ±2.5 LSB INL (typical) and 101 dB SNR, while the AD7678ASTZ is an 18-bit pin-compatible variant with ±1.5 LSB INL (typical) and 101.5 dB SNR. The AD7678ASTZ also offers lower transition noise and improved DC linearity compared with the AD7674ASTZ.
Are the AD7674ASTZ and AD7678ASTZ pin-compatible?
Yes. Both devices are offered in the same 48-lead LQFP (STZ) package and share the same pinout, allowing the AD7678ASTZ to be used as a drop-in upgrade for the AD7674ASTZ in existing layouts, provided the system timing and reference requirements are met.
Do the AD7674ASTZ and AD7678ASTZ have the same sampling rate and interface?
Yes. Both parts provide a maximum throughput of 800 kSPS and support a parallel (byte or word) interface plus a serial SPI/QSPI/MICROWIRE/DSP-compatible interface. Both operate from a 5 V analog supply with a separate 2.7 V to 5.25 V digital supply.
What is the difference in INL and SNR between the two devices?
Per Analog Devices datasheets, the AD7674ASTZ specifies ±2.5 LSB INL (typical) and 101 dB SNR (typical), while the AD7678ASTZ specifies ±1.5 LSB INL (typical) and 101.5 dB SNR (typical). The AD7678ASTZ therefore provides tighter DC linearity and slightly better noise performance.
Can the AD7678ASTZ directly replace the AD7674ASTZ in an existing design?
In most cases yes, because the two devices are pin-compatible and share the same package, supply rails, and digital interface. However, the replacement should be validated against the target design's accuracy budget, reference configuration, and timing margins using the respective Analog Devices datasheets before production release.
What are the power supply requirements for the AD7674ASTZ and AD7678ASTZ?
Both devices require a 5 V analog supply (AVDD) and a separate digital supply (DVDD) that can range from 2.7 V to 5.25 V. Both also provide a reference input and support either an internal or external reference, with power dissipation specified in the Analog Devices datasheets for each part.
Which applications are these 18-bit ADCs suited for?
Both the AD7674ASTZ and AD7678ASTZ are intended for high-resolution data acquisition, medical instrumentation, industrial process control, and precision measurement systems where 18-bit resolution at 800 kSPS and a flexible parallel/serial interface are required. The AD7678ASTZ is preferable where tighter INL and lower transition noise are needed.