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 AD7678ASTZ and AD7677ASTZRL are both 16-bit successive-approximation ADCs from Analog Devices in the same LQFP-48 package, sharing identical resolution, supply architecture, and digital interface family. The AD7678ASTZ offers a faster 100 kSPS throughput versus 1 MSPS-class operation on the AD7677ASTZRL, so the AD7677ASTZRL can serve as a higher-speed functional substitute where the system timing margin and power budget permit, while the AD7678ASTZ remains the lower-power option. Verify dynamic performance, reference configuration, and timing against the target design before committing to a drop-in replacement.
Resolution
High match
Package Type
High match
Sampling Rate
Validation required
Power Consumption
Validation required
Parts at a glance
Part B
AD7677ASTZRL
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4959 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 | AD7678ASTZ | AD7677ASTZRL | Why it matters |
|---|---|---|---|
| Resolution (bits) | 18 | 16 | Resolution determines the smallest signal change the ADC can resolve; an 18-bit part offers 4x finer quantization than a 16-bit part, affecting achievable dynamic range and precision. |
| Sampling Rate (max) | 100 kSPS | 1 MSPS | Maximum throughput defines the highest signal bandwidth the converter can digitize; the 1 MSPS part supports much faster acquisition than the 100 kSPS part. |
| INL (Integral Nonlinearity, max) | ±2.5 LSB | ±1.5 LSB | INL quantifies deviation from an ideal transfer function; tighter INL improves absolute accuracy and linearity of the digitized result. |
| DNL (Differential Nonlinearity, max) | ±1 LSB | ±0.9 LSB | DNL indicates code transition uniformity; values within ±1 LSB guarantee monotonicity, which is critical for closed-loop and control applications. |
| SNR (typ) | 101 dB | 92 dB | Signal-to-noise ratio reflects usable dynamic range; the higher SNR of the 18-bit part enables detection of smaller signals in the presence of noise. |
| THD (typ) | -120 dB | -110 dB | Total harmonic distortion measures spectral purity; lower THD preserves signal fidelity in AC measurement and audio-band applications. |
| Power Consumption (typ) | 65 mW | 115 mW | Power draw affects thermal budget and supply sizing; the lower-power part is preferable for portable or thermally constrained designs. |
| Supply Voltage (analog) | 5 V | 5 V | Analog supply voltage must match the system rail and input signal range; identical 5 V operation allows drop-in compatibility at the supply level. |
| Interface | SPI / QSPI / MICROWIRE / DSP compatible serial | SPI / QSPI / MICROWIRE / DSP compatible serial | A matching serial interface ensures the same host controller and firmware can drive either part without protocol changes. |
| Package | 48-lead LQFP | 48-lead LQFP | Identical package and pinout allow the parts to share the same PCB footprint, simplifying evaluation and potential substitution. |
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Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7678ASTZ | AD7677ASTZRL |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Active |
| Number of Bits | 18 | 16 |
| Sampling Rate(Per Second) | - | 1M |
| 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 |
| Base Product Number | AD7678 | - |
| Sampling Rate (Per Second) | 100k | - |
| Number of A / D Converters | 1 | - |
| Mounting Type | Surface Mount | - |
| Packaging | Tray | - |
Frequently asked questions
What are the key differences between the AD7678ASTZ and AD7677ASTZRL?
The AD7678ASTZ is a 16-bit, 100 kSPS charge redistribution SAR ADC, while the AD7677ASTZRL is a 16-bit, 1 MSPS charge redistribution SAR ADC. The primary differences are throughput rate (100 kSPS vs 1 MSPS) and power consumption, with the AD7677 consuming more power to support its higher sampling rate. Both are pin-compatible in the same 48-lead LQFP package.
Are the AD7678ASTZ and AD7677ASTZRL pin-compatible?
Yes. Both devices are offered in the same 48-lead LQFP (ST-48) package and share a common pinout, which allows the AD7677ASTZRL to be used as a higher-speed drop-in upgrade for the AD7678ASTZ in existing PCB layouts, provided the rest of the system supports the higher throughput and power budget.
What is the maximum sampling rate of each device?
The AD7678ASTZ supports a maximum throughput of 100 kSPS, while the AD7677ASTZRL supports a maximum throughput of 1 MSPS. The higher rate of the AD7677 makes it suitable for faster signal acquisition and wider-bandwidth applications.
Do both ADCs use the same digital interface?
Yes. Both the AD7678ASTZ and AD7677ASTZRL provide a parallel 16-bit interface and also support a serial interface, allowing flexible connection to DSPs, FPGAs, and microcontrollers. The interface timing must be revalidated when moving to the higher-speed AD7677ASTZRL.
How do the power consumption figures compare?
The AD7678ASTZ typically consumes about 15 mW at 100 kSPS, whereas the AD7677ASTZRL typically consumes about 100 mW at 1 MSPS. The higher power of the AD7677 reflects its higher sampling rate; both devices offer power-down modes to reduce consumption when not converting.
What are the input voltage ranges and reference requirements for these ADCs?
Both devices are differential-input SAR ADCs that support a selectable input range of 0 V to VREF or ±VREF/2, with an external reference typically in the 2.5 V to 5 V range. The reference and analog supply must be selected to match the desired full-scale input span.
Can the AD7677ASTZRL directly replace the AD7678ASTZ in an existing design?
Because the two parts are pin-compatible and share the same package and interface family, the AD7677ASTZRL can often serve as a drop-in replacement, but the design must be validated for the higher 1 MSPS throughput, increased power dissipation, and any timing or layout differences. The AD7678ASTZ cannot replace the AD7677ASTZRL where 1 MSPS throughput is required.
What are the typical applications for each device?
The AD7678ASTZ at 100 kSPS is suited to precision data acquisition, industrial instrumentation, and medical monitoring where moderate speed and low power are priorities. The AD7677ASTZRL at 1 MSPS is suited to higher-speed applications such as motor control, power quality monitoring, and fast waveform capture that require higher throughput.