Part A
AD7665ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 3003 PCS
- Package
- LQFP-48
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7665ASTZ and AD7661AST are both 16-bit successive-approximation ADCs from Analog Devices in the same 48-lead LQFP package, sharing a parallel interface and comparable analog input architecture, so the AD7661AST can serve as a functional replacement candidate for the AD7665ASTZ in many designs. However, the two parts differ in throughput rate and analog supply range, so the replacement must be validated against the timing budget and analog rail requirements of the target application before adoption.
Resolution and ADC Architecture
High match
Package and Pin Configuration
High match
Sampling Throughput Rate
Validation required
Analog Supply Voltage Range
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7665ASTZ | AD7661AST | Why it matters |
|---|---|---|---|
| Resolution | 16 bits | 16 bits | Both are 16-bit SAR ADCs, so nominal resolution is identical and not a differentiator for substitutability. |
| Sampling Rate | 570 kSPS | 100 kSPS | The AD7665 supports a much higher throughput, which directly affects achievable signal bandwidth and system timing budget. |
| Number of Input Channels | 4 (single-ended) / 2 (differential) | 1 (single-ended) / 1 (differential) | Channel count determines how many signals can be multiplexed into one converter, affecting board architecture and part count. |
| Input Configuration | Multiplexed single-ended or differential | Single-channel single-ended or differential | Multiplexed inputs allow multiple sensors on one ADC, while a single-channel device requires external multiplexing for multi-signal systems. |
| Interface Type | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Parallel and Serial (SPI/QSPI/MICROWIRE/DSP) | Both offer parallel and serial interfaces, so host-side digital connectivity is broadly compatible between the two parts. |
| Supply Voltage (Analog and Digital) | 5 V analog, 5 V digital | 5 V analog, 5 V digital | Matching 5 V supplies means the parts can share the same power rails without level shifting or regulator changes. |
| Power Consumption | Approximately 87 mW typical | Approximately 40 mW typical | Lower power in the AD7661 benefits thermally constrained or battery-powered designs, while the AD7665 trades power for speed. |
| Package | 48-lead LQFP | 48-lead LQFP | Identical package and pin count simplify footprint reuse, though pinout differences must still be verified before substitution. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Equivalent industrial temperature ratings mean both parts suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7665ASTZ | AD7661AST |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 570k | 100k |
| Number of A/D Converters | 1 | 1 |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Number of Inputs | 1 | - |
| Input Type | Differential | - |
| Data Interface | SPI, Parallel, DSP | - |
| Configuration | S/H-ADC | - |
| Ratio - S / H: ADC | 1:1 | - |
| Architecture | SAR | - |
| Reference Type | External | - |
| Voltage - Supply, Analog | 5V | - |
| Voltage - Supply, Digital | 5V | - |
| Features | True Bipolar | - |
Frequently asked questions
What are the key differences between the AD7665ASTZ and the AD7661AST?
The AD7665ASTZ is a 16-bit, 570 kSPS PulSAR analog-to-digital converter, while the AD7661AST is a 16-bit, 100 kSPS PulSAR ADC. Both are successive-approximation register (SAR) converters with a parallel interface, but they differ in maximum throughput rate and package option. The AD7665ASTZ is specified for 570 kSPS operation, whereas the AD7661AST is specified for 100 kSPS operation.
Are the AD7665ASTZ and AD7661AST pin-compatible?
Both devices are offered in a 48-lead LQFP package, and their pinouts are defined by the respective Analog Devices datasheets. Pin compatibility should be confirmed against the specific datasheet revision for the target design, because the two parts have different throughput ratings and may differ in control-pin timing requirements. Do not assume direct drop-in replacement without verifying the pin functions and timing specifications in both datasheets.
What is the maximum sampling rate of each device?
The AD7665ASTZ supports a maximum throughput of 570 kSPS. The AD7661AST supports a maximum throughput of 100 kSPS. The throughput difference is the primary performance distinction between the two converters and directly affects the achievable Nyquist bandwidth in a given application.
Do both parts provide 16-bit resolution and a parallel interface?
Yes. Both the AD7665ASTZ and the AD7661AST are 16-bit SAR ADCs with a parallel digital output interface. Both are members of Analog Devices' PulSAR family and are intended for high-resolution data acquisition applications requiring a parallel host interface.
Can the AD7661AST be used as a lower-speed substitute for the AD7665ASTZ?
Substitution is possible only if the system's sampling requirements do not exceed 100 kSPS and all timing, interface, and package parameters are validated against both datasheets. Because the AD7661AST has a lower maximum throughput than the AD7665ASTZ, any design requiring sampling above 100 kSPS cannot use the AD7661AST as a substitute. Verify all specifications against the official Analog Devices datasheets before substitution.
What package type do the AD7665ASTZ and AD7661AST use?
Both devices are available in a 48-lead LQFP package. The "ASTZ" and "AST" suffixes in the part numbers correspond to the LQFP package option per Analog Devices ordering information. Confirm the exact package and temperature grade from the manufacturer's ordering guide for the specific part number ordered.
Which part should be selected for a higher-throughput data acquisition design?
The AD7665ASTZ should be selected when the design requires sampling rates up to 570 kSPS. The AD7661AST is limited to 100 kSPS and is therefore suitable only for lower-throughput applications. Selection should be based on the required Nyquist bandwidth, interface timing, and the verified specifications in the respective Analog Devices datasheets.