Part A
AD7621ASTZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 6501 PCS
- Package
- LQFP-48
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7621ASTZ and AD7623AST are both 16-bit, 1 MSPS PulSAR analog-to-digital converters from Analog Devices in the same 48-lead LQFP package, sharing a compatible serial/parallel interface and reference architecture. The AD7623AST offers a higher internal reference voltage and a wider analog input range, so it can serve as a functional replacement for the AD7621ASTZ in many designs, provided the input signal chain and reference configuration are validated against the target system requirements.
Resolution and Sample Rate
High match
Package Type
High match
Analog Input Range
Validation required
Reference Voltage
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 | AD7621ASTZ | AD7623AST | Why it matters |
|---|---|---|---|
| Resolution | 16 bit | 16 bit | Both are 16-bit SAR ADCs, so resolution is identical and not a differentiator for substitutability. |
| Sampling Rate | 3 MSPS | 1.33 MSPS | The AD7621 offers a higher throughput, which matters for applications requiring faster conversion rates. |
| Number of Input Channels | 1 (single-ended/differential) | 1 (single-ended/differential) | Both are single-channel devices, so channel count does not affect interchangeability. |
| Input Type | Differential | Differential | Both accept differential inputs, allowing similar signal conditioning and front-end design. |
| Supply Voltage | 2.5 V (analog and digital) | 2.5 V (analog and digital) | Identical supply requirements simplify power supply design and allow drop-in replacement. |
| Interface | SPI / QSPI / MICROWIRE / DSP compatible serial | SPI / QSPI / MICROWIRE / DSP compatible serial | Same serial interface options mean the digital host connection can remain unchanged. |
| Package / Case | 48-LQFP | 48-LQFP | Identical package and footprint allow physical board-level interchangeability. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Same industrial temperature range supports use in identical environmental conditions. |
| Power Consumption | Approx. 90 mW (typical) | Approx. 70 mW (typical) | Lower power in the AD7623 benefits power-sensitive designs, though both are in a similar class. |
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 | AD7621ASTZ | AD7623AST |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | PulSAR® | PulSAR® |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 3M | 1.33M |
| 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, Internal | - |
| Voltage - Supply, Analog | 2.37V ~ 2.63V | - |
| Voltage - Supply, Digital | 2.37V ~ 2.63V | - |
Frequently asked questions
What are the key differences between the AD7621ASTZ and the AD7623AST?
The AD7621ASTZ is a 16-bit, 3 MSPS PulSAR analog-to-digital converter, while the AD7623AST is a 16-bit, 1.33 MSPS PulSAR ADC. Both are pin-compatible members of the same family and share the same 48-lead LQFP package, but they differ in maximum throughput rate and therefore in their internal timing and power characteristics.
Are the AD7621ASTZ and AD7623AST pin-compatible?
Yes. Both devices are offered in the same 48-lead LQFP (ST-48) package and are designed as pin-compatible members of the AD762x PulSAR family, allowing a common PCB footprint across the family. Designers should still confirm the specific pin functions against the respective datasheets before substitution.
What is the maximum sampling rate of each device?
The AD7621ASTZ supports a maximum throughput of 3 MSPS. The AD7623AST supports a maximum throughput of 1.33 MSPS. Both are 16-bit resolution converters.
Do both parts use the same analog input architecture?
Yes. Both the AD7621ASTZ and AD7623AST are 16-bit charge redistribution successive approximation (SAR) ADCs with a differential analog input range of ±VREF, where VREF is typically 2.5 V, giving a full-scale input span of ±2.5 V (5 V differential). Both integrate a sample-and-hold circuit and an internal reference buffer.
What digital interfaces do the AD7621ASTZ and AD7623AST support?
Both devices provide a flexible parallel interface (word or byte mode) and a serial interface compatible with SPI/QSPI/MICROWIRE/DSP standards. The interface mode is selected via dedicated configuration pins, and both parts support daisy-chaining of multiple converters on the serial bus.
Can the AD7623AST be used as a drop-in replacement for the AD7621ASTZ in an existing design?
Because the two parts are pin-compatible and share the same package and interface architecture, the AD7623AST can often be placed on an AD7621ASTZ footprint. However, the lower 1.33 MSPS throughput of the AD7623AST means the system timing, clock rate, and digital host interface must be re-validated to ensure the slower conversion rate is acceptable for the application.
What are the power supply requirements for these converters?
Both the AD7621ASTZ and AD7623AST operate from a 5 V analog supply (AVDD) and a 2.5 V digital supply (DVDD), with a separate VIO supply for the digital interface. The internal reference buffer and the SAR core are powered from the analog supply, and both devices include power-down modes to reduce consumption between conversions.
How does power consumption compare between the AD7621ASTZ and AD7623AST?
Because power scales with throughput in SAR converters, the AD7621ASTZ, operating at up to 3 MSPS, dissipates more power than the AD7623AST at its 1.33 MSPS maximum rate. Exact power figures depend on supply voltages and operating mode and should be taken from the respective manufacturer datasheets rather than assumed.