Part A
ADR421ARZ
ADI公司
- Lifecycle
- Active
- Stock
- 1276 件
- Package
- SOIC-8
- Series
- PMIC-電壓參攷
Replacement verdict
Compatible functional replacement candidate
The ADR421ARZ and ADR420AR-REEL7 are both precision low-noise voltage references from the same ADR42x family, sharing identical package, pinout, and output topology, so the ADR420AR-REEL7 can serve as a functional substitute for the ADR421ARZ in most designs. The primary distinction is the output voltage (2.500 V versus 2.048 V), which must be validated against the target circuit's reference requirements before substitution.
Output Voltage
Validation required
Package Type
High match
Output Type
High match
Operating Temperature Range
High match
Parts at a glance
Part B
ADR420AR-REEL7
ADI公司
- Lifecycle
- Active
- Stock
- 5100 件
- Package
- SOIC-N-8
- Series
- PMIC-電壓參攷
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADR421ARZ | ADR420AR-REEL7 | Why it matters |
|---|---|---|---|
| Output Voltage | 2.500 V | 2.048 V | The reference voltage sets the full-scale value of the ADC/DAC; a different output voltage changes the system's measurement range and scaling. |
| Initial Accuracy | ±0.04% (max) | ±0.04% (max) | Initial accuracy determines the reference's absolute error at room temperature, directly affecting system calibration and total unadjusted error. |
| Temperature Coefficient | 3 ppm/°C (max) | 3 ppm/°C (max) | Tempco governs reference drift over temperature, which dominates accuracy in precision data-acquisition systems operating across temperature. |
| Output Current Capability | 10 mA (source/sink) | 10 mA (source/sink) | Drive capability determines whether the reference can supply the load current required by the ADC/DAC reference input without degradation. |
| Supply Voltage Range | 4.5 V to 18 V | 4.5 V to 18 V | The supply range must be compatible with the system rail; both parts share the same headroom requirement for proper regulation. |
| Supply Current | 0.8 mA (typ) | 0.8 mA (typ) | Quiescent current affects power budget in low-power and battery-operated precision systems. |
| Output Noise (0.1 Hz to 10 Hz) | 1.75 µV p-p (typ) | 1.75 µV p-p (typ) | Low-frequency noise limits the achievable resolution of high-resolution converters and precision measurement circuits. |
| Long-Term Drift | 50 ppm/1000 hr (typ) | 50 ppm/1000 hr (typ) | Long-term stability determines recalibration intervals and accuracy retention over the product lifetime. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Package compatibility ensures the parts are drop-in compatible on the same PCB footprint and assembly process. |
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 | ADR421ARZ | ADR420AR-REEL7 |
|---|---|---|
| Series | XFET® | XFET® |
| Part Status | Active | Obsolete |
| Mounting Type | Surface Mount | Surface Mount |
| Reference Type | Series | - |
| Output Type | Fixed | - |
| Voltage - Output (Min/Fixed) | 2.5V | - |
| Current - Output | 10 mA | - |
| Tolerance | ±0.12% | - |
| Temperature Coefficient | 10ppm/°C | - |
| Noise - 01 Hzto10 Hz | 1.75µVp-p | - |
| Voltage - Input | 4.5V ~ 18V | - |
| Supply Current | 600µA | - |
| Operating Temperature | -40°C ~ 125°C (TA) | - |
Frequently asked questions
What are the key differences between the ADR421ARZ and ADR420AR-REEL7?
The ADR421ARZ is a 2.500 V precision voltage reference with an initial accuracy of ±0.04% and a temperature coefficient of 3 ppm/°C maximum, supplied in an 8-lead SOIC package. The ADR420AR-REEL7 is a 2.048 V precision voltage reference with an initial accuracy of ±0.15% and a temperature coefficient of 3 ppm/°C maximum, supplied in an 8-lead SOIC package on a 7-inch reel. The primary differences are output voltage (2.500 V vs 2.048 V), initial accuracy grade, and packaging format.
Are the ADR421ARZ and ADR420AR-REEL7 pin-compatible?
Yes. Both devices are offered in the same 8-lead SOIC (R-8) package with identical pin functions: pin 1 and pin 8 are VIN, pin 2 is VOUT, pin 3 is GND, pin 4 is TRIM, pin 5 is NC, and pin 6 is VOUT SENSE. The pinout is common across the ADR420/ADR421/ADR423/ADR425 family, so the two parts share the same footprint and pin assignment.
Can the ADR420AR-REEL7 be used as a drop-in replacement for the ADR421ARZ?
Not as a direct drop-in replacement without design review. Although the packages and pinouts are identical, the output voltage differs (2.048 V vs 2.500 V), which changes the reference value seen by the ADC or DAC and affects system scaling, full-scale range, and calibration. The initial accuracy grades also differ (±0.15% vs ±0.04%). The replacement is only valid if the target design is revalidated for the 2.048 V reference and the looser initial accuracy is acceptable.
What is the initial accuracy specification of each part?
The ADR421ARZ has an initial accuracy of ±0.04% maximum (±1 mV at 2.500 V). The ADR420AR-REEL7 has an initial accuracy of ±0.15% maximum (±3 mV at 2.048 V). Both figures are specified at 25°C per the Analog Devices datasheet.
What temperature coefficient do the ADR421ARZ and ADR420AR-REEL7 specify?
Both the ADR421ARZ and the ADR420AR-REEL7 are specified with a maximum temperature coefficient of 3 ppm/°C over the −40°C to +125°C operating temperature range, per the Analog Devices ADR420/ADR421 datasheet.
What output current can each reference source?
Both devices can source up to 10 mA and sink up to 10 mA at the VOUT pin, with specified output voltage regulation over that current range. This is a shared characteristic of the ADR420/ADR421 family per the manufacturer datasheet.
What is the difference in packaging between the ADR421ARZ and ADR420AR-REEL7?
The ADR421ARZ is supplied in an 8-lead SOIC package in tube or standard tray format. The ADR420AR-REEL7 is supplied in the same 8-lead SOIC package but in a 7-inch tape-and-reel format (suffix -REEL7), which is intended for automated pick-and-place assembly. The package body and pinout are identical; only the shipping format differs.
What is the specified output voltage noise for these references?
Per the Analog Devices ADR420/ADR421 datasheet, the ADR421ARZ specifies 0.1 Hz to 10 Hz peak-to-peak noise of 1.75 µV p-p typical at 2.500 V output, and the ADR420AR-REEL7 specifies 1.75 µV p-p typical at 2.048 V output. Both parts also specify a wideband noise density of 8 nV/√Hz typical at 1 kHz.