Part A
ADR421ARZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 1276 PCS
- Package
- SOIC-8
- Series
- PMIC - Voltage Reference
Replacement verdict
Compatible functional replacement candidate
The ADR425BRZ and ADR421ARZ are both series voltage references in the same SOIC-8 package with identical pinout and 2.5 V output, making them functionally interchangeable in most designs. The ADR425BRZ offers tighter initial accuracy and lower temperature coefficient, while the ADR421ARZ provides lower output noise and a wider operating temperature range. Designers should validate noise and thermal performance against their specific application requirements before substituting.
Output Voltage
High match
Package Type
High match
Initial Accuracy
Validation required
Output Noise
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 | ADR425BRZ | ADR421ARZ | Why it matters |
|---|---|---|---|
| Initial Accuracy | ±0.04% (max) | ±0.12% (max) | Tighter initial tolerance reduces or eliminates the need for system calibration at production. |
| Output Voltage | 5.0 V | 2.5 V | The reference voltage sets the full-scale range of the ADC/DAC; the two parts are not directly interchangeable without redesigning the signal chain. |
| Temperature Coefficient | 3 ppm/°C (max) | 10 ppm/°C (max) | Lower tempco improves accuracy stability over the operating temperature range. |
| Initial Accuracy Grade | B grade | A grade | Grade indicates the guaranteed precision bin; B grade is tighter than A grade for these families. |
| Long-Term Drift | 50 ppm/1000 hr (typ) | 50 ppm/1000 hr (typ) | Long-term drift affects recalibration intervals; both are similar here. |
| Output Current Capability | 10 mA (source/sink) | 10 mA (source/sink) | Determines ability to drive heavier reference loads; both are comparable. |
| Supply Voltage Range | 4.5 V to 18 V | 4.5 V to 18 V | Wide supply range allows operation from various rails; both share the same range. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Same footprint enables drop-in PCB compatibility if voltage requirements match. |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | Industrial temperature range supports harsh environments; both are identical. |
| Supply Current | 0.5 mA (typ) | 0.5 mA (typ) | Low quiescent current benefits portable/low-power designs; both are comparable. |
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 | ADR425BRZ |
|---|---|---|
| Series | XFET® | XFET® |
| Part Status | Active | Active |
| Reference Type | Series | Series |
| Output Type | Fixed | Fixed |
| Voltage - Output (Min/Fixed) | 2.5V | 5V |
| Current - Output | 10 mA | 10 mA |
| Tolerance | ±0.12% | ±0.04% |
| Temperature Coefficient | 10ppm/°C | 3ppm/°C |
| Noise - 01 Hzto10 Hz | 1.75µVp-p | 3.4µVp-p |
| Voltage - Input | 4.5V ~ 18V | 7V ~ 18V |
| Supply Current | 600µA | 600µA |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the key differences between the ADR425BRZ and ADR421ARZ voltage references?
The ADR425BRZ is a 5.000 V precision voltage reference with an initial accuracy of ±0.04% (B grade) and a temperature coefficient of 3 ppm/°C max, while the ADR421ARZ is a 2.500 V reference with an initial accuracy of ±0.04% (A grade) and a temperature coefficient of 10 ppm/°C max. The primary differences are output voltage (5.000 V vs 2.500 V) and temperature coefficient grade.
Are the ADR425BRZ and ADR421ARZ pin-compatible?
Yes. Both devices are offered in the same 8-lead SOIC (R-8) package and share the same pinout, allowing them to be used on a common PCB footprint. However, the output voltage difference (5.000 V vs 2.500 V) must be accounted for in the circuit design.
What is the initial accuracy of each device?
The ADR425BRZ (B grade) provides an initial accuracy of ±0.04% maximum. The ADR421ARZ (A grade) also provides an initial accuracy of ±0.04% maximum. Both are specified at 25°C.
How do the temperature coefficients of the ADR425BRZ and ADR421ARZ compare?
The ADR425BRZ (B grade) specifies a maximum temperature coefficient of 3 ppm/°C over the −40°C to +125°C range. The ADR421ARZ (A grade) specifies a maximum temperature coefficient of 10 ppm/°C over the same temperature range. The ADR425BRZ therefore offers better thermal stability.
What are the operating temperature ranges for these references?
Both the ADR425BRZ and ADR421ARZ are specified for operation over the extended industrial temperature range of −40°C to +125°C.
What output current can the ADR425BRZ and ADR421ARZ source and sink?
Both devices can source up to 10 mA and sink up to 10 mA of output current, making them suitable for driving moderate loads in precision analog circuits.
What are the supply voltage requirements for the ADR425BRZ and ADR421ARZ?
The ADR425BRZ requires a supply voltage of at least 5.5 V (typically 5.5 V to 15 V) to maintain regulation of its 5.000 V output. The ADR421ARZ requires a supply voltage of at least 3.0 V (typically 3.0 V to 15 V) for its 2.500 V output. The headroom requirement differs due to the different output voltages.
What is the long-term stability specification for these voltage references?
Both the ADR425BRZ and ADR421ARZ specify long-term stability of 50 ppm typical for 1,000 hours of operation at 25°C, per the Analog Devices datasheet.