Part A
ADR421ARZ
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 1276 個数
- Package
- SOIC-8
- Series
- PMIC - 電圧リファレンス
Replacement verdict
Compatible functional replacement candidate
The ADR421ARZ and ADR425AR-REEL7 are both precision low-noise voltage references from the same ADR42x family, sharing a common SOIC-8 footprint and series-mode topology, but they differ in output voltage and initial accuracy grade. The ADR425AR-REEL7 can serve as a functional substitute for the ADR421ARZ only where the 5.000 V output and the AR-grade tolerance are acceptable; designers must re-verify the reference voltage against the target system's full-scale requirements before substitution.
Output Voltage
Validation required
Package Type
High match
Reference Topology
High match
Initial Accuracy Grade
Validation required
Parts at a glance
Part B
ADR425AR-REEL7
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 3653 個数
- Package
- SOIC-N-8
- Series
- PMIC - 電圧リファレンス
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 | ADR425AR-REEL7 | Why it matters |
|---|---|---|---|
| Output Voltage | 2.500 V | 5.000 V | The nominal reference voltage determines the full-scale range of the ADC/DAC and the system supply headroom; these parts are not directly interchangeable without redesigning the signal chain. |
| Initial Accuracy | ±0.04% (±1 mV) | ±0.04% (±2 mV) | Initial accuracy sets the absolute error budget at room temperature; the tighter mV figure on the 2.5 V part reflects the same percentage spec applied to a lower voltage. |
| Temperature Coefficient | 3 ppm/°C (max) | 3 ppm/°C (max) | Drift over temperature dominates precision system error; both grades share the same 3 ppm/°C maximum, so thermal performance is equivalent. |
| Output Current Capability | 10 mA (source/sink) | 10 mA (source/sink) | Drive capability determines whether the reference can supply the load directly or needs a buffer; identical ratings mean similar loading behavior. |
| Supply Voltage Range | 4.5 V to 18 V | 7.0 V to 18 V | The minimum supply headroom differs because the 5 V output requires more margin; a 5 V rail cannot power the ADR425, affecting board-level compatibility. |
| Supply Current | 0.5 mA (typ) | 0.5 mA (typ) | Quiescent current affects total power budget in low-power designs; equivalent values indicate comparable efficiency. |
| Output Noise (0.1 Hz to 10 Hz) | 1.75 µV p-p (typ) | 3.4 µV p-p (typ) | Low-frequency noise limits resolution in high-resolution converters; the 2.5 V part has lower absolute noise, which matters for precision measurement front ends. |
| Long-Term Drift | 50 ppm/1000 hr (typ) | 50 ppm/1000 hr (typ) | Long-term stability affects calibration intervals in instrumentation; matching drift specs mean similar lifetime accuracy behavior. |
| Package | 8-Lead SOIC | 8-Lead SOIC | Package and pinout compatibility allows drop-in replacement on an existing PCB footprint; identical SOIC packages simplify substitution. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADR421ARZ | ADR425AR-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 ADR425AR-REEL7 voltage references?
The ADR421ARZ is a 2.500 V precision voltage reference in an 8-lead SOIC package, while the ADR425AR-REEL7 is a 5.000 V precision voltage reference in an 8-lead SOIC package supplied on tape and reel. Both are members of Analog Devices' ADR42x family of low-noise, high-accuracy references, but they differ in output voltage and packaging format.
What initial accuracy and temperature coefficient do these references specify?
The ADR421ARZ (A grade) specifies an initial accuracy of ±0.04% and a temperature coefficient of 3 ppm/°C max. The ADR425AR-REEL7 (A grade) specifies an initial accuracy of ±0.04% and a temperature coefficient of 3 ppm/°C max. Both grades share the same accuracy and drift specifications, differing only in output voltage.
What output voltage does each device provide?
The ADR421ARZ provides a fixed 2.500 V output, while the ADR425AR-REEL7 provides a fixed 5.000 V output. The output voltage is the primary functional difference between the two parts.
Are the ADR421ARZ and ADR425AR-REEL7 pin-compatible?
Both devices are offered in the same 8-lead SOIC package with the same pinout (VOUT, GND, VIN, and related pins), so they are pin-compatible. However, because their output voltages differ (2.5 V vs 5.0 V), they are not electrically interchangeable in a given design without verifying that the system tolerates the different reference voltage.
What is the operating temperature range for these voltage references?
Both the ADR421ARZ and ADR425AR-REEL7 are specified over the industrial temperature range of −40°C to +125°C, consistent with the ADR42x family datasheet specifications.
What supply voltage range do these references require?
The ADR42x family operates from a supply voltage of 4.5 V to 18 V for the 5.0 V output version and 4.5 V to 18 V for the 2.5 V output version, per the Analog Devices datasheet. The minimum supply must exceed the output voltage by the specified dropout headroom.
How does the packaging differ between the two orderable part numbers?
The ADR421ARZ is supplied in an 8-lead SOIC tube/rail format, while the ADR425AR-REEL7 is supplied on a 7-inch tape and reel for automated assembly. The "ARZ" and "AR" suffixes denote the SOIC package and grade, and the "-REEL7" suffix indicates tape-and-reel packaging.
Can the ADR425AR-REEL7 be used as a drop-in replacement for the ADR421ARZ?
No. Although both are pin-compatible 8-lead SOIC devices from the same family, the ADR425AR-REEL7 outputs 5.000 V versus 2.500 V for the ADR421ARZ. A drop-in replacement would change the reference voltage by a factor of two, so the circuit must be redesigned or revalidated for the different output before substitution.