**LM399AH#PBF: The Precision Voltage Reference Standard for Demanding Applications**

In the realm of precision electronics, the stability and accuracy of a voltage reference are paramount. Among the myriad of components available, the **LM399AH#PBF** stands out as an industry-standard, offering unparalleled performance for the most demanding applications. Its unique architecture, centered around a **subsurface buried zener diode**, provides a benchmark for low noise, exceptional long-term stability, and minimal thermal hysteresis.

The core innovation of the LM399AH#PBF lies in its on-chip temperature-regulating oven. This integrated heater maintains the precision zener diode at a constant temperature, typically around 90°C, effectively eliminating errors caused by fluctuations in the ambient environment. This results in an extremely low temperature coefficient (**0.3 ppm/°C typical**), making it virtually immune to external temperature changes. Furthermore, the device delivers an initial accuracy of **±2 mV** and remarkably low noise, which is critical for high-resolution analog-to-digital and digital-to-analog converters.

The long-term stability of the LM399AH#PBF is a key metric for calibration laboratories and instrumentation. It exhibits a typical drift of just **8 µV/1000 hours** (or 20 ppm/1000 hours) after an initial aging period, ensuring that systems maintain their accuracy over extended operational life. This reliability makes it the reference of choice for a wide array of critical applications, including **precision digital multimeters (DMMs)**, calibration equipment, data acquisition systems, and high-end audio converters.

Compared to simpler shunt references or bandgap-based alternatives, the LM399AH#PBF represents a higher-performance tier. While it requires a higher operating current to power its internal heater, the trade-off is justified in systems where measurement integrity is non-negotiable. Its **6.95V output voltage** is a proven industry standard, easily scaled to other common reference voltages like 5V or 10V with minimal external circuitry.

**ICGOOFind**: The LM399AH#PBF remains the definitive precision voltage reference, offering an unmatched combination of thermal stability, low noise, and long-term reliability for mission-critical designs where accuracy cannot be compromised.

**Keywords**: Precision Voltage Reference, Low Noise, Long-Term Stability, Buried Zener Diode, Thermal Hysteresis