**The LM399H#PBF: The Precision Voltage Reference Standard for Demanding Applications**

In the world of high-precision electronics, the stability and accuracy of a voltage reference are paramount. Whether it's in a laboratory-grade digital multimeter, a precision data acquisition system, or a sophisticated medical instrument, the performance of the entire system hinges on the quality of its reference voltage. For decades, the **LM399H#PBF** has stood as the undisputed industry standard, delivering unparalleled performance for the most demanding applications.

At the heart of the LM399's exceptional performance is its unique buried zener diode. Unlike conventional voltage references that are highly susceptible to temperature fluctuations, the LM399H#PBF integrates a **thermally stabilized substrate** and an on-chip heating element. This innovative design maintains the zener diode at a constant, elevated temperature, effectively eliminating errors caused by ambient temperature changes. The result is an extraordinarily low temperature coefficient, typically as low as **0.5 ppm/°C**, ensuring stable output over a wide operating range.

The key specification for any voltage reference is its long-term stability, often referred to as "drift." This is where the LM399H#PBF truly excels. It is renowned for its exceptional long-term stability, characterized by an ultra-low drift of **20 ppm/1000 hours** (and as low as 4ppm/1khrs for selected units). This means that the output voltage remains consistent over months and years of continuous operation, a critical requirement for calibration equipment and standards laboratories where reproducibility is non-negotiable.

Furthermore, the device offers a **6.95V nominal output voltage** with minimal noise. Its simple application circuit, requiring only a few external components to set the operating current and buffer the output, makes it a reliable and straightforward choice for designers. The "H" grade designation signifies its enhanced performance and tighter initial tolerance, while the #PBF suffix confirms it is manufactured with a lead-free process, complying with modern environmental standards.

The LM399H#PBF finds its home in applications where compromise is not an option. It is the reference of choice for:

* **Precision Calibration Instruments** and metrology systems.

* **High-Resolution Digital Multimeters** (e.g., 7.5 and 8.5-digit DMMs).

* **Precision Data Acquisition Systems** and analog-to-digital converters (ADCs).

* **Automated Test Equipment** (ATE) and semiconductor test systems.

* **Medical Diagnostic Equipment** requiring unwavering accuracy.

**ICGOOFind:** The LM399H#PBF remains the benchmark for precision voltage references, offering an unmatched combination of ultra-low temperature coefficient, exceptional long-term stability, and proven reliability. For engineers designing systems where accuracy over time and temperature is the primary concern, the LM399H#PBF continues to be the definitive solution.

**Keywords:** Precision Voltage Reference, Long-Term Stability, Low Temperature Coefficient, Buried Zener, Calibration Standard.