LTZ1000 Voltage Reference Datasheet

LTZ1000 voltage reference onboard the Keysight 34470A multimeter (Source: Dave Jones)

With an integrated heater and temperature sensor, the LTZ1000 is a high-precision, ultra-stable voltage reference that maintains a constant temperature to improve stability. A voltage reference produces a constant voltage regardless of the device’s load, power supply changes, and temperature changes. This article will examine the LTZ1000 characteristics and capabilities as explained in the LTZ1000 voltage reference datasheet.

Features of LTZ1000 Voltage Reference
Voltage Stability	7-7.5V output
Temperature Stability	Temperature drifts of 0.05ppm/°C
Thermal Resistance	Specified for –55°C to 125°C temperature range
Long-term Stability	2µV/√kHr long-term stability
Low Noise	1.2µV peak-to-peak noise

Made by Analog Devices, Inc., the LTZ1000 contains a subsurface Zener diode reference, a heater resistor for temperature stabilization, and a temperature-sensing transistor. For maximum flexibility and long-term stability, external circuitry sets operating currents and stabilizes temperature. When the heater control and thermal layout are correctly managed, the LTZ1000 performs better than many legacy devices that is still available.

Analog Devices also makes the LTZ1000A version, which has the same characteristics as the LTZ1000 except that it uses a proprietary die attach method that provides significantly higher thermal resistance (400°C/W).

LTZ1000 Voltage Reference Datasheet

The LTZ1000 is a popular reference for many high-precision applications. For example, it served as the internal voltage reference for the voltmeter used in the Large Hadron Collider at CERN.

LTZ1000 Applications and Electrical Characteristics

According to the LTZ1000 datasheet, the voltage reference is commonly used in the following applications:

Voltmeters
Calibrators
Standard Cells
Scales
Low Noise RF Oscillators

And the datasheet details the LTZ1000’s electrical characteristics:

LTZ1000 electrical characteristics

Pin Configuration

The LTZ1000 datasheet provides data about its pin configuration in the diagram below:

LTZ1000 Pin configuration

The datasheet also describes the function of each LTZ1000 voltage reference device pin:

Pin Function
1	Heater Positive. Must have a higher positive value than Pin 2 and Pin 4.
2	Heater Negative. Must have a higher positive value than Pin 4. Must have equal or lower potential than Pin 1.
3	Zener Positive. Must have a higher positive value than Pin 4.
4	Substrate and Zener Negative. Must have a higher positive value than Pin 7. If Q1 is zenered (about 7V), a permanent degradation in beta will result.
5	Temperature Compensating Transistor Collector.
6	Temperature Sensing Transistor Base. If the base-emitter junction is zenered (about 7V), the transistor will suffer permanent beta degradation.
7	Emitter of Sensing and Compensating Transistors.
8	Collector of Sensing Transistor.

Using the LTZ1000 Datasheet for PCB Design

The LTZ1000 datasheet details its architecture and operation, including a section that discusses how to set it up for optimal operation. It is essential to use the datasheet’s wealth of information when designing PCBAs for the LTZ1000. Furthermore, it is crucial to rely on accurate CAD data from a reliable component information source, such as Ultra Librarian, as shown below:

LTZ1000 symbol and footprint

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