Features and Benefits
- 7.05 V ultrastable shunt reference
- Low temperature coefficient: 0.2 ppm/℃
- Available in 4-pin TO-46 and 8-terminal LCC
- Typical reference noise for 10 Hz < f < 1 kHz: 1.84 μV rms
- Initial accuracy range: –300 mV to +250 mV
- Low dynamic impedance: 0.04 Ω in TO-46, 0.011 Ω in LCC
- External thermal insulator provided for TO-46
- Upgrade path for legacy LM399, now also in surface-mount technology (SMT)
The ADR1399 precision shunt reference features excellent temperature stability over a wide range of voltage, temperature, and quiescent current conditions. A temperature stabilizing loop is incorporated with the active Zener on a monolithic substrate, which nearly eliminates changes in voltage with temperature. The subsurface Zener circuit is fully specified at a quiescent current IREF of 3 mA and offers minimal noise (1.44 μV p-p, 0.1 Hz to 10 Hz) and excellent long-term stability (7 ppm/√kHr). The ADR1399 offers a lower output dynamic impedance (0.08 Ω) than the LM399, reducing the effects of shunt resistor (RSHUNT) and the supply voltage variation on the reference output.
Ideal applications for the ADR1399 include ultrastable digital voltmeters, precision calibration equipment, and ultrarepeatable analog-to-digital converters (ADCs). The simplicity of the basic pin configurations is shown in Figure 1. The 8-terminal LCC version offers force and sense pins for lower dynamic impedance and for Kelvin sensing.
|Model||Output Voltage (V)||Initial Accuracy Range (mV)|
|ADR1399||7.05||–300 to +250|
|LTZ1000||7.2||–200 to +300|
|LM399||6.95||–200 to +350|
|LT1236||5 and 10||–2.5 to +2.5|
- Precision voltage reference for multimeters
- Calibration equipment voltage standards
- Laboratory measurement equipment
- Industrial monitor and control instrumentation
- Ultrastable data convertors
Markets and Technologies
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
The ADR1399E-EBZ and ADR1399H-EBZ allow the evaluation of the ADR1399KEZ, ultra-stable 7.05V Shunt Voltage Reference. The ADR1399E-EBZ is in 8-Pin LCC package and the ADR1399H-EBZ is in 4-lead TO-46 package.
The DUT on the ADR1399E-EBZ is on a paddle shaped “island” area of PCB for less stress from board flexure and also for thermal isolation. It is inside a captive acrylic enclosure to reduce air flow and further improve thermal isolation. Ground planes are removed under the DUT except for a hatch ground on the bottom side, again to prevent excessive thermal conduction away from the oven-ized reference. On L2 there is a small solid copper area under the reference voltage pins to help ensure an isothermal environment.
The DUT on the ADR1399H-EBZ is elevated on its leads in order to increase the thermal isolation from the 4-layer board ground planes.
Isolated power means that the Reference output is effectively floated, removing the likelihood of ground loops. The isolation is bridged only by a 1Meg resistor. Power may be supplied via the USB-C cable, or 5V may be applied to “VUSB”, or power may be back driven onto the LTM8048 regulator outputs at “VPRE” or V+”. The ultra-stable 7.05V is brought out to both banana jacks and to an edge mounted SMA connector.
Tools & Simulations
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.