Low cost Voltage References
Malone Electronics www.voltagestandard.com 418 W. Main St. #1542 Battle Ground, WA 98604 USA
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.01% Voltage Reference.01% Voltage Reference
How Accurate is your DC Voltmeter?
Find out with our low cost voltage references
Model VREF5-01 Precision
This small, portable,
precision voltage reference can be used to check the calibration of your
DVM or DMM. Different voltage models are available but our most popular is 5.000V and is described here.The VREF5-01 features a 5.000V output, accurate
within 0.01% (output guaranteed
between 4.9995 and 5.0005 Volts) for a minimum of 6 months. The circuit is based on the Texas Instruments' REF5050ID
Reference. Here is a link to the data sheet on the TI web site: http://focus.ti.com/lit/ds/symlink/ref5050.pdf
circuit board was designed to minimize the effects of
mechanical stress on the reference IC. Specifically, the REF5050 was
placed on the edge of the board and 2 adjacent slots decouple stresses
in the board from reaching the reference which could otherwise cause
the output voltage to shift.
The REF5050 is carefully and quickly
soldered to the board and every one of the references that we have sold
easily exceed the specifications listed above.
external power supply is not needed; The included 9V battery makes the
unit self-contained and easily transported. An on-board on/off switch
allows you to maximize battery life when not in use. Reverse polarity
protection is included, so even if the battery is placed in the holder
backwards no damage will result. A high brightness, low current
LED clearly indicates when the reference is turned on.
The worst-case change with temperature is a low 5ppm / oC or only +- 65uV / oC.
The reference chip itself has a temperature coefficient of 3ppm and the
output trim adjustment adds another approximately 2ppm. Before
shipping, the ambient temperature and output voltage are recorded as
explained below. To guarantee a 5V output within .01%, your ambient
temperature must be within 8oC
(14oF) of the
stated calibration temperature. In a typical
indoor environment this usually isn't much of a restriction.
After the unit is assembled, it is powered up with a 9.0V power supply
for a minimum of 250
hours to "age" the reference and improve its long term stability.
After aging, the trim potentiometer is carefully adjusted so that the reference voltage is within 5µV of 5.00000V
as measured by our calibrated, 8.5 digit Keysight 3458A DMM. (Keysight Technologies, Certificate of Calibration 1-8526526825-1, valid through January 31, 2018). The ambient temperature is
also recorded (typically 21oC).
reference circuit is very similar to what was described in our article
in the September
2007 issue of Nuts and Volts magazine, "Build a .01% Accurate
Voltage Reference" http://nutsvolts.texterity.com/nutsvolts/200709/?folio=52.
Nuts and Volts reference was based on the Intersil X60008 reference
chip and numerous reference assemblies were sold through eBay.
Unfortunately, Intersil has discontinued production of the X60008 and
it is no longer available. The REF5050 is vastly superior to the
X60008, and most other reference chips, in one respect: line
regulation. The X60008 output voltage could vary as much as 100uV for
every volt away from its 'sweet spot' of 6.5V input. The REF5050
output is guaranteed, however, to vary only 5uV per Volt. In practical
terms this means that with a fresh 9V battery
and a 5.00000V output,
when the battery gets down to, say, 6V the output will have changed
Recalibration of the REF5-01 is now free for the first two years after purchase - just send it back to us and include $4.00 in stamps for return shipping within the USA. After two years the calibration charge is $5.00 plus shipping. Please inquire for shipping charges to destinations outside USA.
2.048V, 2.500V, 3.000V, 4.096V, and 4.500V
references are also available; please specify desired voltage when placing order.
Prices and specifications subject to change without notice.
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