Getting Started with Anabit's Reference VoltHive

Getting Started with Anabit's Reference VoltHive

Reference VoltHive Summary

Anabit’s Reference VoltHive provides four precision, buffered references—+4.096 V, +2.048 V, –4.096 V, and –2.048 V. Each output is buffered by precision op amps delivering -20mA to 20mA of low noise drive current to your project. Beyond references, the VoltHive simplifies bipolar power needs by supplying –6.2 V and –5 V auxiliary rails to power op-amp stages or other negative-supply blocks.

Pinout description

Below is a diagram showing the VoltHive's pinout, we have the power source input and outputs grouped together on the left and the precision voltage reference outputs on the right. Covering the pins from left to right:

  • There are three ground pins (labeled GND) on the left side, any of these ground pins can be used for the power source input or the outputs
  • The +5V input power (labeled VIN) is needed to power the various power outputs on the design. It should be at or close to 5V (+/- 200mV) to get the correct voltage values out of the rest of the design. You could use 3.3V input power and a subset of the outputs would work, but the +/- 4.096V outputs would not work (they would output close to 3.3V). 
  • The first power source output is the -6.2V generated by a DC to DC inverter from the 5V input. This is a higher noise DC level since it comes from a switch based boost circuit. 
  • The second power source output is the -5V, which is powered by the -6.2V source via a low noise linear regulator with a high PSRR specification (new to PSRR check out this tutorial). Between the linear regulator and the -6.2V signal is an LC filter. the purpose of the filter is to attenuate switching noise from the -6.2V converter. The combination of the linear regulators PSRR and the LC filter ensures a clean low noise -5V source is delivered to the precision op amps. 
  • The symmetric precision voltage reference outputs are found on the right as follows: 4.096V, AGND, -4.096V, 2.048V, AGND, -2.048V.  "AGND" is short for analog ground. The AGND and GND connections on the board are on the same ground plane, but they are labeled different to encourage the user to use the GND side for the noisier power signals and the AGND side for the precision voltage references. 

Reference VoltHive best practices and Demonstration:

  • Ideally you want to use a low noise 5V power source to power the VoltHive. But the VoltHive does employ input power noise filtering so you can expect to get excellent performance on any 5V input source
  • Beware of IR loss error when using the VoltHive! When using the VoltHave reference output, be sure to keep the signal path short and have low resistance to prevent errors due to IR loss. For instance if your using the 2.048V reference voltage at 10mA and its signal path has 0.5 ohms of resistance you will see a 5mV voltage drop (0.5ohms x 10mA = 5mV). That means your circuit that is using the reference will see 2.043V instead of 2.048V
  • If your signal path includes wiring keep the wiring as short as possible. This will not only help with IR loss but also help reduce EMI noise from any radiating noise sources in the area (such as your phone). If you do have long wired signal paths use twisted pair or shielded cabling. 

Here is the precision VoltHive in action, showing the +/- 4.096V outputs on a high accuracy digital voltmeter. In this example the +4.096V reference is showing < 0. 004% error and the -4.096V reference is showing < 0.006%. Well within its spec'd accuracy of 0.025% and 0.04% respectively. 

If you have any questions, issues, or suggestions related to the VoltHive or any Anabit product please go to our Forum 

Reference VoltHive Specifications: 

  • -Accuracy of the 4.096V and 2.048V outputs is 0.025% and the accuracy of the -4.096V and -2.048V outputs is 0.04%
  • Max Current Source and sink per reference output: 20mA to -20mA
  • -5V linear supply output accuracy is 1% and supports a max current of 100mA
  • -6.2V supply can support a max current of 200mA, but that current is shared with the -5V supply so be sure the current output of both -6.2V and -5V supply is < 200mA
  • Small form factor at 44.5mm x 29.5mm. 2.54mm spaced through holes for easy use with a bread board. Utilize the three 3mm holes to support mounting.
  • If all outputs, voltage references and negative supplies, are being used at the maximum rated current then the 5V input could draw as much as 350mA. If you are just using the references at 5mA or less then 5V input current will be < 50mA
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