> Complete documentation index: [llms.txt](/llms.txt). Markdown versions of all pages are available by appending `.md` to page URLs.

# Is the DAC calibrated?

> No Binho DAC is calibrated except the Supernova I3C High-Voltage rail, trimmed since firmware 4.6.0; see the measured error of each voltage rail.

**No, with one exception:** since firmware 4.6.0 the Supernova trims its I3C High-Voltage rail against its own measurement.



**Supernova and Pulsar**

The Supernova and the Pulsar have **no general-purpose analog output**. Their DACs set the target voltage rails (VTARG). How close a rail lands to the set voltage depends on the rail:

| Rail                                     | Range       | How it is set                                         | Measured error                                  |
| ---------------------------------------- | ----------- | ----------------------------------------------------- | ----------------------------------------------- |
| Supernova I3C High-Voltage, firmware 4.6.0 and later | 1.2–3.25 V | Closed loop: set, measure under load, correct     | −7 to +2 mV across the range, in repeated sweeps on a revision C Supernova |
| Supernova I3C High-Voltage, firmware 4.5.1 and earlier | 1.2–3.3 V | Open loop, fixed factory constants                | 1200 mV set gave 1075–1094 mV; spread ~120 mV between units |
| Supernova I3C Low-Voltage                | 0.8–1.2 V   | Open loop, fixed constants                            | +8 to +11 mV, measured on one Supernova                        |
| Multifunction VTARG (both adapters)      | 1.2–3.3 V   | Open loop, fixed constants                            | Supernova +13 to +18 mV, Pulsar −16 to −9 mV, measured on one adapter of each |

"Fixed constants" means the same conversion for every unit, with no per-unit calibration, so other units can land differently. A set on the I3C HV rail takes about 550 ms on firmware 4.6.0 and later.

If the target needs an exact supply, measure VTARG with a multimeter, or power the target from a bench supply and use `use_external_voltage()`.

:::note
The rails can source current but not sink it. Lowering the voltage on a lightly loaded rail takes time: the voltage decays only through the load. Read the rail back before relying on the new value.

:::



**Nova**

The Nova has one DAC output on its signal pins. It is not calibrated. Use it as a near-DC test stimulus, not as a waveform generator.



Related: [Is the ADC calibrated?](/support/faq/is-the-adc-calibrated/)