A strange voltage source symbol with possibly output pin

Question

While checking the block diagram of a chip from its datasheet, I noticed this symbol that I have no idea about (the one marked with red circle):

Without that extra connection line to the right it'd obviously be a voltage source. The fact that the extra line goes to the A/D (analog-to-digital) converter makes me think that the source has some sort of voltage or current output.

Some info about the operation hoping to be useful:

• The chip's operational parameters are set by external components. A resistor (between 100k and 300k) connected across GATELS pin and GND is one of them. During the initialisation after power on the chip measures the resistance, apparently by closing setting switch and applying voltage from that source through its internal resistance and measuring voltage and/or current, and sets its respective internal parameters. So, that source is active only once, and only during initialisation.

The datasheet has no further info about that source. I also tried my best to Google but, to be honest, I don't know what keywords I should've used.

As I said, I'm assuming it to be something like a source with voltage or current output. But I'd like to know or to be sure about what it really is, whether it has some definition or whether it is a standard symbol.

Answer 1

I think I found it.

The chip normally has its own linear regulator which generates 11V ± 0.4V, and is called SUPREG. This voltage is used to supply some internal blocks as well as GATELS driver, as can be seen from the block diagram or the snippet in my question.

Now I noticed a detail about GATELS in the datasheet:

This means that, during initialisation of the settings (i.e. resistance measurement), SUPREG comes from driver to that pin and an extra 1.25V over SUPREG comes via that strange supply by closing settings switch (1.25V is the most common bandgap reference voltage which is easy to make at chip-level).

So, quite possibly, the voltage is applied through a relatively high resistance and the extra line is the output of an internal divider. Should be something like this:

^{simulate this circuit – Schematic created using CircuitLab}

^{NOTE: I'm aware of the fact that the extra source is shown as a ground-referenced in the block diagram. Ultimately, the voltage measured by A/D should be ground-referenced.}

So I understand that this is not a standard symbol.

Answer 2

8.8 External settings
Before the system starts switching, it reads the external settings. Using specific resistor values at the GATELS, SNSSET, and SNSOUT pins, several internal settings can be defined.

Based on section 8.8 I'd venture to say that that symbol is indicating a voltage source & measurement that reads GATELS at startup, then disconnects.

Also, they use a circle with a horizontal line to indicate current sources and there is one other use of a circle with the vertical line used as a 2.5V source.