Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

POL-IN

IEC

IEC polarity indicator at input (active-low input)

The polarity indicator is a small right-angled triangle drawn on the input line where it meets the outline. It states that the L level produces the internal 1 state. Because it refers directly to levels, it does not need a positive or negative logic declaration, which is why device data books favour it.

Drawing use: Schematic
Application: Logic & signals
Reference family: IEC / Manufacturer
Form evidence: Right-angled triangle on the input line next to the outline. Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier.

A distinction that matters

The negation circle is a logic statement that needs a declared convention; the triangle is a level statement.

Full reference

NEG-IN

IEC

IEC logic negation at input

The negation circle at an input means that the external 0 state produces the internal 1 state of the element. It is a pure logic statement: to relate it to voltage levels, the drawing must declare positive or negative logic. TI's public overview notes that this is the older form, with the polarity triangle now preferred in device data books.

Drawing use: Schematic
Application: Logic & signals
Reference family: IEC / Manufacturer
Form evidence: Small circle at the input edge of the outline. Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier.

A distinction that matters

The polarity indicator triangle states an active-low level directly and does not depend on a declared logic convention.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.