How to determine the direction of the chip? The simplest chip principle
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How to determine the direction of the chip? The simplest chip principle

Posted Date: 2024-01-26

How to determine the orientation of a chip

1. Chip identification direction with horizontal bars

For some dual-in-line or dual-in-line patches, there is a horizontal line on the surface of the chip, and this horizontal direction is the direction identification point of the chip pins. The chip is laid flat, the left side of the horizontal bar is the first pin, and the right side is the last pin. The pin numbers increase in counterclockwise direction.

2. Chip identification direction with dots

This dot marking method is very common for dual in-line chips. This dot is the direction identification point. The marking method is similar to the marking method with horizontal bars. Lay the chip flat, the one to the left of the dot is the first pin, and the one to the right of the dot is the last pin. Pin numbers increase in counterclockwise direction.

3. Identify the direction of the chip with a gap

It is most common to use a semicircular gap as a direction identification point. The left side of the gap is the first pin, and the right side of the gap is the last pin, increasing in a counterclockwise direction.

4. Chip identification direction without identification point

There are also many chips that have neither dots, horizontal bars, or gaps on their surfaces, only silk screen printing of letters. For this kind of chip, place the chip upright so that the direction of the silk screen is positive, then the pin on the left is the first pin, the pin on the right is the last pin, and the increasing direction of the number is also counterclockwise.

5. Chip identification direction with dots

LQFP quad flat package chips are more common, and these chips are marked with dots. The pin on the left side of the dot is the first pin, and the pin on the other side is the last pin. The increasing direction is counterclockwise.

Decomposition of chip manufacturing process

So if you want to make a chip, first of all, you have to draw something like this and give it to Foundry (outsourced wafer manufacturing company)▼

Zoom in again▼

We finally see a gate circuit! This is a NAND Gate (NAND gate), something like this▼

A, B are inputs, Y is output

The blue one is metal layer 1, the green one is metal layer 2, the purple one is metal layer 3, and the pink one is metal layer 4. What about transistors ("transistors" since 199X have mainly been MOSFETs, that is, field effect transistors)? Look carefully at the picture. Do you see those white dots inside? That's the underlay, and some green borders? Those are Active Layers (i.e. doped layers).

The simplest chip principle

The simplest chip principle can be illustrated using a logic gate chip. A logic gate chip is a circuit composed of several transistors used to perform basic logic operations.

The simplest logic gate chips include AND gate, OR gate, NOT gate and XOR gate.

- The AND gate accepts multiple input signals, and the output signal is high only when all input signals are high at the same time (usually expressed as 1).

- The OR gate accepts multiple input signals, and as long as at least one of the input signals is high, the output signal is high.

- The NOT gate has only one input signal and will flip the input signal, that is, a high-level input will get a low-level output, and a low-level input will get a high-level output.

- The XOR gate accepts two input signals. When the two input signals are the same, the output signal is low level. When the two input signals are different, the output signal is high level.

Logic gate chips implement specific logic functions through different circuit connections and switching control of transistors. Because these chips contain only a small number of transistors and can directly process binary data, they can be regarded as the most basic components inside a computer.

Although the logic gate chip is one of the simplest chip principles, the design and function of the actual chip are very complex, including more circuits and functions.

Review Editor: Huang Fei


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