1

00:00:01,166 --> 00:00:06,066

Hello everyone, in this lesson we will talk about the common power supply methods in the mainboard

2

00:00:06,566 --> 00:00:09,533

There are 4 common power supply methods in the mainboard

3

00:00:09,733 --> 00:00:15,633

They are switch mode, LDO mode, PWM mode and op amp plus MOS power supply mode

4

00:00:18,600 --> 00:00:20,866

First, let's look at the switch mode

5

00:00:21,166 --> 00:00:26,900

The switching method is very simple, it is the input voltage equal to the output voltage

6

00:00:27,133 --> 00:00:33,500

It is mainly used to reduce the power consumption of the circuit and make the circuit more energy-saving

7

00:00:34,366 --> 00:00:38,566

We can understand the switch mode as the air switch at home

8

00:00:38,766 --> 00:00:42,733

Although the input and output of the open circuit are both 220 volts

9

00:00:43,166 --> 00:00:47,166

But after disconnecting the circuit breaker, there is no electricity at home.

10

00:00:47,166 --> 00:00:50,166

This is more energy efficient and safer

11

00:00:50,700 --> 00:00:54,566

The switch method used in the main board also has this function

12

00:00:55,333 --> 00:01:00,400

For example, the picture on the right, this is a 5 volt to 5 volt switch mode power supply circuit

13

00:01:01,900 --> 00:01:04,666

Next, let's look at the LDO power supply method

14

00:01:05,000 --> 00:01:08,600

The LDO method is a step-down power supply method,

15

00:01:08,866 --> 00:01:12,266

and its input voltage is not equal to the output voltage.

16

00:01:12,400 --> 00:01:15,966

For example, the circuit on the right is an LDO circuit

17

00:01:16,200 --> 00:01:20,200

Its input voltage is 5 volts and its output voltage is 3 volts

18

00:01:21,133 --> 00:01:25,966

The characteristic of the LDO power supply method is that there is a chip and no inductor

19

00:01:26,466 --> 00:01:29,366

It is generally used in circuits with relatively low power

20

00:01:29,733 --> 00:01:32,900

For example, 5VSB to 3VSB on the mainboard

21

00:01:36,100 --> 00:01:37,866

PWM circuit

22

00:01:38,300 --> 00:01:42,000

PWM circuit is also the input voltage is not equal to the output voltage

23

00:01:42,466 --> 00:01:45,333

It is characterized by a chip and an inductance

24

00:01:46,733 --> 00:01:52,433

In terms of purpose, both the PWM method and the LDO method play a role in reducing voltage.

25

00:01:53,200 --> 00:01:56,633

However, the power of the LDO power supply method

26

00:01:56,966 --> 00:02:00,766

is too small to meet the power supply needs of some chips on the mainboard.

27

00:02:00,966 --> 00:02:03,300

So there is a PWM method

28

00:02:03,500 --> 00:02:08,300

The output power supply capability of PWM mode is much larger than that of LDO

29

00:02:08,733 --> 00:02:11,666

For example, memory power supply on the mainboard

30

00:02:13,333 --> 00:02:17,133

The last one is the power supply method of op amp plus MOS

31

00:02:17,366 --> 00:02:22,300

For example, in the picture on the right, the chip in the middle is an op amp chip

32

00:02:22,466 --> 00:02:26,500

There is usually an N-channel MOS tube next to it.

33

00:02:26,700 --> 00:02:31,233

This is the power supply method of op amp plus MOS tube

34

00:02:31,833 --> 00:02:36,700

The op amp plus MOS tube circuit is also a step-down circuit, the input voltage is not equal to the output voltage

35

00:02:37,000 --> 00:02:40,133

Its output power is between PWM mode and LDO mode

36

00:02:41,366 --> 00:02:46,933

But its circuit scale and cost are much smaller than the PWM method

37

00:02:47,900 --> 00:02:52,766

It is mainly used in power supply such as VCCSA and VCCIO in the mainboard