1

00:00:00,533 --> 00:00:05,066

lesson This lesson talks about the circuit related to the work of the SIM card,

2

00:00:05,300 --> 00:00:09,066

that is, the overall circuit structure of the SIM card

3

00:00:09,766 --> 00:00:15,600

In this circuit, first of all, here is the SIM card holder, also called the card slot

4

00:00:17,300 --> 00:00:22,700

This chip is called near-field communication chip, or NFC chip for short.

5

00:00:25,300 --> 00:00:29,566

Here is the power supply, usually the main power supply

6

00:00:30,166 --> 00:00:35,633

This is a CPU, or a baseband CPU with an independent baseband

7

00:00:36,033 --> 00:00:39,533

These are the components in the SIM card circuit

8

00:00:40,366 --> 00:00:42,266

Let's see how it works

9

00:00:43,066 --> 00:00:50,766

First of all, the power supply provides a power supply of about 1.8 volts to 3 volts to the NFC chip

10

00:00:51,233 --> 00:00:55,100

There is a power supply conversion inside the NFC chip,

11

00:00:55,400 --> 00:01:01,200

which converts the input power supply into 1.8 volts and gives it to the SIM card

12

00:01:03,333 --> 00:01:11,433

When we insert the SIM card, the card insertion detection signal will change from low level to high level, 1.8 volts

13

00:01:12,466 --> 00:01:17,333

When no SIM card is inserted, it is grounded, 0 volt

14

00:01:19,733 --> 00:01:23,033

When the baseband CPU detects a voltage change,

15

00:01:23,600 --> 00:01:30,300

it will notify the power supply and the NFC chip to complete the step-down and output power supply

16

00:01:31,866 --> 00:01:35,166

After the power supply is output to the SIM card seat,

17

00:01:35,166 --> 00:01:41,933

the baseband CPU will output a clock signal to the SIM card, and then reset the chip inside the SIM card

18

00:01:45,433 --> 00:01:50,466

After the SIM card receives power supply, clock signal and reset signal,

19

00:01:50,466 --> 00:01:56,133

the baseband CPU can read the information stored in the SIM card to access the network

20

00:01:57,266 --> 00:02:01,033

This is the working process of the SIM card circuit

21

00:02:02,900 --> 00:02:06,466

What we need to know is that the SIM card itself is a chip,

22

00:02:07,066 --> 00:02:11,266

so it needs to have power supply, clock, and reset to work

23

00:02:12,733 --> 00:02:14,900

That's all for this lesson