Mobile Phone Sections and Parts in Every Section

Different Sections on a Mobile Phone PCB, Components in Each Section and Their Function.

Mobile Phone Sections – A Mobile Phone PCB is Divided into 3 Main Sections – (1) Network Section; (2) Power Section; and (3) Audio Section (in Android Smartphone and iPhone). This is applicable to all Mobile Phones and Smartphones of All Brands including – Samsung, Nokia, LG, Motorola, Sony Ericsson, Acer, Alcatel, Apple, Amoi, Asus, BenQ, Siemens, Bird, Blackberry, Blu, Celkon, Dell, Gigabyte, Haier, HTC, Huawai, Micromax, Panasonic, Philips, Sagem, Spice, Toshiba, ZTE Etc.

Mobile Phone Sections and Parts Inside a Mobile Cell Phone

Mobile Phone Sections and Parts Inside a Mobile Cell Phone

Mobile Phone Sections and Components / Parts in Each Section and Their Function

As I mentioned above, there a Mobile Phone or Smartphone PCB can be Broadly Divided into 3 Main Sections – Network Section, Power Section and Audio Section. Now, these Broad Sections can again be Divided in Several Small Sections for Easy of Understanding. Let us Understand these All These Sections in Detail and Electronic Components and IC Parts Present in these Sections and Their Function.

1. Keyboard or Keypad Section

The keyboard section of any mobile cell phone is directly connected with the CPU. This means that rows and columns of keys are directly connected with the CPU. Protector IC or Interface IC or Varactor diode is connected in the row or column line for the protection of key section. In modern mobile cell phones which have qwerty keys, a separate control IC is connected with the CPU for extra protection to the keys.

In Latest Android Smartphones and Apple iPhone, there is No Physical Keypad. The Keys are Displayed and Controlled by the Operating System (OS) and Apps. These Virtual Keys on the Display are Controlled by a Touch Screen Connected Separately to the PCB / Logic Board.

Read: Mobile Phone Keypad Not Working Problem and Solution

2. Display Section

The phone display section is directly connected with the CPU to receive following signals – LCD Data Signal, LCD Reset Signal, LCD WR Signal, LCD RD Signal, LCD FLM Signal, LCD HSYN Signal etc. These signals are given to the LCD Module through the CPU. 2.8V power supply or 1.8V power supply is given to the LCD for functioning. LCD signal interface filter are connected in many mobile cell phones for interfacing these signals of LCD Module.

3. SIM Card Section

The SIM Card Interface section is directly connected with the CPU in most mobile cell phones. If there is no power supply in a mobile phone then the SIM section is connected with the CPU through the Power IC. Mainly V-SIM (3.0V), SIM-RST (2.85V), SIM CLK, SIM-Data (2.5V), and SIM GND are made in the SIM Section. These four pins (Beside SIM GND) are directly connected with the SIM interface / control section and V-SIM volt are given to the SIM data pin from V-SIM pin through the 10-18 Kilo Ohms Resistance.

4. Memory Card Section

Now mostly Micro SD Card is connected in most mobile cell phones which is connected with micro card section through a 8 pin socket. Memory card section is made inside the CPU. Description of these 8 pins are as follows:

  1. MMC-Data-2
  2. MMC Data
  3. MMC CMD (Command)
  4. VMMC / VSD (Positive Supply Pin)
  5. MMC-CLK
  6. GND
  7. MMC-Dta0
  8. MMC Data-1

2.8 Volt Power is supplied to Pin Number 4 from Power Supply for functioning of the MMC Card and connection the 50 tp 100 Kilo Ohms resistance in this power supply. This power supply is given to Pin Numbers – 1,2,3,7,8 of MMC Socket. One MMC detector switch or pin is made in MMC socket at which, if there is no MMC Card then 1.8 V power is continuously received and after the MMC is connected, it becomes zero.

5. MIC Interface Section

MIC interface section is directly connected with the CPU in most mobile phones. Working voltage (MIC Bios) (1.8 to 2.8 V) is supplied from the CPU or the Power Supply Section for functioning of the MIC and MIC Positive and Negative Volt are input through two SMD Capacitors.

6. Ear Speaker Section

In most modern mobile cell phones, in which there is a separate ear speaker, it is directly related to the CPU. It receives sound via signals directly from the CPU or from the audio section inbuilt within the CPU. In some mobile phones, these sound signals are received via SMD Coil / SMD Resistance. Some mobile phones have audio IC in the audio section. Some mobile phones have audio amplifier.

7. Speaker / Ringer Section

Ringer, Buzzer or Speaker in most mobile phones are connected with the audio amplifier IC to obtain loud sound. The amplifier IC amplifies the sound or audio signal received from the CPU of the audio section.

8. Key Backlight Section

LED Lights are connected according to the parallel circuit in the key backlight section. Anode ends of all the LEDs are connected to each other and all the cathode ends are connected to each other. 3 to 3.3 V is supplied for the functioning of these Key LED Lights. This power supply is given to the cathode ends of LEDs from the ground ends. Power supply to the anode ends of LED Lights is controlled bu using LED-Driver or PNR IC.

9. LCD Backlight Section

LCD Backlight in mobile cell phones is made according to the series circuit. A Boost Voltage Generator Section is built for the supply of high voltage (10 to 18V) for the functioning of the LCD LED. Boost coil, Boost Volt Driver IC, Rectifier Diode etc are present in this section.

10. Vibrator Motor Section

Positive power supply is given to this section directly from the positive end of the battery. Negative power supply is given through a NPN transistor or from the ground of any circuit.

Read: Mobile Phone Vibrator Problem and Solution – Vibration Not Working

11. Network Section

Antenna, External Antenna Socket, RX-Band Pass Filter, RF Crystal, FEM, PFO, TX-Band Pass Filter, RF IC, CPU are connected in the Network Section. Signal received at the antenna during the RX is given to the antenna switch or FEM through the antenna socket where the next processing is completed by selecting a frequency of proper band and is passed on to the RF IC through RX-Band Pass Filter. RF Signal out from the RF IC during TX is given to the FEM or PFO to amplify the signal. After the Band Selection Process the signal is passed through the antenna.

Read: Mobile Cell Phone Network Not Working Problem and Solution

12. Battery Charging Section

Charger and system interface connector is made together in most modern mobile cell phones. Regulator section is made separately for the battery charging section. In some mobile phones, the battery charging section is made inside the Power IC.

Read: Mobile Cell Phone Battery Charging Problem and Solution

13. FM Radio Section

FM Radio Driver IC, FM Antenna, Signal and Supply Components are made in the FM Radio Section.

14. Bluetooth Section

Bluetooth Antenna, Bluetooth RF Signal Filter, Bluetooth Driver IC, Supply and Signal Components are made in this section. The Bluetooth sections functions like the Network Section. RF-CLK signal is given to the Bluetooth driver IC during signal processing.

Read: iPhone Bluetooth Not Working – Problem and Solution

15. Set Power ON

Power IC, CPU (UCP), Flash IC, RF-CLK, Crystal, RF-IF, PWR Ket etc components are present this section. Battery positive supply is given to the power IC and connecting the battery (3.7V) from 2.87 to 3.0 Power ON Volts are received at one tip of the Power Key. Supply is given to the CPU, Flash IC, RF-CLK, Generator Section (RF Crystal, RF IC) by which the mobile phone gets switched ON.

16. Hands-free / Earphone Section

Mainly hands free jack, hands free MIC, speaker signal component and hands free audio amplifier are present in this section. Hands free symbol is displayed after connection the Handsfree jack.

Read:

Video: Mobile Phone Sections and Components

Mobile Phone Sections FAQs

The power management IC on a mobile phone PCB regulates the power supply to different components of the device. It receives power from the battery and converts it to the appropriate voltage levels required by different sections, such as the processor, memory, display, and camera.

The RF (Radio Frequency) circuit section on a mobile phone PCB is responsible for transmitting and receiving radio signals for communication. It includes components like the antenna switch, power amplifier, and RF filter, and is crucial for ensuring the device can connect to a cellular network and transmit and receive voice and data signals.

The audio circuit section on a mobile phone PCB is responsible for processing and amplifying sound signals for output through the device's speaker or headphone jack. It includes components like the audio codec, digital signal processor, and amplifier, and is essential for ensuring the device can produce high-quality sound output.

In some cases, individual sections or components on a mobile phone PCB can be repaired or replaced if they are damaged or faulty. However, this requires specialized tools and expertise and is generally not recommended for inexperienced users. It is often more cost-effective to replace the entire PCB or the entire device if major repairs are required.

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Santosh Das

Santosh is an Electronics Geek, Blogger, Young Entrepreneur and Founder of this Mobile Phone Repairing Website. Santosh possesses vast experience in the field of electronics, telecommunication, Soldering, SMT, ESD Safety, Keep visiting for daily dose of Tips and Tutorials.

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33 Responses

  1. ajithkumar says:

    my redmi note 8pro some time low 4g rang and night automaticaly it will emergncy call 12 to 5am after 5am show netwrks.it will happen daily.how can solve this prblm.plz help me

  2. Roshan says:

    This section is no longer available..

    Keeps displaying on screen ..whats this error?

  3. Gaurav.A.C says:

    Thankyou for the quality information sir, ive been facing an issue with my phone’s network (both sim & wifi). Im not really sure what the problem is but it has really become very frustrating. Its been dead without connectivity for 2 weeks almost and due to the lockdown im not able to get it serviced. Any advice would be much appreciated. Thankyou.

    • Dial *#06# and Check if it Shows the IMEI Number. If Not then you have to Flash the IMEI Numbers. I have already Posted on How to Flash IMEI Number.

  4. Giri says:

    I had read your mobile service through your website and I get a idias Very very fentastic keep it up tank you and like it . sir you provide only mobile service are laptop and computer repair also . Why because I need it.

  5. KIIZA EMMANUEL says:

    My brother, I have enjoyed your directions and teachings towards mobile phone repair.
    If I had capital, I would have opened my business with full confidence.

  6. UPENDRA SONKAR says:

    MERA MOBILE MICROMAX E 4815 IS MOBILE KA CHARGING PORT KHARAB HAI BAHUT SLOW CHARGE HOTA HAI AUR MERA MOBILE JB TK WORK KRENGE ON RHTA HAI DISPLY OFF TO MOBILE OFF AGAR KUCH KR RHE HAI JAISE HOTSPOT YA DOWNLOAD USE KR RHE TO ON RHTA HAI OTHERWISE SWICTH OFF PLESE GIVE ME A SOLUTION

  7. Hamed says:

    greeting to you
    my brother in true your work is awesome
    in fact a real concept from electronic and repairing
    am a programmer and engineer in artificial intelligence. but your shocker very very useful for me
    with thanks
    Hamed Behzadi from persia(iran)

  8. Don says:

    My Asus Zenfone max network only works on 4G signal. I have checked the preferred netwok type and its in 2G/3G/4G auto. What should I do.

  9. Priya says:

    It was very helpful in understanding Mobile phone

  10. Jitendra kumar mandal says:

    It most be helpfull site for solve in mobile repairing .thanku bhai.

  11. Atingane Francis says:

    Santosh,
    I am new to this course and am sure it is going to help me a lot
    Thanks

  12. jb says:

    Good work. . . helpful to me

  13. Akissi Simon Yaw says:

    Just wanted to put up a thorough research lesson on all fields of technology. It’s my desire to bring “something” new to the world. I will move the world to any level.

  14. Asjid says:

    Santosh sir how to find out the whether point of sim in short through analog multimetre..??

  15. Sano says:

    Thanks you Mr Santosh Das. We appreciate the knowledge you give us here.

  16. Yilma says:

    thanks

  17. vivek yewale says:

    hello sir, my name is vivek. how to find power ic, rf ic, cpu, blutooth ic, wifi ic

  18. Waqas says:

    Brother mare pas huawei p8lite phone hai.us ka camra open kerta hn tu.lehka ata hai.third party use camera such as torch.plz close and try again.
    So plz help me what’s problem .and tell me it’s solution.

  19. salifu says:

    in my mind this is the most important aspect of becoming a good technician. The issue is that each phone comes with its own topology or design. so Mr. Santosh, what is the secret of identifying these components on any type of mobile phone pcb e.g galaxy s3, htc one m7 etc? thanks

  20. sanju bankar says:

    Nice…

  21. Satish says:

    Thanks to u this very help ful to me

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