UNDERSTANDING KEYPADS CIRCUIT, A WAY TO LEARN HOW TO REPAIR KEYPAD PROBLEM

UNDERSTANDING KEYPADS CIRCUIT, A WAY TO LEARN HOW TO REPAIR KEYPAD PROBLEM

Understanding the Keypad circuit may help and boost your knowledge on fixing keypad problem issues on mobile phones. Keypads is a part of user interface being used to navigate or enter numbers, letters and characters, browse application, sends information and etc.

An schematic diagram  below will help us understand how keypad circuits works and which components or parts did this circuit is being connected.
In this diagram the each and every key switching pads is being divided and grouped into rows andcolumns. Each rows and columns were group into 2 -5 keypads switch. This rows and columns have each corresponding lines according to each and every group of switching pads.

This lines of rows and columns is being filtered for EMI and ESD protection the EMI filter is made of tiny chip that used to protect such EMI and ESD interference.

This rows and columns lines are digital switching signals generated by the application processor to trigger or activate every corresponding digital datas that is being stored and programmed within the mobile phone system memory. This diagram below is an Application Processor that generates and feeds then receives digital data switching signals.

This digital data frequency signals corresponds and interpreted to each key characters that are marked on each keypads. Like for example a combination of row 2 and column 3 will triggered the number 3 when hitting on it.
 this block diagram below shows how the switching signal is being triggered to process a command data.

Various mobile phones have different keypads layouts and specification. A joystick and a volume switch is also parts of keypads switching circuits. Some keypads module designs are made into a flexible wire like those Slide Type package of mobile phones. Some flexible wires are very vulnerable  and common cause of keypad malfunction.