MAX232: Construction, Operation, Types and Application

MAX232: Construction, Operation, Types Application, and different Electronics Circuits


What is MAX232?

Max232 is designed by Maxim Integrated Products. This IC is widely used in RS232 Communication systems in which the conversion of voltage level is required to make TTL devices to be compatible with PC serial port and vice versa.

This chip contains charge pumps which pump the voltage to the Desired Level. It can be powered by a single +5 volt power supply and its output can reach +_7.5 volts. MAX232 comes in 16 Pin Dip and many other packages and it contains Dual Drivers.

It can be used as a hardware layer converter for 2 systems to communicate simultaneously. Max232 is one of the versatile IC to use in most of the signal voltage level conversion problems.

Construction of MAX232:

Mostly MAX232 used in 16-pin DIP package. it consists of 3 major blocks.It can only be powered by 5 volts to make it power supply compatible with most of the embedded systems.

The first block is the voltage doubler in this ic switched capacitor technique is used to make the voltage double. Once the voltage is doubled the second block will converts that voltage to +10 and -10. The third block consists of 2 transmitters and 2 receivers which actually convert the voltage levels.



External components:

Max232 requires a minimum of 4 external capacitors. Their Value can range from 1μf to 10μf and 16 volts or more rating. There are many different versions of this versatile ic available each of them Requires a different capacitor value for proper working.


Application and uses of MAX232:

primarily, MAX232 is used in Serial communication. The problem arises when we have to communicate between TTL logic and CMOS logic-based systems.

RS232 is an internationally defined standard named EIA/TIA-232-E and in this standard logic 0 is the voltage between +3 to +15 and logic 1 is defined as the voltage between -3 to -15.In TTL logic 0 is defined is by 0 volt and 1 is defined by 5 volts so in this scenario this is a very handy IC to be incorporated.

Other Applications & Uses

  • Battery Powered RS 232 Systems
  • Interface Translation
  • Low Power Modems
  • RS 232 Networks (Multi-drop)
  • Portable Computing

PC Serial PORT communication by using a MAX232 IC:
Desktop and some old Laptops have Serial port which comes in DB9 package. For most of the Circuits, the designer is concerned about the Tx and Rx pins only so the function of the rest of the pins is not used here mostly.

In the above circuit, only one Driver is used and the second driver can be used for other purposes. TTL data is available on pin 12 and pin 11 and these pins can be attached to Microcontroller or any system which accepts TTL logic.


GSM Modem Communication:

There are many GSM modems available in the market and most of them are on TTL logic but some of them use RS232 standards and again it becomes a problem to communicate wilt GSM modem by using a Microcontroller, aurdino, or any other TTL platform.MAX232 is used to solve this problem.


Types of MAX232:

  • 1) “MAX232N” where “N” Represent PDIP package Style this package is easy to sold and most widely used.
  • 2) “MAX232D” where “D” indicates the SOIC package which is difficult to sold and required a trained professional to be used correctly.
Common Mistakes:
  • Capacitor voltage rating is less than 16.
  • Interchange Tx and Rx pins on one side of MAX232 at one time.
  • Distorted power supply. Use decoupling capacitor to remove distortion.
  • Check all the connections again.
  • Check the capacitor with a capacitance meter.
  • Use Tantalum Capacitor for better performance.

Credit: Electrical Technology, Scott W Harden, MAXIM

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