What is MAX232 IC : Pin Configuration & Its Applications

The MAX232 IC was developed through Maxim Integrated Products which works like a Voltage Logic Converter for changing TTL Logic level into TIA or EIA-232-F level. It plays a key role in between PC and microcontroller for communication. This IC is used in different applications like terminals, battery-powered systems, computers, modems, etc.

What is MAX232 IC?

MAX232 IC is widely used for serial communication among Microcontrollers & PC. The main function of this integrated circuit is to change the logic levels of TTL/CMOS to RS232 throughout the serial communication process.

Generally, a microcontroller works at TTL of about 0 to 5V while a computer operates on the standards of RS232 like -25 to +25V. So interfacing a computer with a microcontroller is not possible without a MAX232 IC. For example; if you want to connect a PIC microcontroller to the serial pin of a laptop, then you must place MAX232IC among them.


Here, laptop serial ports like 9 pin work through RS232 Voltage Logic whereas the serial ports of Microcontroller like Tx & RX pins work on transistor Logic. The equivalent RS232 Converters of MAX232 are RS232 module, MC1488, RS232 adapter cable & FT232RL

Structure of IC

MAX232 IC includes three main blocks shown in the following diagram. It operates with 5 volts of power supply so that it is compatible with almost all embedded systems. The voltage doubler is the first block and in this IC, a switched capacitor method is utilized to make the voltage twice.

Whenever the voltage is doubled then the next block will convert the voltage to +10 & -10. And the final block includes two transmitters & two receivers which convert the levels of voltage.

MAX232 IC Structure
MAX232 IC Structure

Types of MAX232 IC

MAX232 ICs are available in two types like MAX232N & MAX232D

  • In MAX232N IC, “N” signifies the package style of PDIP and this package is simple to sell & most extensively used.
  • In MAX232D IC, “D” signifies the SOIC package & it is hard to sell but requires a skilled professional to be utilized properly.

MAX232 IC Pin Configuration

MAX232 IC includes 16 pins where each pin is described below. This IC needs four capacitors externally for its proper design. These four capacitors range from 8 to10

MAX232 IC Pin Configuration
MAX232 IC Pin Configuration

uf with up to 16 volts. Here each pin with its function is described below.


  • Pin-1(C1+): The positive terminal of a capacitor is connected to this pin
  • Pin-2(Vs+): The capacitor’s positive leg is connected to it by grounding the negative leg.
  • Pin-3(C1-): The negative pin of the capacitor is connected to this pin and the positive pin is connected to pin1
  • Pin-4(C2+): The positive terminal of a capacitor is connected to this pin
  • Pin-5(C2-): The negative terminal of a capacitor is connected where the positive terminal is connected to Pin4.
  • Pin-6(Vs-): The negative terminal of a capacitor is connected to this pin & 5 volts is provided to the positive terminal of the capacitor.
  • Pin-7(T2OUT): It provides the converted TTL signal in the form of RS-232. Here TTL signal can be obtained by T2IN Pin from the microcontroller and this pin is connected to Pin2 of DB-9 port of your computer like Rxd.
  • Pin-8(R2IN): This Pin gets the signal of RS-232 like an input & provides the changed signal in the form of TTL on the R2OUT pin. This pin is connected to DB9 Port’s Txd pin, which is Pin3.
  • Pin-9(R2OUT): It provides the signal changed within TTL form. The signal is received from Pc at R1In Pin. Connect this pin to your module (TTL) Rxd pin which receives the signal.
  • Pin-10(T2IN): This pin gets transmitted signal from microcontroller & gives the changed RS-232 signal over T2OUT pin. Here, the signal can be transmitted from the microcontroller serial port’s txd pin. This pin can be connected to your Txd pin of the module.
  • Pin-11(T1IN): This pin works like a T2IN.
  • Pin-12(R1OUT): This pin works like an R2OUT.
  • Pin-13(R1IN): This pin works like an R2IN.
  • Pin-14(T1OUT): This pin works like aT2OUT.
  • Pin-15(GND): This pin is a GND pin.
  • Pin-16(VCC): This pin is a voltage supply pin where 5V is provided to this pin.

MAX232 IC Working

We know that the main function of Max 232 IC is to change the signal of TTL logic level into its corresponding RS-232c level signal & then Rs-232c level signal to its corresponding TTL level signal.
This IC is very useful while making a connection between two devices to transfer the data.

For instance, almost all the microcontroller’s functions are on the waveform of TTL logic. These microcontrollers include a UART that can be used to transmit & receive serial data because they work over the TTL level thus they send & receive composed TTL waves from data while typical PC functions on the level of RS-232 waveform.

If we want to send the data from the microcontroller to a personal computer then we require changing data to Rs 232 level from TTL. So MAX232 IC is the best solution for converting this data. This IC works up to 120 Kbits per sec and it includes two receivers & two driver channels.

The highest distance it can transmit data ranges from 12 – 15 meters. So this IC is applicable in terminals, modems, computers, scanners, printers, fax machines, etc.


The main features of MAX232 IC include the following.

  • It is available in 16-pin SOIC, PDIP & SO packages
  • Simple to Setup & Initialize
  • Operating Speed is120kbit/s
  • Operating Current is 8mA
  • Input Levels ±30V
  • Conversion IC from TTL or CMOS to RS232
  • At a time it supports two conversions like dual drivers & receivers
  • The simple way to change the TIA/ EIA 32 to CMOS/TTL is simply a 5V power supply.
  • A 1.0uF capacitor is used to resolve the issue of power decimation.
  • The voltage levels of RS232 devices are different in some cases
  • Its highest working temperature is 150o C.

Packages, Dimensions & Ratings

The packages of MAX232 IC include the following.

  • The packages of MAX-232 IC are SOIC (16), SOP (16) & PDIP (16)
  • The package dimensions of MAX 232 IC include the following.
  • The dimension of the SOIC (16) package is 9.90 X 3.91 mm
  • The dimension of the PDIP (16) package is 19.03 X 6.35 mm
  • The dimension of the SOP (16) package is 10.03 X 5.3 mm
  • The ratings of MAX232 IC are the current, voltage & power ratings of IC that show its power requirement so that how much current & voltage is used for its operation can be known.
  • Input voltage ranges from -0.3 to 6v
  • Output voltage ranges from 0.3 to +0.3
  • The operating temperature is 150oC

MAX232 IC Circuit Diagram

The circuit diagram of MAX32IC for level shifting of RS232-TTL is shown below. The following circuit is applicable for microcontrollers. This circuit mainly permits the levels of shifting in between TTL & RS232.

The circuit can be built with the MAX232 IC and four exterior capacitors for producing maximum voltage internally. This IC has different clones which have similar functionality but are usually not expensive. It’s achievable to exchange them without any problem.

Level Shifting from RS232 to TTL
Level Shifting from RS232 to TTL

If the signal of TTL is low voltage within some modern microcontrollers, then it is essential to swap the MAX232 IC in support of the MAX3232, here both are similar except it functions from approximately 3V up. If the IC is not accessible, it might be feasible to utilize a usual MAX232 through a less voltage supply, however, the output might not be within the limits described through the standard of RS232.

The highest suggested distance is approximately 10 meters at 115200 bps. If maximum distances are required, it is achievable to utilize other protocols or standards like RS485 that employ differential signaling, thus the noise doesn’t change them a lot. Usually, this technique needs more wires.

Where to Use MAX232IC/Applications

The applications of MAX232 IC include the following.

  • It is used to interface microcontroller through PC
  • Computers
  • Used to convert from TTL or CMOS logic to RS232
  • Modem.
  • Terminals
  • Utilized within RS232 cables
  • Portable Computing
  • Transactions of Interface
  • RS232 System Powered with a Battery
  • Fewer Power Modes

Thus, this is all about an overview of the MAX232 IC datasheet and this IC is used widely within the communication systems of RS232 where the voltage level conversion is necessary to create TTL devices to be well-matched through PC serial port. This chip can be used as a hardware converter layer for two different systems to converse at the same time. Max232 IC is one of the flexible ICs to utilize in most of the voltage level signal conversion difficulties. Here is a question for you, what is RS232?