Monday, September 30, 2013

Electronic Component of IC MAX232 as the Peripheral Dual RS-232 Transmitter - Receiver

Robometricschool. - One of electronic component that categorized as the integrated circuit as peripheral transmitter and receiver for serial communication that usually used when we use microcontroller and computer is IC MAX232.

Figure 1. Pin configuration of IC MAX232

As describe that MAX232 is one type of IC circuit interface dual RS-232 transmitter / receiver that meets all specifications standards EIA-232-E. MAX232 IC requires only a 5V power supply (single power supply) as a power supply. IC MAX232 here serves to change the voltage levels on COM1 to the TTL voltage levels / CMOS. MAX232 IC consists of three parts, namely a dual charge-pump voltage converter, RS232 driver and receiver RS232.

Dual Charge-Pump Voltage Converter

IC MAX232 have two internal charge-pump which is used to convert the voltage +5 V to ± 10V (no load) for the operation of the RS232 driver. The first converter uses capacitor C1 to double the input voltage of +5 V to +10 V on C3 at the V + output. The second converter uses capacitor C2 to change the +10 V to-10V output when C4 is in V-.

1. Driver RS232

Output voltage swing (voltage swing) is ± 8V typical driver. This value occurs when the driver loaded with a nominal load of 5kΩ RS232 receiver or Vcc = 5V. Input on unused drivers can be left unconnected where - where. This can happen because the driver IC MAX232 input legs are pull-up resistors of 400kΩ connected keVcc. Pull-up resistor resulting output drivers unused to be low because all output drivers inverted.

2. Receiver RS232

EIA defines the voltage level of more than 3V as a logic 0, based on that all the receivers inverted. Receiver inputs can withstand input voltages up to ± 25V and set the input termination resistor with nominal value of 5k. Receiverhysteresis typical input value is 0.5 V with a minimum value of 0.2 V, and nilaidelay propogasi typicalnya is 600ns.

Figure 2. Typical Operations circuit IC MAX232

The picture above is a typical circuit operation MAX232 IC. Value of C1, C2, C3, C4, and C5 are recommended by 1μF.


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