Many people don't know the difference between the MAX232 and the MAX3232, and sometimes the author is confused, so I can write it myself as a record. Download the MAX232 and MAX3232 manuals on the official website, the man pages are general documents, the number of pages is quite large, briefly compare the common parameters.
1. Comparison of power supply voltage:
MAX232, the front page indicates that the supply voltage is 5V
The MAX3232 supply voltage is 3.0V-5.5V, and there is the word Low-Power, which is estimated to be lower than the MAX232, and the MAX3232 can reach a baud rate of 1Mbps, which is a bit of a flickering component, it is not the MAX3232 that achieves this rate, let's look down.
2. Power consumption comparison:
Let's first look at the MAX232 and MAX232A, this model is close, let's talk about it together, as shown in the figure below, the typical value of the two models in the No load state is about 5mA, MAX232A is slightly lower, this power consumption is relatively high in some low-power situations, pay attention to the selection.
MAX232
MAX232A
Looking at the MAX3232, the power consumption in the No load state is typically only 0.3mA, and the power consumption is okay, which is relatively low.
From the perspective of power consumption performance: NAX3232 is the lowest
MAX3232>MAX232A>MAX232
3. Rate comparison:
MAX232A, a little strange, why is the typical value 200, but the maximum value is 116, written incorrectly? Who knows why, trouble tell me.
MAX232, the rate parameter is not found in the manual table, but the rate is clearly written in the selection table, and the two values of 120(64) refer to the typical value and the maximum value. It can be seen that the performance of the MAX232A is still stronger.
Let's look at the MAX3232, which is better than the MAX232A.
From a rate perspective: MAX3232>MAX232A>MAX232
4. Typical application circuit
The following is a typical application circuit for the MAX232 and MAX232A, noting that the MAX232 has a recommended capacitance of 1uF and the MAX232A has a recommended capacitance of 0.1uF. Also pay attention to the C3 capacitor, this capacitor is connected to V+ here, and the other end is connected to the power supply.
The following is a typical application circuit of the MAX3232, the capacitors used are 0.1uF, pay attention to the C3 capacitor, the comment clearly states that the other end of the capacitor can be connected to the power supply or GND, but the MAX232/232A is not written, this difference should be noted, may cause problems that cannot be replaced with each other.
5. Summary:
1) MAX232/232 supply voltage is higher than MAX3232, now the circuit tends to low-voltage design, such as 3.3V, etc., MAX3232 has a wide supply voltage, more widely used, of course, the price is slightly more expensive.
2) Power performance: MAX3232>MAX232A>MAX232
3) Transfer rate: MAX3232>MAX232A>MAX232
4) Regarding the C3 capacitor problem, in the author's opinion, connecting the power supply and connecting GND here should have little to do with it, because V+ is only a positive power output pin, which requires an external filter capacitor, and the resistance between the power supply and GND is very small, so the connection to the power supply and GND are similar, I just extrapolate here, and have not experimented, of course, the author still recommends using the manual typical connection to design the circuit, after all, the manual is the most authoritative.
6. Digression:
Chips that conform to RS232 specifications are particularly many models on the market, domestic, foreign, high and low performance, high and low price, uneven, in the selection must carefully read the specifications. Especially when replacing a replacement model, be sure to actually test the performance.
Read more: The difference between the MAX232 and MAX3232