Hi,
I found several schematics on the net regarding the connection of a max232 to a pic.
As for its V+ pin is concerned, somtimes it is connected to +5V, sometimes to ground (both through a decoupling cap) whilst its V- pin is always connectd to the ground
Why ?
Do I connect V+ to ground or +5V ? What is the difference ?
PS : I will use the MAX232IN 😉
Regards
I found several schematics on the net regarding the connection of a max232 to a pic.
As for its V+ pin is concerned, somtimes it is connected to +5V, sometimes to ground (both through a decoupling cap) whilst its V- pin is always connectd to the ground
Why ?
Do I connect V+ to ground or +5V ? What is the difference ?
PS : I will use the MAX232IN 😉
Regards
I didn't see the MAX232IN listed in the data sheet, but connections can be found there see p. 17:
http://pdfserv.maxim-ic.com/en/ds/MAX220-MAX249.pdf
V+ and V- are outputs. V+ is connected to a cap, which goes to Vcc. V- is connected to a cap which goes to ground. Vcc is the power supply input.
http://pdfserv.maxim-ic.com/en/ds/MAX220-MAX249.pdf
V+ and V- are outputs. V+ is connected to a cap, which goes to Vcc. V- is connected to a cap which goes to ground. Vcc is the power supply input.
paulb said:
Yes I know that. But once again I've seen schematics where both V+ & V- are connected to ground (trough a cap) !
Why ?
Hello Zers
Those EIA RS232 adapters have to convert 0, 5V ttl to +12/-12 rs232 levels (same as V28 CCITT).
You connect +5V on Vcc pins, and it is all.
In the circuit, you will find a voltage doubler and a voltage inverter in order to output the good levels.
You just have to connect decoupling devices (Capacitor) on the pins V+ and V- . Those tension are internal and permit the +/-12V on the output.
Philippe
Those EIA RS232 adapters have to convert 0, 5V ttl to +12/-12 rs232 levels (same as V28 CCITT).
You connect +5V on Vcc pins, and it is all.
In the circuit, you will find a voltage doubler and a voltage inverter in order to output the good levels.
You just have to connect decoupling devices (Capacitor) on the pins V+ and V- . Those tension are internal and permit the +/-12V on the output.
Philippe
It is a charge pump converter to convert 5v into +/- 10v. Vcc and GND are the power supply pins. The others are internal connections for the charge pump doubler, inverter, etc.
Just do what everyone else does (or should be doing!) and use the schematic shown in the data sheet 🙂 Incidentally Maxim now have a chip to do this job that needs no external capacitors.
Just do what everyone else does (or should be doing!) and use the schematic shown in the data sheet 🙂 Incidentally Maxim now have a chip to do this job that needs no external capacitors.
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