ADM 3202 Rx Tx problem

[absak]

Hi all,

I'm using ADM 3202 as TTL / RS 232 tranceiver, in fact i'm using only Rx Tx, VCC, GND pins of the ADM 3202 (pins 16, 15, 10, 9).

but when i connect the ADM to a 5 V power supply. (with V+ to vcc, V- to gnd), i'm retreiving 5V in the Rx Tx ????? (when the multimeter gnd is connected to V-)

can anybody have idea about this problem?

Regards,
absak

 

[FvM]

Did you connect the part according to the datasheet, including charge pump capacitors?

 

[absak]

No i had only connected only transmitter, receiver, Vcc and Gnd pins. is there a problem if the charge capacitors are not connected, and where to connect them??

Regards,

 

[milan.rajik]

Charge pump capacitors are the ones connected to Cx+ and Cx- pins.

 

[absak]

thank you,


what is their role?
and where to connect theme if i want to use only Rx, Tx, Gnd, Vdd in my transmit / Receive

 

[milan.rajik]

There role is in converting TTL level voltages to RS232 voltage levels. Whether you use only Rx or only Tx, for the Transreceiver to work you need them.