3V~5V TTL/CMOS to RS232 Level Shifter for ADSL Modem
ADSL Modem Serial Cable Circuit (Half-Duplex)
Power supplied by RS232 DTR & RTS (pull high), 6V~12V. For example, 10V/7.5mA
RS-232 Input Resistance: 3K~7K Ohm, typical 5K Ohm.
TTL/CMOS Input Resistanc: 400K Ohm.
Transmitter steals power from receive signal line.
Most RS-232 receivers will correctly interpret any voltage over 2 volts as a space. |