Power Supplies - IBM Series 1 User Manual

R is the impedance looking into the OEM device receive input
pins. For reliable operation, R should be less than 200
ohms.
When the circuit driver is off, the maximum current out
of the transmit output is 500 microamperes and the voltage
across the transmit output pins is ~to
=
.0005 R, where R is
the input impedance of the OEM device receive input.
Solid state ~wit£~ (With Series Customer Supply). The
teletypewriter adapter transmit output is a solid state
switch. In the open or off-state, the maximum voltage the
switch can withstand is 52.8 volts. With this voltage, the
maximum current through the switch is
500
microamperes or
less.
In the closed or on-state, the maximum permissible
current through the switch is 100 mAe The voltage drop
across the switch in the closed or on-state must be less
than 0.08 volts.
Soli!! St~te Sw!tchLTT1 (without Series customer Supply). In
the open or off-state, the maximum output voltage is 5.5
volts at 50 microamperes. The minimum output voltage is 2.4
volts at
1
rnA.
In the closed or on-state the maximum output voltage is
0.8 volts. The minimum output voltage is 0.0 volts.
EIA.
The EIA outputs conform to EIA RS 232-C/CCITT V.24
specifications. The output driver is an SN74150 TTL driver.
If the
±12
volt supply is not installed, the EIA transmitted
data signal and the data terminal ready signal are in the
power-off condition. For attached devices using the EIA
input for receive only operations, the
±12
volt supply
option is not required. In this case, the EIA data terminal
ready signal generated by the attached device should be
wrapped back to the input that would normally be connected
to the data terminal ready output of the teletypewriter
adapter.
The teletypewriter adapter does not require any external
power supplies. All power required
by
the teletypewriter
adapter is obtained from the I/O card file in which the card
is inserted.
The only exception to this is when the user elects to
attach his device to the isolated current loop interface.
In this case, the user must supply a 25 volt (100 mAl power
supply and a current limiting resistor for the transmit loop
and also for the receive loop.
The series resistor should be of such value as to limit
the current in each loop to 20 al. See Pigure 4-9 for a
diagram of how to connect the power supplies and resistors.
4-26
GA34-0033
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