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DIRECTV Set-top box information for the installer
DIRECTV Proprietary November 17, 2005
Version 1.1.a Page 11 of 49 DTV-MD-0058
3.7 Low-Speed Input Characteristics
3.7.1 Input Signaling Characteristics (Pin 3)
The low-speed data port will comply with the input signaling characteristics shown in Table 5.
Table 5: Input Drive Characteristics
Parameter Specification
Space voltage +3.0 volts min, +25 volts max
Mark voltage -25 volts min, -3.0 volts max
Terminating impedance
Resistance
6K < R < 7K resistive to ground
Capacitance C < 150 pf
3.8 Low-Speed Output Characteristics
3.8.1 Output Drive Characteristics (Pin 2)
The STB output drive characteristics are as shown in Table 6.
Table 6: Output Drive Characteristics
Parameter Specification
Space voltage +5.3 volts max at Ioh = 0 mA, +3.0
volts min
Mark voltage -6.0 volts min at Iol = 0 mA, -3.0 volts
max,
Terminating impedance
Resistance
3k < R < 7k resistive to ground
Capacitance C < 2500 pF
3.8.2 Passive Outputs (Pins 1, 6, 8, and 9) (Optional)
If the data port optional pins one (1), six (6), eight (8) and nine (9) are provided, the passive
outputs will be as shown in Table 7.