Рекомендации по выбору LPT кабеля
Для нормальной работы в режимах EPP/ECP согласно рекомендациям IEEE P1284 кабель должен иметь двойной экран и обладать следующими характеристиками:
The minimum conductor size shall be #28AWG (0.080 mm 2 )
The characteristic unbalanced impedance of each signal and ground pair shall be 62 . ± 6 ., over the frequency band of 4–16 MHz.
The unbalanced capacitance of each cable pair shall not exceed 107 pF/m at 1 MHz.
The maximum dc resistance of each cable wire shall be 0.232 ./m at 20 °C.
Maximum end-to-end attenuation shall not exceed 1.5 dB at 5 MHz.
The maximum propagation delay of the cable shall be 58 ns.
The maximum propagation delay difference between any two signal pairs shall be 2.5 ns.
The maximum zero-to-peak crosstalk noise (both near end and far end) shall be 10% as measured with a 5.0 ns rise/fall 2 MHz square wave, with each pair (source and victim) terminated in its char-acteristic impedance at both ends (see figure 33).
The cable shall have a minimum of 85% optical braid coverage over the foil.
The cable shield shall be connected to the connector backshell using a 360° concentric method low impedence connection. A pigtail type connection is not acceptable.
Each signal pair shall be twisted at least 36 turns per meter.
