Seagate HAWK 4, Product Manual

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Product Manual - Hawk 4 Family SCSI-2 (Volume 1), Rev. F 49
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11.6.4 Electrical description
Model "N" uses single ended interface signals. These signals must be terminated with 110 ohm active termi-
nation circuits at each end of the total cable. The terminators are enabled (or disabled) by installing (or
removing) jumper plug TE. See Figure 10.1-1. Single Ended circuits use open collector or three state drivers.
See Figure 11.6.4-1.
The model ST15230ND uses differential interface signals and each of these must be terminated at each end
of the total cable with 330 ohms to +5 V and 330 ohms to ground with 150 ohms between each differential
pair. All I/O circuits are open collector, three state drivers. See Figure 11.6.4-2 for circuit drawing. Differential
I/O drives are shipped without terminators. These drives have no provisions for adding terminators on the
PCB. On these drives some method of external termination must be provided by the user Systems Integrator
or host equipment manufacturer.
11.6.4.1 Single ended drivers/receivers
Typical single ended driver and receiver circuits for the "N" are shown in Figure 11.6.4-1. Terminator circuits
shown (Note [1]) are to be enabled only when the disc drive is first or last in the daisy-chain. See section
11.6.4.3 on terminator requirements.
Transmitter characteristics
Single ended drives use an ANSI SCSI compatible open collector single ended driver. This driver is capable
of sinking a current of 48 mA with a low level output voltage of 0.4 volt.
Receiver characteristics
Single ended drives use an ANSI SCSI single ended receiver with hysteresis gate or equivalent as a line
receiver.