Product Manual - Hawk 1 Family SCSI-2 (Volume 1), Rev. D
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10.2
Synchronized spindles interface
The Synchronized Spindles Interface (SSI) allows several drives operating from the same host to operate
their spindles at a synchronized rotational rate. Details of the electrical and physical interfaces follow in
paragraphs 10.2.1 and 10.2.1.2 and 10.2.1.3. The system operation is described in paragraph 5.7.
10.2.1
Electrical description
The electrical interface consists of one digital TTL reference index signal and ground. The reference index
signal () is an output if the drive is configured as a master and is an input otherwise. The reference
index signal is connected from drive to drive in a daisychain fashion as shown in Figure 5.7-1.
10.2.1.1
Drivers and receivers
Figure 10.2.1-1 shows a diagram of the driver/receiver circuit. The driver circuits have the following electri-
cal specifications.
Negated (False): 0.0
V to +0.4
V @ I
= - 48 mA (max).
Asserted (True): +2.24 V to +5.25 V @ I
= +250 uA.
Notes:
[1] This connection is found only on "NC" drive models
Figure 10.2.1-1. SCSI reference index signal driver/receiver combination
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*See paragraph 10.2.1.2
39
Driver
Receiver
7.5K Ohm
GND
Main PCB
J1 - 37 [1]
J6 - 6
J6 - 5
+5V
SYNC
