Synchronized Spindles Interface; Electrical Description - Seagate ST11200N Product Manual

Product Manual - Hawk 1 Family SCSI-2 (Volume 1), Rev. D
_____________________________________________________________________________________
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 (REFIND+) 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
Asserted (True): +2.24 V to +5.25 V @ I
Notes:
[1] This connection is found only on "NC" drive models
Figure 10.2.1-1. SCSI reference index signal driver/receiver combination
__________
*See paragraph 10.2.1.2
V to +0.4 V @ I = - 48 mA (max).
= +250 uA.
Driver
7.5K Ohm
+5V
Main PCB
Receiver
SYNC
REFIND +
GND
39
J1 - 37 [1]
J6 - 6
J6 - 5