Seagate ST31000640FC Signal characteristics, Device control codes, TTL input characteristics

9.5.12Device control codes

The drive inputs a Device Control Code on the DEV_CTRL_CODE lines at power up to determine the link rate on the Fibre Channel ports. Both ports run at the same rate. If the backpanel does not connect to these lines, the drive has 10K ohm pull up resistors that default the device control code to 7 (1.0625 GHz). Table lists the supported codes.

Table 23:	Device control code values
2 (pin 17)		1 (pin 18)	0 (pin 39)	Definition
0		0	0	Reserved for power failure warning.
0		0	1	Reserved for auto negotiation of link rate.
0		1	0	Reserved.
0		1	1	Reserved.
1		0	0	Reserved.
1		0	1	4.250 GHz operation on both ports.
1		1	0	2.125 GHz operation on both ports.
1		1	1	1.0625 GHz operation on both ports.

9.6Signal characteristics

This section describes the electrical signal characteristics of the drive’s input and output signals. See Table 19 on page 58 for signal type and signal name information.

9.6.1TTL input characteristics

Table 24 provides the TTL characteristics.

Table 24:	TTL characteristics
State		Voltage		Current
Input high		1.9	< VIH < 5.5V	IIH = ±500nA max.
Input low		-0.5V < VIL < 0.9V		IOL = ±500nA max.
Output high (-EN Bypass A, B)		2.4	< VOH < 5.25V	IOH < -3mA
Output low (-EN Bypass A, B)		VOL < 0.5V		IOL < 3mA
Output high (-Parallel ESI)		2.4	< VOH < 0.9 VCC	IOH < -2.4mA
		VOH > 0.9VCC		IOH < -500µA
Output low (-Parallel ESI)		0 < VOL < .45V		IOL < 2.4mA
Output high (all other outputs)		2.4	< VOH < 0.9 VCC	IOH < -1.6mA
		VOH > 0.9VCC		IOH < -500µA
Output low (all other outputs)		0 < VOL < .45V		IOL < 1.6mA

Barracuda ES.2 FC Product Manual, Rev. B 63