Texas Instruments THUNDER TNETX3270 User Manual
Page 52
TNETX3270
ThunderSWITCH
24/3 ETHERNET
SWITCH
WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS
SPWS043B – NOVEMBER 1997 – REVISED APRIL 1999
52
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
Outputs are driven to a minimum high-logic level of 3.3 V and to a maximum low-logic level of 0 V.
Output transition times are specified as follows: For a high-to-low transition on either an input or output signal, the
level at which the signal is said to be no longer high is 1.4 V and the level at which the signal is said to be low is 1.4 V.
For a low-to-high transition, the level at which the signal is said to be no longer low is 0.8 V and the level at which
the signal is said to be high is 2 V, as shown in the following.
The rise and fall times are not specified but are assumed to be those of standard TTL devices, which are typically
1.5 ns.
0.8 V (low)
2 V (high)
1.4 V
test measurement
The test-and-load circuit shown in Figure 12 represents the programmable load of the tester pin that is used
to verify timing parameters of the TNETX3270 output signals.
TTL OUTPUT TEST LOAD
CL
IOH
VLOAD
IOL
Where: I
OL
= Refer to I
OL
in recommended operating conditions.
I
OH
= Refer to I
OH
in recommended operating conditions.
V
LOAD
= 1.5 V, typical dc-level verification or
1.5 V, typical timing verification
C
L
= 45 pF, typical load-circuit capacitance
TTL
Output
Under
Test
Test
Point
Figure 12. Test-and-Load Circuit