8 signal transition levels – Texas Instruments Digital Signal Processor SM320F2812-HT User Manual

Page 91

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0.4 V (V

OL

)

20%

2.4 V (V

OH

)

80%

0.8 V (V

IL

)

10%

2.0 V (V

IH

)

90%

SM320F2812-HT

www.ti.com

SGUS062B

JUNE 2009

REVISED JUNE 2011

6.8

Signal Transition Levels

Note that some of the signals use different reference voltages, see the recommended operating conditions
table. Output levels are driven to a minimum logic-high level of 2.4 V and to a maximum logic-low level of
0.4 V.

Figure 6-5

shows output levels.

Figure 6-5. Output Levels

Output transition times are specified as follows:

For a high-to-low transition, the level at which the output is said to be no longer high is below 80% of
the total voltage range and lower and the level at which the output is said to be low is 20% of the total
voltage range and lower.

For a low-to-high transition, the level at which the output is said to be no longer low is 20% of the total
voltage range and higher and the level at which the output is said to be high is 80% of the total voltage
range and higher.

Figure 6-6

shows the input levels.

Figure 6-6. Input Levels

Input transition times are specified as follows:

For a high-to-low transition on an input signal, the level at which the input is said to be no longer high
is 90% of the total voltage range and lower and the level at which the input is said to be low is 10% of
the total voltage range and lower.

For a low-to-high transition on an input signal, the level at which the input is said to be no longer low is
10% of the total voltage range and higher and the level at which the input is said to be high is 90% of
the total voltage range and higher.

NOTE

See the individual timing diagrams for levels used for testing timing parameters.

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©

2009

2011, Texas Instruments Incorporated

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