STA680 datasheet(37/48 Pages) STMICROELECTRONICS

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DS5877 Rev 13

37/48

STA680

Digital I/O and memory interfaces

Figure 13. Timing diagrams and waveform for the SDRAM interface

Table 17 reports the timing values for the SDRAM interface

For power saving and reduced interference on the board, the SDRAM speed can be

programmed to work at half speed with respect to the internal data processing:



Full Rate SW application: the SDRAM interface works at the same frequency as the

internal data processing (HD 1.0 and HD 1.5 applications supported);



Half Rate SW application: the SDRAM interface works at half frequency with respect to

the internal data processing (only available for HD 1.0 application upon specific

request).

Table 17. SDRAM interface timing values

Symbol

Parameter

Condition

Software

application

Min.

Max.

Unit

Tck

SCL clock period

Core in normal

drive

Full rate

7.35

Half rate

12.05

Tch

CLK high level width

2.5

Tcl

CLK low level width

2.5

Toh

Data out hold time

0.9

Tos

Data out setup time

1.5

Tis

Data In setup time

0.8

Tih

Data In hold time

1.6

Transition time

1.2

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