TMS320C31, TMS320LC31

DIGITAL SIGNAL PROCESSORS

SPRS035B – MARCH 1996 – REVISED JANUARY 1999

25

POST OFFICE BOX 1443

changing XFx from an output to an input

The following table defines the timing parameters for changing the XFx pin from an output pin to an input pin.

The numbers shown in Figure 19 correspond with those in the NO. column of the table below.

timing parameters of XFx changing from output to input mode for TMS320C31 (see Figure 19)

NO.

’LC31-33

’C31-40

’LC31-40

’C31-50

’C31-60

’C31-80

UNIT

MIN

MAX

MIN

MAX

MIN

MAX

MIN

MAX

MIN

MAX

34

th(H3H-XF)

Hold time, XFx after

H3 high

15†

13†

12†

11†

9†

ns

35

tsu(XF-H1L)

Setup time, XFx

before H1 low

10

9

9

8

6

ns

36

th(H1L-XF)

Hold time, XFx after

H1 low

0

0

0

0

0

ns

† This value is characterized but not tested.

Execute

Load of IOF

Buffers Go

From Output

to Output

Synchronizer

Delay

Value on Pin

Seen in IOF

H3

H1

XFx Pin

INXFx Bit

(see Note A)

I / OxFx Bit

(see Note A)

34

35

36

Data

Sampled

Data

Seen

Output

NOTE A: I / OxFx represents either bit 1 or bit 5 of the IOF register, and INXFx represents either bit 3 or bit 7 of the IOF register.

Figure 19. Timing for Change of XFx From Output to Input Mode