SMJ320LC549 Datasheet, PDF (35/52 Pages) Texas Instruments – FIXED-POINT DIGITAL SIGNAL PROCESSOR

serial port transmit timing
SMJ320LC549
FIXEDĆPOINT DIGITAL SIGNAL PROCESSOR
SGUS032B – OCTOBER 2002 – REVISED MAY 2003
switching characteristics over recommended operating conditions for serial port transmit with
external clocks and frames (see Figure 22)
PARAMETER
td(DX) Delay time, TDX valid after TCLKX rising
th(DX) Hold time, TDX valid after TCLKX rising
tdis(DX) Disable time, TDX after TCLKX rising
*Not production tested.
549-60
MIN MAX
25
–5*
40*
UNIT
ns
ns
ns
timing requirements for serial port transmit with external clocks and frames [H = 0.5t_c(CO)]
(see Figure 22)
549-60
UNIT
MIN MAX
tc(SCK) Cycle time, serial port clock
6H*
† _ns
td(FSX) Delay time, TFSX/TFRM after TCLKX rising edge
2H–5 ns
th(FSX) Hold time, TFSX/TFRM after TCLKX falling edge (see Note 1)
th(FSX)H Hold time, TFSX/TFRM after TCLKX rising edge (see Note 1)
6*
ns
2H–5*^‡ ns
tf(SCK) Fall time, serial port clock
6* ns
tr(SCK) Rise time, serial port clock
6* ns
tw(SCK) Pulse duration, serial port clock low/high
3H*
ns
*Not production tested.
† _{The serial port design is fully static and, therefore, can operate with tc(SCK) approaching ∞.}
‡ _{If the TFSX/TFRM pulse does not meet this specification, the first bit of serial data is driven on TDX until the falling edge of TFSX/TFRM. After}
the falling edge of TFSX/TFRM, data is shifted out on TDX pin. The transmit buffer-empty interrupt is generated when the th(FSX) _and th(FSX)H
specification is met.
NOTE 1: Internal clock with external TFSX/TFRM and vice versa are also allowable. However, TFSX/TFRM timings to TCLKX always are defined
depending on the source of TFSX/TFRM, and CLKX timings always are dependent upon the source of CLKX. Specifically, the
relationship of TFSX/TFRM to TCLKX is independent of the source of TCLKX.
TCLKX
TFSX/TFRM
TDX Bit
tc(SCK)
tw(SCK)
tf(SCK)
td(FSX)
th(FSX)H
th(FSX)
td(DX)
tw(SCK)
tr(SCK)
th(DX)
tdis(DX)
1
2
7/15
8/16
Figure 22. Serial Port Transmit Timing With External Clocks and Frames
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