PARAMETER UNIT
TMS320C25-50
SPRS010B— MAY 1987— REVISED NOVEMBER 1990
POST OFFICE BOX 1443 HOUSTON, TEXAS 77001 39
SERIAL PORT TIMING
switching characteristics over recommended operating conditions (see Note 3)
PARAMETER MIN TYP MAX UNIT
td(CH-DX) DX valid after CLKX rising edge (see Note 18) 75 ns
td(FL-DX) DX valid after falling edge (TXM = 0, see Note 18) 40 ns
td(CH-FS) FSX valid after CLKX raising edge (TXM = 1) 40 ns
NOTES: 3. Q = 1/4 tc(C)
18. The last occurrence of FSX falling and CLKX rising.
timing requirements over recommended operating conditions (see Note 3)
MIN NOM MAX UNIT
tc(SCK) Serial port clock (CLKX/CLKR) cycle time160 ns
tf(SCK) Serial port clock (CLKX/CLKR) fall time 25ns
tr(SCK) Serial port clock (CLKX/CLKR) rise time 25ns
tw(SCK) Serial port clock (CLKX/CLKR) low or high pulse duration (see Note 19) 64 ns
tsu(FS) FSX or FSR setup time before CLKX, CLKR falling edge (TXM = 0) 5 ns
th(FS) FSX or FSR hold time before CLKX, CLKR falling edge (TXM = 0) 10 ns
tsu(DR) DR setup time before CLKR falling edge 5 ns
th(DR) DR hold time after CLKR falling edge 10 ns
The serial port was tested at a minimum frequency of 1.25 MHz. However, the serial port was fully static but will properly function down to
fsx = 0 Hz.
Value derived from characterization data and not tested.
NOTES: 3. Q = 1/4 tc(C)
19. The cycle of the serial port must be within 40%-60%.
CONTRAST SUMMARY OF ELECTRICAL SPECIFICATIONS

The following table presents electrical parameters which differ between TMS320C25 (40 MHz, 100 ns) and

TMS320C25-50 (50 MHz, 80 ns).

clock characteristics and timing
TMS320C25 TMS320C25-50
MIN TYP MAX MIN TYP MAX
tc(SCK) 97.7 597 78.13 597 ns
td(CIH-C) 5 30 12 27 ns
tf(C) 5 4 ns
tr(C) 5 4 ns
tw(CL) 2Q – 8 2Q 2Q + 8 2Q – 7 2Q + 3 ns
tw(CH) 2Q – 8 2Q 2Q + 8 2Q – 3 2Q + 7 ns
td(C1-C2) Q – 5 QQ + 5 Q – 6 Q + 2 ns
tsu(S) 5Q – 5 4Q – 4 ns
th(S) 8 4 ns
ADVANCE INFORMATION