TMS320_13 Datasheet, PDF (22/70 Pages) Texas Instruments – TMS320 SECOND GENERATION DIGITAL SIGNAL PROCESSORS

TMS320 SECOND GENERATION
DIGITAL SIGNAL PROCESSORS
SPRS010B — MAY 1987 — REVISED NOVEMBER 1990
CLOCK CHARACTERISTICS AND TIMING
The TMS32020 can use either its internal oscillator or an external frequency source for a clock.
internal clock option
The internal oscillator is enabled by connecting a crystal across X1 and X2/CLKIN (see Figure 2). The frequency
of CLKOUT1 is one-fourth the crystal fundamental frequency. The crystal should be fundamental
mode, and parallel resonant, with an effective series resistance of 30 , a power dissipation of 1 mW,
and be specified at a load capacitance of 20 pF.
PARAMETER
TEST CONDITIONS
f_x
f_xs
C1, C2
Input clock frequency
Serial port frequency
T_A = 0C to 70C
T_A = 0C to 70C
T_A = 0C to 70C
† _{Value derived from characterization data; minimum fsx at test = 825 kHz.}
MIN TYP^† MAX UNIT
6.7
20.5 MHz
50^†
2563 MHz
10
pF
X1
X2/CLKIN
Crystal
C1
C2
Figure 2. Internal Clock Option
external clock option
An external frequency source can be used by injecting the frequency directly into X2/CLKIN with X1 left
unconnected. The external frequency injected must conform to the specifications listed in the following table.
switching characteristics over recommended operating conditions (see Note 3)
t_c(C)
t_d(CIH-C)
t_f(C)
t_r(C)
t_w(CL)
t_w(CH)
td(C1-C2)
PARAMETER
CLKOUT1/CLKOUT2 cycle time
CLKIN high to CLKOUT1/CLKOUT2/STRB high/low
CLKOUT1/CLKOUT2/STRB fall time
CLKOUT1/CLKOUT2/STRB rise time
CLKOUT1/CLKOUT2 low pulse duration
CLKOUT1/CLKOUT2 high pulse duration
CLKOUT1 high to CLKOUT2 low, CLKOUT2 high to CLKOUT1 high, etc.
NOTE 3: Q = 1/4t_c(C).
MIN
195
25
2Q -- 15
2Q -- 15
Q -- 10
NOM MAX
597
60
10
10
2Q 2Q + 15
2Q 2Q + 15
Q Q + 10
UNIT
ns
ns
ns
ns
ns
ns
ns
22
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