ꢀ ꢁꢂ ꢃ ꢄꢅ ꢆꢇ ꢈꢉ ꢄꢅ
ꢊ ꢋꢌ ꢍꢎꢏꢐꢑ ꢋ ꢒꢀ ꢎꢋ ꢓꢋ ꢀꢔꢕ ꢂꢋ ꢓ ꢒꢔꢕ ꢐꢖ ꢑ ꢇꢍ ꢂ ꢂꢑ ꢖ
SPRS080F − MARCH 1999 − REVISED OCTOBER 2008
external multiply-by-N clock option
An external frequency can be used by injecting the frequency directly into CLKIN. This external frequency is
multiplied by N to generate the internal machine cycle.
The external frequency injected must conform to specifications listed in the timing requirements table.
switching characteristics over recommended operating conditions [H = 0.5t
and the recommended operating conditions table)
] (see Figure 11
c(CO)
PARAMETER
MIN
10
4
TYP
MAX
UNIT
ns
†
t
Cycle time, CLKOUT
t
c(CI)/N
c(CO)
t
Delay time, CLKIN high/low to CLKOUT high/low
Fall time, CLKOUT
10
2
16
ns
d(CIH-CO)
t
ns
f(CO)
r(CO)
w(COL)
w(COH)
p
t
t
t
t
Rise time, CLKOUT
2
ns
Pulse duration, CLKOUT low
Pulse duration, CLKOUT high
Transitory phase, PLL lock-up time
H − 2
H − 2
H − 1
H − 1
H
H
ns
ns
35
µs
†
N is the PLL multiplier. N = 1 – 15
timing requirements (see Figure 11)
MIN
10N
10N
10N
MAX
200
100
50
UNIT
Integer PLL multiplier N
PLL multiplier N = x.5
t
Cycle time, CLKIN
ns
c(CI)
PLL multiplier N = x.25, x.75
t
t
Fall time, CLKIN
Rise time, CLKIN
8
ns
ns
f(CI)
8
r(CI)
t
f(CI)
t
r(CI)
t
c(CI)
CLKIN
t
d(CI-CO)
t
f(CO)
t
w(COH)
t
c(CO)
t
w(COL)
t
tp
r(CO)
Unstable
CLKOUT
Figure 11. External Multiply-By-One Clock
43
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TI [ TEXAS INSTRUMENTS ]
