
TMS370Cx9x
8-BIT MICROCONTROLLER
SPNS036B – JANUARY 1996 – REVISED FEBRUARY 1997
44
POST OFFICE BOX 1443
HOUSTON, TEXAS 77251–1443
external clocking requirements for clock divided by 4
(see Figure 19)
NO.
PARAMETER
MIN
MAX
UNIT
1
tw(Cl)
tr(Cl)
tf(CI)
td(CIH-SCL)
CLKIN
Pulse duration, XTAL2/CLKIN (see Note 9)
20
ns
2
Rise time, XTAL2/CLKIN
30
ns
3
Fall time, XTAL2/CLKIN
30
ns
4
Delay time, XTAL2/CLKIN rise to SYSCLK fall
100
ns
Crystal operating frequency
System clock
2
20
MHz
SYSCLK
0.5
5
MHz
For VIL and VIH, refer to recommended operating conditions.
SYSCLK = CLKIN/4
NOTE 9: This pulse can be either a high pulse, which extends from the earliest valid high to the final valid high in an XTAL2/CLKIN cycle or a
low pulse, which extends from the earliest valid low to the final valid low in an XTAL2/CLKIN cycle.
XTAL2/CLKIN
3
2
1
4
SYSCLK
Figure 19. External Clock Timing for Divide-by-4
external clocking requirements for clock divided by 1 (PLL)
(see Figure 20)
NO.
1
PARAMETER
MIN
20
MAX
UNIT
ns
tw(Cl)
tr(Cl)
tf(CI)
td(CIH-SCH)
CLKIN
Pulse duration, XTAL2/CLKIN (see Note 9)
2
Rise time, XTAL2/CLKIN
30
ns
3
Fall time, XTAL2/CLKIN
30
ns
4
Delay time, XTAL2/CLKIN rise to SYSCLK rise
100
Crystal operating frequency
System clock§
2
5
MHz
SYSCLK
2
5
MHz
For VIL and VIH, refer to recommended operating conditions.
§SYSCLK = CLKIN/1
NOTE 9: This pulse can be either a high pulse, which extends from the earliest valid high to the final valid high in an XTAL2/CLKIN cycle or a
low pulse, which extends from the earliest valid low to the final valid low in an XTAL2/CLKIN cycle.
XTAL2/CLKIN
3
2
1
4
SYSCLK
Figure 20. External Clock Timing for Divide-by-1