SPRS377F September 2008 – June 2014 TMS320C6745 , TMS320C6747
PRODUCTION DATA.
The C6745/6747 device includes two choices to provide an external clock input, which is fed to the on-chip PLL to generate high-frequency system clocks. These options are illustrated in Figure 6-6 and Figure 6-7. For input clock frequencies between 12 and 20 MHz, a crystal with 80 ohm max ESR is recommended. For input clock frequencies between 20 and 30 MHz, a crystal with 60 ohm max ESR is recommended. Typical load capacitance values are 10-20 pF, where the load capacitance is the series combination of C1 and C2.
The CLKMODE bit in the PLLCTL register must be 0 to use the on-chip oscillator. If CLKMODE is set to 1, the internal oscillator is disabled.
PARAMETER | MIN | MAX | UNIT | |
---|---|---|---|---|
fosc | Oscillator frequency range (OSCIN/OSCOUT) | 12 | 30 | MHz |
PARAMETER | MIN | MAX | UNIT | |
---|---|---|---|---|
fOSCIN | OSCIN frequency range (OSCIN) | 12 | 50 | MHz |
tc(OSCIN) | Cycle time, external clock driven on OSCIN | 20 | ns | |
tw(OSCINH) | Pulse width high, external clock on OSCIN | 0.4 tc(OSCIN) | ns | |
tw(OSCINL) | Pulse width low, external clock on OSCIN | 0.4 tc(OSCIN) | ns | |
tt(OSCIN) | Transition time, OSCIN | 0.25P or 10 (1) | ns | |
tj(OSCIN) | Period jitter, OSCIN | 0.02P | ns |