
Signals/Connections
2.2 Ground
Table 2-3. Grounds
Ground Name
GND P
GND P1
GND
Description
PLL Ground — A ground dedicated for PLL use. The connection should be provided with an extremely low-impedance
path to ground. V CCP should be bypassed to GND P by a 0.47 μ F capacitor located as close as possible to the chip
package.
PLL Ground 1 —A ground dedicated for PLL use. The connection should be provided with an extremely low-impedance
path to ground.
Ground —Connected to an internal device ground plane. The user must provide adequate external decoupling
capacitors for all GND connections
2.3 Clock
Table 2-4. Clock Signals
Signal
Name
EXTAL
Type
Input
State During
Reset
Input
Signal Description
External Clock/Crystal Input —Interfaces the internal crystal oscillator input to an
external crystal or an external clock.
XTAL
Output
Chip-driven
Crystal Output —Connects the internal crystal oscillator output to an external
crystal. If an external clock is used, leave XTAL unconnected.
2.4 PLL
Table 2-5. Phase-Lock Loop Signals
Signal Name
PCAP
Type
Input
State During
Reset
Input
Signal Description
PLL Capacitor —Connects an off-chip capacitor to the PLL filter.
Connect one capacitor terminal to PCAP and the other terminal to V CCP .
If the PLL is not used, PCAP is tied to V CC , GND, or left floating.
CLKOUT
Output
Chip-driven
Clock Output— Provides an output clock synchronized to the internal
core clock phase.
If the PLL is enabled and both the multiplication and division factors
equal one, then CLKOUT is also synchronized to EXTAL.
If the PLL is disabled, the CLKOUT frequency is half the frequency of
EXTAL.
Note: At operating frequencies above 100 MHz, this signal produces a
low-amplitude waveform that is not usable externally by other devices.
Above 100 MHz, you use the asynchronous bus arbitration option that is
enabled by the Asynchronous Bus Arbitration Enable (ABE) bit in the
Operating Mode Register (OMR). When set, the DSP enters the
Asynchronous Arbitration mode, which eliminates the BB and BG setup
and hold time requirements with respect to CLKOUT.
DSP56311 User’s Manual, Rev. 2
2-4
Freescale Semiconductor