PCX755BVZFU300LE Atmel, PCX755BVZFU300LE Datasheet - Page 40

• Manufacturer Part Number: PCX755BVZFU300LE
• Description: IC MPU 32BIT 300MHZ 360PBGA
• Manufacturer: Atmel

Specifications of PCX755BVZFU300LE

• Processor Type: PowerPC 32-Bit RISC
• Speed: 300MHz
• Voltage: 2V
• Mounting Type: Surface Mount
• Package / Case: 360-PBGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

40
PC755/745
The PC755 generates the clock for the external L2 synchronous data SRAMs by dividing the
core clock frequency of the PC755. The divided-down clock is then phase-adjusted by an on-
chip delay-lock-loop (DLL) circuit and should be routed from the PC755 to the external RAMs. A
separate clock output, L2SYNC_OUT is sent out half the distance to the SRAMs and then
returned as an input to the DLL on pin L2SYNC_IN so that the rising-edge of the clock as seen
at the external RAMs can be aligned to the clocking of the internal latches in the L2 bus
interface.
The core-to-L2 frequency divisor for the L2 PLL is selected through the L2CLK bits of the L2CR
register. Generally, the divisor must be chosen according to the frequency supported by the
external RAMs, the frequency of the PC755 core, and the phase adjustment range that the L2
DLL supports.
obtained for a given set of core frequencies. The minimum L2 frequency target is 80 MHz.
Table 9-2.
Note:
The core and L2 frequencies are for reference only. Some examples may represent core or L2 fre-
quencies which are not useful, not supported, or not tested for by the PC755; see
Specifications” on page 28
L2CLK frequencies less than 110 MHz.
Core Frequency in MHz
Sample Core-to-L2 Frequencies
Figure 8-9 on page 33
250
266
275
300
325
333
350
366
375
400
for valid L2CLK frequencies. The L2CR[L2SL] bit should be set for
shows various example L2 clock frequencies that can be
250
266
275
300
325
333
350
366
375
400
1
166
177
183
200
217
222
233
244
250
266
1.5
125
133
138
150
163
167
175
183
188
200
2
100
106
110
120
130
133
140
146
150
160
2.5
2138G–HIREL–05/06
“L2 Clock AC
100
108
111
117
122
125
133
83
89
92
3