AC Electrical Characteristics
8
AC Electrical Characteristics
The timing waveforms shown in the AC electrical characteristics section are tested with a VIL maximum of 0.8V and a VIH
minimum of 2.0V for all pins. AC timing specifications, which are referenced to a device input signal, are measured in production
with respect to the 50% point of the respective input signal’s transition. DSP56371 output levels are measured with the production
test machine VOL and VOH reference levels set at 1.0V and 1.8V, respectively.
NOTE
Although the minimum value for the frequency of EXTAL is 0 MHz (PLL bypassed), the
device AC test conditions are 5 MHz and rated speed.
9
Internal Clocks
Table 17. INTERNAL CLOCKS
No.
1
Characteristics
Comparison Frequency
Input Clock Frequency
Symbol
Fref1
Min
Typ
Max UNIT
Condition
5
--
20
MHZ
Fref = FN/NR
2
FIN
Fref*NR
NR is input divider
value
3
Output clock Frequency (with
PLL enabled2,3
FOUT
75
(1000/Etc × MF x
FM)/
(PDF × DF x OD)
--
MHZ
FOUT=FVCO/NO
where NO is output
divider value
4
5
Output clock Frequency (with
PLL disabled2,3
FOUT
--
--
1000/Etc
50
--
MHZ
%
---
Duty Cycle
40
60
FVCO=300MHZ~60
0MHZ
Notes:
1. See users manual for definition.
2. DF = Division Factor
Ef = External frequency
MF = Multiplication Factor
PDF = Predivision Factor
FM= Feedback Multiplier
OD = Output Divider
3. Maximum frequency will vary depending on the ordered part number.
34
DSP56371 Technical Data
Freescale Semiconductor
FREESCALE [ Freescale ]
