Datasheet

XC167CI-16F
Derivatives
Electrical Parameters
Data Sheet 73 V1.3, 2006-08
4.4.3 External Clock Drive XTAL1
Figure 17 External Clock Drive XTAL1
Note: If the on-chip oscillator is used together with a crystal or a ceramic resonator, the
oscillator frequency is limited to a range of 4 MHz to 16 MHz.
It is strongly recommended to measure the oscillation allowance (negative
resistance) in the final target system (layout) to determine the optimum
parameters for the oscillator operation. Please refer to the limits specified by the
crystal supplier.
When driven by an external clock signal it will accept the specified frequency
range. Operation at lower input frequencies is possible but is verified by design
only (not subject to production test).
Table 19 External Clock Drive Characteristics
(Operating Conditions apply)
Parameter Symbol Limit Values Unit
Min. Max.
Oscillator period t
OSC
SR 25 250
1)
1) The maximum limit is only relevant for PLL operation to ensure the minimum input frequency for the PLL.
ns
High time
2)
2) The clock input signal must reach the defined levels V
ILC
and V
IHC
.
t
1
SR 6 – ns
Low time
2)
t
2
SR 6 – ns
Rise time
2)
t
3
SR – 8 ns
Fall time
2)
t
4
SR – 8 ns
MCT05572
t
1
t
2
t
OSC
t
3
t
4
0.5 V
DDI
V
ILC
V
IHC