PXB4219E Datasheet, PDF (76/290 Pages) Infineon Technologies AG – Interworking Element for 8 E1/T1 Lines

IWE8, V3.4
PXB 4219E, PXB 4220E, PXB 4221E
Operational Description
f/f₀
2d
Mp
1
0.9
0.1
Tr, Tr1: Rise time
Tp: Peak time
Tl: Lock in time
Mp: Peak overshoot
2d: Tuning range
f₀:
Target frequency
Tr1 Tr Tp
Figure 20 Transient Parameters
Tl
t
ACM Transient Parameters
The tuning range of the DCO is limited to the value programmed to bits “tur” in register
“condN”. If the phase detector requests a higher frequency deviation the DCO enters
out-of-range condition. In this case the DCO’s output will be clipped and bit “max” of
register “statN” will be set. If the number of out-of-range conditions during 16 ATM cells
exceeds the value given by field “tr_acm” of register “treshN”, an out-of-lock message,
indicated via field “ola” of register “oolN”, is generated.
Increasing the loop-gain reduces the damping of the PLL-ACM. This will reduce the rise
time but results in overshoot and long lock-in times.
Reducing the loop-gain increases the damping. This results in lower cut off frequencies,
and prevents overshoot. Thus, CDV is less likely to drive the PLL out of lock. The rise
and lock-in time are increased. If the loop-gain is too low, the amount of bytes required
to drive the DCO over it's tuning range could cause a data buffer over- or underflow.
Optimized damping allows minimum lock-in time without overshoot. In this case PLL-
ACM’s frequency is moving asymptotically to the correct value.
Data Sheet
76
2003-01-20