PXF4333 Datasheet, PDF (111/361 Pages) Infineon Technologies AG – ABM 3G ATM Buf fer Manager

ABM-3G
PXF 4333 V1.1
Operational Description
Table 4-4 shows minimum PCR shaper rates for all the possible values of TstepC
calculated at a SYSCLK of 51.84 MHz and 60 MHz with TPmax and Equation (14).
Table 4-4 Minimum Shaper Rates as a Function of TstepC and SYSCLK
SYSCLK = 51.84 [MHz]
SYSCLK = 60 [MHz]
TstepC 1/Tstep
PCR_RSmin
[cells/s]
PBR_RSmin
[bit/s]
PCR_RSmin
[cells/s]
PBR_RSmin
[bit/s]
0
256
6.185
2622
7.160
3036
1
128
12.371
5245
14.320
6072
2
64
24.743
10491
28.639
12143
3
32
49.487
20982
57.278
24286
4
16
98.975
41965
114.555
48572
5
8
197.950
83930
229.110
97143
6
4
395.900
167861
458.219
194285
7
2
791.800
335723
916.437
388569
The accuracy of the shaping rate is defined as:
acc_PCR
=
P_----C_-----R_{----i--n----–----}P_----C_-----R_{----o---u---t}
PCR_{o u t}
(18)
with PCR_in denoting the desired PCR and PCR_out denoting the delivered PCR, which is
always less than PCR_in.
PCR_out is calculated by first deriving TP from PCR_in in Equation (15) and then
substituting TP in Equation (14).
The accuracy improves towards lower shaping rates and higher values of TstepC.
Note: The improvement is not monotonic and depends on the rounding error made at
the calculation of TP. However, from the formulas given above, it can be deduced
that the accuracy is always better than:
acc _{P C R}
≤
--------------------^P-----^C----^R-----ⁱ-ⁿ----------------------
2 × SYSCLK × Tstep
(19)
Data Sheet
111
2001-12-17