PDSP16540 Zarlink Semiconductor, PDSP16540 Datasheet - Page 7

• Manufacturer Part Number: PDSP16540
• Description: 32K BUCKET BUFFER
• Manufacturer: Zarlink Semiconductor

amount of overlap to be any value within 32 words. The 5 bit
overlap code defines groups of 32 new words which are
written to the buffer, in addition to the minimum number of 32
words. The smaller the number of new words written, the
greater is the overlap with the previous block.
be high impedance and the 5 bit code is inputed on D9:5. This
high impedance state also allows the PDSP16510 control
parameters to be inputed on its AUX 15:0 bus without any
conflicts.
be such that 1024 words can be transferred between the
devices, transformed , and then moved to the output circuit for
analysis before the DAV flag goes active again. Since the read
operation is interrupted for one cycle every time a write
operation occurs, the equation controlling the minimum writ-
ing period is given by;
Characteristic
RS Period,Tp
RS Low Time
RS High Time
WS Period
WS Period
WS Low Time
WS High Time
WEN set up wrt WS going high
WEN Hold wrt WS going high
Data In Set Up wrt RS going high
Data In Hold Time wrt RS going high
Delay from RS going high to O/P Data
DAV,RMF transition wrt to RS going high 10ns
Time to go Low Z wrt to RS going high
Time to go High Z wrt to RS going high
IMAG'
REAL
SYSTEM
CLOCK
Figure 2 shows a 1024 point system which allows the
During reset the D31:0 outputs from the PDSP16540 will
The rate at which data is written to the PDSP16540 must
Figure 1. Typical 1024 Point FFT System
WEN
GND
SAMPLE CLOCK
RS
PDSP16540
BUCKET
BUFFER
MD5:0
GND
WS
DAV
RES
510 PARAMETERS
POWER ON RESET
AUX
D
PDSP16510
Min
25ns
8ns
8ns
2Tp+10ns
Tp x L
10ns
10ns
2 ns
8 ns
8 ns
0 ns
GND
N
Table 1. Timing Information
R
I
Max
19ns
18ns
19ns
12ns
where N is the amount of new data written to the buffer, S is
the period of the write strobe, B is the read strobe period, T is
the transform time as given in the data sheet for the
PDSP16510, and D is the time to transfer data from the
PDSP16510 to the next system device.
applies if continuous inputs are to transformed without the loss
of any incoming information. Peak writing rates can be much
higher if gaps occur within the incoming data stream. The
minimum periods given in Table 1 then limit the writing rate.
transformed data with a 40MHz strobe, and the PDSP16540
uses a 40 MHz read strobe, then the minimum S period is149
ns. This equates to a 6.7 MHz writing rate when blocks are not
overlapped, 3.35 MHz with 50% overlaps ( 512 new words), or
1.675MHz with 75% overlaps ( 256 new words).
IMAG'
REAL
NS > 1024B + 1024BS + T + D
It must be noted that the above minimum write period only
When the PDSP16510 uses a 40 MHz clock, dumps its
SYSTEM
CLOCK
Figure 2. System with Non Standard Overlaps
Both conditions must be satisfied
L = Block length, N = amount of new data written
WEN going active or in-active
All output delays are with 30pf loads
Going active or in-active
Occurs when DAV also goes active
Occurs when DAV also goes in-active
31:16
GND
15:0
WEN MD5
IP
IP
RS
PDSP16540
MD2:1 MD0
GND
+5V
BUCKET
BUFFER
SAMPLE CLOCK
Notes
GND
WS
31:16
DAV
5 BIT OVERLAP CODE
RES
15:0
D
S-B
510 PARAMETERS
D
POWER ON RESET
AUX
D
PDSP16510
PDSP16540
GND
R
I
5