tc9447f TOSHIBA Semiconductor CORPORATION, tc9447f Datasheet - Page 12

• Manufacturer Part Number: tc9447f
• Description: Single-chip Audio Digital Signal Processor
• Manufacturer: TOSHIBA Semiconductor CORPORATION

TC9447F
(2-3) Setting RAM (ACMP mode)
In ACMP mode, the TC9447F does not write data directly to coefficient RAM (CRAM) or offset
RAM (OFRAM). In this mode, data must first be written to the interface buffer RAM (IFB-RAM).
Then, all the data are updated together in a period of 1 fs.
For example, if a signal flow filter is designed as in the following diagram, unless the K1 to K5
data are batch-updated, the circuit may resonate. The same applies to the K6 to K10 data.
Using ACMP mode can reduce the noise caused by updating coefficients while the TC9447F is
operating. This mode can suppress noise in almost all cases.
IFB-RAM is 32-word memory. Therefore, data can be updated at one time in units of up to 32
words. The format of IFB-RAM is similar to the format of the RAM in 2-2 above. The length of the
data field is 2 × n bytes, where n ” 32.
In ACMP mode, the IFOK pin outputs an ACMP operation end flag.
When ACMP operations complete, the flag is set to Low (1) and is initialized at the next low chip
select CS signal (2).
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2002-02-05