SM5844 NPC [Nippon Precision Circuits Inc], SM5844 Datasheet - Page 19

• Manufacturer Part Number: SM5844
• Description: Asynchronous Sample Rate Converter
• Manufacturer: NPC [Nippon Precision Circuits Inc]

Internal Arithmetic Timing Auto-reset
The clock on LRCI should pass through 1 cycle for
every 384 (ICKSL = HIGH) or 256 (ICKSL = LOW)
ICLK clock cycles to maintain correct internal
arithmetic sequence. If the number of ICLK cycles is
different, increases or decreases, or any jitter is
present, device operation could be affected.
There is a fixed-value tolerance within which the
internal sequence and LRCI clock timing are not
adversely affected.
Table 13. Clock tolerance
Whenever the allowable tolerance is exceeded, the
internal sequence is automatically reset so that the
internal sequence matches the LRCI clock. When
this occurs, there is a possibility that click noise will
be generated.
Output Format Control (OW18N,
OW20N, IISN)
The output is in MSB-first, 2s-complement, L/R
alternating, bit serial format with a continuous bit
clock.
Table 14. Output format selection
M o d e
1
2
3
4
5
6
7
HIGH (384fs mode)
L O W (256fs mode)
H I G H
L O W
IISN
I C K S L
O W 2 0 N O W 1 8 N
H I G H
H I G H
H I G H
H I G H
L O W
L O W
L O W
Inputs
H I G H
H I G H
H I G H
L O W
L O W
L O W
length
16 bits
18 bits
20 bits
20 bits
16 bits
18 bits
20 bits
W ord
Allow a b le clock variation
Output format
+8/ 6 cycles
+4/ 3 cycles
selection
Non IIS
IIS
IIS
Front/rear
p a cking
Rear
Front
SM5844AF
Output Timing Calculation
The output timing is calculated to maintain the
desired ratio between the output data cycle and the
input data cycle.
Filter Characteristic Selection
Conversion rates from 0.5 to 2.0 times are supported
using the following 4 filter types.
The ratio between the output sample rate and input
sample rate is measured automatically and the most
suitable filter type for this ratio is selected
automatically.
Table 15. fs ratio and filter selection
When the selected fs conversion ratio and the actual
sample rate conversion ratio do not coincide, the
following phenomenon are generated.
Table 16. fs ratio mismatch
Note: An output noise may be generated if the fs conversion ratio
changes at a rate greater than 0.057%/sec.
M o d e
Actual sample rate conversion
ratio is low er than the selected
filter conversion ratio
Actual sample rate conversion
ratio is higher than the selected
filter conversion ratio
1
2
3
4
48.0 to 44.1 kHz
44.1 to 32.0 kHz
48.0 to 32.0 kHz
Condition
Up converter
Filter
NIPPON PRECISION CIRCUITS—19
fs ratio (fso/fsi)
1.0 to 2.0
0.91875
0.72562
0.66667
The audio band high-pass
develops aliasing noise.
The audio band high-pass is cut
off.
Affect
Selects range
0.711 to 0.865
0.865 to 0.97
0.711
0.97