SM5849F Datasheet, PDF (18/26 Pages) Nippon Precision Circuits Inc – Asynchronous Sample Rate Converter

SM5849AF
Attenuator operation
A change in the attenuation data DATT causes the
gain to change smoothly from its previous value
towards the new setting. The new attenuation data is
stored in the attenuation data register and the current
attenuation level is stored in a temporary register.
Consequently, if a new attenuation level is read in
before the previously set level is reached, the gain
changes smoothly from the current value towards the
latest setting as shown in figure 4.
The attenuation counter output changes, and hence
the gain changes, by 1 step every output sample. The
time taken to reduce the gain from 0dB (or 12dB) to
−∞dB is (1024/fso), which corresponds to approxi-
mately 23.2ms when fso = 44.1kHz.
0 dB
Level 1
Gain
—∞
Level 2
∆t
Level 3
Level 5
Level 4
Time
Mute (DMUTE)
Figure 4. Attenuator operation example
Direct mute
Table 7. DMUTE operation ON/OFF
Table 8. Other mute operations
DMUT
E
LOW
HIGH
Function
Normal data is output from the next output word (mute
OFF)
0 data is output from the next output word (mute ON)
Other mute operations
The direct mute function is also invoked at the fol-
lowing times.
s When the reset input (RSTN) changes.
s When the fs setting changes, for deemphasis,
using either FSI1, FSI2 inputs or FFSI1, FFSI2
flags.
s When the ICKSL, IFM1, or IFM2 setting changes.
s When the ICLK input system clock stops.
Input
RSTN = LOW
RSTN = HIGH
FSI1, FSI2 input settings
changed (MCOM = LOW).
FFSI1, FFSI2 input settings
changed (MCOM = HIGH)
ICKSL, IFM1, IFM2 input
settings change.
ICLK input system clock stops.
ICLK input system clock
restarts.
Function
0 data is output from the next
output word (mute ON)
Normal data is output from the
3073rd output word (mute OFF)
0 data is output from the next
output word (mute ON).
Normal data is output from the
3073rd output word (mute OFF)
0 data is output from the next
output word (mute ON)
Normal data is output from the
3073rd output word (mute OFF)
NIPPON PRECISION CIRCUITS—18