SM5849BF 查看數據表（PDF） - Nippon Precision Circuits
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SM5849BF Datasheet PDF : 25 Pages
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SM5849BF
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 approximately
23.2ms when fso = 44.1kHz.
0 dB
Level 1
Gain
—∞
Level 2
∆t
Level 3
Level 5
Level 4
Time
Figure 4. Attenuator operation example
Mute (DMUTE)
Direct mute
Table 7. DMUTE operation ON/OFF
DMUTE
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 following times.
I When the reset input (RSTN) changes.
I When the fs setting changes, for deemphasis, using either FSI1, FSI2 inputs or FFSI1, FFSI2 flags.1
I When the ICKSL, IFM1, or IFM2 setting changes.
I When the ICLK input system clock stops.
Table 8. Other mute operations
Input
Function
RSTN = LOW
0 data is output from the next output word (mute ON)
RSTN = HIGH
FSI1, FSI2 input settings changed (MCOM = LOW).1
FFSI1, FFSI2 input settings changed (MCOM = HIGH).1
ICKSL, IFM1, IFM2 input settings change.
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)
ICLK input system clock stops.
0 data is output from the next output word (mute ON)
ICLK input system clock restarts.
Normal data is output from the 3073rd output word (mute OFF)
1. Mute function does not operate when the deemphasis filter ON/OFF is switched (DEEM (MCOM = LOW), FDEEM (MCOM = HIGH)).
SEIKO NPC CORPORATION —16
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