BM28723AMUV
Description of Function
1
DSP Block Functional Overview
No. Function
Specification
1
Pre-Scaler
•Lch/Rch become same set point.
•+48dB to -79dB (0.5dB step), -infinity dB
•It is able to set mixing of Left and Right channel which are inputted digital signal
to Audio DSP
2
Channel Mixer
•Selectable in L, (L+R) /2, L-R, R, MUTE
3
12 Band BQ
•12 Band Bi-quad (BQ) type filter.
•Only 5 coefficients are required. (b0, b1, b2, a1, a2)
•Lch/Rch dependent or independent.
•The Filter types which can be attained are
Peaking/Low-shelf/High-shelf/Low-pass/High-pass/All-pass/Notch.
•There is soft transition function.
4
5
Fine Master Volume
3 Band DRC
•Lch/Rch become same set point or independent set.
•+24dB to -103dB (0.125dB step), -infinity dB
•There are soft transition and soft mute functions.
•There are 3 band DRC.
•It is possible to set the slope of compression level.
6
7
Post-scaler
•Lch/Rch become same set point.
•+48dB to -79dB (0.5dB step), -infinity dB
•Lch/Rch become independent set point.
•+0.7dB to -0.8dB (0.1dB step)
Fine Post-scaler
8
9
DC cut HPF
Hard Clipper
•1st order HPF
•Cut OFF frequency fc: 1Hz
•Lch/Rch become same set point.
•Clip level: 0dB to -22.5dB (-0.1dB step)
I2S
LJ
RJ
Fine
post
scaler/
ch
Fine
Master
Volum
e/ch
Pre
Scaler
Chanel
Mixer
DC cut
HPF
Hard
Clipper
3Band
DRC
Post
Scaler
12Band
/ch BQ
Input1
Main
Figure 31. DSP Block Diagram
About description of the register setting the register value is written at hex.
Also, the value with blue background is initial value.
2
RSTX Pin(Note 13) (Note 14) , MUTEX Pin Function
RSTX
(29pin)
MUTEX
(30pin)
Speaker Output
DSP Block
Reset ON
(OUT1P, OUT1N, OUT2P, OUT2N)
High-Z_low(Note 15)
Low
Low
Low
(Low power consumption)
High-Z_low(Note 15)
Normal operation
(Mute ON)
High
(Mute ON) (Note 16)
Normal operation
(Mute OFF)
Normal operation
High
Low
High
High
(Mute OFF)
Don’t use.
(Note 13) When RSTX is set to low, internal registers are initialized.
(Note 14) If VDVDD is under 3V, RSTX is set to low once for 10ms (Min), and set to high again. Then DSP is needed to set parameter again.
(Note 15) This means that all output transistors are OFF and output pins are pulled down by 10kΩ (Typ).
(Note 16) Speaker output becomes High-Z_low after elapse of PWM stop time after setting MUTEX Low.
Refer to PWM Sampling Frequency in next page for PWM stop time.
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TSZ02201-0C1C0E900720-1-2
31.Aug.2018 Rev.001
© 2018 ROHM Co., Ltd. All rights reserved.
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TSZ22111 • 15 • 001
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