STMICROELECTRONICS STA308

STA308
MULTICHANNEL DIGITAL AUDIO PROCESSOR WITH DDX™
PRODUCT PREVIEW
■
8 DDXTM Channels Capability (24 bit)
■
From 32kHz to 192kHz Input Sample Rates
Supported
■
Volume Control from 0 to -100dB (0.5 dB steps)
■
Variable Digital Gain from 0 to 24dB (0.5dB
steps) with Digital Limiter Functionality and
Variable Attack and Release Time
■
I2S Inputs and Outputs
■
Individual Channel and Master Gain/
Attenuation
■
Individual Channel Mute and Zero Input Detect
Auto-Mute
■
Selectable Serial Audio Data Interface
■
Bass/Treble Controls
■
Channel Mapping of any Input to any
Processing/DDXTM Channel
■
Active Crossover Capability
■
DC Blocking Selectable High-Pass Filter
■
Selectable Bass Management on Channel 6
■
Selectable Adjacent Channel Mixing Capability
■
Selectable DDXTM Headphone Output on
Channels 7 & 8
■
Selectable Clock Input Ratio
■
Selectable De-emphasis
■
Selectable DDXTM Ternary, or Binary PWM
output
■
AM Interference Reduction Mode
■
I2C Control
TQFP64
ORDERING NUMBER: STA308
DESCRIPTION
The STA308 is a single chip solution for digital audio
processing and control in multi-channel applications.
It provides output capabilities for DDXTM (Direct Digital Amplification). In conjunction with a DDXTM power
device, it provides high-quality, high-efficiency, all
digital amplification. The device is extremely versatile
allowing for input of most digital formats including 6.1
channel and 192kHz, 24-bit DVD-Audio.
The internal 24-bit DSP allows for high resolution
processing at all standard input sample frequencies.
Processing includes volume control, filtering, bass
management, gain compression/limiting and PCM
and DDXTM outputs. Filtering includes five user-programmable 28-bit biquads for EQ per channel, as
well as bass, treble and DC blocking. External clocking can be provided at 4 different ratios of the input
sample frequency. All sample frequencies are upsampled for processing. Each internal processing
channel can receive any input channel, allowing flexibility and the ability to perform active digital crossover for powered loudspeaker systems.
The serial audio data interface accepts many different formats, including the popular I2S format. Eight
channels of DDX processing are performed.
December 2002
This is preliminary information on a new product foreseen to be developed. Details are subject to change without notice.
1/33
STA308
BLOCK DIAGRAM
SCL
SA
SDA
MVO
OUT1A/B
LRCKI
BICKI
2
IC
SERIAL
DATA
IN
SDI12
SDI34
OUT2A/B
OUT3A/B
OVERSAMPLING
SYSTEM
CONTROL
SDI56
OUT4A/B
DDX
OUT5A/B
OUT6A/B
SDI78
OUT7A/B
VARIABLE
OVERSAMPLING
CHANNEL
MAPPING
TREBLE,
BASS, EQ
(BIQUADS)
OUT8A/B
VOLUME
LIMITING
SYSTEM TIMING
PLL
PLLB
XTI
VARIABLE
DOWNSAMPLING
POWER
DOWN
CKOUT
PWDN
LRCKO
BICKO
SDO12
SERIAL
DATA
OUT
SDO34
SDO56
SDO78
EAPD
Figure 1. Signal Flow Diagram
Channels 1-8
1st Stage
Interpolation
Output
Scale
& Mix
Bass Management
(Channel 6 only)
Interp_Rate
8 Inputs
From I2S
BME
Channel
Mapping
1x,2x,4x
Interp
Biquads
B/T
Volume
Limiter
2x
Interp
DDX
Output
Noise & Distortion Reduction
PWM
DDX
(Channels 7&8 only)
2/33
Headphone
STA308
OUT1_B
OUT1_A
EAPD
VDD3
GND
VDD
BICKO
LRCKO
SDO_12
SDO_34
GND
VDD3
VDD
SDO_56
SDO_78
PWDN
IN CONNECTION (Top view)
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
MVO
1
48
OUT2_A
GND
2
47
OUT2_B
VDD3
3
46
VDD
GND
4
45
GND
VDD
5
44
VDD3
SDI_78
6
43
OUT3_A
SDI_56
7
42
OUT3_B
SDI_34
8
41
OUT4_A
SDI_12
9
40
OUT4_B
LRCKI
10
39
OUT5_A
BICKI
11
38
OUT5_B
VDD3
12
37
VDD
GND
13
36
GND
VDD
14
35
VDD3
RESET
15
34
OUT6_A
PLLB
16
33
OUT6_B
OUT7_A
OUT7_B
OUT8_A
OUT8_B
VDD3
GND
VDD
CKOUT
VDD3
GNDA
VDDA
FILTER_PLL
XTI
SCL
SA
SDA
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
D02AU1356
PIN FUNCTION
PIN
1
NAME
MVO
TYPE
I
DESCRIPTION
Master Volume Override
3, 12, 24, 28,
35, 44, 52, 59
2, 4, 13, 27,
36, 45, 53, 60
5, 14, 26, 37,
46, 54, 61
VDD3
3.3V Digital Supply
GND
Digital Ground
VDD
2.5V Digital Supply
6
7
8
9
10
11
15
SDI_78
SDI_56
SDI_34
SDI_12
LRCKI
BICKI
RESET
I
I
I
I
I
I
I
Input I2S Serial Data Channels 7 &
Input I2S Serial Data Channels 5 &
Input I2S Serial Data Channels 3 &
Input I2S Serial Data Channels 1 &
Inputs I2C Left/Right Clock
Inputs I2C Serial Clock
Global Reset
16
PLLB
I
PLL Bypass
17
SA
I
Select Address (I2C)
18
SDA
I/O
I2C Serial Data
19
SCL
I
I2C Serial Clock
PAD TYPE
CMOS Input Buffer with
Pull-Down
3.3V Digital Power
Supply Voltage (pad ring)
Digital Ground
8
6
4
2
2.5V Digital Power
Supply Voltage (core +
ring)
5V Tolerant TTL Input Buffer
5V Tolerant TTL Input Buffer
5V Tolerant TTL Input Buffer
5V Tolerant TTL Input Buffer
5V Tolerant TTL Input Buffer
5V Tolerant TTL Input Buffer
5V Tolerant TTL Schmitt
Trigger Input Buffer
CMOS Input Buffer with
Pull-Down
CMOS Input Buffer with
Pull-Down
Bidirectional Buffer:
5V Tolerant TTL Schmitt
Trigger Input;
3.3V Capable 2 mA
Slew-rate control Output;
5V Tolerant TTL Schmitt
Trigger Input Buffer
3/33
STA308
PIN FUNCTION (continued)
4/33
PIN
20
NAME
XTI
TYPE
I
DESCRIPTION
Crystal Oscillator Input (Clock Input)
21
22
FILTER_PLL
VDDA
23
25
GNDA
CKOUT
O
PLL Ground
Clock Output
29
OUT8_B
O
PWM Channel 8 Output B
30
OUT8_A
O
PWM Channel 8 Output A
31
OUT7_B
O
PWM Channel 7 Output B
32
OUT7_A
O
PWM Channel 7 Output A
33
OUT6_B
O
PWM Channel 6 Output B
34
OUT6_A
O
PWM Channel 6 Output A
38
OUT5_B
O
PWM Channel 5 Output B
39
OUT5_A
O
PWM Channel 5 Output A
40
OUT4_B
O
PWM Channel 4 Output B
41
OUT4_A
O
PWM Channel 4 Output A
42
OUT3_B
O
PWM Channel 3 Output B
43
OUT3_A
O
PWM Channel 3 Output A
47
OUT2_B
O
PWM Channel 2 Output B
48
OUT2_A
O
PWM Channel 2 Output A
49
OUT1_B
O
PWM Channel 1 Output B
50
OUT1_A
O
PWM Channel 1 Output A
51
EAPD
O
External Amplifier Power Down
55
BICKO
O
Output I2S Serial Clock
56
LRCKO
O
Output I2S Left/Right Clock
57
SDO_12
O
Output I2S Serial Data Channels 1 & 2
58
SDO_34
O
Output I2S Serial Data Channels 3 & 4
62
SDO_56
O
Output I2S Serial Data Channels 5 & 6
63
SDO_78
O
Output I2S Serial Data Channels 7 & 8
64
PWDN
I
Device Powerdown
PLL Filter
PLL 2.5V Supply
PAD TYPE
3.3V Tolerant TTL Schmitt
Trigger Input Buffer
Analog Pad
2.5V Analog Power
Supply Voltage
Analog Ground
3.3V Capable TTL Tristate
4mA Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
3.3V Capable TTL 2mA
Output Buffer
5V Tolerant TTL Schmitt
Trigger Input Buffer
STA308
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
VDD_3.3
3.3V I/O Power Supply
VDD_2.5
2.5V Logic Power Supply
Value
Unit
-0.5 to 4
V
-0.5 to 3.3
V
Vi
Voltage on input pins
-0.5 to (VDD+0.5)
V
Vo
Voltage on output pins
-0.5 to (VDD+0.3)
V
Tstg
Storage Temperature
-40 to +150
°C
Tamb
Ambient Operating Temperature
-20 to +85
°C
Value
Unit
85
°C/W
Value
Unit
THERMAL DATA
Symbol
Rthj-amb
Parameter
Thermal resistance Junction to Ambient
RECOMMENDED DC OPERATING CONDITIONS
Symbol
Parameter
VDD_3.3
I/O Power Supply
3.0 to 3.6
V
VDD_2.5
Logic Power Supply
2.3 to 2.7
V
-20 to +125
°C
Tj
Operating Junction Temperature
5/33
STA308
ELECTRICAL CHARACTERISTCS (VDD3 = 3.3V ± 0.3V; VDD = 2.5V ± 0.2V; Tamb = 0 to 70 °C; unless otherwise specified)
GENERAL INTERFACE ELECTRICAL CHARACTERISTICS
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
Note
Iil
Low Level Input no pull-up
Vi = 0V
1
µA
1
Iih
High Level Input no pull-down
Vi = VDD3
2
µA
1
IOZ
Tristate output leakage without
pullup/down
Vi = VDD3
2
µA
1
Vesd
Electrostatic Protection
Leakage < 1µA
V
2
2000
Note 1: The leakage currents are generally very small, < 1na. The values given here are maximum after an electrostatic stress on the pin.
Note 2: Human Body Model
DC ELECTRICAL CHARACTERISTICS: 3.3V BUFFERS
Symbol
Parameter
VIL
Low Level Input Voltage
VIH
High Level Input Voltage
Test Condition
Min.
Typ.
Max.
Unit
0.8
V
2.0
V
VILhyst
Low Level Threshold
Input Falling
0.8
1.35
V
VIHhyst
High Level Threshold
Input Rising
1.3
2.0
V
0.3
0.8
V
0.4
V
Vhyst
Schmitt Trigger Hysteresis
VOL
Low Level Output
IoI = 100uA
VOL
High Level Output
Ioh = -100uA
VDD3-0.2
V
DC ELECTRICAL CHARACTERISTICS: 2.5V BUFFERS
Symbol
Parameter
Test Condition
VILst
Low Level Input Voltage
Schmitt input
VIHst
High Level Input Voltage
Schmitt input
VILhyst
Low Level Threshold
non Schmitt, Input
Falling
VIHhyst
High Level Threshold
non Schmitt, Input
Rising
Vhyst
Schmitt Trigger Hysteresis
VOL
Low Level Output
Note 1
VOH
High Level Output
Note 1
Typ.
Max.
Unit
0.26*VDD
V
0.7*VDD
V
0.5*VDD
1.3
0.5*VDD
V
2.0
0.23*VDD
Notes: 1. Source/Sink current under worst-case conditions.
6/33
Min.
V
0.15*VDD
0.85*VDD
V
V
V
STA308
1.0 PIN DESCRIPRTION
1.1 MVO: Master Volume Override
This pin enables the user to bypass the Volume Control on all channels. When MVO is pulled High, the Master
Volume Register is set to 00h, which corresponds to its Full Scale setting. The Master Volume Register Setting
offsets the individual Channel Volume Settings, which default to 0dB.
1.2 SDI_12 through 78: Serial Data In
Audio information enters the device here. Six format choices are available including I2S, left- or right-justified,
LSB or MSB first, with word widths of 16, 18, 20 and 24 bits.
1.3 RESET
Driving this pin (low) turns off the outputs and returns all settings to their defaults.
1.4 I2C
The SA, SDA and SCL pins operate per the Philips I2C specification. See Section 2.
1.5 PLL: Phase Locked Loop
The phase locked loop section provides the System Timing Signals and CKOUT.
1.6 CKOUT: Clock Out
System synchronization and master clocks are provided by the CKOUT.
1.7 OUT1 through OUT8: PWM Outputs
The PWM outputs provide the input signal for the power devices.
1.8 EAPD: External Amplifier Power-Down
This signal can be used to control the power-down of DDX power devices.
1.9 SDO_12 through 78: Serial Data Out
Audio information exits the device here. Six different format choices are available including I2S, left- or rightjustified, LSB or MSB first, with word widths of 16, 18, 20 and 24 bits.
1.10 PWDN: Device Power-Down
This puts the STA308 into a low-power state via appropriate power-down sequence. Pulling PWDN low begins
power-down sequence, and EAPD goes low ~30ms later.
2.0 II2C BUS SPECIFICATION
The STA308 supports the I2C protocol. This protocol defines any device that sends data on to the bus as a
transmitter and any device that reads the data as a receiver. The device that controls the data transfer is known
as the master and the other as the slave. The master always starts the transfer and provides the serial clock
for synchronization. The STA308 is always a slave device in all of its communications.
7/33
STA308
2.1 COMMUNICATION PROTOCOL
2.1.1 Data Transition or change
Data changes on the SDA line must only occur when the SCL clock is low. SDA transition while the clock is
high is used to identify a START or STOP condition.
2.1.2 Start Condition
START is identified by a high to low transition of the data bus SDA signal while the clock signal SCL is stable
in the high state. A START condition must precede any command for data transfer.
2.1.3 Stop Condition
STOP is identified by low to high transition of the data bus SDA signal while the clock signal SCL is stable in the
high state. A STOP condition terminates communication between STA308 and the bus master.
2.1.4 Data Input
During the data input the STA308 samples the SDA signal on the rising edge of clock SCL. For correct device
operation the SDA signal must be stable during the rising edge of the clock and the data can change only when
the SCL line is low.
2.2 DEVICE ADDRESSING
To start communication between the master and the STA308, the master must initiate with a start condition.
Following this, the master sends onto the SDA line 8-bits (MSB first) corresponding to the device select address
and read or write mode.
The 7 most significant bits are the device address identifiers, corresponding to the I2C bus definition. In the
STA308 the I2C interface has two device addresses depending on the SA pin configuration, 0x30 or 0011000x
when SA = 0, and 0x32 or 0011001x when SA = 1.
The 8th bit (LSB) identifies read or write operation RW, this bit is set to 1 in read mode and 0 for write mode.
After a START condition the STA308 identifies on the bus the device address and if a match is found, it acknowledges the identification on SDA bus during the 9th bit time. The byte following the device identification byte is
the internal space address.
2.3 WRITE OPERATION
Following the START condition the master sends a device select code with the RW bit set to 0. The STA308
acknowledges this and the writes for the byte of internal address. After receiving the internal byte address the
STA308 again responds with an acknowledgement.
2.3.1 Byte Write
In the byte write mode the master sends one data byte, this is acknowledged by the STA308. The master then
terminates the transfer by generating a STOP condition.
2.3.2 Multi-byte Write
The multi-byte write modes can start from any internal address. The master generating a STOP condition terminates the transfer.
8/33
STA308
Write Mode Sequence
ACK
BYTE
WRITE
ACK
DEV-ADDR
START
ACK
SUB-ADDR
DATA IN
RW
STOP
ACK
MULTIBYTE
WRITE
ACK
DEV-ADDR
START
ACK
SUB-ADDR
ACK
DATA IN
DATA IN
STOP
RW
Read Mode Sequence
ACK
CURRENT
ADDRESS
READ
DEV-ADDR
NO ACK
DATA
RW
START
STOP
ACK
RANDOM
ADDRESS
READ
DEV-ADDR
ACK
SUB-ADDR
RW
RW= ACK
HIGH
START
SEQUENTIAL
CURRENT
READ
ACK
DEV-ADDR
DEV-ADDR
START
NO ACK
DATA
RW
ACK
STOP
ACK
DATA
DATA
NO ACK
DATA
STOP
START
ACK
SEQUENTIAL
RANDOM
READ
DEV-ADDR
START
ACK
ACK
SUB-ADDR
RW
DEV-ADDR
START
ACK
DATA
ACK
DATA
NO ACK
DATA
RW
STOP
Table 1. Register summary
Address
Name
D7
D6
D5
D4
D3
D2
D1
D0
00h
ConfA
MPC
HPE
BME
IR1
IR0
MCS2
MCS1
MCS0
01h
ConfB
DRC
ZCE
SAIFB
SAI2
SAI1
SAI0
ZDE
DSPB
02h
ConfC
HPB
CSZ4
CSZ3
CSZ2
CSZ1
CSZ0
OM1
OM0
03h
ConfD
BQL
PSL
COS1
COS0
C78BO
C56BO
C34BO
C12BO
04h
ConfE
DCV
SAOFB
SAO2
SAO1
SAO0
DEMP
VOLEN
MIXE
05h
ConfF
EAPD
AME
COD
I2SD
PWMD
06h
Mmute
07h
Mvol
MV7
MV6
MV5
MV4
MV3
MV2
MV1
MV0
08h
Cmute
C8M
C7M
C6M
C5M
C4M
C3M
C2M
C1M
09h
C1Vol
C1V7
C1V6
C1V5
C1V4
C1V3
C1V2
C1V1
C1V0
0Ah
C2Vol
C2V7
C2V6
C2V5
C2V4
C2V3
C2V2
C2V1
C2V0
0Bh
C3Vol
C3V7
C3V6
C3V5
C3V4
C3V3
C3V2
C3V1
C3V0
0Ch
C4Vol
C4V7
C4V6
C4V5
C4V4
C4V3
C4V2
C4V1
C4V0
0Dh
C5Vol
C5V7
C5V6
C5V5
C5V4
C5V3
C5V2
C5V1
C5V0
0Eh
C6Vol
C6V7
C6V6
C6V5
C6V4
C6V3
C6V2
C6V1
C6V0
0Fh
C7Vol
C7V7
C7V6
C7V5
C7V4
C7V3
C7V2
C7V1
C7V0
MMute
9/33
STA308
10h
C8Vol
11h
C8V6
C8V5
C8V4
C8V2
C8V1
C8V0
C12im
C2IM2
C2IM1
C2IM0
C1IM2
C1IM1
C1IM0
12h
C34im
C4IM2
C4IM1
C4IM0
C3IM2
C3IM1
C3IM0
13h
C56im
C6IM2
C6IM1
C6IM0
C5IM2
C5IM1
C5IM0
14h
C78im
C8IM2
C8IM1
C8IM0
C7IM2
C7IM1
C7IM0
15h
C1234ls
C4LS1
C4LS0
C3LS1
C3LS0
C2LS1
C2LS0
C1LS1
C1LS0
16h
C5678ls
C8LS1
C8LS0
C7LS1
C7LS0
C6LS1
C6LS0
C5LS1
C5LS0
17h
L1ar
L1R3
L1R2
L1R1
L1R0
L1A3
L1A2
L1A1
L1A0
18h
L1atrt
L1AT3
L1AT2
L1AT1
L1AT0
L1RT3
L1RT2
L1RT1
L1RT0
19h
L2ar
L2R3
L2R2
L2R1
L2R0
L2A3
L2A2
L2A1
L2A0
1Ah
L2atrt
L2AT3
L2AT2
L2AT1
L2AT0
L2RT3
L2RT2
L2RT1
L2RT0
1Bh
Tone
TTC3
TTC2
TTC1
TTC0
BTC3
BTC2
BTC1
BTC0
1Ch
Cfaddr
CFA7
CFA6
CFA5
CFA4
CFA3
CFA2
CFA1
CFA0
1Dh
B2cf1
C1B23
C1B22
C1B21
C1B20
C1B19
C1B18
C1B17
C1B16
1Eh
B2cf2
C1B15
C1B14
C1B13
C1B12
C1B11
C1B10
C1B9
C1B8
1Fh
B2cf3
C1B7
C1B6
C1B5
C1B4
C1B3
C1B2
C1B1
C1B0
20h
B0cf1
C2B23
C2B22
C2B21
C2B20
C2B19
C2B18
C2B17
C2B16
21h
B0cf2
C2B15
C2B14
C2B13
C2B12
C2B11
C2B10
C2B9
C2B8
22h
B0cf3
C2B7
C2B6
C2B5
C2B4
C2B3
C2B2
C2B1
C2B0
23h
A2cf1
C3B23
C3B22
C3B21
C3B20
C3B19
C3B18
C3B17
C3B16
24h
A2cf2
C3B15
C3B14
C3B13
C3B12
C3B11
C3B10
C3B9
C3B8
25h
A2cf3
C3B7
C3B6
C3B5
C3B4
C3B3
C3B2
C3B1
C3B0
26h
A1cf1
C4B23
C4B22
C4B21
C4B20
C4B19
C4B18
C4B17
C4B16
27h
A1cf2
C4B15
C4B14
C4B13
C4B12
C4B11
C4B10
C4B9
C4B8
28h
A1cf3
C4B7
C4B6
C4B5
C4B4
C4B3
C4B2
C4B1
C4B0
29h
B1cf1
C5B23
C5B22
C5B21
C5B20
C5B19
C5B18
C5B17
C5B16
2Ah
B1cf2
C5B15
C5B14
C5B13
C5B12
C5B11
C5B10
C5B9
C5B8
2Bh
B1cf3
C5B7
C5B6
C5B5
C5B4
C5B3
C5B2
C5B1
C5B0
2Ch
Cfud
WA
W1
2Dh
DC1
DCC23
DCC22
DCC21
DCC20
DCC19
DCC18
DCC17
DCC16
2Eh
DC2
DCC15
DCC14
DCC13
DCC12
DCC11
DCC10
DCC9
DCC8
2Fh
BIST1
R4BEND
R3BEND
R2BEND
R1BEND
R4BACT
R3BACT
R2BACT
R1BACT
30h
BIST2
R5BBAD
R4BBAD
R3BBAD
R2BBAD
R1BBAD
10/33
C8V7
C8V3
STA308
3.0 CONFIGURATION REGISTER A (ADDRESS 00H)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
MPC
MPE
BME
IR1
IR0
MCS2
MCS1
MCS0
RST
1
0
0
0
0
0
1
1
3.0.1 Master Clock Select
BIT
R/W
RST
NAME
DESCRIPTION
0
R/W
1
MCS0
1
R/W
1
MCS1
Master Clock Select : Selects the ratio between the input I2S
sample frequency and the input clock.
2
R/W
0
MCS2
The STA308 will support sample rates of 32kHz, 44.1kHz, 48Khz, 88.2kHz, 96kHz, 176.4kHz, and 192kHz.
Therefore the internal clock will be:
– 65.536Mhz for 32kHz
– 90.3168Mhz for 44.1khz, 88.2kHz, and 176.4kHz
– 98.304Mhz for 48kHz, 96kHz, and 192kHz
The external clock frequency provided to the XTI pin must be a multiple of the input sample frequency(fs). The
relationship between the input clock and the input sample rate is determined by both the MCSx and the IRx (Input Rate) register bits. The MCSx bits determine the PLL factor generating the internal clock and the IRx bits
determine the oversampling ratio used internally.
Input Sample Rate
fs (kHz)
IR
MCS(2..0)
1xx
011
010
001
000
32, 44.1, 48
00
128fs
256fs
384fs
512fs
768fs
88.2, 96
01
64fs
128fs
192fs
256fs
384fs
176.4, 192
10
64fs
128fs
192fs
256fs
384fs
3.0.2 Interpolation Ratio Select
BIT
R/W
RST
NAME
DESCRIPTION
2
R/W
0
IR0
3
R/W
0
IR1
Interpolation Ratio Select : Selects internal interpolation ratio based on input I2S
sample frequency
The STA308 has variable interpolation (oversampling) settings such that internal processing and DDX output
rates remain consistent. The first processing block interpolates by either 4 times, 2 times, or 1 time (passthrough). The IR bits determine the oversampling ratio of this interpolation.
Table 2. IR bit settings as a function of Input Sample Rate.
Input Sample Rate Fs
IR(1,0)
1st Stage Interpolation Ratio
32kHz
00
4 times oversampling
44.1kHz
00
4 times oversampling
48kHz
00
4 times oversampling
88.2kHz
01
2 times oversampling
96kHz
01
2 times oversampling
176.4kHz
10
Pass-Through
192kHz
10
Pass-Through
11/33
STA308
3.0.3 Bass Management Enable
BIT
R/W
RST
NAME
5
R/W
0
BME
DESCRIPTION
Bass Management Enable : 0 – No Bass Management
1 – Bass Management operation on channel 6, scale and add inputs
Channel 6 of the STA308 features a bass management mode that enables redirection of information in all other
channels to this channel and which can then be filtered appropriately using the EQ(Biquad) section. Setting the
BME bit selects the output of the scale and mix block for channel 6 instead of the output of the channel mapping
block. The settings for the scale and mix block are provided by the CxBMS registers
3.0.4 DDX Headphone Output Enable
BIT
R/W
RST
NAME
6
R/W
0
HPE
DESCRIPTION
DDX Headphone Enable :
0 – Channels 7,8 normal DDX operation.
1 – Channels 7,8 DDX Headphone operation.
Channels 7 and 8 of the STA308 have the option to be processed for headphones. The headphone output can
then be driven using an appropriate output device. This signal is a fully differential 3-wire drive called DDX
Headphone
3.0.5 Max Power Correction
BIT
R/W
RST
NAME
7
R/W
1
MPC
DESCRIPTION
Max Power Correction : Setting of 1 enables DDX correction for THD reduction
near maximum power output.
Setting the MPC bit turns on special processing that corrects the DDX power device at high power. This mode
should lower the THD+N of a full DDX system at maximum power output and slightly below. This mode will only
be operational in OM= 00 or 10.
3.1 Configuration Register B (address 01h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
DRC
ZCE
SAIFB
SAI2
SAI1
SAI0
ZDE
DSPB
RST
0
1
0
0
0
0
1
0
3.1.1 DSP Bypass
BIT
R/W
RST
NAME
0
R/W
0
DSPB
DESCRIPTION
DSP Bypass Bit : 0 – Normal Operation
1 – Bypass of Biquad and Bass/Treble Functionality
Setting the DSPB bit bypasses the biquad and bass/treble functionality of the STA308.
3.1.2 Zero-Detect Mute Enable
BIT
R/W
RST
NAME
1
R/W
1
ZDE
DESCRIPTION
Zero-Detect Mute Enable : Setting of 1 enables the
automatic zero-detect mute
Setting the ZDE bit enables the zero-detect automatic mute.
The zero-detect circuit looks at the input data to each processing channel after the channel mapping block. If
any channel receives 2048 consecutive zero value samples (regardless of fs) then that individual channel is
muted if this function is enabled.
12/33
STA308
Serial Audio Input Interface Format
BIT
R/W
RST
NAME
2
R/W
0
SAI0
3
R/W
0
SAI1
4
R/W
0
SAI2
DESCRIPTION
Serial Audio Input Interface Format : Determines the
interface format of the input serial digital audio interface.
The STA308 features a configurable digital serial audio interface. The settings of the SAIx bits determine how
the input to this interface is interpreted. Six formats are accepted.
Table 3. Interface format as a function of SAI bits.
SAI(2..0)
Interface Format
000
I2S
001
Left-Justified Data
010
Right-Justified 16-bit Data
011
Right-Justified 18-bit Data
100
Right-Justified 20-bit Data
101
Right-Justified 24-bit Data
Figure 2. Serial Audio Signals
2
SAI=000 I S
Left
LRCLK
Right
SCLK
MSB
SDATA
LSB
MSB
LSB
MSB
SAI=001 Left Justified
Left
LRCLK
Right
SCLK
SDATA
MSB
LSB
MSB
LSB
MSB
SAI=010 to 101 Right Justified
Left
LRCLK
Right
SCLK
SDATA
MSB
LSB
MSB
LSB
MSB
13/33
STA308
3.1.3 Serial Audio Input Interface First Bit
BIT
R/W
RST
NAME
DESCRIPTION
5
R/W
0
SAIFB
Determines MSB or LSB first for all SAI formats
0 – MSB First, 1 – LSB First
3.1.4 Zero-Crossing Volume Enable
BIT
R/W
RST
NAME
6
R/W
1
ZCE
DESCRIPTION
Zero-Crossing Volume Enable :
1 – Volume adjustments will only occur at digital zero-crossings
0 – Volume adjustments will occur immediately
The ZCE bit enables zero-crossing volume adjustments. When volume is adjusted on digital zero-crossings,
"zipper noise" is eliminated
3.1.5 Dynamic Range Compression/Anti-Clipping Bit
BIT
R/W
RST
NAME
6
R/W
0
DRC
DESCRIPTION
Dynamic Range Compression/Anti-Clipping
0 – Limiters act in Anti-Clipping Mode
1- Limiters act in Dynamic Range Compression Mode
Both limiters can be used in one of two ways, anti-clipping or dynamic range compression. When used in anticlipping mode the limiter threshold values are constant and dependent on the gain/attenuation settings applied
to the input signal. In dynamic range compression mode the limiter threshold values vary with the volume settings allowing for limiting to occur independently of the gain/attenuation but dependent on the input signal
3.2 Configuration Register C (address 02h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
HPB
CSZ4
CSZ3
CSZ2
CSZ1
CSZ0
OM1
OM0
RST
0
1
1
1
1
1
0
0
3.2.1 DDX Power Output Mode
BIT
R/W
RST
NAME
0
R/W
0
OM0
1
R/W
0
OM1
DESCRIPTION
DDX Power Output Mode : Selects configuration of DDX output.
The DDX Power Output Mode selects how the DDX output timing is configured. Different power devices use
different output modes. The DDX recommended use is OM = 00. The variable mode uses the OMVx bits for
adjustment
OM(1,0)
14/33
Output Stage - Mode
00
Fixed Compensation for DDX-2060, DDX-2100 power amplifiers
01
Tapered Compensation for Discrete Output Stage
10
Full Power Mode
11
Variable Compensation (CSZx bits, see 3.3.2)
STA308
3.2.2 DDX Compensating Pulse Size Register
BIT
R/W
RST
NAME
DESCRIPTION
2
R/W
1
CSZ0
Contra Size Register : When OM(1,0) = 11, this register determines the
size of the DDX compensating pulse from 0 clock ticks to 31 clock periods.
3
R/W
1
CSZ1
4
R/W
1
CSZ2
5
R/W
1
CSZ3
6
R/W
1
CSZ4
CSZ(4..0)
Compensating Pulse Size
00000
0 Clock period Compensating Pulse Size
00001
1 Clock period Compensating Pulse Size
…
…
11111
31 Clock period Compensating Pulse Size
3.2.3 High-Pass Filter Bypass
BIT
R/W
RST
NAME
DESCRIPTION
7
R/W
0
HPB
High-Pass Filter Bypass Bit. Setting of one bypasses internal AC
coupling digital high-pass filter
The STA308 features an internal digital high-pass filter for the purpose of AC coupling. The purpose of this filter
is to prevent DC signals from passing through a DDX amplifier. DC signals can cause speaker damage
3.3 Configuration Register D (address 03h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
BQL
PSL
COS1
COS0
C78BO
C56BO
C34BO
C12BO
RST
0
0
1
0
0
0
0
0
3.3.1 Binary Output Enable Registers
BIT
R/W
RST
NAME
DESCRIPTION
0
R/W
0
C12BO
1
R/W
0
C34BO
Channels 1&2, 3&4, 5&6, 7&8 Binary Output Mode Enable
Bits. A setting of 0 indicates ordinary DDX tri-state output. A
setting of 1 indicates binary output mode.
2
R/W
0
C56BO
3
R/W
0
C78BO
Each two-channel pair of outputs can be set to output a binary PWM stream. In this mode, output A
of a channel will be considered the positive output and output B is negative inverse. For example, setting C34BO
= 1 sets channels 3&4 to Binary Output (PWM) Mode.
3.3.2 Clock Output Select
BIT
R/W
RST
NAME
DESCRIPTION
4
R/W
0
COS0
Clock Output Select
5
R/W
1
COS1
Clock Output Select
15/33
STA308
The Clock Output Select register selects the frequency of the clock output pin relative to the PLL clock output.
The PLL clock runs at 2048fs for 32, 44.1, and 48kHz, at 1024fs for 88.2kHz and 96 kHz, and at 512fs for
176.4kHz and 192kHz.
COS(1,0)
CKOUT Frequency
01
PLL Output/4
10
PLL Output/8
11
PLL Output/16
3.3.3 Post-Scale Link
BIT
R/W
RST
NAME
6
R/W
0
PSL
DESCRIPTION
Post-Scale Link :0 – Each Channel uses individual Post-Scale value
1 - Each Channel uses Channel 1 Post-Scale value
For multi-channel applications, the post-scale values can be linked to the value of channel 1 for ease of use and
update the values faster.
3.3.4 Biquad Coefficient Link
BIT
R/W
RST
NAME
7
R/W
0
BQL
DESCRIPTION
Biquad Link :
0 – Each Channel uses coefficient values
1- Each Channel uses Channel 1 coefficient values
For ease of use, all channels can use the biquad coefficients loaded into the Channel 1 Coefficient RAM space
by setting the BQL bit to 1. Then any EQ updates would only have to be performed once.
3.4 Configuration Register E (address 04h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
DCV
SAOFB
SAO2
SAO1
SAO0
DEMP
VOLEN
MIXE
RST
0
0
0
0
0
0
1
0
BIT
R/W
RST
NAME
0
R/W
0
MIXE
DESCRIPTION
Mix Enable: 0 – Normal Operation
1 - Adjacent Channel Mix Mode
The scale and mix functionality can be used to mix adjacent channels instead of for bass management. By setting this bit(BME must be set to 0) odd channels will be mixed with their adjacent even channel and output in
the place of the even channel. The odd channel wills pass-through unscaled. The values used for this function
are the same as for bass management. Since this function occurs post channel mapping a large number of
possibilities are present for two channel mixing. Up to four mixed channels can be obtained.
BIT
R/W
RST
NAME
1
R/W
1
VOLEN
DESCRIPTION
Volume Enable: 0 – Volume Operation Bypassed
1 - Volume Operation Normal
When VOLEN set to 1, volume operation is normal. When set to 0, volume operation is bypassed and the volume stages are all set to pass-through. This also eliminates the digital volume offset of ~-0.6dB that is used to
16/33
STA308
map full-scale digital input to full DDX modulation output.
BIT
R/W
RST
NAME
2
R/W
0
DEMP
DESCRIPTION
Deemphasis : 0 – No Deemphasis, 1- Deemphasis
By setting this bit to one deemphasis will implemented on all channels. When this is used it takes the place of
biquad #1 in each channel and any coefficients using biquad #1 will be ignored. DSPB(DSP Bypass) bit must
be set to 0 for Deemphasis to function.
BIT
R/W
RST
NAME
3
R/W
0
SAO0
4
R/W
0
SAO1
5
R/W
0
SAO2
DESCRIPTION
Serial Audio Output Interface Format : Determines the interface
format of the output serial digital audio interface.
The STA308 features a configurable digital serial audio interface. The settings of the SAIx bits determine how
the output to this interface is interpreted. Six formats are accepted.
Table 4. Interface format as a function of SAO bits.
SAO(2..0)
Interface Format
000
I2S
001
Left-Justified Data
010
Right-Justified 16-bit Data
011
Right-Justified 18-bit Data
100
Right-Justified 20-bit Data
101
Right-Justified 24-bit Data
BIT
R/W
RST
NAME
6
R/W
0
SAOFB
BIT
R/W
RST
NAME
7
R/W
0
DCV
DESCRIPTION
Determines MSB or LSB first for all SAO formats;
0 – MSB First
1 – LSB First
DESCRIPTION
Distortion Compensation Variable:
0 – Use Standard DC Coefficient
1- Use DCC bits for DC Coefficient
3.5 Configuration Register F (address 05h)
BIT
D7
NAME
RST
D6
D3
D2
D1
D0
EAPD
AME
COD
SID
PWMD
0
0
0
0
0
BIT
R/W
RST
NAME
0
R/W
0
PWMD
D5
D4
DESCRIPTION
PWM Output Disable: 0 – PWM Output Normal
1- No PWM Output
17/33
STA308
1
R/W
0
SID
Serial Interface(I2S Out) Disable: 0 – I2S Output Normal
1- No I2S Output
2
R/W
0
COD
Clock Output Disable: 0 – Clock Output Normal
1- No Clock Output
3
R/W
0
AME
AM Mode Enable : 0 – Normal DDX operation.
1 – AM reduction mode DDX operation.
The STA308 features a DDX processing mode that minimizes the amount of noise generated in frequency range
of AM radio. This mode is intended to be used when DDX is operating in a device with an AM tuner active. The
SNR of the DDX processing is reduced to ~83dB in this mode, which is still greater than the SNR of AM radio.
BIT
R/W
RST
NAME
7
R/W
0
EAPD
DESCRIPTION
External Amplifier Power Down:
0 – External Power Stage Power Down Active
1 - Normal Operation
This output bit, on pin 51 of the device, is used to mute the DDX Power Devices for Power-Down.
3.6 Master Mute Register (address 06h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
MMUTE
RST
0
3.7 Master Volume Register (address 07h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
MV7
MV6
MV5
MV4
MV3
MV2
MV1
MV0
RST
1
1
1
1
1
1
1
1
3.8 Channels 1,2,3,4,5,6,7,8 Mute (address 08h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C8M
C7M
C6M
C5M
C4M
C3M
C2M
C1M
RST
0
0
0
0
0
0
0
0
3.9 Channel 1 Volume (address 09h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C1V7
C1V6
C1V5
C1V4
C1V3
C1V2
C1V1
C1V0
RST
0
0
1
1
0
0
0
0
3.10 Channel 2 Volume (address 0Ah)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C2V7
C2V6
C2V5
C2V4
C2V3
C2V2
C2V1
C2V0
RST
0
0
1
1
0
0
0
0
18/33
STA308
3.11 Channel 3 Volume (address 0Bh)
BIT
NAME
RST
D7
D6
D5
D4
D3
D2
D1
D0
C3V7
C3V6
C3V5
C3V4
C3V3
C3V2
C3V1
C3V0
0
0
1
1
0
0
0
0
3.12 Channel 4 Volume (address 0Ch)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C4V7
C4V6
C4V5
C4V4
C4V3
C4V2
C4V1
C4V0
RST
0
0
1
1
0
0
0
0
3.13 Channel 5 Volume (address 0Dh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C5V7
C5V6
C5V5
C5V4
C5V3
C5V2
C5V1
C5V0
RST
0
0
1
1
0
0
0
0
3.14 Channel 6 Volume (address 0Eh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C6V7
C6V6
C6V5
C6V4
C6V3
C6V2
C6V1
C6V0
RST
0
0
1
1
0
0
0
0
3.15 Channel 7 Volume (address 0Fh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C7V7
C7V6
C7V5
C7V4
C7V3
C7V2
C7V1
C7V0
RST
0
0
1
1
0
0
0
0
3.16 Channel 8 Volume (address 10h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C8V7
C8V6
C8V5
C8V4
C8V3
C8V2
C8V1
C8V0
RST
0
0
1
1
0
0
0
0
The Volume structure of the STA308 consists of individual volume registers for each channel and a master volume register that provides an offset to each channels volume setting. The individual channel volumes are adjustable in 0.5dB steps from +24dB to -103dB. As an example if C5V = 0Bh or +18.5dB and MV = 21h or 16.5dB, then the total gain for channel 5 = +2dB. The Master Mute when set to 1 will mute all channels at once,
whereas the individual channel mutes(CxM) will mute only that channel. Both the Master Mute and the Channel
Mutes provide a "soft mute" with the volume ramping down to mute in 8192 samples from the maximum volume
setting at the internal processing rate(~192kHz). A "hard mute" can be obtained by commanding a value of all
1's(255) to any channel volume register or the master volume register. When volume offsets are provided via
the master volume register any channel that whose total volume is less than -103dB will be muted. All changes
in volume take place at zero-crossings when ZCE = 1(configuration register B) on a per channel basis as this
creates the smoothest possible volume transitions. When ZCE=0, volume updates will occur immediately.
19/33
STA308
Table 5. Master Volume Offset as a function of MV(7..0).
MV(7..0)
Volume Offset from Channel Value
00000000(00h)
0dB
00000001(01h)
-0.5dB
00000010(02h)
-1dB
…
…
01001100(4Ch)
-38dB
…
…
11111110(FEh)
-127dB
11111111(FFh)
Hard Master Mute
Channel Volume as a function of CxV(7..0)
CxV(7..0)
Volume
00000000(00h)
+24dB
00000001(01h)
+23.5dB
00000010(02h)
+23dB
…
…
00101111(2Fh)
+0.5dB
00110000(30h)
0dB
00110001(31h)
-0.5dB
…
…
11111110(FEh)
-103dB
11111111(FFh)
Hard Channel Mute
3.17 Channel Input Mapping Channels 1 & 2 (address 11h)
BIT
D7
D6
D5
D4
NAME
C2IM2
C2IM1
RST
0
0
D3
D2
D1
D0
C2IM0
C1IM2
C1IM1
C1IM0
1
0
0
0
D2
D1
D0
3.18 Channel Input Mapping Channels 3 & 4 (address 12h)
BIT
D7
D6
D5
D4
D3
NAME
C4IM2
C4IM1
C4IM0
C3IM2
C3IM1
C3IM0
RST
0
1
1
0
1
0
D2
D1
D0
3.19 Channel Input Mapping Channels 5 & 6 (address 13h)
BIT
D6
D5
D4
NAME
C6IM2
C6IM1
C6IM0
C5IM2
C5IM1
C5IM0
RST
1
0
1
1
0
0
20/33
D7
D3
STA308
3.20 Channel Input Mapping Channels 7 & 8 (address 14h)
BIT
D7
D6
D5
D4
NAME
C8IM2
C8IM1
RST
1
1
D3
D2
D1
D0
C8IM0
C7IM2
C7IM1
C7IM0
1
1
1
0
Each channel received via I2S can be mapped to any internal processing channel via the Channel Input Mapping registers. This allows for flexibility in processing, simplifies output stage designs, and enables the ability
to perform crossovers. The default settings of these registers map each I2S input channel to its corresponding
processing channel.
For example, to map input 2 to Channel 5, set Address 11h, bits D6, D5 and D4 to 100. Now, inputs 2 and 5 go
to Channel 5.
Table 6. Channel Mapping as a function of CxIM bits
CxIM(2..0)
I2S Input Mapped to:
000
Channel 1
001
Channel 2
010
Channel 3
011
Channel 4
100
Channel 5
Channel 1
Channel 2
Channel 3
Channel 4
Channel 5
Channel 6
Channel 7
Channel 8
101
Channel 6
CxIM(2..0)
110
Channel 7
111
Channel 8
8:1
Mux
Channel X
3
DDX-8000 Output Phasing
CH1
CH2
CH3
CH4
CH5
CH6
CH7
CH8
1/384kHz or 2.874us
21/33
STA308
3.21 Channel Limiter Select Channels 1,2,3,4 (address 15h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C4LS1
C4LS0
C3LS1
C3LS0
C2LS1
C2LS0
C1LS1
C1LS0
RST
0
0
0
0
0
0
0
0
3.22 Channel Limiter Select Channels 5,6,7,8 (address 16h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C8LS1
C8LS0
C7LS1
C7LS0
C6LS1
C6LS0
C5LS1
C5LS0
RST
0
0
0
0
0
0
0
0
3.23 Limiter 1 Attack/Release Rate (address 17h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
L1R3
L1R2
L1R1
L1R0
L1A3
L1A2
L1A1
L1A0
RST
1
0
1
0
0
1
1
0
3.24 Limiter 1 Attack/Release Threshold (address 18h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
L1AT3
L1AT2
L1AT1
L1AT0
L1RT3
L1RT2
L1RT1
L1RT0
RST
0
1
1
0
0
1
1
1
3.25 Limiter 2 Attack/Release Rate (address 19h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
L2R3
L2R2
L2R1
L2R0
L2A3
L2A2
L2A1
L2A0
RST
1
0
1
0
0
1
1
0
3.26 Limiter 2 Attack/Release Threshold (address 1Ah)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
L2AT3
L2AT2
L2AT1
L2AT0
L2RT3
L2RT2
L2RT1
L2RT0
RST
0
1
1
0
0
1
1
1
22/33
STA308
Basic Limiter and Volume Flow Diagram.
Limiter
RMS
Attenuation
Saturation
Gain/Volume
Input
Output
Gain
A limiter is basically a variable gain device, where the amount of gain applied depends on the input signal level.
As the name implies, compression limits the dynamic range of the signal.
The STA308 includes 2 independent limiter blocks. The purpose of the limiters is to automatically reduce the
dynamic range of the input signal to prevent the outputs from clipping in anti-clipping mode or to actively reduce
the dynamic range for a better listening environment such as a night-time listening mode which is often needed
for DVDs. The two modes are selected via the DRC bit in Configuration Register B; address 0x02, bit 7.
Each channel can be mapped to either limiter or not mapped. Non-mapped channels will clip when 0dBFS is
exceeded. Each limiter will look at the present value of each channel that is mapped to it, select the maximum
absolute value of all these channels, perform the limiting algorithm on that value, and then, if needed, adjust the
gain of the mapped channels in unison.
The limiter attack thresholds are determined by the LxAT registers. It is recommended in anti-clipping mode to
set this to 0dBFS, which corresponds to the maximum unclipped output power of a DDX amplifier. Since gain
can be added digitally within the STA308 it is possible to exceed 0dBFS or any other LxAT setting. When this
occurs, the limiter, when active, will automatically start reducing the gain. The rate at which the gain is reduced
when the attack threshold is exceeded is dependent upon the attack rate register setting for that limiter. The
gain reduction occurs on a peak-detect algorithm.
The release of limiter (uncompression), when the gain is again increased, is dependent on a RMS-detect algorithm. The output of the volume/limiter block is passed through a RMS filter. The output of this filter is compared
to the release threshold, determined by the Release Threshold register. When the RMS filter output falls below
the release threshold, the gain is again increased (uncompressed) at a rate dependent upon the Release Rate
register. The gain can never be increased past its set value and therefore the release will only occur if the limiter
has already reduced the gain. The release threshold value can be used to set what is effectively a minimum
dynamic range, this is helpful as over-limiting can reduce the dynamic range to virtually zero and cause program
material to sound "lifeless". In AC mode the attack and release thresholds are set relative to full-scale. In DRC
mode the attack threshold is set relative to the maximum volume setting of the channels mapped to that limiter
and the release threshold is set relative to the maximum volume setting plus the attack threshold.
Table 7. Channel Limiter Mapping as a function of CxLS bits.
CxLS(1,0)
Channel Limiter Mapping
00
Channel has limiting disabled
01
Channel is mapped to limiter #1
10
Channel is mapped to limiter #2
23/33
STA308
Table 8. Limiter Attack Rate as a function of LxA bits.
LxA(3..0)
Attack Rate dB/ms
0001
0010
0011
LxA(3..0)
1.3536
0000
0.9024
0110
0.4512
0111
0.2256
1000
0.1504
1001
0.1123
1010
0.0902
1011
0.0752
1100
0.0645
1101
0.0564
1110
0.0501
1111
0.0451
note: Shaded areas are Default Settings
Table 9. Limiter Release Rate and Uncompression Threshold as a function of LxR bits
24/33
LxR(3..0)
Release Rate dB/ms
0000
0.5116
0001
0.1370
0010
0.0744
0011
0.0499
0100
0.0360
0101
0.0299
0110
0.0264
0111
0.0208
1000
0.0198
1001
0.0172
1010
0.0147
1011
0.0137
1100
0.0134
1101
0.0117
1110
0.0110
1111
0.0104
STA308
Table 10. Limiter Attack Threshold as a function of LxAT bits.
LxAT(3..0)
AC(dB relative to FS)
DRC(db relative to Volume)
0000
-12
-22
0001
-10
-20
0010
-8
-18
0011
-6
-16
0100
-4
-14
0101
-2
-12
0110
0
-10
0111
+2
-8
1000
+3
-7
1001
+4
-6
1010
+5
-5
1011
+6
-4
1100
+7
-3
1101
+8
-2
1110
+9
-1
1111
+10
0
Table 11. Limiter Release Threshold as a function of LxRT bits
LxRT(3..0)
AC(dB relative to FS)
DRC(db relative to Volume + LxAT)
0000
•
•
0001
-23dB
-33dB
0010
-16.9dB
-26.9dB
0011
-13.4dB
-23.4dB
0100
-10.9dB
-20.9dB
0101
-9.0dB
-19.0dB
0110
-7.4dB
-17.4dB
0111
-6.0dB
-16.0dB
1000
-4.9dB
-14.9dB
1001
-3.8dB
-13.8dB
1010
-2.9dB
-12.9dB
1011
-2.1dB
-12.1dB
1100
-1.3dB
-11.3dB
1101
-0.65dB
-10.65dB
1110
0dB
-10dB
1111
+0.6dB
-9.4dBdB
25/33
STA308
3.27 Bass and Treble Tone Control(address 1Bh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
TTC3
TTC2
TTC1
TTC0
BTC3
BTC2
BTC1
BTC0
RST
0
1
1
1
0
1
1
1
The STA308 contains bass and treble tone control adjustments. These are selectable from +12dB to -12dB of
boost or cut. These are 1st order shelving filters with a corner frequency of 150Hz for bass and 3kHz for treble.
Any gain introduced in the tone controls will carry through to the volume and limiting block without saturation.
Table 12. Tone Control Boost/Cut as a function of BTC and TTC bits
BTC(3..0)/TTC(3..0)
Boost/Cut
0000
-12dB
0001
-12dB
…
…
0111
-4dB
0110
-2dB
0111
0dB
1000
+2dB
1001
+4dB
…
…
1101
+12dB
1110
+12dB
1111
+12dB
3.28 Coefficient Address Register (address 1Ch)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
CFA7
CFA6
CFA5
CFA4
CFA3
CFA2
CFA1
CFA0
RST
0
0
0
0
0
0
0
0
3.29 Coefficient b2 Data Register Bits 23..16 (address 1Dh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C1B23
C1B22
C1B21
C1B20
C1B19
C1B18
C1B17
C1B16
RST
0
0
0
0
0
0
0
0
3.30 Coefficient b2 Data Register Bits 15..8 (address 1Eh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C1B15
C1B14
C1B13
C1B12
C1B11
C1B10
C1B9
C1B8
RST
0
0
0
0
0
0
0
0
3.31 Coefficient b2 Data Register Bits 7..0 (address 1Fh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C1B7
C1B6
C1B5
C1B4
C1B3
C1B2
C1B1
C1B0
RST
0
0
0
0
0
0
0
0
26/33
STA308
3.32 Coefficient b0 Data Register Bits 23..16 (address 20h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C2B23
C2B22
C2B21
C2B20
C2B19
C2B18
C2B17
C2B16
RST
0
0
0
0
0
0
0
0
3.33 Coefficient b0 Data Register Bits 15..8 (address 21h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C2B15
C2B14
C2B13
C2B12
C2B11
C2B10
C2B9
C2B8
RST
0
0
0
0
0
0
0
0
3.34 Coefficient b0 Data Register Bits 7..0 (address 22h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C2B7
C2B6
C2B5
C2B4
C2B3
C2B2
C2B1
C2B0
RST
0
0
0
0
0
0
0
0
3.35 Coefficient a2 Data Register Bits 23..16 (address 23h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C3B23
C3B22
C3B21
C3B20
C3B19
C3B18
C3B17
C3B16
RST
0
0
0
0
0
0
0
0
3.36 Coefficient a2 Data Register Bits 15..8 (address 24h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C3B15
C3B14
C3B13
C3B12
C3B11
C3B10
C3B9
C3B8
RST
0
0
0
0
0
0
0
0
3.37 Coefficient a2 Data Register Bits 7..0 (address 25h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C3B7
C3B6
C3B5
C3B4
C3B3
C3B2
C3B1
C3B0
RST
0
0
0
0
0
0
0
0
3.38 Coefficient a1 Data Register Bits 23..16 (address 26h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C4B23
C4B22
C4B21
C4B20
C4B19
C4B18
C4B17
C4B16
RST
0
0
0
0
0
0
0
0
3.39 Coefficient a1 Data Register Bits 15..8 (address 27h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C4B15
C4B14
C4B13
C4B12
C4B11
C4B10
C4B9
C4B8
RST
0
0
0
0
0
0
0
0
27/33
STA308
3.40 Coefficient a1 Data Register Bits 7..0 (address 28h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C4B7
C4B6
C4B5
C4B4
C4B3
C4B2
C4B1
C4B0
RST
0
0
0
0
0
0
0
0
3.41 Coefficient b1 Data Register Bits 23..16 (address 29h)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C5B23
C5B22
C5B21
C5B20
C5B19
C5B18
C5B17
C5B16
RST
0
0
0
0
0
0
0
0
3.42 Coefficient b1 Data Register Bits 15..8 (address 2Ah)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C5B15
C5B14
C5B13
C5B12
C5B11
C5B10
C5B9
C5B8
RST
0
0
0
0
0
0
0
0
3.43 Coefficient b1 Data Register Bits 7..0 (address 2Bh)
BIT
D7
D6
D5
D4
D3
D2
D1
D0
NAME
C5B7
C5B6
C5B5
C5B4
C5B3
C5B2
C5B1
C5B0
RST
0
0
0
0
0
0
0
0
D3
D2
D1
D0
WA
W1
3.44 Coefficient Write Control Register (address 2Ch)
BIT
D7
D6
D5
D4
NAME
RST
Coefficients for EQ and Bass Management are handled internally in the STA308 via RAM. Access to this RAM
is available to the user via an I2C register interface. A collection of I2C registers is dedicated to this function.
One contains a coefficient base address, five sets of three store the values of the 24-bit coefficients to be written
or that were read, and one contains bits used to control the writing of the coefficient(s) to RAM. The following
are step instructions for reading and writing coefficients.
Reading a coefficient from RAM
– write 8-bit address to I2C register 1Ch
– ead top 8-bits of coefficient in I2C address 1Dh
– ead middle 8-bits of coefficient in I2C address 1Eh
– ead bottom 8-bits of coefficient in I2C address 1Fh
Writing a single coefficient to RAM
– write 8-bit address to I2C register 1Ch
– write top 8-bits of coefficient in I2C address 1Dh
– write middle 8-bits of coefficient in I2C address 1Eh
– write bottom 8-bits of coefficient in I2C address 1Fh
– write 1 to W1 bit in I2C address 2Bh
28/33
STA308
Writing a set of coefficients to RAM
– write 8-bit starting address to I2C register 1Ch
– write top 8-bits of coefficient b2 in I2C address 1Dh
– write middle 8-bits of coefficient b2 in I2C address 1Eh
– write bottom 8-bits of coefficient b2 in I2C address 1Fh
– write top 8-bits of coefficient b0 in I2C address 20h
– write middle 8-bits of coefficient b0 in I2C address 21h
– write bottom 8-bits of coefficient b0 in I2C address 22h
– write top 8-bits of coefficient a2 in I2C address 23h
– write middle 8-bits of coefficient a2 in I2C address 24h
– write bottom 8-bits of coefficient a2 in I2C address 25h
– write top 8-bits of coefficient a1 in I2C address 26h
– write middle 8-bits of coefficient a1 in I2C address 27h
– write bottom 8-bits of coefficient a1 in I2C address 28h
– write top 8-bits of coefficient b1 in I2C address 29h
– write middle 8-bits of coefficient b1 in I2C address 2Ah
– write bottom 8-bits of coefficient b1 in I2C address 2Bh
– write 1 to WA bit in I2C address 2Ch
The mechanism for writing a set of coefficients to RAM provides a method of updating the five coefficients corresponding to a given biquad (filter) simultaneously to avoid possible unpleasant acoustic side effects. When
using this technique, the 8-bit address would specify the address of the biquad b2 coefficient (e.g. 0, 5, 10, 15,
…, 50, … 195 decimal), and the STA308 will generate the RAM addresses as offsets from this base value to
write the complete set of coefficient data.
Equalization:
Figure 3. Data Flow for single channel Biquad / Bass / Treble block.:
From
1st Interpolation
Stage
PreScale
To
Volume/
Limiter
Biquad1
Biquad2
Biquad3
Biquad4
Biquad5
Bass/
Treble
Five user-programmable 28-bit biquads are available per channel in the STA308. These biquads run at 192kHz
for 48kHz, 96kHz, or 192kHz input and at 176.4kHz for 44.1kHz, 88.2kHz, and 176.4kHz input. The PreScale
block is used for attenuation when filters are to be designed that boost frequencies above 0dBFS. This is a
single 28-bit signed multiply, with 800000h = -1 and 7FFFFFh = 0.9999998808. These values are labeled
CxPS, with x representing the channel. The biquads use this equation:
Y[n] = 2(b0/2)X[n] + 2(b1/2)X[n-1] + b2X[n-2] - 2(a1/2)Y[n-1] - a2Y[n-2]
= b0X[n] + b1X[n-1] + b2X[n-2] - a1Y[n-1] - a2Y[n-2]
29/33
STA308
Y[n] represents the output and X[n] represents the input. Coefficients are defined in the following manner:
CxHx0 = b2
CxHx1 = b0/2
CxHx2 = -a2
CxHx3 = -a1/2
CxHx4 = b1/2
The first x represents the channel and the second the biquad number. For example C3H41 is the b0/2 coefficient in the fourth series biquad in channel 3. The biquad link bit allows all channels to use the coefficients of
channel 1.
Bass Management
Channel 6 provides the ability to scale and mix all channels before the biquad block. This allows for information
from any channel to be redirected to this channel and then filtered appropriately for a subwoofer application.
When the BME bit is set (bit D5 of Configuration Register A, at address 00h) the input to the biquad section is
routed from the scale and mix block instead of the normal channel 6 1st stage interpolation output. Eight scaling
coefficients are provided to perform this function. They are labeled CxBMS with x representing the channel that
is being scaled. Each input channel is multiplied by its corresponding scale factor and summed. The output of
the summation is the output of the scale and mix block.
Post-Scale
The STA308 provides one additional multiplication after the last interpolation stage and before the distortion
compensation on each channel. This is a 24-bit signed fractional multiply. The scale factor for this multiply is
loaded into RAM using the same I2C registers as the biquad coefficients and the bass-management. All channels can use the channel 1 by setting the post-scale link bit.
RAM Block for Biquads and Bass Management:
Index
(Decimal)
Index
(Hex)
Coefficient
Default
C1H10(b2)
000000h
01h
C1H11(b0/2)
3FFFFFh
2
02h
C1H12(a2)
000000h
3
03h
C1H13(a1/2)
000000h
4
04h
C1H14(b1/2)
000000h
5
05h
Channel 1 - Biquad 2
C1H20
000000h
…
…
…
…
…
24
18h
Channel 1 - Biquad 5
C1H54
000000h
25
19h
Channel 2 - Biquad 1
C2H10
000000h
26
1Ah
C2H11
3FFFFFh
…
…
…
…
0
00h
1
30/33
Channel 1 - Biquad 1
…
STA308
45
2Dh
Distortion Compensation
DCC 23…0
000000h
…
…
…
…
…
49
31h
Channel 2 - Biquad 5
C2H54
000000h
50
32h
Channel 3 - Biquad 1
C3H10
000000h
…
…
…
…
…
199
C7h
Channel 8 - Biquad 5
C8H54
000000h
200
C8h
Channel 1 - Pre-Scale
C1PS
800000h
201
C9h
Channel 2 – Pre-Scale
C2PS
800000h
202
CAh
Channel 3 – Pre-Scale
C3PS
800000h
…
…
…
…
…
207
CFh
Channel 8 –Pre-Scale
C8PS
800000h
208
D0h
Channel 1 – BassM Scale
C1BMS
000000h
209
D1h
Channel 2 – BassM Scale
C2BMS
000000h
…
…
…
…
…
215
D7h
Channel 8 – BassM Scale
C8BMS
000000h
216
D8h
Channel 1 – Post-Scale
C1PS
800000h
217
D9h
Channel 2 – Post-Scale
C2PS
800000h
…
…
…
C8PS
800000h
…
…
…
…
223
DFh
Channel 8 – Post-Scale
224
F0h
Not Used
…
255
…
FFh
…
Not Used
31/33
STA308
mm
DIM.
MIN.
inch
TYP.
MAX.
A
MIN.
TYP.
1.60
A1
0.05
A2
1.35
B
C
0.063
0.15
0.002
0.006
1.40
1.45
0.053
0.055
0.057
0.18
0.23
0.28
0.007
0.009
0.011
0.12
0.16
0.20
0.0047 0.0063 0.0079
D
12.00
0.472
D1
10.00
0.394
D3
7.50
0.295
e
0.50
0.0197
E
12.00
0.472
E1
10.00
0.394
E3
7.50
0.295
L
0.40
0.60
L1
0.75
OUTLINE AND
MECHANICAL DATA
MAX.
0.0157 0.0236 0.0295
1.00
0.0393
TQFP64
0°(min.), 7°(max.)
K
D
D1
A
D3
A2
A1
48
33
49
32
0.10mm
E
E1
E3
B
B
Seating Plane
17
64
1
16
C
L
L1
e
K
TQFP64
32/33
STA308
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences
of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics
 2002 STMicroelectronics - All Rights Reserved
DDX is a trademark of Apogee Technology inc.
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