Data Sheet

[AK4688]
AK4688
Asynchronous Stereo CODEC with Capless Line I/O
GENERAL DESCRIPTION
The AK4688 is a stereo audio CODEC. The integrated ADC and DAC interfaces accept up to 24-bit
input/output data and support an asynchronous operation. The input range of the pre-amplifier, that
supports line inputs, is adjustable by an external resistor. A ground referenced 2Vrms output with a 3.3V
single power supply is achieved by an integrated charge pump, reducing external parts such as
AC-coupling capacitors and mute circuits. The ADC block of the AK4688 achieves a dynamic range of
99dB, and the DAC block achieves a dynamic range of 105dB. The AK4688 is suitable for digital
recording systems, digital TVs, Blu-ray recorders and Home theater systems.
FEATURES
† Asynchronous ADC/DAC Operation
† Capless Stereo Pre-amplifier for Line Input/Output
† 24bit Stereo ADC
- 64x Oversampling
- Sampling Rate up to 48kHz
- Linear Phase Digital Anti-Alias Filter
- S/(N+D): 83dB
- Dynamic Range, S/N: 99dB
- Digital HPF for Offset Cancellation
† 24bit Stereo DAC
- 128x Oversampling
- Sampling Rate up to 192kHz
- 24bit 8 times Digital Filter
- S/(N+D): 95dB
- Dynamic Range, S/N: 105dB
- De-emphasis Filter
† High Jitter Tolerance
† External Master Clock Input:
256fs, 384fs, 512fs 768fs (fs=32kHz ∼ 48kHz)
128fs, 192fs, 256fs 384fs (fs=64kHz ∼ 96kHz)
128fs, 192fs (fs=128kHz ~ 192kHz)
† 2 Audio Serial I/F (PORT1, PORT2)
- Master/Slave mode (PORT1)
- I/F format
PORT1, 2: MSB, LSB justified (16/24 bit), I2S
† Hardware / I2C-bus Control
† Operating Voltage:
- Digital I/O and Charge Pump: 3.0V ∼ 3.6V
- ADC Analog: 3.0V ∼ 3.6V
- DAC Analog: 3.0V ∼ 3.6V
† Package: 36pin QFN
MS1420-E-00
2012/05
-1-
[AK4688]
2Vrms
+/-50mVDC input
PORT1
PWAD bit
PDN1 pin
LO
LI
PDN1
LIN
2ch
ADC
RIN
HPF
Serial
I/F
MCLK1
BICK1
LRCK1
SDTO
MSN
RI
RO
CVEE
CP
CN
Charge
Pump
Control
I/F
PWAD/PWDA bit
PDN1/PDN2 pin
PWDA bit
PDN2 pin
I2C
SDA
SCL
PORT2
2Vrms
LOUT
2ch
DAC
De-em
Serial
I/F
MCLK2
BICK2
LRCK2
SDTI
ROUT
PDN2
CAD0/CKS
AVDD1 AVSS1 AVDD2 AVSS2
DVDD
DVSS
VREF
Figure 1. AK4688 Block Diagram
MS1420-E-00
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-2-
[AK4688]
■ Ordering Guide
AK4688EN
AKD4688
-20 ∼ +85°C
36pin QFN (0.5mm pitch)
Evaluation Board for the AK4688
■ Pin Layout
RO
R1
AVDD1
AVSS1
AVSS2
AVDD2
VREF
LOUT
ROUT
27
26
25
24
23
22
21
20
19
36 pin QFN (0.5mm pitch)
LO
28
18
CVEE
LI
29
17
CN
RIN
30
16
CP
NC
31
15
DVSS
14
DVDD
13
TEST2
AK4688
LIN
32
I2C
33
SDA
34
12
TEST1
SCL
35
11
CAD0
MSN
36
10
STDI
6
7
8
9
MCLK2
BICK2
LRCK2
4
MCLK1
PDN2
3
BICK1
5
2
LRCK1
PDN1
1
SDTO
Top View
MS1420-E-00
2012/05
-3-
[AK4688]
PIN/FUNCTION
No.
1
2
3
4
5
Pin Name
SDTO
LRCK1
BICK1
MCLK1
I/O
O
I/O
I/O
I
Function
Audio Serial Data Output Pin (for PORT1)
Channel Clock Pin (for PORT1)
Audio Serial Data Clock Pin (for PORT1)
ADC Master Clock Input Pin (for PORT1)
Power-Down Mode for ADC
PDN1
I
When “L”, the ADC is powered-down.
6
Power-Down Mode for DAC
PDN2
I
When “L”, the DAC is powered-down.
7
MCLK2
I
DAC Master Clock Input Pin (for PORT2)
8
BICK2
I
Audio Serial Data Clock Pin (for PORT2)
9
LRCK2
I
Input Channel Clock Pin (for PORT2)
10
SDTI
I
Audio Serial Data Input Pin (for PORT2)
CAD0
I
CAD Address Pin (I2C pin = “H”)
11
ADC MCLK Speed Select Pin (I2C pin = “L”)
CKS
I
“H”: MCLK=768fs, “L”: MCLK=256fs
12
TEST1
I
This pin must be connected to the ground
13
TEST2
I
This pin must be connected to the ground
14
DVDD
Digital Power Supply Pin, 3.0V∼3.6V
15
DVSS
Digital Ground Pin, 0V
16
CP
I
Positive Charge Pump Capacitor Terminal Pin (for Analog Input/Output)
17
CN
I
Negative Charge Pump Capacitor Terminal Pin (for Analog Input/Output)
18
CVEE
O
Charge Pump Circuit Negative Voltage Output Pin (for Analog Input/Output)
19
ROUT
O
Rch Analog Output Pin
20
LOUT
O
Lch Analog Output Pin
Reference Output Pin
21
VREF
O
Connect to AVSS2 with a 1µF low ESR capacitor over all temperatures.
22
AVDD2
DAC Analog Power Supply Pin, 3.3V∼3.6V
23
AVSS2
ADC Analog Ground Pin, 0V
24
AVSS1
ADC Analog Ground Pin, 0V
25
AVDD1
ADC Analog Power Supply Pin, 3.0V∼3.6V
26
RI
O
Rch Feedback Resistor Input Pin
27
RO
O
Rch Feedback Resistor Output Pin
28
LO
O
Lch Feedback Resistor Output Pin
29
LI
O
Lch Feedback Resistor Input Pin
30
RIN
I
Rch Input Pin
31
NC
This pin must be connected to the ground
32
LIN
I
Lch Input Pin
I2C Pin
33
I2C
I
“H”= I2C control, “L”= H/W control
Control Data Pin (I2C pin = “H”)
34
SDA
I/O
When the I2C pin = “L” (H/W control), the SDA pin must be connected to DVSS.
Control Data Clock Pin (I2C pin = “H”)
35
SCL
I
When the I2C pin = “L” (H/W control), the SCL pin must be connected to DVSS.
PORT1 Master Mode Select Pin.
36
MSN
I
“L”(connected to the ground): Slave mode.
“H”(connected to DVDD) : Master mode.
Note: All digital input pins must not be allowed to float.
MS1420-E-00
2012/05
-4-
[AK4688]
ABSOLUTE MAXIMUM RATINGS
(AVSS1=AVSS2=DVSS=0V; Note 1)
Parameter
Power Supply
Symbol
DVDD
AVDD1
AVDD2
IIN
VIND
min
-0.3
-0.3
-0.3
-0.3
Input Current (any pins except for supplies)
Digital Input Voltage
(MCLK1-2, PDN1-2, LRCK1-2, SDTI,
BICK1-2, SDA, SCL, MSN, CAD0 pins)
Analog Input Voltage
VINA
-0.3
(LIN1-3, RIN1-3 pins)
Ambient Operating Temperature
Ta
-20
Storage Temperature
Tstg
-65
Note 1. AVSS1, AVSS2 and DVSS must be connected to the same analog ground plane.
max
4.0
4.0
4.0
±10
DVDD+0.3
Unit
V
V
V
mA
V
AVDD1+0.3
V
85
150
°C
°C
WARNING: Operation at or beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
RECOMMENDED OPERATING CONDITIONS
(AVSS1=AVSS2=DVSS= 0V; Note 1)
Parameter
Symbol
min
typ
max
Unit
Power Supply (Note 2)
DVDD
3.0
3.3
3.6
V
AVDD1
3.0
3.3
3.6
V
AVDD2
3.0
3.3
3.6
V
Note 2. The AVDD1 and AVDD2 must be the same voltage.
The voltage difference between DVDD and other voltages (AVDD1 and AVDD2) must be less than 0.3V.
*AKM assumes no responsibility for the usage beyond the conditions in this datasheet.
MS1420-E-00
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[AK4688]
ANALOG CHARACTERISTICS
(Ta=25°C; AVDD1=AVDD2 = DVDD= 3.3V; AVSS1=AVSS2=DVSS =0V; fs=48kHz; BICK=64fs;
Signal Frequency=1kHz; 24bit Data; Measurement Frequency = 20Hz∼ 20kHz at fs=48kHz, 20Hz~40kHz at fs=96kHz;
20Hz~40kHz at fs=192kHz, all blocks are synchronized, unless otherwise specified)
Parameter
min
typ
max
Unit
Pre-Amp Characteristics:
Feedback Resistance Rf
12
39
92
kΩ
Input Resistance
Ri
18
47
92
kΩ
Output Level
LO / RO pins
(ADC=0dBFs)
(Note 3)
1.82
1.91
2.00
Vrms
Load Resistance
RL
(Note 4)
18
kΩ
Load Capacitance CL
(Note 4)
20
pF
Analog Input (LIN, RIN pin) to ADC Analog Input Characteristics
Resolution
24
Bits
S/(N+D)
(-1dBFS)
fs=48kHz
83
dB
DR
(-60dBFS)
fs=48kHz, A-weighted
99
dB
S/N
(input off)
fs=48kHz, A-weighted
99
dB
Interchannel Isolation
(Note 5)
100
dB
Interchannel Gain Mismatch
0
dB
Gain Drift
50
ppm/°C
Power Supply Rejection
(Note 6)
50
dB
DAC to Analog Output (LOUT, ROUT pin) Characteristics
Resolution
24
Bits
S/(N+D)
(0dBFS)
fs=48kHz
95
dB
fs=96kHz
93
dB
fs=192kHz
93
dB
DR
(-60dBFS)
fs=48kHz, A-weighted
105
dB
fs=96kHz, A-weighted
105
dB
fs=192kHz, A-weighted
105
dB
S/N
(“0” data)
fs=48kHz, A-weighted
105
dB
fs=96kHz, A-weighted
105
dB
fs=192kHz, A-weighted
105
dB
Interchannel Isolation
100
dB
Interchannel Gain Mismatch
0
dB
DC Offset (at output pin)
–5
0
+5
mV
Gain Drift
50
ppm/°C
Output Voltage
LOUT/ROUT= 2 x AVDD2/3.3
1.85
2
2.15
Vrms
Load Resistance
5
kΩ
Load Capacitance
(C1)
30
pF
Power Supply Rejection
(Note 6)
62
dB
Note 3. Input range for ADC full scale when the external input resistance is 47kΩ, feedback resistance is 39kΩ and input
signal is 2.3Vrms.
Note 4. RL or CL of Figure 3. Load resistance and capacitance when the output signal of the LO/RO pin is used for an
external device.
Note 5. This value is the channel isolation for all other channels between LIN and RIN.
Note 6. PSR is applied to AVDD1, AVDD2 and DVDD with 1kHz, 50mVpp.
MS1420-E-00
2012/05
-6-
[AK4688]
LOUT/ROUT
470
AK4688
C1
Analog
Out
2.2nF
Figure 2. Lineout Circuit Example
(R L)
(CL)
Rf
LI
0V
R i LIN
LO
-
ADC
+
0V
AK4688
Figure 3. External Circuit of Pre-Amp
MS1420-E-00
2012/05
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[AK4688]
Power Supplies
Parameter
min
typ
max
Unit
Power Supply Current
Normal Operation (PDN1 pin = PDN2 pin = “H”)
AVVD1
3
mA
AVDD2
11
mA
DVDD
13
mA
DVDD+AVDD1+AVDD2
27
40
mA
Power-Down Mode (PDN1 pin = PDN2 pin = “L”; Note 7)
DVDD+AVDD1+AVDD2
1
20
μA
Note 7. PDN1-2 and TEST1-2 pins are held at DVSS, and all digital inputs including clock pins (MCLK1-2, BICK1-2,
LRCK1-2, SDTI, SDA, SCL, MSN and CAD0 pins) are held at DVDD or DVSS. However, the LRCK and BICK
pins should be open since these pins become output state when the MSN pin is fixed to DVDD.
FILTER CHARACTERISTICS
(Ta=25°C; AVDD1=AVDD2= DVDD= 3.3V; fs=48kHz)
Parameter
Symbol
min
typ
max
Unit
ADC Digital Filter (Decimation LPF):
Passband
(Note 8)
PB
0
18.8
kHz
±0.1dB
21.1
kHz
-0.2dB
21.7
kHz
-3.0dB
Stopband
SB
28.5
kHz
Stopband Attenuation
SA
73
dB
Group Delay
(Note 10)
GD
17
1/fs
Group Delay Distortion
0
µs
ΔGD
ADC Digital Filter (HPF):
Frequency Response (Note 8)
-3dB
FR
1.0
Hz
-0.1dB
7.1
Hz
DAC Digital Filter:
PB
0
21.7
kHz
Passband
±0.05dB (Note 9)
24.0
kHz
-6.0dB
Stopband (Note 9)
SB
26.3
kHz
Passband Ripple
PR
dB
± 0.05
Stopband Attenuation
SA
64
dB
Group Delay (Note 10)
GD
24
1/fs
De-emphasis Filter (DEM = ON)
De-emphasis Error
fs = 32kHz
–1.5/0
dB
(DC Reference)
fs = 44.1kHz
–0.2/+0.2
dB
fs = 48kHz
0/+0.6
dB
DAC Digital Filter + Analog Filter: (DEM = OFF)
Frequency Response
20.0kHz fs=44.1kHz
FR
dB
± 0.2
40.0kHz fs=96kHz
FR
dB
± 0.3
80.0kHz fs=192kHz
FR
dB
± 1.0
Note 8. The passband and stopband frequencies scale with fs.
For example, 21.8kHz at –0.1dB is 0.454 x fs (DAC). The reference frequency of these responses is 1kHz.
Note 9. The passband and stopband frequencies scale with fs (system sampling rate).
For example, PB=0.4535×fs(@±0.05dB), SB=0.546×fs.
Note 10. The calculating delay time occurred by digital filtering. This time is from an input of the analog signal until 24bit
data of both channels is set into the output register of PORT1. For DAC, this time is from setting 16/24bit data of
both channels into the input register of PORT2 until an analog signal is output.
MS1420-E-00
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[AK4688]
DC CHARACTERISTICS
(Ta= 25°C; AVDD1=AVDD2= DVDD= 3.3V)
Parameter
Symbol
min
High-Level Input Voltage
VIH
70%DVDD
Low-Level Input Voltage
VIL
High-Level Output Voltage (Iout=-400μA)
VOH
DVDD-0.4
Low-Level Output Voltage
VOL
(Iout= -400μA(except SDA pin), 3mA(SDA pin))
Iin
Input Leakage Current
-
typ
-
max
30%DVDD
0.4
Unit
V
V
V
V
-
±10
μA
SWITCHING CHARACTERISTICS
(Ta=25°C; AVDD1=AVDD2 =DVDD= 3.3V; CL= 20pF (except for SDA pin), Cb=400pF(SDA pin))
Parameter
Symbol
min
typ
max
Master Clock Timing
Frequency
fECLK
8.192
36.864
Duty
dECLK
40
50
60
Master Clock
256fsn, 128fsd:
fCLK
8.192
12.288
Pulse Width Low
tCLKL
0.37
Pulse Width High
tCLKH
0.37
384fsn, 192fsd:
fCLK
12.288
18.432
Pulse Width Low
tCLKL
0.37
Pulse Width High
tCLKH
0.37
512fsn, 256fsd, 128fsq:
fCLK
16.384
24.576
Pulse Width Low
tCLKL
0.37
Pulse Width High
tCLKH
0.37
768fsn, 384fsd, 192fsq:
fCLK
24.576
36.864
Pulse Width Low
tCLKL
0.37
Pulse Width High
tCLKH
0.37
Unit
MHz
%
MHz
1/fCLK
1/fCLK
MHz
1/fCLK
1/fCLK
MHz
1/fCLK
1/fCLK
MHz
1/fCLK
1/fCLK
LRCK1Timing (Slave Mode)
fsn
32
48
kHz
Duty Cycle
Duty
45
55
%
LRCK2Timing (Slave Mode)
Normal Speed Mode
fsn
32
48
kHz
Double Speed Mode
fsd
32
96
kHz
Quad Speed Mode
fsq
128
192
kHz
Duty Cycle
Duty
45
55
%
LRCK1 Timing (Master Mode)
Normal Speed Mode
fsn
32
48
kHz
Duty Cycle
Duty
50
%
Power-down & Reset Timing
PDN Pulse Width
(Note 11)
tPD
150
ns
PDN “↑” to SDTO valid (Note 12)
tPDV
2640
1/fs
Note 11. Refer to the “■ System Reset” paragraph for the reset by PDN1 and PDN2 pins.
Note 12. After a rising edge of PDN1, the internal counter starts by divided clock of MCLK and ADC power down is
released by a falling edge of CVEE after 64/fs on LRCK, then SDTIO is output 528/fs later.
MS1420-E-00
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[AK4688]
Parameter
Symbol
min
Audio Interface Timing (Slave Mode)
PORT2(DAC)
BICK2 Period
tBCK
81
BICK2 Pulse Width Low
tBCKL
20
Pulse Width High
tBCKH
20
LRCK2 Edge to BICK2 “↑” (Note 13)
tLRB
20
BICK2 “↑” to LRCK2 Edge (Note 13)
tBLR
20
SDTI Hold Time
tSDH
10
SDTI Setup Time
tSDS
10
PORT1 (ADC)
BICK1 Period
tBCK
324
BICK1 Pulse Width Low
tBCKL
128
Pulse Width High
tBCKH
128
LRCK1 Edge to BICK1 “↑” (Note 13)
tLRB
80
BICK1 “↑” to LRCK1 Edge (Note 13)
tBLR
80
LRCK1 to SDTO (MSB)
tLRS
BICK1 “↓” to SDTO
tBSD
Audio Interface Timing (Master Mode)
BICK1 Frequency
fBCK
BICK1 Duty
dBCK
BICK1 “↓” to LRCK1 Edge
tMBLR
-20
BICK1 “↓” to SDTO
tBSD
Control Interface Timing (I2C Bus):
SCL Clock Frequency
fSCL
Bus Free Time Between Transmissions
tBUF
1.3
Start Condition Hold Time
tHD:STA
0.6
(prior to first clock pulse)
Clock Low Time
tLOW
1.3
Clock High Time
tHIGH
0.6
Setup Time for Repeated Start Condition
tSU:STA
0.6
SDA Hold Time from SCL Falling (Note 14)
tHD:DAT
0
SDA Setup Time from SCL Rising
tSU:DAT
0.1
Rise Time of Both SDA and SCL Lines
tR
Fall Time of Both SDA and SCL Lines
tF
Setup Time for Stop Condition
tSU:STO
0.6
Pulse Width of Spike Noise Suppressed by Input Filter
tSP
Capacitive load on bus
Cb
0
Note 13. BICK rising edge must not occur at the same time as LRCK edge.
Note 14. Data must be held for sufficient time to bridge the 300 ns transition time of SCL.
Note 15. I2C-bus is a trademark of NXP B.V.
MS1420-E-00
typ
max
Unit
ns
ns
ns
ns
ns
ns
ns
80
80
ns
ns
ns
ns
ns
ns
ns
20
20
Hz
%
ns
ns
400
-
kHz
μs
μs
0.3
0.3
50
400
μs
μs
μs
μs
μs
μs
μs
μs
ns
pF
64fs
50
2012/05
- 10 -
[AK4688]
■ Timing Diagram
1/fCLK
VIH
MCLK
VIL
tCLKH
tCLKL
1/fsn, 1/fsd, 1/fsq
VIH
LRCK
VIL
tBCK
VIH
BICK
VIL
tBCKH
tBCKL
Clock Timing (Normal mode)
VIH
LRCK
VIL
tBLR
tLRB
tLRS
VIH
BICK
VIL
tBSD
50% TVDD
SDTO
tSDS
tSDH
VIH
SDTI
VIL
Audio Interface Timing
LRCK= LRCK1, LRCK2
BICK= BICK1, BICK2
MS1420-E-00
2012/05
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[AK4688]
LRCK
50% DVDD
tMBLR
50% DVDD
BICK
tBSD
50% DVDD
SDTO
Audio Interface timing (Master Mode)
tPD
VIH
PDN
VIL
tPDV
SDTO
50% DVDD
Power Down & Reset Timing
VIH
SDA
VIL
tLOW
tBUF
tR
tHIGH
tF
tSP
VIH
SCL
VIL
tHD:STA
Stop
Start
tHD:DAT
tSU:DAT
tSU:STA
tSU:STO
Start
Stop
I2C Bus mode Timing
MS1420-E-00
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[AK4688]
OPERATION OVERVIEW
■ System Clock
The AK4688 has two audio serial interfaces (PORT1 and PORT2) which can be operated asynchronously. The PORT2 is
the audio data interface for DAC, and the PORT1 is for ADC. At each PORT, the external clocks, which are required to
operate the AK4688 in slave mode, are MCLK1 (MCLK2), LRCK1 (LRCK2) and BICK1 (BICK2). The MCLK1
(MCKK2) must be synchronized with LRCK1 (LRCK2) but the phase is not critical.
The AK4688 has independent power-down function for ADC and DAC controlled by the PDN1 and PDN2 pins (or
PWAD and PWDA bits). In I2C control mode, the AK4688 is in normal operation when PDN1pin=PDN2 pin= “H” and
PWAD bit = PWDA bit = “1” (Table 1, Table 3). In H/W control mode (Table 2, Table 4), the AK4688 is in normal
operation when PDN1 pin = PDN2 pin = “H”. The AK4688 is automatically powered down when MCLK1 clock is
stopped in master mode (MSN pin = “H”), or when MCLK1 (MCLK2), LRCK1 (LRCK2) and BICK1 (BICK2) are
stopped in slave mode (MSN pin = “L”). In this case, the ADC output is “0” data and DAC output is pulled down to VSS.
The power-down state is released and the AK4688 starts operation when MCLK1 is input in master mode (MSN pin =
“H”), or when MCLK1 (MCLK2), LRCK1 (LRCK2) and BICK1 (BICK2) are input in slave mode (MSN pin = “L”).
When the reset is released (PDN1/2 pin = “L” → “H”), such as after power up the device, the ADC/DAC of AK4688 is in
power-down state until MCLK1/2, LRCK1/2 and BICK1/2 are input.
PDN1 pin
PWAD bit
L
H
H
H
×
0
1
1
Master mode: MCLK1
Slave mode: MCLK1,LRCK1 and BICK1
×
×
Non-active
active
ADC stauts
ADC OUT
Power down
Power down
Power down
Power up
0
0
0
ADC output
(×: Don’t Care)
Table 1. System CLOCK for ADC (I2C Control Mode, PORT1)
Master mode: MCLK1
Slave mode: MCLK1,LRCK1 and BICK1
×
Non-active
active
PDN1 pin
L
H
H
ADC stauts
ADC OUT
0
0
ADC output
(×: Don’t Care)
Table 2. System CLOCK for ADC (H/W Control Mode, PORT1)
PDN2 pin
PWDA bit
L
H
H
H
×
0
1
1
MCLK2,LRCK2
and BICK2
×
×
Non-active
active
Power down
Power down
Power up
DAC stauts
DAC OUT
VSS
VSS
VSS
DAC output
(×: Don’t Care)
Table 3. System CLOCK for DAC (I2C Control Mode, PORT2)
PDN2 pin
L
H
H
MCLK2,LRCK2
and BICK2
×
Non-active
active
Power down
Power down
Power down
Power up
DAC stauts
DAC OUT
Power down
Power down
Power up
VSS
VSS
DAC output
(×: Don’t Care)
Table 4. System CLOCK for DAC (H/W Control Mode, PORT2)
MS1420-E-00
2012/05
- 13 -
[AK4688]
■ Master/Slave Mode
The MSN pin controls master/slave mode of the PORT1. The PORT2 supports slave mode only. In master mode, LRCK1
and BICK1 pins are output pins. In slave mode, LRCK1 (LRCK2) and BICK1 (BICK2) pins are input pins (Table 5).
PORT1 (ADC)
BICK1, LRCK1
Input (slave mode)
Output “L”(master mode)
MSN pin
L
H
PORT2 (DAC)
BICK2, LRCK2
Input (slave mode)
Input (slave mode)
Table 5. Master/Salve Mode
■ PORT1 (ADC) Clock Control
In master mode (MSN pin = “H”), the required clock is MCLK1. The CKS1-0 bits and the CKS pin select the clock
frequency (Table 6, Table 7). The ADC is in power-down state until MCLK1, BICK1 and LRCK1 are supplied.
CKS1 bit
CKS0 bit
Clock Speed
0
0
256fs
0
1
384fs
1
0
512fs
1
1
768fs
(default)
2
Table 6. PORT1(ADC) Master Clock Control (Master Mode, I C Control Mode)
CKS pin
Clock Speed
L
256fs
H
768fs
Table 7. PORT1(ADC) Master Clock Control (Master Mode, H/W Control Mode)
In slave mode (MSN pin = “L”), required clocks are MCLK1, BICK1 and LRCK1. The master clock (MCLK1) must be
synchronized with LRCK1 but the phase is not critical. After exiting reset following a power-up (PDN1 pin = “L” →
“H”), the ADC of AK4688 is in power-down state until MCLK1, LRCK1 and BICK1 are input.
The ADC only supports Normal Speed Mode (fs = 32k ~ 48kHz).
LRCK1
MCLK1 (MHz)
Fs
256fs
384fs
512fs
32.0kHz
8.1920
12.2880
16.3840
44.1kHz
11.2896
16.9344
22.5792
48.0kHz
12.2880
18.4320
24.5760
768fs
24.5760
33.8688
36.8640
BICK1 (MHz)
64fs
2.0480
2.8224
3.0720
Table 8. PORT1(ADC) System Clock Example
MS1420-E-00
2012/05
- 14 -
[AK4688]
■ PORT2 (DAC) Clock Control
External clocks (MCLK2, BICK2 and LRCK2) must always be present whenever the DAC is in normal operation (PDN
pin = “H” or PWDA2 bit= “1”). The master clock (MCLK2) must be synchronized with LRCK2 but the phase is not
critical. MCLK2 clock is used for interpolation filter and delta sigma modulator. During operation, DAC is automatically
reset and the analog output goes to 0V (typ) if MCLK2, LRCK2 and BICK2 are stopped. This reset is released, and the
DAC starts operation when MCLK2, LRCK2 and BICK2 are input again. The DAC is in power-down mode until
MCLK2, BICK2 and LRCK2 are supplied.
There are two modes for controlling the sampling speed of DAC. One is the Manual Setting Mode (ACKS bit = “0”) using
the DFS1-0 bits, and the other is Auto Setting Mode (ACKS bit = “1”).
1. Manual Setting Mode (ACKS bit = “0”)
When the ACKS bit = “0”, DAC is in Manual Setting Mode and the sampling speed is selected by DFS1-0 bits (Table 9).
DFS1 bit
0
0
1
1
DFS0 bit
0
1
0
1
DAC Sampling Speed (fs)
Normal Speed Mode
32kHz~48kHz
Double Speed Mode
64kHz~96kHz
Quad Speed Mode
128kHz~192kHz
Not Available
-
(default)
Table 9. PORT2(DAC) Sampling Speed (ACKS bit = “0”, Manual Setting Mode)
LRCK2
Fs
32.0kHz
44.1kHz
48.0kHz
256fs
8.1920
11.2896
12.2880
MCLK2 (MHz)
384fs
512fs
12.2880
16.3840
16.9344
22.5792
18.4320
24.5760
768fs
24.5760
33.8688
36.8640
BICK2 (MHz)
64fs
2.0480
2.8224
3.0720
Table 10. PORT2(DAC) system Clock Example (Normal Speed Mode @Manual Setting Mode)
LRCK2
Fs
88.2kHz
96.0kHz
128fs
11.2896
12.2880
MCLK2 (MHz)
192fs
256fs
16.9344
22.5792
18.4320
24.5760
384fs
33.8688
36.8640
BICK2 (MHz)
64fs
5.6448
6.1440
Table 11. PORT2(DAC)system Clock Example(Double Speed Mode @Manual Setting Mode)
LRCK2
Fs
176.4kHz
192.0kHz
128fs
22.5792
24.5760
MCLK2 (MHz)
192fs
256fs
33.8688
36.8640
-
384fs
-
BICK2 (MHz)
64fs
11.2896
12.2880
Table 12. PORT2(DAC) system Clock Example (Quad Speed Mode @Manual Setting Mode)
MS1420-E-00
2012/05
- 15 -
[AK4688]
2. Auto Setting Mode (ACKS bit = “1”)
When the ACKS bit = “1”, DAC is in Auto Setting Mode and the sampling speed is selected automatically by the ratio of
MCLK2/LRCK2, as shown in Table 13 and Table 14. In this mode, the settings of DFS1-0 bits are ignored.
MCLK2
512fs, 768fs
256fs, 384fs
128fs, 192fs
DAC Sampling Speed (fs) LRCK2
Normal Speed Mode
32kHz~48kHz
Double Speed Mode
64kHz~96kHz
Quad Speed Mode
128kHz~192kHz
Table 13. PORT2(DAC) Sampling Speed (ACKS bit = “1”, Auto Setting Mode)
LRCK
fs
32.0kHz
44.1kHz
48.0kHz
32.0kHz
44.1kHz
48.0kHz
88.2kHz
96.0kHz
176.4kHz
192.0kHz
128fs
-
22.5792
24.5760
192fs
-
33.8688
36.8640
MCLK (MHz)
256fs
384fs
512fs
16.3840
22.5792
24.5760
8.192
12.288
11.2896
16.9344
12.288
18.432
22.5792
33.8688
24.5760
36.8640
Table 14. System Clock Example
768fs
24.5760
33.8688
36.8640
1152fs
36.8640
-
Sampling
Speed
Normal
Double
-
-
Quad
When MCLK= 256fs/384fs, the AK4688 supports sampling rate of 32kHz~96kHz (Table 15). However, when the
sampling rate is 32kHz~48kHz, DR and S/N will degrade as compared to when MCLK= 512fs/768fs.
MCLK
DR, S/N
256fs/384fs
102dB
512fs/768fs
105dB
Table 15. MCLK Frequency and DR, S/N (fs = 48kHz)
■ De-emphasis Filter
The DAC of AK4688 includes a digital de-emphasis filter (tc=50/15μs) by IIR filter. Setting the DEM1 bit to “1” enables
the de-emphasis filter. Refer to “FILTER CHARACTERISTICS” about the gain error when this filter is ON. The
de-emphasis filter is OFF in double speed mode (MCLK2= 256fs/38fs ) and quad speed mode (MCLK2=128fs/192fs).
The filter setting is executed in I2C control mode and DEM bit controls ON/OFF of the filter. (Table 16)
DEM bit
De-emphasis Filter
1
ON
(default)
0
OFF
Table 16. De-emphasis Control (Normal Speed Mode)
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2012/05
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[AK4688]
■ Digital High Pass Filter
The ADC has a digital high pass filter for DC offset cancellation. The cut-off frequency of the HPF is 1.0Hz at fs=48kHz
and frequency response scales with sampling rate (fs).
■ Audio Serial Interface Format
Each PORT1/2 can select audio interface format independently. The DIF1 bit controls audio data format of the PORT1.
The DIF21-20 bits control the audio data format of the PORT2. In all modes the serial data is MSB-first, 2’s complement
format. The SDTO pin is clocked out on the falling edge of BICK1 and the SDTI pin is latched on the rising edge of
BICK2. SDTI input formats can be used for 16-24bit data by zeroing the unused LSBs.
1. PORT1 (ADC) Setting
The MSN pin and DIF1 bit select following four serial data formats (Table 17).
Mode
MSN
pin
DIF1
bit
0
L
0
1
L
1
2
H
0
3
H
1
LRCK1
L/R
I/O
SDTO
BICK1
speed
I/O
≥ 48fs or
I
32fs
I
≥ 48fs
24/16bit
H/L
I
Left Justified
24bit, I2S
L/H
I
24bit
H/L
O
64fs
Left Justified
2
24bit, I S
L/H
O
64fs
Table 17. Audio Interface Format (ADC)
O
(default)
(default)
O
2. PORT2 (DAC) Setting
The DIF21-20 bits select following four serial data formats (Table 18).
Mode
DIF21
bit
DIF20
bit
0
1
2
3
0
0
1
1
0
1
0
1
LRCK2
L/R
I/O
16bit, Right justified
H/L
I
24bit, Right justified
H/L
I
24bit, Left justified
H/L
I
24bit, I2S
L/H
I
Table 18. Audio Interface Format (DAC)
SDTI
MS1420-E-00
BICK2
speed
I/O
I
≥ 32fs
I
≥ 48fs
I
≥ 48fs
I
≥ 48fs
(default)
2012/05
- 17 -
[AK4688]
LRCK
0
1
2
12
13
14
24
25
31
0
1
2
12
13
14
24
25
31
0
1
BICK(64fs)
SDTO(o)
23 22
SDTI(i)
12 11 10
Don’t Care
0
15 14
23 22
8
7
1
12
11 10
Don’t Care
0
0
15 14
SDTO-23:MSB, 0:LSB; SDTI-15:MSB, 0:LSB
Lch Data
23
8
7
1
0
Rch Data
Figure 4. PORT1= Mode0/2, PORT2=Mode0 Timing
LRCK
0
1
2
8
9
10
24
25
31
0
1
2
8
9
10
24
25
31
0
1
BICK (64fs)
SDTO(o)
23 22
16 15 14
Don’t Care
SDTI(i)
0
23 22
23:MSB, 0:LSB
23 22
8
7
1
16 15 14
Don’t Care
0
0
23 22
Lch Data
23
8
7
1
0
Rch Data
Figure 5. PORT1= Mode0/2, PORT2=Mode1 Timing
LRCK
0
1
2
21
22
23
24
28
29
30
31
0
1
2
22
23
24
28
29
30
31
0
1
BICK (64fs)
SDTO(o)
23 22
2
1
0
SDTI(i)
23 22
2
1
0
23:MSB, 0:LSB
Don’t Care
23 22
2
1
0
23 22
2
1
0
Lch Data
23
Don’t Care
23
Rch Data
Figure 6. PORT1= Mode0/2, PORT2=Mode2 Timing
LRCK
0
1
2
3
22
23
24
25
29
30
31
0
1
2
3
22
23
24
25
29
30
31
0
1
BICK (64fs)
SDTO(o)
23 22
2
1
0
SDTI(i)
23 22
2
1
0
23:MSB, 0:LSB
Don’t Care
23 22
2
1
0
23 22
2
1
0
Lch Data
Don’t Care
Rch Data
Figure 7. PORT1= Mode1/3, PORT2=Mode3 Timing
MS1420-E-00
2012/05
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[AK4688]
■ Pre-Amp and Input ATT
The input attenuation circuit is constructed by connecting input resistors (Ri) to LIN/RIN pin and feedback resistors (Rf)
between LI/RI pin and LO/RO pin (Figure 8). The input voltage tolerance of the LO/RO pin is typically 1.91Vrms.
Therefore, excessive inputs such as 2Vrms or 4Vrms to the LIN/RIN pin via Ri resistors must be attenuated to 1.91Vrms
by these Ri and Rf resistors. Table 19 shows resistance examples of Ri and Rf.
Rf
LO
LI
Ri
LIN
Pre-Amp
Figure 8. Pre-Amp and Input ATT
Input Range
Ri (kΩ)
4Vrms
2.2Vrms
1Vrms
47
47
47
Rf (kΩ)
20
39
82
ATT Gain (dB)
LO/RO pin
ADC output (typ)
-7.42
-1.62
+4.83
1.70Vrms
1.82Vrms
1.74Vrms
-1.0dBFS
-0.39dBFS
-0.78dBFS
Table 19. Input ATT example
MS1420-E-00
2012/05
- 19 -
[AK4688]
■ Charge Pump Circuit
The internal charge pump circuit generates negative voltage (CVEE) from CVDD voltage for analog input and output.
The power up time of charge pump circuit is [email protected] When PWAD and PWDA bits = “1”, the ADC and DAC are
powered-up after the charge pump circuit is powered-up.
The power-up conditions of the charge pump circuit are:
I2C Control Mode
• PDN1 pin = “H”, PWAD bit = “1” and MCLK1, LRCK1 and BICK1 (MCLK1 only in master mode) are input.
• PDN2 pin = “H”, PWDA bit = “1” and MCLK2, LRCK2 and BICK2 are input.
H/W Control Mode
• PDN1 pin = “H” and MCLK1, LRCK1 and BICK1 (MCK1 only in master mode) are input.
• PDN2 pin = “H” and MCLK2, LRCK2 and BICK2 are input.
PDN1
pin
PWAD
bit
H
x
1
x
Master mode: MCLK1
Slave mode:
MCLK1,LRCK1, BICK1
active
×
PDN2
pin
PWDA
bit
MCLK2, BICK2, LRCK2
CP status
×
H
×
1
×
active
ON
ON
(×: Don’t Care)
Table 20. Charge Pump Power ON Conditions (I2C Control Mode)
PDN1
pin
H
x
Master mode: MCLK1
Slave mode: MCLK1, LRCK1, BICK1
Active
×
PDN2
pin
×
H
MCLK2, BICK2, LRCK2
CP status
×
active
ON
ON
(×: Don’t Care)
Table 21. Charge Pump Power ON Conditions (H/W Control Mode)
AK4688
DVDD
Charge
Pump
CP
CN
Negative Power
DVSS
(+)
1uF
Cb
VEE
1uF
(+)
Ca
Figure 9. Charge Pump Circuit
Note: Connect a 1µF low ESR capacitor between CP and CN pins, and between DVSS and VEE pins.
MS1420-E-00
2012/05
- 20 -
[AK4688]
■ Analog Input/Output (LIN/RIN, LOUT/ROUT pins)
Power supply voltage for analog input/output is applied from a regulator for positive power and a charge-pump for
negative power. The analog output is single-ended and centered on 0V (AVSS2). Therefore, a capacitor for AC-coupling
can be removed. The minimum load resistance is 5kΩ. When the DAC input signal level is 0dBFS, the output voltage is
2Vrms.
■ Soft Mute
The DAC has a soft mute function. The soft mute operation is performed at digital domain. When the SMUTE bit goes to
“1”, the input data is attenuated by -∞ in 1024LRCK cycle. When the SMUTE bit returns to “0”, the mute is cancelled and
the attenuation level gradually changes to 0dB in 1024 LRCK cycle. If the soft mute is cancelled before attenuating to -∞
after starting the operation, the attenuation is discontinued and the attenuation level returns to 0dB in the same cycle. The
soft mute is effective for changing the signal source without stopping the signal transmission.
SMUTE bit
1024/fs
0dB
1024/fs
(1)
(3)
Attenuation
Level
-∞
GD
(2)
GD
LOUT/ROUT
Notes:
(1) In normal speed mode, the input data is attenuated to -∞ in 1024LRCK cycle. This time is 2048LRCK cycles
(2048/fs) in Double Speed Mode, and 4096LRCK cycle (4096/fs) in Quad Speed Mode.
(2) The analog output corresponding to the digital input has group delay, GD.
(3) If the soft mute is cancelled before attenuating to -∞ after starting the operation, the attenuation is discontinued and
the attenuation level returns to 0dB in the same cycle.
Figure 10. Soft Mute Function
■ System Reset
When power-up the AK4688, the PDN1 and PDN2 pins should be “L” and changed to “H” after all power supplies
(DVDD, AVDD1, and AVDD2) are supplied. After this reset is released (PDN1 and PDN2 pins = “L” → “H”), all blocks
are in power-down mode. This ensures that all internal registers are reset to their initial values. ADC internal circuit,
control registers for ADC (Addr: 01h-02h) and PWAD bit are reset by PDN1 pin = “L”. DAC internal circuit, control
registers for DAC (Addr: 03h) and PWDA bit are reset by the PDN2 pin = “L”. When both PDN1 and PDN2 pins are “L”,
all blocks, registers and charge pump are powered-down. In H/W control mode, register settings are ignored, and the
power-down control by PDN1 and PDN2 pins are available.
MS1420-E-00
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[AK4688]
■ Power ON/OFF Sequence
The ADC and DAC blocks of the AK4688 are placed in power-down mode by bringing the PDN1 pin and PDN2 pin to
“L” respectively and both digital filters are reset at the same time. The PDN1 pin = PDN2 pin =“L” also reset the control
registers to their default values. In power-down mode, the DAC outputs 0V and the SDTO pin goes to “L”. This reset must
always be executed after power-up.
In master mode, the ADC starts operation on the rising edge of MLCK1 after power-down mode is released by a status
change of the PDN1 pin from “L” to “H”. In slave mode, when power down mode is released by a status change of the
PDN1 pin from “L” to “H”, the ADC starts operation on the rising edge of LRCK1 following MLCK1, LRCK1 and
BICK1 inputs.
The DAC starts operation on the rising of the LRCK2, after power-down mode is released by a status change of the PDN2
pin from “L” to “H”, and MCLK2, LRCK2 and BICK2 are input.
The analog initialization cycle of ADC starts after exiting the power-down mode. Therefore, the output data, SDTO
becomes available after 2640 cycles of LRCK1 clock. In case of the DAC, an analog initialization cycle starts after exiting
the power-down mode. The analog outputs are 0V during the initialization. Figure 11 shows power-down and power-up
sequence.
The ADC and DAC can be powered-down individually by PWAD and PWDA bits. Register values are not initialized by
these bits. When PWAD bit = “0”, the ADC output goes to “L”. When PWDA bit = “0”, the DAC output goes to 0V.
Power
(1)
PDN1 pin =
PDN2 pin
(2)
CVEE pin
0V
CVEE
VREF1/2 pin
0V
80% AVDD2
0V
(7)
(8)
ADC Internal
State
timeA
(3)
Init Cycle
(9)
Normal Operation
Power-down
timeB (4)
DAC Internal
State
Normal Operation
(5)
GD
Power-down
GD
ADC In
(Analog)
(6)
ADC Out
(Digital)
“0”data
DAC In
(Digital)
“0”data
“0”data
“0”data
GD
(5)
GD
DAC Out
(Internal Status)
Clock In
Don’t care
Don’t care
MCLK1,LRCK1,BICK1
MCLK2,LRCK2,BICK2
Figure 11. Power-up/down sequence example
MS1420-E-00
2012/05
- 22 -
[AK4688]
Notes:
(1) The PDN1 and PDN2 pins should be changed from “L” to “H” after power up.
“L” time of 150ns or more is needed to reset the AK4688. The PDN pins must be held to “L” until all power supply
pins are fed. After all powers are risen up, the PDN1 and PDN2 pins should be set to “H”.
(2) Charge Pump Circuit Power-up:
When MCLK1/2, BICK1/2 and LRCK1/2 are input after the PDN1/2 pin = “L” → “H”, the voltage on the CVEE
pin rises to CVEE voltage approximately in [email protected]
Note: If the PWAD and PWDA bits are set to “1”, or PDN1 and PDN2 pins are set to “H” during a power-up
sequence of the charge-pump, ADC and DAC are initialized after the charge-pump circuit is powered on.
(3) The analog block of ADC is initialized after exiting the power-down state. timeA=528/fs
(4) The analog block of DAC is initialized after exiting the power-down state.
In case of connecting a 1µF capacitor to the VREF2 pin, timeB is shown below.
timeB= 6/fs x 8 x 2: Normal Speed Mode
timeB=12/fs x 8 x 2: Double Speed Mode
timeB= 24/fs x 8 x 2: Quad Speed Mode
D/A data input become available after the timeB period.
(5) Digital outputs corresponding to analog inputs and analog outputs corresponding to digital inputs have group delay
(GD).
(6) ADC outputs “0” data in power-down state.
(7) Charge Pump Circuit Power-down
(PDN1 pin = “H”→“L” or No MCLK1, BICK1 and LRCK1 inputs) and (PDN2 pin = “H”→“L” or No MCLK2,
BICK2 and LRCK2 inputs)
The CVEE pin output becomes 0V according to a flying capacitor and an internal resistor. The internal resistance
is 50kΩ (typ). Therefore, when the CVEE pin has a flying capacitor of 1µF, the time constant is 50msec (typ).
(8) It takes 2048/fs for VREF1 stabilization after the charge pump is powered up.
(9) It takes approximately 5msec (typ) until VREF1/2 rises up after power-down mode of ADC/DAC is released.
MS1420-E-00
2012/05
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[AK4688]
■ Serial Control Interface
The AK4688 supports fast-mode I2C-bus system (max: 400kHz).
1. Data Transfer
In order to access any IC devices on the I2C BUS, input a start condition first, followed by a single slave address which
includes the device address. IC devices on the BUS compare this slave address with their own addresses and the IC device
which has an identical address with the slave-address generates an acknowledgement. The IC device with the identical
address executes either a read or a write operation. After the command execution, input a stop condition.
1-1. Data Change
Change the data on the SDA line while SCL line is “L”. SDA line condition must be stable and fixed while the clock is
“H”. Change the Data line condition between “H” and “L” only when the clock signal on the SCL line is “L”. Change the
SDA line condition while SCL line is “H” only when the start condition or stop condition is input.
SCL
SDA
DATA LINE
STABLE :
DATA VALID
CHANGE
OF DATA
ALLOWED
Figure 12. Data Transfer
1-2. Start Condition and Stop Condition
A start condition is generated by the transition of “H” to “L” on the SDA line while the SCL line is “H”. All instructions
are initiated by a start condition. A stop condition is generated by the transition of “L” to “H” on SDA line while SCL line
is “H”. All instructions end by a stop condition.
SCL
SDA
START CONDITION
STOP CONDITION
Figure 13. START and STOP Conditions
MS1420-E-00
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[AK4688]
1-3. Acknowledge
An external device that is sending data to the AK4688 releases the SDA line (“H”) after receiving one-byte of data. An
external device that receives data from the AK4688 then sets the SDA line to “L” at the next clock. This operation is
called “acknowledgement”, and it enables verification that the data transfer has been properly executed. The AK4688
generates an acknowledgement upon receipt of a start condition and Slave address. For a write instruction, an
acknowledgement is generated whenever receipt of each byte is completed. For a read instruction, succeeded by
generation of an acknowledgement, the AK4688 releases the SDA line after outputting data at the designated address, and
it monitors the SDA line condition. When the master side generates an acknowledgement without sending a stop
condition, the AK4688 outputs data at the next address location. When no acknowledgement is generated, the AK4688
ends data output (not acknowledged).
Clock pulse
for acknowledge
SCL FROM
MASTER
1
8
9
DATA
OUTPUT BY
TRANSMITTER
not acknowledge
DATA
OUTPUT BY
RECEIVER
START
CONDITION
acknowledge
Figure 14. Acknowledge on the I2C-bus
1-4. FIRST BYTE
The First Byte which includes the Slave-address is input after the Start condition is set, and a target IC device that will be
accessed on the bus is selected by the Slave-address. The Slave-address is configured with the upper 7-bits. Data of the
upper 6-bits is “001001”. The next 1 bit is the address bit that selects the desired IC (CAD0 bit). Set CAD0 bit according
to the CAD0 pin setting (CAD0 pin = “L”: CAD0 bit = “0”, CAD0 pin = “H”: CAD0 bit = “1”). When the Slave-address
is inputted, an external device that has the identical device address generates an acknowledgement and executes
commands. The 8th bit of the First Byte (LSB) is allocated as R/W bit. When the R/W bit is “1”, a read instruction is
executed, and when it is “0”, a write instruction is executed.
0
0
1
0
0
1
CAD0
R/W
Figure 15. The First Byte
MS1420-E-00
2012/05
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[AK4688]
2. WRITE Operations
Set R/W bit = “0” for the WRITE operation of the AK4688.
After receipt of the start condition and the first byte, the AK4688 generates an acknowledge, and awaits the second byte
(register address). The second byte consists of the address for control registers of AK4688. The format is MSB first, and
those most significant 3-bits are “Don’t care”.
*
*
*
A4
A3
A2
A1
A0
(*: Don’t care)
Figure 16. The Second Byte
After receipt of the second byte, the AK4688 generates an acknowledge, and awaits the third byte. Those data after the
second byte contain control data. The format is MSB first, 8bits.
D7
D6
D5
D4
D3
D2
D1
D0
Figure 17. Byte Structure after the Second Byte
The AK4688 is capable of more than one byte write operation by one sequence.
After receipt of the third byte, the AK4688 generates an acknowledge, and awaits the next data again. The master can
transmit more than one data word instead of terminating the write cycle after the first data word is transferred. After the
receipt of each data, the internal address counter is incremented by one, and the next data is taken into next address
automatically. If the address exceeds 03H prior to generating a stop condition, the address counter will “roll over” to 00H
and the previous data will be overwritten.
S
T
A
R
T
SDA
Register
Address(n)
Slave
Address
S
T
Data(n+x) O
P
Data(n+1)
Data(n)
P
S
A
C
K
A
C
K
A
C
K
A
C
K
Figure 18. WRITE Operation
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[AK4688]
3. READ Operations
Set R/W bit = “1” for a READ operation of the AK4688.
The master can read next address’s data by generating an acknowledge instead of terminating the write cycle after the
receipt of the first data word. After the receipt of each data, the internal 3bits address counter is incremented by one, and
the next data is taken into next address automatically. If the address exceeds 03H prior to generating stop condition, the
address counter will “roll over” to 00H and the previous data will be overwritten.
The AK4688 supports two basic read operations: CURRENT ADDRESS READ and RANDOM READ.
3-1. CURRENT ADDRESS READ
The AK4688 contains an internal address counter that maintains the address of the last word accessed, incremented by
one. Therefore, if the last access (either a read or write) was to address “n”, the next CURRENT READ operation would
access data from the address “n+1”.
After receipt of the slave address with R/W bit set to “1”, the AK4688 generates an acknowledge, transmits 1byte data,
which address is set by the internal address counter, and increments the internal address counter by 1. If the master does
not generate an acknowledge but generate stop condition, the AK4688 discontinues transmission
S
T
A
R
T
SDA
Slave
Address
Data(n)
Data(n+1)
S
Data(n+x) T
O
P
Data(n+2)
P
S
A
C
K
A
C
K
A
C
K
A
C
K
Figure 19. CURRENT ADDRESS READ
3-2. RANDOM READ
Random read operation allows the master to access any memory location at random. Prior to issuing the slave address
with the R/W bit set to “1”, the master must first perform a “dummy” write operation.
The master issues a start condition, slave address(R/W bit=“0”) and then the register address to read. After the register
address’s acknowledge, the master immediately reissues the start condition and the slave address with the R/W bit set to
“1”. Then the AK4688 generates an acknowledge, 1byte data and increments the internal address counter by 1. If the
master does not generate an acknowledge but generate the stop condition, the AK4688 discontinues transmission.
S
T
A
R
T
SDA
S
T
A
R
T
Word
Address(n)
Slave
Address
S
Slave
Address
Data(n)
S
Data(n+x) T
O
P
Data(n+1)
P
S
A
C
K
A
C
K
A
C
K
A
C
K
A
C
K
Figure 20. RANDOM READ
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[AK4688]
■ Register Map
Addr
00H
01H
02H
03H
Register Name
Powerdown/Control
(Reserved)
ADC Clock
DAC Clock
D7
0
0
0
0
D6
0
0
0
ACKS
D5
0
0
0
DFS1
D4
0
0
DIF1
DFS0
D3
0
0
0
DEM
D2
0
0
CKS1
DIF21
D1
PWDA
0
CKS0
DIF20
D0
PWAD
0
0
SMUTE
Note: For addresses from 04H to 1FH, data must not be written.
All registers are initialized to their default values by setting the PDN1 and PDN2 pins to “L”.
ADC is powered down by setting the PDN1 pin to “L”. Registers for ADC (Addr: 01h-02h) and PWAD bit are
initialized.
DAC is powered down by setting the PDN2 pin to “L”. Registers for DAC (Addr: 03h) and PWDA bit are
initialized.
ADC is powered down by setting the PWAD bit to “0”. However, registers for ADC (Addr: 01h-02h) are not
initialized.
DAC is powered down by setting the PWDA bit to “0”. However, registers for DAC (Addr: 03h) is not initialized.
The bits defined as 0 must contain a “0” value.
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[AK4688]
■ Register Definitions
Addr
00H
Register Name
Power down/Control
R/W
Default
D7
0
RD
0
D6
0
RD
0
D5
0
RD
0
D4
0
RD
0
D3
0
RD
0
D2
0
RD
0
D1
PWDA
R/W
0
D0
PWAD
R/W
0
D6
0
RD
0
D5
0
RD
0
D4
0
RD
0
D3
0
RD
0
D2
0
RD
0
D1
0
RD
0
D0
0
RD
0
PWAD: ADC Power-down Control
0: Power-down (default)
1: Normal operation
PWDA: DAC Power-down Control
0: Power-down (default)
1: Normal operation
Addr
01H
Register Name
(Reserved)
R/W
Default
D7
0
RD
0
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[AK4688]
Addr
02H
Register Name
ADC Clock
R/W
Default
D7
0
RD
0
D6
0
RD
0
D5
0
RD
0
D4
DIF1
R/W
0
D3
0
RD
0
D2
CKS1
R/W
1
D1
CKS0
R/W
1
D0
0
RD
0
D3
DEM
R/W
0
D2
DIF21
R/W
1
D1
DIF20
R/W
0
D0
SMUTE
R/W
0
CKS1-0: PORT1 (ADC) Clock Control in Master Mode
See Table 6.
DIF1: PORT1 Audio Format Select
See Table 17.
Addr
03H
Register Name
DAC Clock
R/W
Default
D7
0
RD
0
D6
ACKS
R/W
1
D5
DFS1
R/W
0
D4
DFS0
R/W
0
SMUTE: Soft Mute control for DAC
0: Normal Operation (default)
1: LOUT/ROUT outputs soft-muted
DIF21-20: PORT2 Audio Format Select
See Table 18.
DEM: DAC De-emphasis Response Control
See Table 16.
DFS1-0: PORT2 (DAC) Sampling Speed Control
See Table 9. DFS1-0 bits setting is ignored in Auto Setting Mode (ACKS bit = “1”).
ACKS: PORT2 (DAC) Auto Setting Mode Control
0: Disable, Manual Setting Mode
1: Enable, Auto Setting Mode (default)
The MCLK frequency is detected automatically when ACKS bit= “1”. In this case, DFS1-0 bits
settings are ignored. When ACKS bit = “0”, DFS1-0 bits select the sampling speed mode, and the
MCLK frequency is automatically detected in each mode.
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[AK4688]
SYSTEM DESIGN
Figure 21 shows the system connection diagram. An evaluation board (AKD4688) demonstrates the optimum layout,
power supply arrangements and measurement results.
Micro
Controller
47k
3.3V
47k
3.3V
Analog in
Audio DSP1
LO 28
LI 29
RIN 30
NC 31
LIN 32
I2C 33
SDA 34
SCL 35
MSN 36
39k
1 SDTO
RO 27
2 LRCK1
R1 26
39k
AVDD1 25
3 BICK1
0.1u
4 MCLK1
3.3V
AVSS1 24
AK4688EN
5 PDN1
AVSS2 23
6 PDN2
AVDD2 22
0.1u
10u
+
1u (∗)
3.3V
Analog Out
18 CVEE
17 CN
16 CP
ROUT 19
15 DVSS
9 LRCK2
14 DVDD
LOUT 20
13 TEST2
8 BICK2
12 TEST1
VREF 21
11 CAD0
7 MCLK2
10 SDTI
Audio DSP2
Reset and
Power down
+
10u
0.1u
+
1u (∗)
1u (∗)
3.3V
Figure 21. Typical Connection Diagram (I2C Control mode, CAD0 pin = “L”, Master mode)
Notes:
(1) Use low ESR (Equivalent Series Resistance) capacitors for the capacitors with (*). When using polarized
capacitors, the positive polarity pin should be connected to the CP or VREF1/2 pin, and the negative polarity pin
should be connected to the CVEE pin.
(2) AVSS1, AVSS2 and DVSS must be connected to the same analog ground plane.
(3) Digital input pins should not be allowed to float.
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[AK4688]
47k
47k
Analog in
3.3V
Audio DSP1
LO 28
LI 29
RIN 30
NC 31
LIN 32
1 SDTO
RO 27
2 LRCK1
R1 26
39k
AVDD1 25
3 BICK1
0.1u
4 MCLK1
+
10u
3.3V
AVSS1 24
AK4688EN
5 PDN1
AVSS2 23
6 PDN2
AVDD2 22
0.1u
10u
+
1u (∗)
3.3V
Analog Out
18 CVEE
17 CN
16 CP
ROUT 19
15 DVSS
9 LRCK2
14 DVDD
LOUT 20
13 TEST2
8 BICK2
12 TEST1
VREF 21
10 SDTI
7 MCLK2
11 CAD0
Reset and
Power down
Audio DSP2
I2C 33
SDA 34
SCL 35
MSN 36
39k
0.1u
+
1u (∗)
1u (∗)
3.3V
Figure 22. Typical Connection Diagram (H/W Control mode, MCLK=768fs, Master mode)
Notes:
(1) Use low ESR (Equivalent Series Resistance) capacitors for the capacitors with (*). When using polarized
capacitors, the positive polarity pin should be connected to the CP or VREF1/2 pin, and the negative polarity pin
should be connected to the CVEE pin.
(2) AVSS1, AVSS2 and DVSS must be connected to the same analog ground plane.
(3) Digital input pins should not be allowed to float.
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[AK4688]
1. Grounding and Power Supply Decoupling
The AK4688 requires careful attention to power supply and grounding arrangements. AVDD1, AVDD2 and DVDD are
usually supplied from the system’s analog supply. If AVDD1, AVDD2 and DVDD are supplied separately, the power up
sequence is not critical. AVSS1, AVSS2 and DVSS of the AK4688 must be connected to the same analog ground
plane. System analog ground and digital ground should be wired separately and connected together as close as possible to
where the supplies are brought onto the printed circuit board. Decoupling capacitors should be as near to the AK4688 as
possible, with the small value ceramic capacitor being the nearest.
2. Voltage Reference Inputs
The voltage difference between AVDD1 and AVSS1 sets the analog input range, and the voltage difference between
AVDD2 and AVSS2 sets the analog output range. VREF is a signal common of this chip. A 1µF ceramic capacitor
connected between the AVSS1/AVSS2 and VREF pins eliminates the effects of high frequency noise. No load current
may be drawn from the VREF pin. All signals, especially clocks, should be kept away from the VREF pin in order to
avoid unwanted coupling into the AK4688.
3. Analog Inputs
The analog input is single-ended and supplied to the Pre-amp via external resistors. Select the feedback resistance to make
the pre-amp output match to the input range (typ. 1.91Vrms) of the ADC (LO and RO pins). The ADC output data format
is 2’s complement. The internal digital HPF removes the DC offset. The AK4688 samples the analog inputs at 64fs. The
digital filter rejects noise above the stop band except for multiples of 64fs. The AK4688 includes an anti-aliasing filter
(RC filter) to attenuate a noise around 64fs.
4. Analog Outputs
The analog outputs are single-ended and centered around the AVSS2 (0V typ.) voltage. The output signal range is
typically 2.0Vrms (typ @AVDD2=3.3V). The internal switched-capacitor filter (SCF) and continuous-time filter (CTF)
attenuate the noise generated by the delta-sigma modulator beyond the audio passband. Using a 1st-order LPF (Figure 23)
can reduce noise beyond the audio passband.
The output voltage is a positive full scale for 7FFFFFH (@24bit) and a negative full scale for 800000H (@24bit). The
ideal output is 0V (VSS) for 000000H (@24bit). The DC offset is within ±5mV.
AK4688
470
Analog
Out
L/ROUT
2.0Vrms (typ)
2.2nF
(fc = 154kHz, gain = -0.28dB @ 40kHz, gain = -1.04dB @ 80kHz)
Figure 23. External Circuit Example1
5. Attention to the PCB Wiring
LIN and RIN pins are the summing nodes of the Pre-Amp. Attention should be given to avoid coupling with other signals
on those nodes. This can be accomplished by making the wire length of the input resistors as short as possible. The same
theory also applies to the LI/RI pins and feedback resistors; keep the wire length to a minimum. Unused input pins among
LIN and RIN pins must be left open.
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[AK4688]
PACKAGE
36-pin QFN (Unit: mm)
6.00
0.40±0.10
B
4.10
5.75
6.00
5.70
A
4.10
0.25
M
AB
0.85+0.15
-0.05
0.10
C0.6MAX
0.50
+0.05
-0.07
0.08 C
0.02 +0.03
-0.02
0.20
C
■ Material & Lead Finish
Package molding compound: Epoxy, Halogen (Br and Cl) free
Lead frame material: Cu
Lead frame surface treatment: Solder (Pb free) plate
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[AK4688]
MARKING
4688
XXXX
1
Pin #1 indication
Date Code: XXXX (4 digits)
REVISION HISTORY
Date (YY/MM/DD)
12/05/29
Revision
00
Reason
First Edition
Page
MS1420-E-00
Contents
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[AK4688]
IMPORTANT NOTICE
z These products and their specifications are subject to change without notice.
When you consider any use or application of these products, please make inquiries the sales office of Asahi Kasei
Microdevices Corporation (AKM) or authorized distributors as to current status of the products.
z Descriptions of external circuits, application circuits, software and other related information contained in this
document are provided only to illustrate the operation and application examples of the semiconductor products. You
are fully responsible for the incorporation of these external circuits, application circuits, software and other related
information in the design of your equipments. AKM assumes no responsibility for any losses incurred by you or third
parties arising from the use of these information herein. AKM assumes no liability for infringement of any patent,
intellectual property, or other rights in the application or use of such information contained herein.
z Any export of these products, or devices or systems containing them, may require an export license or other official
approval under the law and regulations of the country of export pertaining to customs and tariffs, currency exchange,
or strategic materials.
z AKM products are neither intended nor authorized for use as critical componentsNote1) in any safety, life support, or
other hazard related device or systemNote2), and AKM assumes no responsibility for such use, except for the use
approved with the express written consent by Representative Director of AKM. As used here:
Note1) A critical component is one whose failure to function or perform may reasonably be expected to result,
whether directly or indirectly, in the loss of the safety or effectiveness of the device or system containing it, and
which must therefore meet very high standards of performance and reliability.
Note2) A hazard related device or system is one designed or intended for life support or maintenance of safety or
for applications in medicine, aerospace, nuclear energy, or other fields, in which its failure to function or perform
may reasonably be expected to result in loss of life or in significant injury or damage to person or property.
z It is the responsibility of the buyer or distributor of AKM products, who distributes, disposes of, or otherwise places
the product with a third party, to notify such third party in advance of the above content and conditions, and the buyer
or distributor agrees to assume any and all responsibility and liability for and hold AKM harmless from any and all
claims arising from the use of said product in the absence of such notification.
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