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[AK4421]
AK4421
192kHz 24-Bit Stereo DAC with 2Vrms Output
GENERAL DESCRIPTION The AK4421 is 3.3V 24-bit stereo DAC with an integrated 2Vrms output buffer. A charge pump in the buffer develops an internal negative power supply rail that enables a ground-referenced 2Vrms output. Using AKM's multi bit modulator architecture, the AK4421 delivers a wide dynamic range while preserving linearity for improved THD+N performance. The AK4421 integrates a combination of switched-capacitor and continuous-time filters, increasing performance for systems with excessive clock jitter. The 24-bit word length and 192kHz sampling rate make this part ideal for a wide range of consumer audio applications, such as portable A/V players, set-top boxes, and digital televisions. The AK4421 is offered in a space saving 16pin TSSOP package. FEATURES Sampling Rate Ranging from 8kHz to 192kHz 128 times Oversampling (Normal Speed Mode) 64 times Oversampling (Double Speed Mode) 32 times Oversampling (Quad Speed Mode) 24-Bit 8 times FIR Digital Filter Switched-Capacitor Filter with High Tolerance to Clock Jitter Single Ended 2Vrms Output Buffer Soft mute I/F format: 24-Bit MSB justified or I2S Master clock: 512fs, 768fs or 1152fs (Normal Speed Mode) 256fs or 384fs (Double Speed Mode) 128fs or 192fs (Quad Speed Mode) THD+N: -92dB (-3dB output level) Dynamic Range: 102dB Automatic Power-on Reset Circuit Power supply: +3.0 +3.6V Ta = -20 to 85C Small Package: 16pin TSSOP (6.4mm x 5.0mm)
MCLK VDD DZF VSS1
SMUTE DIF
Control Interface
Clock Divider Modulator Modulator
LRCK BICK SDTI
Audio Data Interface
8X Interpolator 8X Interpolator Charge Pump
CP 1 CN
SCF LPF SCF LPF
AOUTL
AOUTR
VEE 1
VSS2
CVDD
MS0945-E-01 -1-
2008/08
[AK4421]
Ordering Guide
AK4421ET AKD4421 -20 +85C 16pin TSSOP (0.65mm pitch) Evaluation Board for AK4421
Pin Layout
CN CP SMUTE MCLK BICK SDTI LRCK DIF
1 2 3 4 5 6 7 8
16 15 14
VEE VSS2 CVDD DZF VSS1 VDD AOUTL AOUTR
AK4421 Top View
13 12 11 10 9
Compatibility with AK4420, AK4421 and AK4424
AK4420 24-bit MSB justified IS SMUTE DIF +4.5 +5.5V -92dB 105dB ET: -20 +85C VT: -40 +85C AK4421 24-bit MSB justified IS SMUTE DIF +3.0 +3.6V -92dB (-3dBFS) 102dB ET: -20 +85C AK4424 X IS DEM SMUTE +4.5 +5.5V -92dB 105dB ET: -20 +85C -: Not available X: Available
Digital de-emphasis I/F format Pin out Power Supply THD+N DR Operating Temperature Pin#3 Pin#8
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[AK4421]
PIN/FUNCTION
Function Negative Charge Pump Capacitor Terminal Pin Connect to CP with a 1.0F low ESR (Equivalent Series Resistance) capacitor 1 CN I over temperature. When this capacitor is polarized, the positive polarity pin should be connected to the CP pin. Non-polarized capacitors can also be used. Positive Charge Pump Capacitor Terminal Pin Connect to CN with a 1.0F low ESR (Equivalent Series Resistance) 2 CP I capacitor over temperature. When this capacitor is polarized, the positive polarity pin should be connected to the CP pin. Non-polarized capacitors can also be used. Soft Mute Enable Pin (Internal pull down: 100k) 3 SMUTE I "H": Enable, "L": Disable 4 MCLK I Master Clock Input Pin 5 BICK I Audio Serial Data Clock Pin 6 SDTI I Audio Serial Data Input Pin 7 LRCK I L/R Clock Pin Audio Data Interface Format Pin 8 DIF I "L": Left Justified, "H": I2S Right channel Analog Output Pin 9 AOUTR O When PDN pin = "L", outputs VCOM voltage(0V, typ). Left channel Analog Output Pin 10 AOUTL O When PDN pin = "L", outputs VCOM voltage(0V, typ). 11 VDD DAC Power Supply Pin, 3.0V3.6V 12 VSS1 Ground Pin 1 13 DZF O Zero Input Detect Pin 14 CVDD Charge Pump Power Supply Pin, 3.0V3.6V 15 VSS2 Ground Pin 2 Negative Voltage Output Pin Connect to VSS2 with a 1.0F low ESR capacitor over temperature. When 16 VEE O this capacitor is polarized, the positive polarity pin should be connected to the VSS2 pin. Non-polarized capacitors can also be used. Note: All input pins except for the CN pin should not be left floating. No. Pin Name I/O
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[AK4421]
ABSOLUTE MAXIMUM RATINGS
(VSS1=VSS2=0V; Note 1) Parameter Power Supply Symbol VDD CVDD IIN VIND Ta Tstg min -0.3 -0.3 -0.3 -20 -65 max +6.0 +6.0 10 VDD+0.3 85 150 Units V V mA V C C
Input Current (any pins except for supplies) Input Voltage Ambient Operating Temperature Storage Temperature Note 1. All voltages with respect to ground. Note 2. VSS1, VSS2 connect to the same analog grand.
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
(VSS1=VSS2=0V; Note 1) Parameter Power Supply Note 3. CVDD should be equal to VDD *AKEMD assumes no responsibility for the usage beyond the conditions in this datasheet. Symbol VDD CVDD min +3.0 typ +3.3 VDD max +3.6 Units V
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[AK4421]
ANALOG CHARACTERISTICS (Ta = 25C; VDD=CVDD = +3.3V; fs = 44.1 kHz; BICK = 64fs; Signal Frequency = 1 kHz; 24bit Input Data; Measurement frequency = 20Hz 20kHz; RL 5k) Parameter min typ max Resolution 24 Dynamic Characteristics (Note 4) THD+N (-3dBFs) fs=44.1kHz, BW=20kHz -92 -84 (Note 5) fs=96kHz, BW=40kHz -92 fs=192kHz, BW=40kHz -92 Dynamic Range (-60dBFS with A-weighted, Note 6) 96 102 S/N (A-weighted, Note 7) 96 102 Interchannel Isolation (1kHz, -3dBFs) 90 100 Interchannel Gain Mismatch(-3dBFs) 0.2 0.5 DC Accuracy DC Offset (at output pin) -60 0 +60 Gain Drift 100 Output Voltage (Note 8) 0dBFS 2.00 -3dBFS 1.27 1.42 1.57 Load Capacitance (Note 9) 25 Load Resistance 5 Power Supplies Power Supply Current: (Note 10) 20 30 Normal Operation (fs96kHz) 22 33 Normal Operation (fs=192kHz) 10 100 Power-Down Mode (Note 11) Note 4. Measured by Audio Precision (System Two). Refer to the evaluation board manual. Note 5. -60dB(typ) at 0dBFs (RL 10k) Note 6. 98dB for 16-bit input data Note 7. S/N does not depend on input data size. Note 8. Full-scale voltage (0dB). Output voltage is proportional to the voltage of VDD: AOUT (typ.@0dB) = 2Vrms x VDD/3.3. AOUT (typ.@-3dB) = 1.42Vrms x VDD/3.3. Note 9. In case of driving capacitive load, inset a resistor between the output pin and the capacitive load. Note 10. The current into VDD and CVDD. Note 11. All digital inputs including clock pins (MCLK, BICK and LRCK) are fixed to VSS or VDD
Units Bits dB dB dB dB dB dB dB mV ppm/C Vrms Vrms pF k
mA mA A
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[AK4421]
FILTER CHARACTERISTICS (Ta = 25C; VDD=CVDD = +3.0 +3.6V; fs = 44.1 kHz) Parameter Symbol min typ max Units Digital filter PB 0 20.0 kHz Passband 0.05dB (Note 12) 22.05 kHz -6.0dB Stopband (Note 12) SB 24.1 kHz Passband Ripple PR dB 0.02 Stopband Attenuation SA 54 dB Group Delay (Note 13) GD 19.3 1/fs Digital Filter + LPF Frequency Response 20.0kHz fs=44.1kHz FR dB 0.05 40.0kHz fs=96kHz FR dB 0.05 80.0kHz fs=192kHz FR dB 0.05 Note 12. The passband and stopband frequencies scale with fs (system sampling rate). For example, PB=0.4535xfs (@0.05dB), SB=0.546xfs. Note 13. Calculated delay time caused by the digital filter. This time is measured from setting the 16/24bit data of both channels to input register to the output of the analog signal.
DC CHARACTERISTICS (Ta = 25C; VDD=CVDD = +3.0 +3.6V) Parameter Symbol min typ max High-Level Input Voltage VIH 70%VDD Low-Level Input Voltage VIL 30%VDD High-Level Output Voltage (Iout = -80uA) VOH VDD-0.4 Low-Level Output Voltage (Iout = 80uA) VOL 0.4 Input Leakage Current (Note 14) Iin 10 Note 14. The SMUTE pin is not included. The SMUTE pin has internal pull-down resistor (typ.100k).
Units V V V V A
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[AK4421]
SWITCHING CHARACTERISTICS (Ta = 25C; VDD=CVDD = +3.0 +3.6V) Parameter Symbol min typ fCLK 4.096 11.2896 Master Clock Frequency dCLK 40 Duty Cycle LRCK Frequency 8 fsn Normal Speed Mode 32 fsd Double Speed Mode 120 fsq Quad Speed Mode 45 Duty Duty Cycle Audio Interface Timing BICK Period tBCK 1/128fsn Normal Speed Mode tBCK 1/64fsd Double Speed Mode tBCK 1/64fsq Quad Speed Mode tBCKL 30 BICK Pulse Width Low tBCKH 30 Pulse Width High tBLR 20 BICK "" to LRCK Edge (Note 15) tLRB 20 LRCK Edge to BICK "" (Note 15) tSDH 20 SDTI Hold Time tSDS 20 SDTI Setup Time Note 15. BICK rising edge must not occur at the same time as LRCK edge.
max 36.864 60 48 96 192 55
Units MHz % kHz kHz kHz %
ns ns ns ns ns ns ns ns ns
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[AK4421]
Timing Diagram
1/fCLK MCLK tCLKH tCLKL VIH VIL
dCLK=tCLKH x fCLK, tCLKL x fCLK
1/fs VIH VIL tBCK VIH VIL tBCKH tBCKL
LRCK
BICK
Figure 1. Clock Timing
LRCK tBLR tLRB
VIH VIL
BICK tSDS tSDH
VIH VIL
SDTI
VIH VIL
Figure 2. Serial Interface Timing
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[AK4421]
OPERATION OVERVIEW
System Clock
The external clocks required to operate the AK4421 are MCLK, LRCK, and BICK. The master clock (MCLK) should be synchronized with LRCK, but the phase is not critical. The MCLK is used to operate the digital interpolation filter and the delta-sigma modulator. Sampling speed and MCLK frequency are detected automatically, and then the internal master clock is set to the appropriate frequency (Table 1). The AK4421 is automatically placed in power saving mode when MCLK and LRCK stop during normal operation mode, and the analog output goes to 0V(typ). When MCLK and LRCK are input again, the AK4421 is powered up. After exiting reset following power-up, the AK4421 is not fully operational until MCLK and LRCK are input. LRCK fs 32.0kHz 44.1kHz 48.0kHz 88.2kHz 96.0kHz 176.4kHz 192.0kHz MCLK (MHz) 256fs 384fs 512fs 16.3840 22.5792 24.5760 22.5792 33.8688 24.5760 36.8640 Table 1. System Clock Example When MCLK= 256fs/384fs, the Auto Setting Mode supports sampling rate of 32kHz~96kHz (Table 1). But, when the sampling rate is 32kHz~48kHz, DR and S/N will degrade by approximately 3dB as compared to when MCLK= 512fs/768fs (Table 2). MCLK DR,S/N 256fs/384fs 99dB 512fs/768fs 102dB Table 2. Relationship between MCLK frequency and DR, S/N (fs= 44.1kHz) Sampling Speed Normal Double Quad
128fs 22.5792 24.5760
192fs 33.8688 36.8640
768fs 24.5760 33.8688 36.8640 -
1152fs 36.8640 -
Audio Serial Interface Format
The audio data is shifted in via the SDTI pin using the BICK and LRCK inputs. The DIF pin can select between two serial data modes as shown in Table 3. In all modes the serial data is MSB-first, two's complement format and it is latched on the rising edge of BICK. In one cycle of LRCK, eight "H" pulses or more must not be input to the DIF pin.
Mode 0 1
DIF L H
SDTI Format 24bit MSB justified 24bit I2S
BICK 48fs 48fs
Figure Figure 3 Figure 4
Table 3. Audio Data Formats
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2008/08
[AK4421]
LRCK
0 1 2 22 23 24 30 31 0 1 2 22 23 24 30 31 0 1
BICK (64fs) SDTI
23 22 23:MSB, 0:LSB 1 0 Don't care 23 22 1 0 Don't care 23 22
Lch Data
Figure 3. Mode 0 Timing
Rch Data
LRCK
0 1 2 3 23 24 25 31 0 1 2 3 23 24 25 31 0 1
BICK (64fs) SDTI
23 22 23:MSB, 0:LSB 1 0 Don't care 23 22 1 0 Don't care 23
Lch Data
Figure 4. Mode 1 Timing
Rch Data
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2008/08
[AK4421]
Zero detect function
When the input data for both channels are continuously zero for 8192 LRCK cycles, the DZF pin goes to "H". The DZF pin immediately returns to "L" if the input data for both channels are not zero (Figure 5).
Analog output block
The internal negative power supply generation circuit (Figure 5) provides a negative power supply for the internal 2Vrms amplifier. It allows the AK4421 to output an audio signal centered at VSS (0V, typ) as shown in Figure 6. The negative power generation circuit (Figure 5) needs 1.0uF capacitors (Ca, Cb) with low ESR (Equivalent Series Resistance). If this capacitor is polarized, the positive polarity pin should be connected to the CP and VSS2 pins. This circuit operates by clocks generated from MCLK. When MCLK stops, the AK4421 is placed in reset mode automatically and the analog outputs settle to VSS (0V, typ).
AK4421 CVDD Charge Pump
Negative Power
CP
(+)
CN
1uF
VSS2
Cb
(+)
VEE
1uF
Ca
Figure 5. Negative Power Generation Circuit
AK4421
2Vrms 0V AOUTR (AOUTL)
Figure 6. Audio Signal Output
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2008/08
[AK4421]
Soft Mute Operation
Soft mute operation is performed in the digital domain. When the SMUTE pin is set "H", the output signal is attenuated to - in 1024 LRCK cycles. When the SMUTE pin is returned to "L", the mute is cancelled and the output attenuation gradually changes to 0dB in 1024 LRCK cycles. If the soft mute is cancelled within the 1024 LRCK cycles after starting this operation, the attenuation is discontinued and it is returned to 0dB by the same cycle. Soft mute is effective for changing the signal source without stopping the signal transmission.
SMUTE pin 1024/fs 0dB Attenuation (1) (3) 1024/fs
-
GD (2) AOUT (4) 8192/fs GD
DZF pin
Notes: (1) The time for input data attenuation to - is : Normal Speed Mode: 1024 LRCK cycles (1024/fs). Double Speed Mode: 2048 LRCK cycles (2048/fs). Quad Speed Mode : 4096 LRCK cycles (4096/fs). (2) The analog output corresponding to a specific digital input has a group delay, GD. (3) If soft mute is cancelled before attenuating to - after starting the operation, the attenuation is discontinued and returned to ATT level in the same cycle. (4) When the input data for both channels are continuously zero for 8192 LRCK cycles, the DZF pin goes to "H". The DZF pin immediately returns to "L" if the input data are not zero. Figure 7. Soft Mute and Zero Detect Function
MS0945-E-01 - 12 -
2008/08
[AK4421]
System Reset
The AK4421 is in power down mode upon power-up. The MLCK should be input after the power supplies are ramped up. The AK4421 is in power-down mode until LRCK are input.
Power Supply
(VDD, CVDD)
(6) MCLK
Low 20 us
Analog
Circuit
Power down
(1)
Power-up 2, 3 LRCK
Digital
Circuit
Power down
(2)
Power-up
Charge Pump
Circuit
Power down
Power-up
(3) Charge Pump
Counter circuit Time A
D/A In (Digital) D/A Out (Analog) DZF
"0" data
MUTE (D/A Out)
(4) (5)
Notes: (1) Approximately 20us after a MCLK input is detected, the internal analog circuit is powered-up. (2) The digital circuit is powered-up after 2 or 3 LRCK cycles following the detection of MCLK. (3) The charge pump counter starts after the charge pump circuit is powered-up. The DAC outputs a valid analog signal after Time A. Time A = 1024/ (fs x 16): Normal speed mode Time A = 1024/ (fs x 8): Double speed mode Time A = 1024/ (fs x 4): Quadruple speed mode (4) No audible click noise occurs under normal conditions. (5) The DZF pin is "L" in the power-down mode. (6) The power supply must be powered-up when the MCLK pin is "L". MCLK must be input after 20us when the power supply voltage achieves 80% of VDD. If not, click noise may occur at a different time from this figure. Figure 8. System Reset Diagram
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[AK4421]
Reset Function
When the MCLK or LRCK stops, the AK4421 is placed in reset mode and its analog outputs are set to VSS (0V, typ). When the MCLK and LRCK are restarted, the AK4421 returns to normal operation mode.
Internal State D/A In (Digital) D/A Out (Analog)
Clock In
MCLK, BICK, LRCK
Normal Operation
Reset
Normal Operation
(1)
GD
(2)
(3)
VSS
(3)
(4) MCLK Stop
DZF
Clock In
MCLK, BICK, LRCK
(6)
(4) (5) LRCK Stop
DZF
(6)
Notes: (1) Digital data can be stopped. The click noise after MCLK and LRCK are input again can be reduced by inputting the "0" data during this period. (2) The analog output corresponding to a specific digital input has group delay (GD). (3) No audible click noise occurs under normal conditions. (4) Clocks (MCLK, BICK, LRCK) can be stopped in the reset mode (MCLK or LRCK is stopped). (5) The AK4421 detects the stop of LRCK if LRCK stops for more than 2048/fs. When LRCK is stopped, the AK4421 exits reset mode after LRCK is inputted.. (6) The DZF pin is set to "L" in the reset mode. Figure 9. Reset Timing Example
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[AK4421]
SYSTEM DESIGN
Figure 10 shows the system connection diagram. An evaluation board (AKD4421) is available for fast evaluation as well as suggestions for peripheral circuitry.
1u (1)
1 + 2 3
CN CP SMUTE MCLK BICK SDTI LRCK DIF
VEE 16 VSS2 15 CVDD 14 DZF 13
1u (1) + 0.1u + 10u
Analog 3.3V
Master Clock
4 5 6 7 8
10 External Mute Circuits 0.1u + 10u Lch Out Rch Out
ModeSetting
64fs 24bit Audio Data
AK4421
VSS1 12 VDD 11 AOUTL 10 AOUTR 9
fs
Digital Ground
Analog Ground
Note: Use low ESR (Equivalent Series Resistance) capacitors. When using polarized capacitors, the positive polarity pin should be connected to the CP and VSS2 pin. VSS1 and VSS2 should be separated from digital system ground. Digital input pins should not be allowed to float. Figure 10. Typical Connection Diagram
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[AK4421]
1. Grounding and Power Supply Decoupling
VDD, CVDD and VSS are supplied from the analog supply and should be separated from the system digital supply. Decoupling capacitors, especially 0.1F ceramic capacitors for high frequency bypass, should be placed as near to VDD and CVDD as possible. The differential voltage between VDD and VSS pins set the analog output range. The power-up sequence between VDD and CVDD is not critical.
2. Analog Outputs
The analog outputs are single-ended and centered around the VSS (ground) voltage. The output signal range is typically 2.0Vrms (typ @VDD=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 11) can reduce noise beyond the audio passband. The output voltage is positive full scale for 7FFFFFH (@24-bit data) and negative full scale for 800000H (@24-bit data). The ideal output is 0V (VSS) for 000000H (@24bit). The DC offset is 60mV or less.
AK4421 470 AOUT 2.2nF
Analog Out 2.00Vrms (typ)
(fc = 154kHz, gain = -0.28dB @ 40kHz, gain = -1.04dB @ 80kHz) Figure 11. External 1st order LPF Circuit Example
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[AK4421]
PACKAGE
16pin TSSOP (Unit: mm)
*5.00.1 1.050.05
16
9 *4.40.1 A 6.40.2 0.170.05 Detail A 0.10.1 0-10 0.50.2 0.10
Epoxy Cu Solder (Pb free) plate 2008/08 - 17 -
1 0.220.1
8 0.65
0.13 M
Seating Plane
NOTE: Dimension "*" does not include mold flash.
Package & Lead frame material
Package molding compound: Lead frame material: Lead frame surface treatment:
MS0945-E-01
[AK4421]
MARKING
AKM 4421ET XXYYY
1) 2)
3) 4)
Pin #1 indication Date Code : XXYYY (5 digits) XX: Lot# YYY: Date Code Marketing Code : 4421ET Asahi Kasei Logo
REVISION HISTORY
Date (YY/MM/DD) 08/03/31 Revision Reason 00 First Edition Error Correct DC CHARACTERISTICS A row for the output voltage value was written as for input High-Level Input Voltage High-Level Output Voltage Low-Level Input Voltage Low-Level Output Voltage VIH VOH VIL VOL Page Contents
08/08/01
01
6
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[AK4421]
IMPORTANT NOTICE 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 EMD Corporation (AKEMD) or authorized distributors as to current status of the products. AKEMD assumes no liability for infringement of any patent, intellectual property, or other rights in the application or use of any information contained herein. 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. AKEMD products are neither intended nor authorized for use as critical componentsNote1) in any safety, life support, or other hazard related device or systemNote2), and AKEMD assumes no responsibility for such use, except for the use approved with the express written consent by Representative Director of AKEMD. 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. It is the responsibility of the buyer or distributor of AKEMD 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 AKEMD harmless from any and all claims arising from the use of said product in the absence of such notification.
MS0945-E-01 - 19 -
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