AKM AK7846

AKEMDAKEMD
CONFIDENTIAL
[AK7846]
AK7846
Stereo Audio Class-D Amp with Power Booster for Piezo
Speakers
GENERAL DESCRIPTION
THE AK7846 is Stereo Class-D amplifier for driving Piezo-Electric Speakers. Built-in Boost DCDC
converter generates adequate high voltage for driving Piezo Speakers from Li-Ion battery.
AKM state-of-the-art filter-less solution eliminates LC-filters, which are normally required at Class-D
outputs. That contributes to total space saving. Class-D operation ensures higher power efficiency,
and couple with Piezo Speaker that is low-power- consumption and low-profile figure. The AK7846 is
very applicable for cellular phones with piezo speakers.
FEATURES
□ Class-D Amplifier :
• Piezo-Electric Speaker Driver
• Single-ended analog Input
• BTL output
• Output voltage = 8Vrms @VDD1=13V
• Filter-less solution
• Stereo mode
• Pop noise suppressor
• Output short protection
□ Boost DCDC Converter :
• Input voltage (Battery) = 2.7V ∼ 4.5V Æ Boosted voltage will be 13V
• Over-current protection
• Over-voltage protection
□ Control function :
• Pre-gain amplifier −6dB ∼ +15dB, 3dB step * Adjustable by Pin (PG0, PG1 and PG2) control
• Built-in Second order lowpass filter at Input.
• Cutoff Frequency (4kHz,8kHz,16kHz)
* Adjustable by Pin (PG0, PG1 and PG2) control
• Power-on/off control
• Over-temperature protection
□ Operational voltage
: VBAT=2.7V ∼ 4.5V、DVDDI=1.65V ∼ 4.5V
□ Operational temperature
□ Package
Rev.04.9
: −30°C ∼ 85°C
: 31pin WL-CSP (3.0mm × 3.0mm, 0.5mm pitch)
–1–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
BLOCK DIAGRAM
VBAT
FC1
FC0
Power Booster
PG2
VCOIL
VFB
PG1
PG 0
ERRO
DVDDI
VSS3
PDN
VDD1
INL
Pre
GainL
LPF L
Fc:
4/8/16kHz
Class-D
AMP L
VCLN
VCLP
VSS1
-6 ~ +15dB
3dB step
VSS4
VDD2
INR
VC
Pre
GainR
LPF R
Class-D
AMP R
VCRN
VCRP
VSS2
VREF
Figure 1. BLOCK DIAGRAM
Rev.04.9
–2–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
PIN ASSIGNMENT
A
B
D
C
E
F
6
5
4
3.0mm
3
2
1
0.25
0.25
0.5
<TOP
6
5
4
3
2
1
Rev.04.9
A
NC
VCRP
ERRO
PG2
VCOIL
NC
B
VDD2
VCRN
VSS2
VSS4
VSS3
<Index>
VIEW>
C
D
VFB
NC
NC
NC
-
-
-
-
PG1
FC1
PG0
DVDDI
Figure 2. Pin Assighnment
–3–
E
VDD1
VCLN
VSS1
VBAT
FC0
PDN
F
NC
VCLP
INL
INR
VC
NC
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
Pin / FUNCTION
No.
Pin Name
I/O
Function
A1
A2
A3
NC
VCOIL
PG2
-
-
I
A4
ERRO
A5
A6
B1
B2
B3
B4
B5
B6
C1
C2
C3
C4
C5
C6
D1
D2
D3
D4
D5
D6
VCRP
NC
-
VSS3
VSS4
VSS2
VCRN
VDD2
PG0
PG1
-
-
NC
VFB
DVDDI
FC1
-
-
NC
NC
E1
PDN
I
E2
E3
E4
E5
E6
F1
F2
F3
F4
F5
F6
FC0
VBAT
VSS1
VCLN
VDD1
NC
VC
INR
INL
VCLP
NC
I
-
-
O
No Connection pin. Connect to ground.
Inductor pin for Boost DCDC.
Pre Gain setting pin2 (available when I2CEN=”L”)
Phase compensation capacitor connection pin for Boost DCDC.
Connect a 0.1µF capacitor between VC pin and ground.
Right channel Class D amp plus output (+)
No Connection pin. Connect to ground.
<Index>
Power Booster ground pin:VSS3=0V
Internal analog circuit ground pin:VSS4=0V
Right channel Class D amp ground pin:VSS2=0V
Right channel Class D amp minus output (-)
Right channel Class D amp power supply:VDD2=13V(typ.)
Pre Gain setting pin0
Pre Gain setting pin1
-
-
No Connection pin. Connect to ground.
Boosted voltege feedback pin.
Digital interface power:DVDDI=1.65V~4.5V
SCF cutoff frequency setting pin1
-
-
No Connection pin. Connect to ground.
No Connection pin. Connect to ground.
Power down contorol:schmitt trigger input
“High”:poewer up、”Low”:power down
SCF cutoff frequency setting pin2
Battery voltage input:VBAT=2.7V~4.5V
Left channel Class D amp ground pin:VSS1=0V
Left channel Class D amp minus output (-)
Left channel Class D amp power supply:VDD1=13V(typ.)
No Connection pin. Connect to ground.
Voltage reference output. Connect a 0.01µF capacitor between VC pin and ground.
Right channel analog signal input
Left channel analog signal input
Left channel Class D amp plus output (+)
No Connection pin. Connect to ground.
O
-
-
I
O
I
I
-
-
I
-
-
I
I
O
Note 1. Digital input pins (PDN, PG2, PG1, PG0, FC1, FC0) must not be open.
„ Unused Pins
Unused pins should be configured as below.
Category
NoConnection
Rev.04.9
Pin Name
Configuration
NC
VSS
–4–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
ABSOLUTE MAXIMUM RATINGS
(VSS1=VSS2=VSS3=VSS4=0V;Note 3)
Parameter
Symbol
min
max
Units
Power Supplies:
(Note.4)
VBAT
DVDDI
VDD1,2
IIN
VINA
VIND
Ta
Tstg
−0.3
−0.3
−0.3
-10
−0.3
−0.3
−30
−65
6.5
6.5
15
+10
VBAT+0.3
DVDDI+0.3
85
150
V
V
V
mA
V
V
°C
°C
Battery
Digital I/F
Class-D Amp
Input Current, Any Pin Except Supplies
Analog Input Voltage (Note 4) (Note 6)
Digital Input Voltage (Note 5) (Note 6)
Ambient Temperature (powered applied)
Storage Temperature
Note 2. All voltages are with respect to ground.
Note 3. VSS1, VSS2, VSS3, VSS4 pin must be connected to the same analog ground plane.
Note 4. INL,INR pin
Note 5. PDN, PG2, PG1, PG0, FC1, FC0 pin
Note 6. Maximum value must not exceed 6.5V even if VBAT or DVDDI is more than 6.2V.
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=VSS3=VSS4=0V; Note 2)
Parameter
Symbol
min
typ
max
Units
Power Supplies Battery (Note 7)
VBAT
VDD (Note 8) VDDx
DigitalI/F(Note 7) DVDDI
2.7
12
1.65
3.6
13
2.8
4.5
14
4.5
V
V
V
Note 2. All voltages are with respect to ground.
Note 7. Should sustain “VBAT≧ DVDDI” condition
Note 8. Supply with boosted voltage (typ. 13V) by the Power Booster.
* AKM assumes no responsibility for usage beyond the conditions in this datasheet.
DC CHARACTERISTICS
(Ta=25°C; VBAT=2.7 ∼ 4.5V,DVDDI = 1.65~4.5V,VSS1=VSS2=VSS3=VSS4=0V)
Parameter
High-Level Input Voltage1
Low-Level Input Voltage1
High-Level Input Voltage2
Low-Level Input Voltage2
Input Leakage CurrentI
(Note 9)
(Note 9)
(Note 10)
(Note 10)
Symbol
min
typ
max
Units
VIH1
VIL1
VIH2
VIL2
70%DVDDI
80%DVDDI
-
-
30%DVDDI
20%DVDDI
±10
V
V
V
V
µA
Note 9. Applied to PG0, PG1, PG2.
Note 10. Applied to PDN, FC1, FC2 (Summit trigger input).
Rev.04.9
–5–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
ANALOG CHARACTERISTICS
(Unless otherwise noted, Ta=25℃、VBAT=3.6V、DVDDI=2.8V、VSS1,2,3,4=0V, Input Signal Frequency =1kHz ,
Measurement Band Width =20~20kHz ,PreGain=0dB , Fc= 16kHz Class-D ampu Output Load Impedance ZL=150nF)
Parameter
Condition
min
typ
max
Units
Idd
No input signal.
With output Load
T.B.D
ShutdownCurrent
PDN pin = ”Low”
1.0
10
μA
Input Impedance
INL
INR
50
50
75
75
kΩ
kΩ
+15
dB
25
25
PreGain
Control Range
PreGain
Step Size
(Note 11)
Output Voltage
Output
Offset Voltage
THD+N
SNR
PSRR
(Note 13)
Cross Talk
Switching
Frequency
Startup Time
(Note 14)
-6
PG2=”Low”,PG1=” Low”,PG0=” Low”
PG2=”Low”,PG1=” Low”,PG0=” High”
PG2=”Low”,PG1=” High”,PG0=” Low”
PG2=”Low”,PG1=” High”,PG0=” High”
PG2=” High”,PG1=” Low”,PG0=” Low”
PG2=” High”,PG1=” Low”,PG0=” High”
PG2=” High”,PG1=” High”,PG0=” Low”
PG2=” High”,PG1=” High”,PG0=” High”
VCL(R)P/VCL(R)N
Input Signal=0.7Vrms
VCL(R)P/VCL(R)N
No input signal
VCL(R)P/VCL(R)N (Note 12)
Input Signal=0.7Vrms
VCL(R)P/VCL(R)N (Note 12)
Input Signal=0.7Vrms
using an A wating filter.
VCL(R)P/VCL(R)N (Note 12)
[email protected] sinwave
INL:NoInput 、INR=2Vpp
Lch:OutputPin monitoring.
INR:NoInput 、INL=2Vpp
Rch:OutputPin monitoring.
Class-D Amp
PowerBooster
C3=0.01uF, C5=C6= 0.1uF(Note 15)
VBAT=2.7V
mA
-7
-4
-1
+2
+5
+8
+11
+14
-6
-3
0
+3
+6
+9
+12
+15
-5
-2
+1
+4
+7
+10
+13
+16
dB
dB
dB
dB
dB
dB
dB
dB
7.2
8.0
8.8
Vrms
-
-
T.B.D.
mV
-
-
-30
dB
70
80
-
dB
50
225
900
70
dB
70
dB
250
1000
28
275
1100
kHz
ms
Note 11. Setting accuracy of each setting is within ±1dB. Monotony is guaranteed.
Note 12 . Measure signals between VCL(R)N and VC L(R)P through Low-Pass-Filter (fc=20kHz).
Note 13. [email protected] superimposed signal at VBAT pin, and measured output.
Note 14. Time period from “PDN” turns “High” to stability operation.
Note 15. Refer to section “TYPICAL APPLICATION CIRCUIT”.
Rev.04.9
–6–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
OPERATION OVERVIEW
„ Power Control
The AK7848 enters SHUT-DOWN MODE by setting PDN pin to Logic “Low” level.
Power-Up Control
Power supply (VBAT pin, DVDDI pin) sequence must be either (1) or (2) as follows.
(1) VBAT and DVDDI are simultaneously turned on.
(2) First, VBAT pin is turned on. Next, DVDDI is turned on.
z Simultaneous turn-on of DVDDI pin and PDN pin is prohibited. At least 1 us delay is needed before the
transision (“L”→”H”) of PDN pin.
VBAT “ON”
0V
DVDDI “ON”
0V
PDN pin
0V
> 1us
Power-Up Sequence (1)
VBAT “ON”
0V
DVDDI “ON”
0V
0V
PDN pin
0V
>0
> 1us
Power –Up Sequence (2)
CAUTION: The performance of the device will not be guaranteed after the sequence below.
(3) First, DVDDI pin = ”H”, Next VBAT = ”H”
Rev.04.9
–7–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
Power-Down Control
Power supply (VBAT, DVDDI) sequences must be either (4) or (5) as follows.
(4) VBAT and DVDDI are simultaneously turned-off.
(5) First DVDDI is turned-off, Next, VBAT is turned-on.
* Simultaneous turn-off of PDN pin and DVDDI pin is prohibited. At least 1 us delay is needed before the
transision (“L”→”H”) of DVDDI pin.
z In case PDN pin is “High” and VBAT/DVDDI supply is suddenly cut off due to unexpected event, pop
noise may be detected, however, LSI will not be harmed even under such a case.
VBAT “OFF”
0V
DVDDI “OFF”
0V
> 1us
PDN pin
0V
Power-Down Sequence (4)
///VBAT “OFF”
>0
DVDDI “OFF”
> 1us
PDN pin
0V
0V
0V
Power –Down Sequence (5)
CAUTION: The performance of the device will not be guaranteed after the sequence below.
(5) First VBAT is turned-off, Next, DVDDI is turned-off.
Rev.04.9
–8–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
„ Analog inputs
AC-coupling capacitor is required at analog inputs. Recommended capacitance is 0.1µF. This AC-coupling
capacitance configures High-Pass-Filter, and used to configuration of POP NOISE SUPPRESSOR as well.
Therefore, any variation of this capacitance affects both HPF cut-off frequency and POP NOISE SUPPRESSOR
operation.
Additional input filter is applicable. When using filter at analog input, place it before AC-coupling capacitors.
Note 16. Cut off frequency (fc) of the High-pass filter, used as decoupling before input, is caluculated by an
equation, 1 / (2 × π × R × C). For example, when Input impedance of INN and INP pins are 50kΩ(typ.) and
AC coupling capacitors are 0.1µF, then the cut off frequency will be 31.8Hz.
„ Pre AMP
THE AK7846 has internal Pre-Amplifier, which supports from −6dB to +15dB(3dB/step) gain range.
Pre-Amplifier gain is adjusted by PG0,PG1 and PG2 like as shown below.
PG2
“Low”
“Low”
“Low”
“Low”
“High”
“High”
“High”
“High”
PG1
“Low”
“Low”
“High”
“High”
“Low”
“Low”
“High”
“High”
PG0
“Low”
“High”
“Low”
“High”
“Low”
“High”
“Low”
“High”
Pre Gain Setting Value
−6dB
-3dB
0dB
+3dB
+6dB
+9dB
+12dB
+15dB
Table. 1 Pre Gain Setting
„ Class-D AMP
Class-D architecture features higher efficiency and low power consumption operation.
AKM filter-less solution offers Class-AB performance with Class-D efficiency and minimal board space.
„ Pop Noise Suppressor
The AK7846 features extensive pop noise suppression circuitry.
„ Power Booster
Built-in BOOST DCDC CONVERTER generates adequate high voltage for Piezo-Speaker. Input voltage range
corresponds with Li-Ion battery voltage range (2.7V ~ 4.5V), and output voltage is 13V. Normally, output connected
to and supply VDD1 and VDD2 for Class-D operation.
„ Lowpass Filter
The AK7846 has a built-in Lowpass Filter at the input side. Cutoff frequency can be adjusted by FC0 and FC1 as
follows. FC0 and FC1 must be connected to either ground (VSS4) or DVDDI.
FC1
FC0
CurOff Frequency
“Low”
“Low”
16kHz
“Low”
“High”
8kHz
“High”
“Low”
4kHz
“High”
“High”
4kHz
Table. 2 Adjustable Cutoff Frequency of Lowpass filter
Rev.04.9
–9–
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
„ Protection
The AK7846 supports following protection circuits for protecting against any damages.
Output Short-Circuit Protection
In case of detecting VCL(R)P and VCL(R)N short, the AK7846 clamps peak current of Class-D output circuit
without shutting down the outputs.
Over-Temperature Protection
The AK7846 is designed to shutdown at +150°C of inside temperature so that it can be protected from heat
damage. Note that the AK7846 DOES NOT support resume function from Over-Temperature Protection. Once it is
activated, the AK7846 does not back in normal operation unless “PDN” is toggled (“L” Æ “H”).
Over-Current Protection
Class-D amplifiers’ current-limiting protection clamps the output current without shutting down the outputs.
Over-Voltage Protection
Boost DCDC Converter has the voltage-limiting function to avoid destrying itself.
Rev.04.9
– 10 –
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
Performance characteristics
※
The following various characteristics are typical characteristic data in the typical condition. It is not the one
necessarily to secure the characteristic of the description.
(TBD)
Rev.04.9
– 11 –
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
LEVEL DIAGRAM
The gain of AK7846 are determined by Pre-Amplifier, LPF and Class-D Amp, Total gain will be +21dB while
Pre-Amplifier is default setting (PG=0). LPF gain and Class-D Amp gain are not changeable.
Figure 3 shows level diagram of two example, PG=0dB and PG=+15dB.
INx
[dBV]
25
Pre
AMP
LPF
Class-D
AMP
-3dB to +15dB
3dB step
+6dB
+15dB
0dBV = 1Vrms
VCxN
VCxP
1kHz
Class-D AMP maximum output
with 150nF load : 8.0Vrms
20
Output : 18.0dBV (8.0Vrms)
15
+15dB
10
5
0
+6.02dB
Input (1) : -3.01dBV (0.70Vrms)
*Pre Gain = 0dB
Input path Limit : -3.01dBV
0dB
-5
3.01dBV (0.70Vrms)
-3.01dBV (0.70Vrms)
- 10
+15dB
- 15
Input (2) : -18.01dBV (0.126Vrms)
*Pre Gain = +15dB
- 20
Figure 3. Level Diagram
*1Vrms=0dBV=2.83Vpp (sin wave)
Rev.04.9
– 12 –
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
TYPICAL APPLICATION CIRCUIT
Li-ion Battery
C4
L1
ERRO PDN
VFB
C9
VBAT
VCOIL
Boost DCDC
DVDDI
FC1
FC0
PG2
PG1
PG0
VSS3
C1
VDD1
VCLN
Pre
Gain
INL
C5
D1
LPF
ClassD
L
Piezo Speaker
VCLP
C7
VSS1
VSS4
VDD2
Pre
Gain
INR
C6
VC
C3
LPF
VCLN
Class-D
R
VREF
Piezo Speaker
VCLP
C8
VSS2
Figure 4 AK7846 Application Schematic
Recommended external components are shown in Table. 3 as follows.
Reference
L1
D1
C1
C3
C4, C5, C6
C7,C8
C9
Type
Inductor ※
Diode
/ Schottky
Capacitor
/ Ceramic
Capacitor
/ Ceramic
Capacitor
/ Ceramic
Capacitor
/ Ceramic
Value
Manufacturer
CoilCraft
TDK
Part No.
LPS3010-102ML
TFC252008MC-1R0
Size (mm)
2.95 ×2.95 ×0.9
2.5 ×2.0 ×0.8
(30V, 1A)
SANYO
SS1003EJ
1.6 × 0.8 × 0.6
10µF / 25V
Taiyo Yuden
TMK325BJ106MD-B
3.2 × 2.5 × 0.85
0.01µF / 16V
Taiyo Yuden
EMK105BJ103KV
1.0 × 0.5 × 0.5
0.1µF / 16V
Taiyo Yuden
EMK105BJ104KV-B
1.0 × 0.5 × 0.5
2.2µF / 16V
Taiyo Yuden
EDK107BJ225KA
1.6 × 0.8 × 0.8
1.0uF
Table. 3 External Recommendation Parts
※Chose one of inductors in Table. 3
Selection of L1, C1 and D1 are very important because they affect DCDC converter paformance directly. For stability
operation, AKM recommends them described in Table. 3
Rev.04.9
– 13 –
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
1. Grounding and Power Supply Decoupling
The AK7846 requires careful attention to power supply and grounding arrangements. VBAT is usually supplied from
Li-Ion battery in the system. VDD1 and VDD2 are supplied from smoothed boosted voltage. VSS1, VSS2, VSS3 and
VSS4 must be connected to analog ground plane. Analog and digital ground in the system should be connected
together near where the supplies are brought onto the printed circuit board. Decoupling capacitors with the small
value ceramic should be as close to the AK7846 as possible.
2. Voltage Reference
VC is a signal ground of this device. A 0.01µF ceramic capacitor (C3) between VC and VSS4 pin eliminates the
effects of high frequency noise. This capacitor should be as close to the VC pin as possible. Do not take out load
current from the VC pin. All signals, especially clocks should be kept away from the VC pin in order to avoid
unwanted coupling.
3. Class-D analog Inputs
AC-coupling capacitors are necessary in series to INL and INR respectively.
4. Class-D Outputs
The Class-D outputs are in BTL signal format. Locate the outputs close to the speaker to minimize interconnect
resistance and capacitance to suppress noise. Match the length and pattern of the plus and minus output interconnect.
Keep AK7846 or Class-D outputs away as far away as possible from the devices such as antennas that are sensitive to
high frequency noise.
5. Effect on RF bands
Power Booster or Class-D Outputs may affect high frequency signal outside the AK7846.
Apply previous section (4. Class-D Outputs) in PCB layout.
6. Drivable Piezo Speakers
The AK7846 is designed to drive typical piezo speakers but in some cases electric characteristics of the speakers
differ by manufacturers. Feel free to ask us whether your speakers can be driven or not before using them.
7. Boost DCDC Converter
Ceramic capacitor (C1, C9), Inductance (L1) and Schottky Diode (D1) should be located as close to the
AK7846 as possible.
Rev.04.9
– 14 –
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
PACKAGE
■ MARKING
7846
XXXX
1
A
XXXX : Date code (4 digit)
■ 31pin WL-CSP Package Outline (Unit : mm)
Rev.04.9
– 15 –
2008/03
AKEMDAKEMD
CONFIDENTIAL
[AK7846]
IMPORTANT NOTICE
These products and their specifications are subject to change without notice. Before considering any use or application,
consult the Asahi Kasei Microsystems Co., Ltd. (AKM) sales office or authorized distributor concerning their current
status.
AKM assumes no liability for infringement of any patent, intellectual property, or other right 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.
AKM products are neither intended nor authorized for use as critical components in any safety, life support, or other
hazard related device or system, and AKM assumes no responsibility relating to any such use, except with the express
written consent of the Representative Director of AKM. As used here:
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.
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.
It is the responsibility of the buyer or distributor of an AKM product who distributes, disposes of, or otherwise places
the product with a third party to notify that 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.
Rev.04.9
– 16 –
2008/03