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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable
DESCRIPTION
The PAM8302 is a 2 Watt, 8-pin, class D audio amplifier with Enable function, it offers low THD+N (0.10%), allowing it to produce high-quality sound reproduction. The PAM8302 runs off of a 5 Volt supply at much higher efficiencies than their class AB cousins, making it ideal for many portable applications. The PAM8302 only requires very few external components (as few as two tiny capacitors), results in significant cost and board space savings. The PAM8302 is available in a SOP8 package.
FEATURES
2 Watts @ 10% THD output into a 4 load at 5V Support speakers or earphone (4 to 32 ). With Enable function. Superior low noise without input. Supply voltage from 2.5V to 5.5V. 85% efficiency above. Short Circuit Protection. Less output capacitor and inductor to save the space and cost. Low THD+N Low quiescent current < 10 mA
APPLICATIONS
Notebook Computers. PDAs/ GPS Navigator/ e-Dictionary Portable DVD Players, Game Machines. Cellular Phones, VoIP Phones, Screen Phones MP3 or PMP Players. Portable Speaker System, Portable Amplifier LCD monitor / TV. Bluetooth Car-Kit
TYPICAL APPLICATION CIRCUIT
Vdd
33 H
VDD
0.47 F Input
10K
IN
+OUT
0.47 F Speaker 33 H
Enable
GND
-OUT
0.47 F
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1
PAM8302 data sheet, Rev. 0.1
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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable TOP MARKING & PIN CONFIGURATION
8 7 6 5
Absolute Maximum Ratings:
Supply voltage: *6V Input voltage: -0.3V to VDD +0.3V Operation Temperature range: 40OC to 85OC Operation junction temperature: -40OC to 125OC Storage Temperature: -65OC to 150OC Maximum Junction Temperature: 150OC Soldering temperature: 250 OC, 10 secretary
A Y WW AYWW
1 2
3 4 Weekly Year Assembly Location
SOP8
Recommended operating Conditions:
Supply voltage Range: 2.5V to 5.5V Operation Temperature Range: -40OC to 85OC Junction Temperature Range: -40OC to 125OC
Pin Description
Pin No.
1 2 3 4 5 6 7 8
Pin Name
IN_R VDD EN GND NC GND +OUT -OUT
Description
Right channel audio input. Supply voltage, need a 1uF ceramic decouple capacitor very close bet ween this pin to GND pin. Chip enable, high active. GNDChip ground. Not connected Chip ground. Non-inverted output Inverted output
Thermal Information:
Thermal Resistance ( SOP8: DIP8
JA JC):
90 OC/W
O
C/W
*Note: Without input signal.
ORDERING INFORMATION
Ordering Number Package Shipping
2,500 Units/ Reel
PAM8302S8R SOP-8
ELECTRONIC SPECIFICATIONS
PARAMETER
Vdd Range Vdd Quiescent current SW On Resistance SW Frequency PSRR Gain SNR Input impedance Each channel VDD = 5V No Input Signal VDD = 2.5V to 5.5V VDD = 2.5V to 5.5V, 0 input resistor VDD = 5V, Po = 1.5W, 8 Load 100 0.4 500 -45 10 60 kHz dB V/V dB K
CONDITION
MIN
2.5
TYP
5
MAX
5.5 10
UNITS
V mA
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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable BLOCK DIAGRAM
Vdd
C1 Input Signal 1F Enable 1 Bit Speaker
Controller
Over Current
TEST CIRCUIT FOR GRAPHS
PAM8302 Demo Board +OUT Input AP System One Generator GND -OUT VDD Load AP Low Pass Filter AUX-0025 AP System One Analyzer
Power Supply
Notes: 1.The AP AUX-0025 low pass filter is necessary for every class D amplifier measurement done by AP analyzer. 2.A 33 H inductor is used in series with load resistor to emulate the small speaker for efficiency measurement.
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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable
(%) 100 50 20 10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 (W) (%) 100 50 20 10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 (W)
Ap
Ap
1
600u
100m
200m
500m
600u
100m
200m
500m
1m
2m
5m
10m
20m
50m
1m
2m
5m
10m
20m
50m
2 3
1
THD+N vs. Output Power 8 , 1kHz, VDD = 5V
(%) 100 50 20 10 5 2 1 0.5 0.2 0.1 0.05 0.02 0.01 20 (Hz) 20k 0% 0 Efficiency 100%
THD+N vs. Output Power 4 , 1kHz, VDD = 5V
Efficiency VS Output Power
Ap
80%
60%
40%
20%
1 Power
2
2 3
3
50
100 200
500
1k
2k
5k
1
10k
THD+N vs. Frequency 8 , 500mW output, VDD = 5V
1.4 1.2 Power Dissipation -W 1.0 0.8 0.6 0.4 0.2 0.0 (dBr)
+0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 -150 20
Power Dissipation vs. Output Power 4 , 1kHz, VDD = 5V
0
0.5
1
Output Power -W
1.5
2
(Hz)
50 100 200 500 1k 2k 5k 10k 20k
Power Dissipation vs. Output Power 4 , 1kHz, VDD = 5V Class AB = Blue line PAM8202 = Magenta line Power Analog Microelectronics, Inc.
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FFT Noise Floor (16k FFT)
4
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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable OPERATION INFORMATION
Calculating Output Power of BTL amplifier
Output power is related to supply voltage and the saturation Vsupply Vsat voltage (Vsat). The Maximum peak-to-peak output voltage on one side of BTL amplifier output is Vp-p = ( Vsupply - 2 X Vsat ) Vp-p 22
Vpk-pk
Vrms = Vsat Vsupply
One side
Maximum output power of a BTL amplifier with 1% THD is Pout (1%) = 4 X Vrms2/ Rload Maximum output power of a BTL amplifier with 10% THD is Pout (10%) = Pout (1%) X 1.25
Output Power vs. Vp-p
BTL Output Power 5.0 Output Power @THD 10% 4.0 4 3.0 2.0 8 1.0 0.0 0
1
2 3 4 Vdd - Vsat (V)
5
6
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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable
Vdd
C1
C2 33 H
0.47 F Input
10K
IN
VDD +OUT
0.47 F Speaker 33 H
Enable
GND
-OUT
0.47 F
Fig. 1
Setting Amplifier voltage gain
It is very important to know the maximum output level (0dB) of the signal source connected to a power amplifier in order to prevent hard clipping during operation.
Gain (max) = Vsupply/ Vin (p-p)
Insufficient voltage gain will cause low output level and maybe not enough to drive speaker properly. On the other hand, the distortion will be very high if the voltage gain is too high in an audio system. There is a 10k input resistor integrated in side IN (input) node, and since the integrated feedback resistor is 100k , so the maximum voltage gain of PAM8302 is limited at 10V/V (100k/10k, one output). With an external input resistor (Rin) placed between signal source & input node, the voltage gain will be
Gain = 100k/ (10k + Rin) = Vsupply/ Vin (p-p)
Actual voltage gain is two times of this calculation because of BTL connection.
Decouple capacitor
PAM8302 is a high performance, high speed class D amplifier, and it requires a 1 F, X7R ceramic decouple capacitor (C1) placed very close between VDD & GND pins to ensure the total harmonic distortion plus noise (THD+N) performance is as designed. This is also very important for efficiency and lowering noise floor. Another 100 F to 1000 F main decouple capacitor (C2) should be placed close to supply pin for low frequency Ecoupling.
Input capacitor
Input capacitor (Cin) blocks the DC voltage between signal source & amplifier to ensure the DC balancing will not be broken between two systems. It also form a high-pass-filter (HPF) with input resistors (Rin + 10k), the lower corner frequency (FCL) is determine by equation below.
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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable
FCL = 1/ [2 X Cin X (Rin + 10k)]
FCL is the lower corner on frequency response curve. Cin is very important consider to the lower frequency performance. The Cin should not be too large with small speakers as the load, because such small speakers usually can not response with lower frequency, delivering too much low frequency energy into a small speaker which usually got resonant frequency (Fs) around 150Hz is meaningless and dangerous. This will easily over drive the small speakers. The movement of speaker cone will be too much under such condition and this also creates unnecessary distortion on mid-to high frequency range because the speaker is now operating in non-linear area. Speakers can only generate heat but not low frequency sound when it is over driven, the will cause speaker or amplifier failure in some cases. Cin should have 10% tolerance or less because the tolerance can cause the input impedance mismatch at FCL and below.
Output filter
The L and C on each output node of PAM8302 form the low-pass-filter (LPF), the higher corner frequency (FCH) is determine by equation below.
FCH = 1/ [2
X sqr (L X C)]
FCH is the higher corner on frequency response curve.
Important Notice
The L-C filters (-12dB/Oct) gives twice much attenuation and lower impedance (means lower insertion loss) compare to those R-C filters (-6dB), but remember, the FCH above is also the resonant frequency of this LC network. The quality factor (Q) of this resonant network can be very high, depended on the Q of L and C. The high resonant Q which is usually caused by open-load can generate a very high voltage on speaker terminal, and the impedance of the L-C network can be very low, thus induces large amount of current flows from output stage of PAM8302. This always causes part failure. So Do Not test open-load on any class D amplifier with output filters.
LC filter calculator with output load impedance and cut-off frequency 1 f= 2 LC , XL= 2 fL , XC= 1 2 fC
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PAM8302
Tiny Package 2 Watt Class-D Audio Amplifiers With Enable OUTLINE DIMENSION
SOP8
5.80 - 6.20
0.35 - 0.49
1.27 TYP. 3.80 - 4.00 45 0.19 - 0.25 0 - 0.15 0.40 - 0.90 1.35 - 1.75 0 ~8
4.80 - 5.00
Note: Package outline exclusive of mold flash and metal burr.
Power Analog Microelectronics, Inc.
CONFIDENTIAL. DO NOT DISTRIBUTE OR REPRODUCE WITHOUT PERMISSION FROM P.A.M.
CONFIDENTIAL INFORMATION

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