PA4894_15 [UTC]
1.8 WATT DIFFERENTIAL AUDIO POWER AMPLIFIER;
| 型号： | PA4894_15 |
| 厂家： | 
Unisonic Technologies |
| 描述： | 1.8 WATT DIFFERENTIAL AUDIO POWER AMPLIFIER 放大器 功率放大器 |
| 文件： | 总11页 (文件大小：489K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
UNISONIC TECHNOLOGIES CO., LTD
PA4894
CMOS IC
1.8 WATT DIFFERENTIAL
AUDIO POWER AMPLIFIER
WITH SELECTABLE
SHUTDOWN
DESCRIPTION
The UTC PA4894 is a differential audio power amplifier,
characterized by its selectable shutdown mode for flexible operation.
Shutdown may be enabled by either logic high or low depending on
the voltage applied on the SD MODE pin and the shutdown mode
features low power consumption.
This device provides customers perfect sound performance by
its high quality audio, moreover, less external components and lower
power dissipation are required.
Operating with a 5.5V power supply, the UTC PA4894 is
capable of driving an 8.0Ω load at a continuous average output of
1.8W under a 10% THD+N. If it works with a 5.0V voltage under the
same load conditions, 1.0W power will be delivered and the
distortion will be less than 0.01%.
The UTC PA4894 incorporates protection circuit to avoid the
click and pop noise, which may occur during the transition state
between turn-on and turn-off.
The UTC PA4894 can be directly connected to a battery without
an LDO since it has perfect PSRR. The UTC PA4894 can be
configured externally with resistors to provide a controlled gain and
with bypass capacitor to provide a controlled turn-on time for more
flexibility.
MSOP-10
FEATURES
* Differential amplification
* Selectable and low current shutdown
mode
* 1.0W/Ch(typ.)into a 8Ω load @5.0V
* Directly connected to the battery due to
excellent PSRR
* Operation supply: 2.2 V-5.5 V
* External controlled gain and turn-on
time configuration
* Circuits for protection
* Thermal overload protection circuit
* “Click and pop” noise protection circuit
* Halogen Free
The UTC PA4894 is suitable for applications, such as portable
electronic devices, PDAs and mobile phones.
ORDERING INFORMATION
Ordering Number
PA4894G-SM2-R
Package
Packing
MSOP-10
Tape Reel
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PA4894
CMOS IC
PIN CONFIGURATION
PIN DESCRIPTION
PIN NO.
PIN NAME
SD SELECT
INM
TYPE
DESCRIPTION
1
2
O
I
(Note)
Negative differential input
3
SD MODE
INP
I
Shutdown high or low selectivity (Note)
Positive differential input
4
I
5
BYPASS
OUTB
VM
O
I
Bypass capacitor pin which provides the common mode voltage
6
Negative BTL output
Ground
7
I
8
NC
-
No connection
9
VP
I
Positive analog supply of the cell
Positive BTL output
10
OUTA
I
Note: The SD SELECT pin must be toggled to the same state as the SD MODE pin to force the device in shutdown
mode.
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PA4894
CMOS IC
BLOCK DIAGRAM
VP
9
INM
2
10
OUTA
5
1
BYPASS
SD SELECT
SHUTDOWN
CONTROL
SD MODE
INP
3
4
6
OUTB
7
VM
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PA4894
CMOS IC
ABSOLUTE MAXIMUM RATING (Ta=25°C, unless otherwise specified)
PARAMETER
SYMBOL
VP
RATINGS
6.0
UNIT
V
Supply Voltage
Operating Supply Voltage
Input Voltage
VOPR
VIN
2.2 ~ 5.5
-0.3 ~ VCC +0.3
500
V
V
Max Output Current
IOUT
PD
mA
Power Dissipation (Note 2)
Junction Temperature
Operating Temperature (TA)
Storage Temperature Range
Internally Limited
150
TJ
°C
°C
°C
TOPR
TSTG
-40 ~+85
−65 ~ +150
Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
2. The thermal shutdown set to 160°C (typical) avoids irreversible damage on the device due to power
dissipation.
THERMAL DATA
PARAMETER
Junction to Ambient
SYMBOL
RATINGS
200
UNIT
°C/W
θJA
ELECTRICAL CHARACTERISTICS (Ta= −40°C~ +85°C, unless otherwise specified).
PARAMETER
Common Mode Voltage
SYMBOL
VCM
TEST CONDITIONS
MIN TYP MAX UNIT
VP/2
V
V
High
VTHD(H)
VTHD(L)
1.4
SD Select Threshold
Low
0.4
30
V
VP = 3.0V, RL= 8.0Ω
VP = 5.0V, RL= 8.0Ω
2.5
4.3
V
Output Swing
VO(SW)
Ta= 25°C
4.0
V
Ta= -40°C ~ +85°C 3.85
-30
V
Output Offset Voltage
VO(OFF) 2.2V≤VP≤5.5V
1.0
1.9
2.1
2.0
2.2
20
mV
mA
mA
mA
mA
nA
μA
ms
ms
W
VP = 3.0 V, No Load
VP = 5.0 V, No Load
Supply Quiescent Current
IQ
VP = 3.0 V, 8.0Ω
VP = 5.0 V, 8.0 Ω
4.0
600
2.0
2.2V≤VP≤5.5V
ISHDN
Ta= 25°C
Shutdown Current
SDM=SDS=GND
Ta= -40°C ~ +85°C
Turning On Time
Turning Off Time
TWU
TSD
CBYP = 1.0μF
140
20
VP = 3.0 V
VP = 3.3 V
VP = 5.0 V
0.39
0.48
1.08
-80
-80
-85
-85
160
64
RMS Output Power
PO(RMS) RL= 8.0Ω, THD+N<0.1%
W
W
VP=5.0V
F=217 Hz
dB
dB
dB
dB
°C
%
G=2.0, RL=8.0Ω
CBYP= 1.0μF
VP=3.0V
Power Supply Ratio
PSRR
V
P(RIPP_PP)= 200mV
Input Terminated with 10Ω
VP=5.0V
F=1.0 kHz
VP=3.0V
Over Temperature Shutdown
Efficiency
OTS
VP = 3.0 V, PO(RMS)= 380mW
VP = 5.0 V, PO(RMS)= 1.0W
VP = 3.0V, F = 1.0 kHz
RL= 8.0Ω, AV= 2.0, PO= 0.32 W
VP = 5.0V, F = 1.0 kHz
η
63
%
0.007
0.006
%
%
Total Harmonic Distortion
THD
RL= 8.0Ω, AV= 2.0, PO= 1.0 W
Notes: 1. Min and Max limits are guaranteed by design, test or statistical analysis.
2. See page 8 for a theoretical approach of these parameters.
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PA4894
CMOS IC
TYPICAL APPLICATION CIRCUIT
Differential Input
RF1
20kΩ
VP
CS
1µF
CI1
RIN1
VP
INM
Negative Diff
Input from DAC
OUTA
20kΩ
390nF
BYPASS
Cb
1µF
RL
8Ω
SHUTDOWN CONTROL
SD SELECT
SD MODE
SD SELECT
STATUS
0
0
1
1
0
1
0
1
SHUTDOWN
ON
ON
SHUTDOWN
SHUTDOWN
CONTROL
SD MODE
INP
OUTB
CI2
RIN2
Positive Diff
Input from DAC
20kΩ
VM
390nF
20kΩ
RF2
Driving Headphone
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PA4894
CMOS IC
APPLICATION INFORMATION
Detailed Description
The UTC PA4894 includes two power amplifiers internally. Two of them provide a controlled gain with external
components RIN and RF; the gain is calculated by the ratios of the resistors. The load is driven differentially through
OUTA and OUTB outputs. This configuration is saving the use of an output coupling capacitor.
The UTC PA4894 is operating on a 2.6V to 5.5V power supply, when VP is 2.6V it delivers 320mW rms output
power to 4.0Ω load, and when VP is 5.0V, it delivered 1.0W rms output power to 8.0Ω load.
Internal Power Amplifier
The internal power amplifier contains output PMOS and NMOS transistors, which is used to deliver the output
power of the specifications without clipping. The channel resistance (RON) of the NMOS and PMOS transistors does
not exceed 0.6Ω when they drive current.
The structure of the internal power amplifier is composed of three symmetrical gain stages, first and medium
gain stages are transconductance gain stages to obtain maximum bandwidth and DC gain.
Turn-On and Turn-Off Transitions
Output power in the load established must be slowly or cut for minimize the click and pop noise during the
transitions between turn-on and turn-off conditions. When shutdown mode is over，, the bypass voltage begins to rise
exponentially and once the output DC level is around the common mode voltage, the turn-on mode is over.
The turn−on time is determined by the following equation (at 25°C):
T
ON = 0.95×R×CBYP
(CBYP: bypass capacitor R: internal 150 k resistor with a 25% accuracy)
The turned off operation is as the same as the turn-on operation. Through applying a same logic state on the SD
SELECT and SD MODE pins, the system enters this mode. During the shutdown mode, amplifier outputs are
connected to the ground to discharge.
Shutdown Function
When SD SELECT and SD MODE pins are in the same logic state, the system enters shutdown mode. This
brings flexibility to the design, as the SD MODE pin must be permanently connected to VP or GND on the PCB. In
many applications, the output of a microcontroller or microprocessor is connected to the SD SELECT pin, so it is not
better to allow this pin float. During the shutdown state, the DC quiescent current has a typical value of 10nA.
Current Limit Circuit
The current limit circuit protects the device from damage from excessive current. The maximum output power of
the circuit (PO(RMS) =1.0W, VP = 5.0V, RL = 8.0Ω) requires a peak current in the load of 500mA. When short-circuit
occurs between both outputs, the current limit in the load is fixed to 800mA for limiting the excessive power
consumption.
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PA4894
CMOS IC
APPLICATION INFORMATION(Cont.)
Thermal Overload Protection
When the temperature of the UTC PA4894 is higher than160°C for any reasons, the thermal overload protection
function turns the amplifiers off until the temperature drop below 140°C.
The UTC PA4894 is unity gain stable and requires no external components besides gain setting resistors, an
input coupling capacitor and a proper bypassing capacitor in the typical application. Both internal amplifiers are
externally configurable (RF and RIN) with gain configuration.
The differential ended amplifier has two main benefits compared to single-ended:
* The differential ended amplifier will yield 4 times larger the output power on the load at the same conditions
compared to a single ended amplifier.
* Output pins (OUTA and OUTB) are biased at the same potential VP/2, which is saving the use of an output
coupling capacitor that is required with a single ended amplifier configuration.
The differential closed loop gain of the amplifier is correlated as seen in the following ratio:
RF
VO(RMS)
Avd =
=
RIN
VIN(RMS)
V
V
O(RMS): the rms value of the voltage seen by the load
IN(RMS):the rms value of the input differential signal)
Output power delivered to the load is defined as follows:
(VO(PEAK) )2
PO(RMS) =
2×RL
VO(PEAK) is the peak differential output voltage
When choosing gain configuration to obtain the desired output power, check that the amplifier is not current
limited or clipped.
VO(PEAK)
RL
The maximum current which can be delivered to the load is 500mA IO(PEAK) =
Gain−Setting Resistor Selection (RIN and RF)
The UTC PA4894 requires low gain configurations for a better performance. Since the RIN and RF determine the
closed−loop gain of both amplifiers, it is critical to choose both of them.
The low gain configuration minimizes THD + noise values and maximizes the signal to noise ratio, and the
amplifier can still be used without running into the bandwidth limitations.
A closed loop gain in the range from 2 ~ 5 is recommended to optimize overall system performance.
22 kΩ input resistor (RIN)is recommended.
Input Capacitor Selection (CIN)
The input coupling capacitor blocks the DC voltage at the amplifier input terminal. A high−pass filter is generated
by this capacitor and Rin, and the cut−off frequency is defined by the following fomula:
1
fC =
2×π×RIN ×CIN
The size of the capacitor must be large enough to couple in low frequencies without severe attenuation.
However a large input coupling capacitor requires more time to reach its quiescent DC voltage (VP/2) and can
increase the turn−on pops.
An input capacitor value between 0.1μ and 0.39μF is sugguested in most applications.
Bypass Capacitor Selection (CBYP
)
To avoid the pop noise, the bapass capacitor should be chosen prompty. The bypass capacitor determines the
rate at which this device starts and it provides half−supply filtering.
A 1.0μF bypass capacitor value (CIN≤ 0.39μF) should produce clickless and popless shutdown transitions. So a
1.0μF bypassing capacitor is recommended to be used.
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PA4894
CMOS IC
APPLICATION INFORMATION(Cont.)
Demo Board Schematic
R4
VP
J2
20kΩ
VP
C4
1µF
GND
R2
VP
C2
INM
OUTA
20kΩ
1µF
BYPASS
C3
1µF
J3
VP
J1
RL
8Ω
J4
100kΩ
SD SELECT
SHUTDOWN
CONTROL
R3
J5
SD MODE
INP
OUTB
C1
R1
20kΩ
VM
1µF
J7
20kΩ
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PA4894
CMOS IC
TYPICAL CHARACTERISTICS
THD+N vs. Output Power
THD+N vs. Output Power
VP=3V
RL=8Ω
F=1kHz
10
1
10
1
VP=5V
RL=8Ω
F=1kHz
0.1
0.1
0.01
0.01
0.001
0.001
0
200 400 600 800 1000 1200
0
100
200
300
400
500
Output Power (mW)
Output Power (mW)
THD+N vs. Output Power
2000
RL=8Ω
F=1kHz
1800
1600
1400
1200
1000
800
THD+N =10%
600
THD+N =1%
400
200
2.5
3.0
3.5 4.0 4.5
Output Power (mW)
5.0 5.5
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PA4894
CMOS IC
TYPICAL CHARACTERISTICS(Cont.)
Power DissipationOutput Power
Power DissipationOutput Power
0.4
0.35
0.3
0.25
0.2
RL=4Ω
0.25
0.2
0.15
0.1
RL=8Ω
0.15
0.1
VP=3V
RL=8Ω
F=1KHz
VP=2.6V
F=1KHz
THD+N<0.1%
0.05
0
0.05
0
THD+N<0.1%
0
0.1
0.2
0.3
0.4
0
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Output Power, POUT (W)
Output Power, POUT (W)
Turning-on Sequence
Turning-on Sequence Zoom
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PA4894
CMOS IC
TYPICAL CHARACTERISTICS(Cont.)
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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