PA4894 Unisonic Technologies, PA4894 Datasheet - Page 7

• Manufacturer Part Number: PA4894
• Description: 1.8 Watt Differential Audio Power Amplifier With Selectable Shutdown
• Manufacturer: Unisonic Technologies

PA4894
Thermal Overload Protection
function turns the amplifiers off until the temperature drop below 140°C.
input coupling capacitor and a proper bypassing capacitor in the typical application. Both internal amplifiers are
externally configurable (R
compared to a single ended amplifier.
coupling capacitor that is required with a single ended amplifier configuration.
limited or clipped.
Gain−Setting Resistor Selection (R
closed−loop gain of both amplifiers, it is critical to choose both of them.
amplifier can still be used without running into the bandwidth limitations.
Input Capacitor Selection (C
by this capacitor and Rin, and the cut−off frequency is defined by the following fomula:
However a large input coupling capacitor requires more time to reach its quiescent DC voltage (VP/2) and can
increase the turn−on pops.
Bypass Capacitor Selection (C
rate at which this device starts and it provides half−supply filtering.
1.0μF bypassing capacitor is recommended to be used.
The maximum current which can be delivered to the load is 500mA
When the temperature of the UTC PA4894 is higher than160°C for any reasons, the thermal overload protection
The UTC PA4894 is unity gain stable and requires no external components besides gain setting resistors, an
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
* Output pins (OUTA and OUTB) are biased at the same potential VP/2, which is saving the use of an output
The differential closed loop gain of the amplifier is correlated as seen in the following ratio:
V
V
Output power delivered to the load is defined as follows:
V
When choosing gain configuration to obtain the desired output power, check that the amplifier is not current
The UTC PA4894 requires low gain configurations for a better performance. Since the R
The low gain configuration minimizes THD + noise values and maximizes the signal to noise ratio, and the
A closed loop gain in the range from 2 ~ 5 is recommended to optimize overall system performance.
22 kΩ input resistor (R
The input coupling capacitor blocks the DC voltage at the amplifier input terminal. A high−pass filter is generated
The size of the capacitor must be large enough to couple in low frequencies without severe attenuation.
An input capacitor value between 0.1μ and 0.39μF is sugguested in most applications.
To avoid the pop noise, the bapass capacitor should be chosen prompty. The bypass capacitor determines the
A 1.0μF bypass capacitor value (C
P
f
Avd
APPLICATION INFORMATION(Cont.)
C
O(RMS)
IN(RMS)
O(PEAK)
O
(
=
RMS
=
2
×
)
R
: the rms value of the voltage seen by the load
R
:the rms value of the input differential signal)
UNISONIC TECHNOLOGIES CO., LTD
=
π
is the peak differential output voltage
www.unisonic.com.tw
IN
F
(
×
V
=
R
1
O
2
IN
V
V
(
PEAK
×
IN
O
×
R
(
(
RMS
RMS
C
L
IN
)
)
)
2
)
F
IN
and R
)is recommended.
IN
)
BYP
IN
) with gain configuration.
)
IN
IN
and R
≤ 0.39μF) should produce clickless and popless shutdown transitions. So a
F
)
I
O
(
PEAK
)
=
V
O
(
R
PEAK
L
)
IN
and R
F
CMOS IC
QW-R502-379.A
determine the
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