TA2021B Ver la hoja de datos (PDF) - Tripath Technology Inc.
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Fabricante
TA2021B
Tripath Technology Inc.
TA2021B Datasheet PDF : 12 Pages
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Tripath Technology, Inc. - Technical Information
connected to the FAULT pin, the HIGH output of the FAULT pin will toggle the MUTE pin and
automatically reset the fault condition.
Overload (Output Active Low)
The OVERLOADB pin is a 5V logic active-low output. When low, it indicates that the level of the
input signal has overloaded the amplifier resulting in increased distortion at the output. The
OVERLOADB signal can be used to control a distortion indicator light or LED through a simple
buffer circuit.
Sleep Pin (Input Active High)
The SLEEP pin is a 5V logic input that, when pulled high (>3.5V), puts the part into a low
quiescent current mode. This pin is internally clamped by a zener diode to approximately 6V thus
allowing the pin to be pulled up through a large valued resistor (1MΩ recommended, 100KΩ
minimum) to VDD. To disable SLEEP mode, the sleep pin should be grounded.
Fault Pin (Output Active High)
The FAULT pin is a 5V logic output that indicates various fault conditions within the device.
These conditions include: low supply voltage, low charge pump voltage, low 5V regulator voltage,
over current at any output, and junction temperature greater than approximately 155°C. The
FAULT output is capable of directly driving an LED through a series 2KΩ resistor. If the FAULT
pin is connected directly to the MUTE input an automatic reset will occur in the event of an over-
current condition.
Performance Measurements of the TA2021B
The TA2021B operates by generating a high frequency switching signal based on the audio input.
This signal is sent through an external low-pass filter that recovers an amplified version of the
audio input. The frequency of the switching pattern is spread spectrum in nature and typically
varies between 100kHz and 1MHz (which is well above the 20Hz – 20kHz audio band). The
pattern itself does not alter or distort the audio input signal, but it does introduce some inaudible
components.
The measurements of certain performance parameters, particularly noise related specifications
such as THD+N, are significantly affected by the design of the low-pass filter used on the output
as well as the bandwidth setting of the measurement instrument used. Unless the filter has a
very sharp roll-off just beyond the audio band or the bandwidth of the measurement instrument is
limited, some of the inaudible noise components introduced by the TA2021B amplifier switching
pattern will degrade the measurement.
One feature of the TA2021B is that it does not require large multi-pole filters to achieve excellent
performance in listening tests, usually a more critical factor than performance measurements.
Though using a multi-pole filter may remove high-frequency noise and improve THD+N type
measurements (when they are made with wide-bandwidth measuring equipment), these same
filters degrade frequency response. The TA2021B Evaluation Board uses the Application/Test
Circuit of this data sheet, which has a simple two-pole output filter and excellent performance in
listening tests. Measurements in this data sheet were taken using this same circuit with a limited
bandwidth setting in the measurement instrument.
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TA2021B – 3.0/04.03
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