Datasheet

TPS7A49
IN
+18V
OUT
EN GND
-18V
TPS7A30
IN OUT
EN GND
EVM
+15V
-15V
TPS7A49xx
www.ti.com SBVS121B –AUGUST 2010–REVISED JANUARY 2010
APPLICATION INFORMATION
POWER FOR PRECISION ANALOG
The TPS7A49xx offers a wide-bandwidth, very-high
One of the primary TPS7A49xx applications is to power-supply rejection ratio. This specification makes
provide ultralow-noise voltage rails to it ideal for post dc/dc converter filtering, as shown in
high-performance analog circuitry in order to Figure 29. It is highly recommended to use the
maximize system accuracy and precision. maximum performance schematic shown in
Figure 28. Also, verify that the fundamental frequency
The TPS7A49xx family of positive high-voltage linear
(and its first harmonic, if possible) is within the
regulators in conjunction with its negative counterpart
bandwidth of the regulator PSRR, shown in
(the TPS7A30xx family of negative high-voltage linear
Figure 18.
regulators), provide ultralow-noise, positive and
negative voltage rails for high-performance analog
circuitry, such as operational amplifiers, ADCs, DACs,
and audio amplifiers.
Because of the ultralow noise levels at high voltages,
analog circuitry with high-voltage input supplies can
be used. This characteristic allows for
high-performance analog solutions to optimize the
voltage range, maximizing system accuracy.
POST DC/DC CONVERTER FILTERING
Most of the time, the voltage rails available in a
system do not match the voltage specifications
demanded by one or more of its circuits; these rails
must be stepped up or down, depending on specific
voltage requirements.
DC/DC converters are the preferred solution to step
up or down a voltage rail when current consumption
is not negligible. They offer high efficiency with
minimum heat generation, but they have one primary
Figure 29. Post DC/DC Converter Regulation to
disadvantage: they introduce a high-frequency
High-Performance Analog Circuitry
component, and the associated harmonics, on top of
the dc output signal.
AUDIO APPLICATIONS
This high-frequency component, if not filtered
properly, degrades analog circuitry performance,
Audio applications are extremely sensitive to any
reducing overall system accuracy and precision.
distortion and noise in the audio band from 20Hz to
20kHz. This stringent requirement demands clean
voltage rails to power critical high-performance audio
systems.
The very-high power-supply rejection ratio (> 55dB)
and low noise at the audio band of the TPS7A49xx
maximize performance for audio applications; see
Figure 18.
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