Datasheet

TPS7A49
IN
+18V
OUT
EN GND
-18V
TPS7A30
IN OUT
EN GND
EVM
+15V
-15V
TPS7A3001-EP
www.ti.com SBVS174 –OCTOBER 2011
APPLICATION INFORMATION
POWER FOR PRECISION ANALOG
One of the primary TPS7A3001 applications is to provide ultralow noise voltage rails to high-performance analog
circuitry in order to maximize system accuracy and precision.
In conjunction with its positive counterpart, the TPS7A49xx family of positive high-voltage linear regulators, this
negative high voltage linear regulator provides ultralow noise positive and negative voltage rails to
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 disadvantage:
they introduce a high-frequency component, and the associated harmonics, on top of the dc output signal.
This high-frequency component, if not filtered properly, degrades analog circuitry performance, reducing overall
system accuracy and precision.
The TPS7A3001 offers a wide-bandwidth, very-high power-supply rejection ratio. This specification makes it ideal
for post dc/dc converter filtering, as shown in Figure 32. It is highly recommended to use the maximum
performance schematic shown in Figure 30. Also, verify that the fundamental frequency (and its first harmonic, if
possible) is within the bandwidth of the regulator PSRR, shown in Figure 19.
Figure 32. Post DC/DC Converter Regulation to High-Performance Analog Circuitry
AUDIO APPLICATIONS
Audio applications are extremely sensitive to any 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 TPS7A3001
maximize performance for audio applications; see Figure 19.
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