Datasheet

TPS7A4001
OUT
FB
GND
C
10 F
IN
m
R
1
C
10nF
BYP
C
10 F
OUT
m
IN
EN
V
IN
V
OUT
R
2
V
OUT
V
REF
- 1 R =R
1 2
V
OUT
R +R
1 2
³ 10 Am,where
TPS7A4001
SBVS162A –MARCH 2011– REVISED MARCH 2011 www.ti.com
THEORY OF OPERATION
GENERAL DESCRIPTION ENABLE PIN OPERATION
The TPS7A4001 belongs to a new generation of The TPS7A4001 provides an enable pin (EN) feature
linear regulators that use an innovative BiCMOS that turns on the regulator when V
EN
> 1.5V.
process technology to achieve very high maximum
input and output voltages.
CAPACITOR RECOMMENDATIONS
This process not only allows the TPS7A4001 to
Low equivalent series resistance (ESR) capacitors
maintain regulation during very fast high-voltage
should be used for the input, output, and bypass
transients up to 105V, but it also allows the
capacitors. Ceramic capacitors with X7R and X5R
TPS7A4001 to regulate from a continuous
dielectrics are preferred. These dielectrics offer more
high-voltage input rail. Unlike other regulators created
stable characteristics. Ceramic X7R capacitors offer
using bipolar technology, the TPS7A4001 ground
improved over-temperature performance, while
current is also constant over its output current range,
ceramic X5R capacitors are the most cost-effective
resulting in increased efficiency and lower power
and are available in higher values.
consumption.
Note that high ESR capacitors may degrade PSRR.
These features, combined with a high thermal
performance MSOP-8 PowerPAD package, make this
INPUT AND OUTPUT CAPACITOR
device ideal for industrial and telecom applications.
REQUIREMENTS
The TPS7A4001 high voltage linear regulator
ADJUSTABLE OPERATION
achieves stability with a minimum output capacitance
The TPS7A4001 has an output voltage range of
of 4.7µF and input capacitance of 1µF; however, it is
~1.175V to 90V. The nominal output voltage of the
highly recommended to use 10μF output and input
device is set by two external resistors, as shown in
capacitors to maximize ac performance.
Figure 13.
BYPASS CAPACITOR REQUIREMENTS
Although a bypass capacitor (C
BYP
) is not needed to
achieve stability, it is highly recommended to use a
10nF bypass capacitor to maximize ac performance
(including line transient, noise and PSRR).
MAXIMUM AC PERFORMANCE
In order to maximize line transient, noise, and PSRR
performance, it is recommended to include 10μF (or
Figure 13. Adjustable Operation for Maximum AC
higher) input and output capacitors, and a 10nF
Performance
bypass capacitor, as shown in Figure 13. The
solution shown delivers minimum noise levels of
58μV
RMS
and power-supply rejection levels above
R
1
and R
2
can be calculated for any output voltage
36dB from 10Hz to 10MHz.
range using the formula shown in Equation 1. To
ensure stability under no-load conditions, this
resistive network must provide a current greater than
TRANSIENT RESPONSE
or equal to 10μA.
As with any regulator, increasing the size of the
output capacitor reduces over/undershoot magnitude
but increases duration of the transient response.
(1)
Note that the presence of the C
BYP
capacitor may
If greater voltage accuracy is required, take into
greatly improve the TPS7A4001 line transient
account the output voltage offset contributions
response, as noted in Figure 1.
because of the feedback pin current and use 0.1%
tolerance resistors.
8 Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated
Product Folder Link(s): TPS7A4001