Datasheet
Time(20ms/div)
V
IN
V
EN
V
OUT
TPS7A3401
OUT
FB
GND
C
10 F
IN
m
R
1
R
2
C
10nF
BYP
C
10 F
OUT
m
IN
EN
V
IN
V
OUT
V
OUT
V
REF
- 1
R =R
1 2
V
OUT
R +R
1 2
³ 5 Am,where
TPS7A3401
www.ti.com
SBVS163 –JUNE 2011
THEORY OF OPERATION
GENERAL DESCRIPTION This functionality allows for different system power
management topologies:
The TPS7A3401 belongs to a new generation of
• Connecting the EN pin directly to a negative
linear regulators that use an innovative bipolar
voltage, such as V
IN
, or
process to achieve low noise and high PSRR levels
• Connecting the EN pin directly to a positive
at a wide input voltage range. These features,
voltage, such as the output of digital logic circuitry.
combined with a high thermal performance MSOP-8
with PowerPAD package, make this device ideal for
analog applications.
ADJUSTABLE OPERATION
The TPS7A3001 has an output voltage range
of –1.184 V to –17 V. The nominal output voltage of
the device is set by two external resistors, as shown
in Figure 18.
Figure 19. Enable Pin Positive/Negative
Threshold
Figure 18. Adjustable Operation for Maximum AC
Performance
CAPACITOR RECOMMENDATIONS
Low equivalent series resistance (ESR) capacitors
R
1
and R
2
can be calculated for any output voltage
should be used for the input, output, noise reduction,
range using the formula shown in Equation 1. To
and bypass capacitors. Ceramic capacitors with X7R
ensure stability under no load conditions, this
and X5R dielectrics are preferred. These dielectrics
resistive network must provide a current equal to or
offer more stable characteristics. Ceramic X7R
greater than 5 μA.
capacitors offer improved over-temperature
performance, while ceramic X5R capacitors are more
cost-effective and are available in higher values.
(1)
Note that high ESR capacitors may degrade PSRR.
If greater voltage accuracy is required, take into
account the output voltage offset contributions
INPUT AND OUTPUT CAPACITOR
because of the feedback pin current and use 0.1%
REQUIREMENTS
tolerance resistors.
The TPS7A3401 negative, high-voltage linear
regulator achieves stability with a minimum input and
ENABLE PIN OPERATION
output capacitance of 2.2 μF.
The TPS7A3401 provides a dual polarity enable pin
(EN) that turns on the regulator when |V
EN
| > 2.0 V,
TRANSIENT RESPONSE
whether the voltage is positive or negative, as shown
As with any regulator, increasing the size of the
in Figure 19.
output capacitor reduces over/undershoot magnitude
but increases duration of the transient response.
Copyright © 2011, Texas Instruments Incorporated 9