TPS7A39
ZHCSGP0A –JULY 2017–REVISED SEPTEMBER 2017
www.ti.com.cn
VOUTx
B
F
A
C
D
E
G
H
IOUTx
图 69. Load Transient Waveform
表 8. Load Transient Waveform Description
REGION
DESCRIPTION
COMMENT
A
B
Regulation
Regulation
Output current ramping
Initial voltage dip is a result of the depletion of the output capacitor charge.
Recovery from the dip results from the LDO increasing its sourcing current, and leads
to output voltage regulation.
C
LDO responding to transient
At high load currents the LDO takes some time to heat up. During this time the output
voltage changes slightly.
D
E
F
Reaching thermal equilibrium
Regulation
Regulation
Initial voltage rise results from the LDO sourcing a large current, and leads to the
output capacitor charge to increase.
Output current ramping
Recovery from the rise results from the LDO decreasing its sourcing current in
combination with the load discharging the output capacitor.
G
H
LDO responding to transient
Regulation
Regulation
8.1.10 DC Performance
8.1.10.1 Output Voltage Accuracy (VOUTx
)
The device features an output voltage accuracy that includes the errors introduced by the internal reference, load
regulation, line regulation, process variation, and operating temperature as specified by the table. Output voltage
accuracy specifies minimum and maximum output voltage error, relative to the expected nominal output voltage
stated as a percent (for very low output voltages this specification is in mV).
8.1.10.2 Dropout Voltage (VDO
)
Generally speaking, the dropout voltage often refers to the minimum voltage difference between the input and
output voltage (|VDO| = |VINx| – |VOUTx|) that is required for regulation. When VINx drops below the required VDOx
for the given load current, the device functions as a resistive switch and does not regulate output voltage.
Dropout voltage is proportional to the output current because the device is operating as a resistive switch.
8.1.11 Reverse Current
As with most LDOs, this device can be damaged by excessive reverse current.
Reverse current is current that flows through the substrate of the device instead of the normal conducting
channel of the pass element. This current flow, at high enough magnitudes, degrades long-term reliability of the
device resulting from risks of electromigration and excess heat being dissipated across the device.
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