Datasheet

D I O O
P (V V ) I= - ´
J A
D(max)
JA
T max T
P
R
q
-
=
V
O
V
I
OUT
FB
R2
GND
EN
IN
≤
0.9 V
≥ 1.7 V
TPS76901-Q1
1 µF
3
1
4
2
R1
5
ESR = 0.2 Ω
4.7 µF
TPS76901-Q1, TPS76912-Q1, TPS76915-Q1
TPS76918-Q1, TPS76925-Q1, TPS76927-Q1
TPS76928-Q1, TPS76930-Q1, TPS76933-Q1, TPS76950-Q1
www.ti.com SGLS118C –DECEMBER 2001–REVISED JUNE 2012
Figure 22. TPS76901-Q1 Adjustable LDO Regulator Programming
Power Dissipation and Junction Temperature
Specified regulator operation is assured to a junction temperature of 125°C; the maximum junction temperature
should be restricted to 125°C under normal operating conditions. This restriction limits the power dissipation the
regulator can handle in any given application. To ensure the junction temperature is within acceptable limits,
calculate the maximum allowable dissipation, P
D(max)
, and the actual dissipation, P
D
, which must be less than or
equal to P
D(max)
.
The maximum-power-dissipation limit is determined using the following equation:
(3)
Where:
T
J
max is the maximum allowable junction temperature
R
θJA
is the thermal resistance junction-to-ambient for the package, see the dissipation rating table.
T
A
is the ambient temperature.
The regulator dissipation is calculated using:
(4)
Power dissipation resulting from quiescent current is negligible. Excessive power dissipation will trigger the
thermal protection circuit.
Regulator Protection
The TPS769xx-Q1 PMOS-pass transistor has a built-in back diode that conducts reverse current when the input
voltage drops below the output voltage (for example, during power down). Current is conducted from the output
to the input and is not internally limited. If extended reverse voltage operation is anticipated, external limiting
might be appropriate.
The TPS769xx-Q1 features internal current limiting and thermal protection. During normal operation, the
TPS769xx-Q1 limits output current to approximately 350 mA. When current limiting engages, the output voltage
scales back linearly until the overcurrent condition ends. While current limiting is designed to prevent gross
device failure, care should be taken not to exceed the power dissipation ratings of the package. If the
temperature of the device exceeds approximately 165°C, thermal-protection circuitry shuts it down. Once the
device has cooled down to below approximately 140°C, regulator operation resumes.
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Product Folder Link(s): TPS76901-Q1 TPS76912-Q1 TPS76915-Q1 TPS76918-Q1 TPS76925-Q1 TPS76927-Q1
TPS76928-Q1 TPS76930-Q1 TPS76933-Q1 TPS76950-Q1